DO THE TON

Blood Sweat Tears and Grease => Projects => Cafe Racers => Topic started by: Tim of all trades on Jan 16, 2018, 17:51:47

Title: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 17:51:47
I've had this bike in my shed for 6 years and I didn't even own it when it first got to my place. since then I have moved house 3 times and