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Blood Sweat Tears and Grease => Projects => Restorations => Topic started by: TranceMachineVienna on Nov 08, 2017, 04:08:24

Title: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Nov 08, 2017, 04:08:24
Hey guys!

Looks like I got a new project!A good friend of mine asked me to help him with the resto-mod of his CB 750.
He has 2 ex-police Cb 750 bikes in his barn and wants to make one fully working nicely refurbished bike out of it.

Yesterday we took some time and started checking the bikes:

Electrical system seems to work to 80% (hi/low on the headlights,oil pressure,blinkers left and right,blinker relais)

Not working: Starter button,no spark,neutral light-->We checked the fuse box, all fuses are ok?

Any ideas how where to start on the NO SPARK problem?
Starter button is dead too, any ideas where to start on that problem?

We took a screwdriver and bridged the starter relais, the starter motor turns nicely with a fresh battery and the motor seems to have good compression (will check with a tool next time, what should this motor have psi wise in compression?).

Any advise in the right direction would be appreciacted!

First up will be cleaning the carbs and getting a spark going!

Motor:
CB750E 2734730

Frame:
Cb750K 2733839

Is it normal that frame and motor number do not match up with these hondas?
in the registration papers it is the same,just asking since on my old yamahas the numbers normally match up.

This is going to be a full rechrome,powdering the frame full-on resto...lets see where this will lead us!

Thanks in advance guys!
 8)

Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on Nov 08, 2017, 07:39:18
Most excellent. 

For no spark, start running through the ignition from the plugs back which means check the resistor caps.  The F model I helped get running recently had just that problem after sitting since the 80s.  The resistor caps showed infinity on the meter.  A quick change with a new set of caps and it fired up. 

Your starter button issue could be the neutral switch.  Did you have it in neutral with the clutch pulled in when you started it up?

And as far as the frame/motor ID, they never matched on Hondas.  That motor number (CB750E) tells you that is a facelift model.  E for European because Honda added Euro features. 

By those carbs, that looks like a 77 or 78.  I'm not going to lie.  Those carbs are a bitch to get clean because of the accelerator pump circuit.  Once they're right, they're awesome.  Also airbox for that year is only for that year.  It has a notch for the choke that other years don't have.

I hope you guys have fun with this one.  I still love the 750s, even though I turned mine into a chopper. 
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: djmaynard on Nov 08, 2017, 09:46:30
I wondered what year also. I have a 77 Honda CB750K that was going to clean the carbs out this winter.


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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Nov 08, 2017, 10:42:28
Most excellent. 

For no spark, start running through the ignition from the plugs back which means check the resistor caps.  The F model I helped get running recently had just that problem after sitting since the 80s.  The resistor caps showed infinity on the meter.  A quick change with a new set of caps and it fired up. 

Your starter button issue could be the neutral switch.  Did you have it in neutral with the clutch pulled in when you started it up?

And as far as the frame/motor ID, they never matched on Hondas.  That motor number (CB750E) tells you that is a facelift model.  E for European because Honda added Euro features. 

By those carbs, that looks like a 77 or 78.  I'm not going to lie.  Those carbs are a bitch to get clean because of the accelerator pump circuit.  Once they're right, they're awesome.  Also airbox for that year is only for that year.  It has a notch for the choke that other years don't have.

I hope you guys have fun with this one.  I still love the 750s, even though I turned mine into a chopper.

Thanks Irk for jumping right in!
Had bad sparc too on my XS750 project,ended up switching out caps,cables and ignition box.
Is there a way to measure the plug caps (you stated showing infinity) with a multimeter?if yes hwo doI need to set the mulitmeter up?thanks!
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on Nov 08, 2017, 10:51:58
Thanks Irk for jumping right in!
Had bad sparc too on my XS750 project,ended up switching out caps,cables and ignition box.
Is there a way to measure the plug caps (you stated showing infinity) with a multimeter?if yes hwo doI need to set the mulitmeter up?thanks!
Pull the caps off the wires, put one lead in the wire end and the other lead in the spark plug end.  Set the meter to 1k ohms.  For a 76 or later, they should read 10k ohms or less than 11k.  Any more than that and the caps are burned out.  Pre-76 will be 7.5k ohms and are burned out at 9.5k ohms.  You can get replacement NGK resistor caps at 5k ohms and improve spark.  It's not a bad idea to do it regardless. 
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Nov 08, 2017, 12:23:15
Pull the caps off the wires, put one lead in the wire end and the other lead in the spark plug end.  Set the meter to 1k ohms.  For a 76 or later, they should read 10k ohms or less than 11k.  Any more than that and the caps are burned out.  Pre-76 will be 7.5k ohms and are burned out at 9.5k ohms.  You can get replacement NGK resistor caps at 5k ohms and improve spark.  It's not a bad idea to do it regardless.

Thank you irk!since we are doing a full nearly total resto we will go for fresh plugs and caps!I will however measure just for fun the caps!

As for the carbs: I´ve already been warned that these carbs are a nightmare.How would you go about?
The carb slides are stuck and don´t move a bit, the bike however was well stored (the tank inside is immaculate) and I have hope that the engine won´t need a total rebuild...

My friend Der_Nanno advised me just to take the bowls off, clean the main and idle jets and leave the other things alone.
But I guess this won´t help me with the stuck carb slides....
I have access to a ultrasonic cleaner, but throwing the whole rack into the bath without "top end" dissassembly of the carb will probably ruin the carb i guess...
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on Nov 08, 2017, 12:40:07
Just cleaning the main and idle jets doesn't usually work on these carbs.  PD carbs are unique in a lot of ways.  The biggest issue with these carbs is the accelerator pump circuit.  It's prone to clogging when left stored for too long, and it's vital to the performance of this motor.  You can try to spray through the circuit with carb cleaner, and if you're lucky, it will work.  But you need to get full spray on all for carbs coming from the pump nozzles.  The tendency is for #2, which is where the pump is located, to clear and the fluid just stream through that circuit.   The pump circuit is the rubber tubes that run between each carb.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Nov 09, 2017, 04:23:03
Just cleaning the main and idle jets doesn't usually work on these carbs.  PD carbs are unique in a lot of ways.  The biggest issue with these carbs is the accelerator pump circuit.  It's prone to clogging when left stored for too long, and it's vital to the performance of this motor.  You can try to spray through the circuit with carb cleaner, and if you're lucky, it will work.  But you need to get full spray on all for carbs coming from the pump nozzles.  The tendency is for #2, which is where the pump is located, to clear and the fluid just stream through that circuit.   The pump circuit is the rubber tubes that run between each carb.

Thanks Irk!That sounds really complicated...cleaned already a lot of carbs but never a bank of four with a pump...thinking about outsourcing this to one of few firms that specialises in overhauling these carbs...will cost some $$$ but since the owner is prepared to invest I think this is the way to go.
Is there someone in the forum that offers this service?
Do you have recommendations?

Thanks!
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on Nov 09, 2017, 07:49:02
You can do it.  It's more a pain in the ass then it is complicated.  Check the pump circuit first.  I may not be that bad.  That said, paying someone $150 to rebuild these carbs for you might be worth it. 
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Nov 09, 2017, 09:42:49
You can do it.  It's more a pain in the ass then it is complicated.  Check the pump circuit first.  I may not be that bad.  That said, paying someone $150 to rebuild these carbs for you might be worth it.

Yep,I will try, lets see..just had a word with a firm that does oldschool inline 4´s and they charge around 500$ for that job....
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: der_nanno on Nov 11, 2017, 05:10:03
Is there someone in the forum that offers this service?
Do you have recommendations?

Well, yes there is.

With regards to no spark: clean the points and then follow the procedures. Checking plug caps, put the multimeter in resistance mode and set it to 20k. Caps should be around 5k. (Don't worry if they show 4000 or 6000, that's just down to the inaccuracy of cheap multimeters, as long as it shows some resistance, you're most likely fine.)

'77 750 shouldn't have a clutch or neutral switch cut-out switch.

Be aware that the exhaust, if polished up, might be quite sought after. If reasonably rust-free as only the early versions are available as replicas.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on Nov 11, 2017, 08:04:19
Well, yes there is.

With regards to no spark: clean the points and then follow the procedures. Checking plug caps, put the multimeter in resistance mode and set it to 20k. Caps should be around 5k. (Don't worry if they show 4000 or 6000, that's just down to the inaccuracy of cheap multimeters, as long as it shows some resistance, you're most likely fine.)

'77 750 shouldn't have a clutch or neutral switch cut-out switch.

Be aware that the exhaust, if polished up, might be quite sought after. If reasonably rust-free as only the early versions are available as replicas.
Stock resistance on the 1977 plug caps is 10k ohms.  They left very little room from being good to being burned out.  5K is what the NGK OEM style replacements should be.  Also, 1977 model does have a neutral safety switch and a clutch safety switch. 

(http://www.oregonmotorcycleparts.com/Diagrams/CB750k37.jpg)
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Nov 15, 2017, 03:52:51
Hey guys!

"neutral safety switch and a clutch safety switch"-->does that mean that the bike won´t have spark if started in 1st or any other gear?Irk could you elaborate?

Nanno, the exhaust (OEM Honda,we have 2 sets of them) is in amazing shape,it will however get a rechrome,since the back ends are corroded and need a repair.(see pic).

The first task will be getting the bike to start and run a few strokes.
New intake rubbers (I hope I will get the carbs out of the hardened old ones,heatgun will help),cleaning the carbs and points,probably new plug caps,plugs and plug wires and fresh gas,lets see what happens :-)
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: der_nanno on Nov 15, 2017, 05:05:27
Check the sidestand and the clutch lever. If there's (electrical) cables, you actually have a cutout switch. With the bike obviously being ex-Austrian-police-spec, I doubt there is. Normally such would prevent the starter from working and not the ignition.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on Nov 15, 2017, 07:53:02
I don’t know the nuances of a police spec 7fitty, but you normally need to have the bike in neutral with the clutch engaged to get the starter to turn as der_ nanno said. You still get power to the coils, so that can be checked with a meter. I swapped out for a different solenoid to bypass my safety switches, but you can also install a jumper. I’m not sure how the police version would’ve done it.


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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: djmaynard on Nov 23, 2017, 23:27:00
I don’t know the nuances of a police spec 7fitty, but you normally need to have the bike in neutral with the clutch engaged to get the starter to turn as der_ nanno said. You still get power to the coils, so that can be checked with a meter. I swapped out for a different solenoid to bypass my safety switches, but you can also install a jumper. I’m not sure how the police version would’ve done it.


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Engaged clutch? Wondered why mine just spit gas out and didn’t turn over. Didn’t know that was an issue!

My floats were stuck and couldn’t get them and a simple “clutch pull” hopefully will be nice. Thanks.


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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Apr 06, 2019, 06:53:49
ATTENTION ATTENTION ATTENTION  8) 8) 8)

Reopening the thread...the projekt is in full swing.The bike already got transfered into my basement and the first works started on the dirty old girl   ;D ;D ;D
Its a former police bike so I will be swearing a bit while I do this project in order to de baptise the bike...no good police stories in Austria.

The first stop will be making the bike run.The carbs are now off for cleaning.Checking for spark and checking the electrical system is next.
Any Advise is like and needed for this looooong run..I´m doing this beside my day job so go easy on me  :D

A few pics.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Apr 13, 2019, 08:06:16
First up the carburetors... Starting disassembling and sorting the parts.
I ordered rebuild kits. The carb is being disassembled and ultrasonically cleaned.

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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Apr 17, 2019, 03:34:26
Carbs are dissassembled and now the search for the O Rings start.
The Keyster rebuild kit have 4 O rings plus the big O Ring for the float bowl.
I located a few already.Where do the the other ones go?

EDIT: Looks like 2 Orings go where the brass pipes connect th 4 carbs....Since I´m not planning on splitting the carbs these will stay.

The carbs now get soaked to get the most crud of then they will be ultasonically cleaned.
If you guys have any special advice on what to look out for It would be very helpful.

The first aim is to start the bike but not without changing out the old oil and oil filter.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: pidjones on Apr 17, 2019, 07:29:52
And, if you have a leak on one of the cross-over tubes, you get to pull the rack and separate the carbs to fix it. Might be best to do all of that now.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Apr 17, 2019, 07:40:49
And, if you have a leak on one of the cross-over tubes, you get to pull the rack and separate the carbs to fix it. Might be best to do all of that now.

Was thinking about that too....But since pulling these carbs was so easy (in comparison to my XS 750) I will risk that.Normally I would go all the way, but a good friend advised NOT and NEVER to split these carbs  ;D

I have a question converning changing the oil on that bike:
SInce this is a dry sump is it possible to drain the oil fully without running the engine?...I read that there is a valve that shuts the oil supply when the engine is not running.
Thanks!
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on Apr 17, 2019, 07:45:24
This is a guide to totally rebuilding these carbs and separating the rack, but I wouldn't do it unless absolutely necessary.  The throttle shaft requires a set of felt O rings that you'll need to get  or replace with viton to do it.

http://forums.sohc4.net/index.php?topic=146893.0
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: chicagobob on Apr 17, 2019, 09:31:59
I got so fed up with the carbs on my '78 (and I did separate them during the rebuild) that I replaced them with a set of round-tops from a '72 (eBay and a rebuild kit).  Very simple carbs to work on.  I needed new boots, airbox and cables, but now, no more choke cable and easy bowl access without removing the entire rack.  Bike runs like a champ.
(https://live.staticflickr.com/65535/33751617168_1ba8f79b41_z.jpg)

(https://live.staticflickr.com/65535/47628890771_92cea1a202_z.jpg)
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Apr 17, 2019, 10:03:50
I got so fed up with the carbs on my '78 (and I did separate them during the rebuild) that I replaced them with a set of round-tops from a '72 (eBay and a rebuild kit).  Very simple carbs to work on.  I needed new boots, airbox and cables, but now, no more choke cable and easy bowl access without removing the entire rack.  Bike runs like a champ.
(https://live.staticflickr.com/65535/33751617168_1ba8f79b41_z.jpg)

(https://live.staticflickr.com/65535/47628890771_92cea1a202_z.jpg)

Thank you!
That might be the way to go when everything goes wrong.The guy that owns the bike has a second doppelgänger bike with the same carbs so I guess that doesnt help.For now we´ll be cleaning them and then see how it goes.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Apr 25, 2019, 03:30:15
So guys-----
SUCCESS!!!!

We have spark!
I cleaned the points with some fine grit paper, puilled the clutch and off we go!!
Needs a new battery since the battery I used is the old battery of off my XS 750 produces not enough power to make a good spark.

So now I face a different problem.The carbs are stripped down, not split and theres this jet that is just stuck into the carb body (see picture).These jets are blocked on all 4 cylinders...theres no way to get these free.Where do these jets/orifices go?I would like to blow trough from the other side and see if it will work..Even a guitar string was useless.Should I remove these?

Thanks in advance!
(https://uploads.tapatalk-cdn.com/20190425/e97eec96b5ef4f9bd9ae6b6613928235.jpg)(https://uploads.tapatalk-cdn.com/20190425/7e500c4679f306dc757ea0deb27e61cb.jpg)(https://uploads.tapatalk-cdn.com/20190425/cc2ede0cf7f3351831fa112521493e57.jpg)
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on Apr 25, 2019, 07:54:29
Grip with with vice grips, twist and rock to get out.  They'll come out.  I would ultrasonic clean the carbs first, but if that doesn't work then they have to come out.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Apr 25, 2019, 15:53:24
Grip with with vice grips, twist and rock to get out.  They'll come out.  I would ultrasonic clean the carbs first, but if that doesn't work then they have to come out.
OK thank you.... Little anxious with these carbs :)

The electrical system seems to have hibernated in good condition. Just a few very rusted connections under the tank.
Had to weld a bolt onto one of the screws holding the coils in place :)

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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Apr 30, 2019, 09:24:35
Ok so there is NO WAY getting these jets free whatsoever?They are seriously gummed up.Ultrasonical, carb cleaner, air no way, even getting them out was impossible.

For starters: Where do these jets go to?And what are they for?I cannot find any info on the net about these .
Maybe if I can find the "rear" part of this circuit I can blow or poke trough there....

I also cannot find these in the aprts diagram...can anyone point me out where I can find them in the diagram?

The other circuits and passageways are clean and show a good stream of carb cleaner when blown trough.Keyster kits are installed.

Thanks in advance for your help!
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on Apr 30, 2019, 09:58:00
Those are your pilot jets, so unfortunately they are hugely important.  You can spend a few cans of carb cleaner and keep spraying them out and digging at the crap with an E string.  They should come out, albeit very resistantly.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 05, 2019, 17:55:34
More progress on the Cb....
We  finally got the carbs cleaned and nearly ready for putting them back on the bike.
The pilot jets came out and all orifices and jets are clean and free.
We made sure that the pumper circuit was also free and clean.
We are missing a few little pieces and hoses but all in all we are good to go.
Next up is draining the old oil and changing the old oil filter before the first start.
Before we can start the bike we need to 'find a spark'.
It currently has no spark on all 4 cylinders. (https://uploads.tapatalk-cdn.com/20190505/673809db22d2b9a528d7d135a097b57e.jpg)(https://uploads.tapatalk-cdn.com/20190505/58802d37d25bae8f00e799fec0f6de31.jpg)(https://uploads.tapatalk-cdn.com/20190505/340b80ccdd6f7e5074c38bb47197471d.jpg)(https://uploads.tapatalk-cdn.com/20190505/9a18f57741aa22fb11977ebc91aefed1.jpg)(https://uploads.tapatalk-cdn.com/20190505/50c19e58c1d31bb4ba4ae1fdece3da0c.jpg)

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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on May 05, 2019, 18:20:03
Awesome you got the carbs sorted.  That is the biggest piece of hell working on these things.  What have you checked for spark?  If it still has stock ignition, don't overlook testing the resistor caps.  I've gotten these after sitting for years, and all the plug caps were bad.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 06, 2019, 02:04:55
Yes irk.... Thank you again for your help... The carbs were a piece of work and took awhile I'm happy that for now they are sorted.
We had weak spark a few days ago with a half good Battery... Tried with a new good battery no spark.
How do you test the resistor caps you wrote about?
If you mean the spark plug caps we will be replacing these and the ignition cables... Tried cutting away a piece but it didn't really help.

One interesting thing I found too today when I drained the oil... There is no other part in there than the oil filter. No spring, no washer like in my Yamahas...is this normal? Will be checking in the diagram later.



Thanks(https://uploads.tapatalk-cdn.com/20190506/b20b00543456ae050b493a182ce134df.jpg)

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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: pidjones on May 06, 2019, 07:41:19
Yes, the filter needs both the spring and washer they go over the bolt first with washer against the filter. The spark plug wires on these use a solid conducter wire with 5k ohm resistors inside each plug cap, and non-resistor plugs. The wires screw onto threaded (like course wood screw threads) posts on both the coils and caps to give good contact. The screw in the cap can be gripped with pliers and pulled out to permit cleaning the resistor ends and contacts, but the caps are still available (NGK) and fairly inexpensive. There are good step-by-step ignition troubleshooting instructions in the Honda FSM.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on May 06, 2019, 07:51:48
There should be an O ring and spring for sure.  If this isn't a pure resto, you may want to consider getting the oil filter adapter so you can run a standard car type filter.  It makes life way easier.  You can get them with ports for adding and oil cooler too.

https://www.randakks.com/standard-oil-filter-conversion-kit-version-a-see-fitment-chart.html
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 06, 2019, 10:26:31
Looks like theres something wrong...maybe the police changed out the oil before it was hibernated wrongly....No spring no washer like in the diagram.And no copper washer under the drain plug...I ll talk to the owner about the spin on conversion! Do you have pics of the converted part on your engine irk?


Sounds very reasonable!Irk do I find the one with the adapters for the oil cooler also on this website?

thank you!
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on May 06, 2019, 11:37:07

Sounds very reasonable!Irk do I find the one with the adapters for the oil cooler also on this website?


(http://images.tapatalk-cdn.com/15/09/15/0029eb5d621c8fb64eed0e454bb178d0.jpg)

You can see it in this pic of the whole bike. 

(http://www.dotheton.com/gallery/77150-211018190948-45851032.jpeg)

I use the Wix filters because they're high quality and come with a check valve.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 06, 2019, 12:08:10
Looks very cool man!I´ll ask the customer what he wants...lets see!
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 16, 2019, 09:33:54
For now we are keeping the stock oil filter system as it is...maybe a mod we´ll do later because the whole oil change is messy as hell!

Next up since the carbs look clean and ready is the spark.
This weekend I´ll be cleaning all plugs and contacts of the ingntion coils and cleaning the breaker points with some fine grit paper.
New spark plugs, spark cables and resistor caps will be mounted.

I also ordered new condensers and breaker points since the owner wants to keep the stock ignition and we will be having these as surplus.

Is there a method to measure the ignition coils and see if they are up to par?

thanks!
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on May 16, 2019, 10:21:37

Is there a method to measure the ignition coils and see if they are up to par?


Set your multimeter to the lowest ohm setting (probably 200), touch leads against both wires to the coil.  It can be at the bullet connectors, or at the coil itself.  You should get 3 - 5 ohms.  Stock is 5 ohms.  Leave one wire in the connector, change the multimeter to 20k ohms, then put the other wire into the plug cap where the spark plug goes.  You should see more than 10k, and preferably around 14k.  If you get no reading, take the plug cap off and stick the lead into the plug wire and see if you get a number.  No number with the cap probably means the cap is bad.  You can test the caps for resistance by themselves, also.  They should be around 5k ohms, iirc.  When the go bad, they typically don't give a reading at all.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 16, 2019, 11:25:48
Set your multimeter to the lowest ohm setting (probably 200), touch leads against both wires to the coil.  It can be at the bullet connectors, or at the coil itself.  You should get 3 - 5 ohms.  Stock is 5 ohms.  Leave one wire in the connector, change the multimeter to 20k ohms, then put the other wire into the plug cap where the spark plug goes.  You should see more than 10k, and preferably around 14k.  If you get no reading, take the plug cap off and stick the lead into the plug wire and see if you get a number.  No number with the cap probably means the cap is bad.  You can test the caps for resistance by themselves, also.  They should be around 5k ohms, iirc.  When the go bad, they typically don't give a reading at all.

Thank you Irk for your insight!
I´ll be doing these tests tomorrow evening!

The oil sump got me on the wrong foot.
When I took of the oil sump there were bits of gasket and some hard pieces which I first identified as a circlip.I stored the pieces on a baggy and wemt to bed (I admit I had a few beers).
The next day I took the pieces put them into alcohol to clean them  and suddenly I found out that the circlip come out to be a Oring... :D :D :D
The bike now gets an oil refill with a fresh filter (waiting for the missing parts that I wrote about earlier).
Hope to have here starting soon!
(https://uploads.tapatalk-cdn.com/20190516/bb4df6d7fb402657b5819e67d7963f53.jpg)
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 18, 2019, 09:04:04
More progress on the Honda.
Cleaned out the oil sump yesterday after letting it sit in diesel.Drained all the remaining old oil from the oil tank.
Slow but good progress.
The fine dust on the oil pump grid turned out to be rubber dust.
Cleaned the oil sump screws. This will go back on the bike today.
(https://uploads.tapatalk-cdn.com/20190518/578aa11c5e909dd9014d0efb908d661b.jpg)(https://uploads.tapatalk-cdn.com/20190518/b649606c27d8c033ce735c7e355f6f26.jpg)(https://uploads.tapatalk-cdn.com/20190518/5dcc72376a4c26bb972a5bd44d094715.jpg)

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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 20, 2019, 06:50:25
GOOD PROGRESS ON THE CB!  8)

Invested some more time and now I have spark on all 4cylinders!

Cleaned the points,regapped one of them (it wasnt not closing properly) mounted new plug boots on 2 of 4 cylinders.
and boom! we have spark!

Here I have a question: Is it possible to remove the spark plug wires from the coils?They look like they are "hardwired" to the coils?I would like to replace them.

Also I cleaned the oil system with some fresh oil, drained and flushed the oil tank with oil.
Remounted the oil sump.

Hopefully I will be able to start her up soon!
(https://uploads.tapatalk-cdn.com/20190520/d38b962e61a4e529b06059bbd318f96d.jpg)(https://uploads.tapatalk-cdn.com/20190520/64428e106569f2073975058a06aa0542.jpg)(https://uploads.tapatalk-cdn.com/20190520/62bd1a57711273fd6bbfaeefbceda69a.jpg)
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on May 20, 2019, 08:00:02
I have tried those particular ones, so I'm speculating, but I have done several others that came on Cb360's.  The coils had a hole with a metal screw center in the bottom.  The wires were pushed into the hole with epoxy from the factory.  So, all I had to do was break up th epoxy, pull the wire out, push a new one in with epoxy.  Pretty easy.  It would be nice if yours are the same way, but I haven't tried with them.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: der_nanno on May 20, 2019, 12:02:01
Epoxied in. 50:50 chance at best to get them out without breaking the coils.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 20, 2019, 14:59:42
Put in the work..
Popped in the carbs and boom the bike ran for a few strokes!
Carbs were losing gas over the brass pipes on 1 and 4 and no gas in them so I guess I swapped float chamber 1 and 4...or do you guys have another idea?
The floats and needles look like they are in good order (new needles).
(https://uploads.tapatalk-cdn.com/20190520/07dcae620cc2966403cc96c20219761b.jpg)(https://uploads.tapatalk-cdn.com/20190520/2ea462fadac132c3ed55d0ed8f3b90ed.jpg)(https://uploads.tapatalk-cdn.com/20190520/d17bf2e1da8a4997a41f8d1e13eaceb5.jpg)(https://uploads.tapatalk-cdn.com/20190520/da7110078e107d1e74c9454b73db6498.jpg)

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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on May 20, 2019, 17:03:05
Try polishing the seats of the float valves.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: pidjones on May 20, 2019, 17:20:12
The needles can stick at first - try tapping the float bowl with the handle of a screwdriver. The brass overflow tubes also develop cracks along their length, can be soldered.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 21, 2019, 10:19:29
So just pulled one of the carb bowls. Looks like there are tiny holes in the brass pipes. Is this supposed to be down there?
These brass tubes are supposed to be without any holes till the top to work as an overflow aren't they?

I will fill the chambers with fuel and pump some air from the bottom to see if these holes are really holes or just caverns.


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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: pidjones on May 22, 2019, 11:10:33
Just pour rubbing alcohol (isopropyl) in them and see if it comes out the tube (with the drain closed, of course). They can be soldered with plumbing solder and a powerful (I use butane powered) iron and using acid flux. Clean well first.

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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 22, 2019, 11:58:42
Try polishing the seats of the float valves.

Again success!

I did all what you guys said...Took the carbs off and polished the needle seat with some tooth paste and q tips.Then I checked on the cylinder 1-4 brass pipes and YES, number one has  at least 5 holes in it.The needles were sticking to because I tried filling the bowl with gas and the drip was minimal.
I will solder these holes but for now I will leave them since after polishing the carb seems to hold up fine!

I litered the carb out, there seems to be a big difference in float height setting.Do you guys know the right float height setinng for the K7 models?Normally these are in 20MM range.
I cannot find anything about that in my manual.

Before I start the bike I would like to see that the oil is coming up into the head, how can I check on that?
Thought about removing one of the caps on the head, remove the spark plug caps and then turn the engine with the electric start to see if oil is going there.

Thanks in advance!
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: teazer on May 22, 2019, 12:32:16
I would suggest checking the FUEL level.  You could do that by replacing the drain screws with adapters and set teh fuel levels on all 4 at 3mm below the gasket surface.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: der_nanno on May 22, 2019, 14:17:57
Check the float height with one of the floats being set parallel to the gasket face ...and then set the others to the same height. This might not be the 100 percent setting, but it should be good enough to move on.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: Maritime on May 22, 2019, 14:27:52
To answer the oil question yes do exactly that. pull plugs to make it easier to turn over. pull a cover and turn over with the starter until you see oil flow in the head. Good idea to do that so you don't have the first start be dry.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: teazer on May 22, 2019, 15:24:10
Check the float height with one of the floats being set parallel to the gasket face. This might not be the 100 percent setting, but it should be good enough to move on.

"should be" sums that up.  That's more or less how much of us do it, but you may be surprised how far off the actual fuel levels are.  That's why it's better to set FUEL level on any older bike.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 22, 2019, 15:33:27
I will do the fuel level for sure thanks teazer!

I call that a success!
The bike runs even for now just with a screwdriver :)
Put the carbs back on and tried it.
The bike holds no idle runs only on choke  and needs to get revved up so I guess I will need to check the small jet system in the carbs again....
The ignition gaps needs to be set too correctly.

Cylinder 2 and 3 still run the old spark plugs.
All spark plug boots are fresh.


https://youtu.be/xBiaWKEXH80

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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: pidjones on May 22, 2019, 21:25:20
The 750s take quite a while to warm up enough that they don't need the choke.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: der_nanno on May 23, 2019, 06:01:51
"should be" sums that up.  That's more or less how much of us do it, but you may be surprised how far off the actual fuel levels are.  That's why it's better to set FUEL level on any older bike.

Yeah, I got interrupted mid sentence. I corrected it above.

From my experience it is more important to set all to the same height than the exact value. Personally I like to set floats rather high to make sure, I don't run in any starvation issues. But this is really *JUST* a personal preference.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on May 23, 2019, 08:28:54
I need to check too if the cam is lubed properly.
There is definitely coming oil to the head but I will check more next time I start the bike up again.
Still stoked that the bike ran on the 2 bad old fouled plugs...
When I know that the engine is sound (which it really feels like at the moment, no clacking or bad sounds) the bike will be fully disassembled.
Frame will be cleaned from the police brackets that were welded on and the bike will be Black with the stock Honda decals.
Long way to go but I feel motivated now! (https://uploads.tapatalk-cdn.com/20190523/41217a73083c94d06a78bebeef247318.jpg)(https://uploads.tapatalk-cdn.com/20190523/6b8652339193be32c367e438f81778f0.jpg)(https://uploads.tapatalk-cdn.com/20190523/09efdc6da912808bfec2390c9b98876c.jpg)

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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Jun 25, 2019, 10:18:27
So good news guys!

The CB runs on its own terms, starts on the first push of the button and I tried with a q tip and the head gets oil to the camshaft!
The only thing that bothers me is that the cam chain makes a bit of noise...So I will try to do the cam chain tensioning drill...Found this video on Youtube.
What I dont get is that the guy on the video refers to the most right cylinder as cylinder 1?maybe it is because i´m left handed but this seems illogical...
help is appreciated!

https://www.youtube.com/watch?v=8841eO5tvro
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on Jun 25, 2019, 10:43:12
So good news guys!

The CB runs on its own terms, starts on the first push of the button and I tried with a q tip and the head gets oil to the camshaft!
The only thing that bothers me is that the cam chain makes a bit of noise...So I will try to do the cam chain tensioning drill...Found this video on Youtube.
What I dont get is that the guy on the video refers to the most right cylinder as cylinder 1?maybe it is because i´m left handed but this seems illogical...
help is appreciated!

https://www.youtube.com/watch?v=8841eO5tvro
Normally, we number the cylinders left to right as sitting on the bike.  The video shows he has the exhaust tappet cover open, which is all the way left as you sit, but in the video it's all the way right, since he's facing the bike on the exhaust side.  That's definitely #1.


The way the cam is set up on these, the 1/4 and 2/3 are at TDC at the same time, but intake on 1/3 and 2/4 are open at the same time and exhaust on 1/2 and 3/4 are open at the same time.  This is why Honda did 4-into-2 and 4-into-1 exhausts with 1/2 and 3/4 matched.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Aug 06, 2019, 05:53:53
Hey guys!
Long time no hear.

I was able to re adjust the cam chain...the bike now runs way smoother so the restoration continues!
We were able to take 75 per cent of the bike apart.
Took of the loom too so there is good progress.
The exhaust of cylinder number 2 is damaged and has a good amount of rust...
The exhausts overall all seem to be in rough shape...
When I shake the exhaust there seems to be seomthing inside (maybe its just soot or rust).Rechroming and restoring that exhaust...I dont know.

Are there any quality replacement options that match the quality of the stock exhaust?
(https://uploads.tapatalk-cdn.com/20190806/bcb409b759988eacd68c5836ecfb37b4.jpg)(https://uploads.tapatalk-cdn.com/20190806/f1a6dd9997cd25b7773f16c92574631d.jpg)(https://uploads.tapatalk-cdn.com/20190806/9ffa2b99166e57c9b5f8f2099553561b.jpg)(https://uploads.tapatalk-cdn.com/20190806/3f154a447aaca5f181a0df9c0fe14260.jpg)(https://uploads.tapatalk-cdn.com/20190806/7f17d5c432c6ba984e3cedd1dad70d18.jpg)(https://uploads.tapatalk-cdn.com/20190806/5666e4fe498e09d913b242cc7ea83f31.jpg)(https://uploads.tapatalk-cdn.com/20190806/7f3b648a03cb65273024299a12f35e4b.jpg)
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: pidjones on Aug 06, 2019, 16:30:53
Re-chroming once upon a time was a good  thing if the steel was good - but that was 60's, early 70's. You will need to do some shopping, I'm afraid. You are making great progress, and I really like your workshop.
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Aug 08, 2019, 03:03:25
Thank you!

Yes I need to check the condition more throughly though.
Looks like one of these was welded already badly by the police.The welded exhaust seems to have been bent by riding over a sidewalk or some kind.

All the other parts are in good order, bagged up and ready for cleaning, plating or restoration.

Some parts are so heavily crusted that I will need to soak them in diesel for a good amount of time.

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Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: irk miller on Aug 08, 2019, 08:28:42
Not sure how the chroming prices are for you in Austria, but here in the US it's gotten to be pretty expensive with the government regulations.  We'll spend more restoring a set of stock pipe than buying new aftermarket pipes.  There are hundreds of options for the SOHC 750s.  I would consider that route. 
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: der_nanno on Aug 08, 2019, 08:53:56
I actually may have a contact North of the border in CZ (if he's still in business...)
Title: Re: Honda "l'arancio dolce" CB 750 Resto-Mod Project
Post by: TranceMachineVienna on Sep 06, 2019, 06:39:44
Hey guys... Finally again some time to continue on this project.
The stock exhaust looks generally good except for some repairs I will need to do.
The exhaust of cylinder 3 is worst. There is a lot of soot on the inside and I guess the muffler on the inside is terribly rusted.
I checked the backside of the muffler am I right that the muffler assembly is spot welded onto the chromed exhaust on the backside?
My plan was to remove the spot welds carefully then bend the metal and pull out the old then blast the inside of the exhaust then spot weld on the new muffler.
What's you're take on this one?

Chroming the exhaust without this is pretty senseless.... (https://uploads.tapatalk-cdn.com/20190906/d67035d16f1812afdcfcdea24bb9a9a2.jpg)(https://uploads.tapatalk-cdn.com/20190906/58b940f94a852f9c6638ed5011553734.jpg)(https://uploads.tapatalk-cdn.com/20190906/3f8029049c7213dacb0e49f508dd7023.jpg)(https://uploads.tapatalk-cdn.com/20190906/1a4f59e8f46378806d6d466631c2014b.jpg)

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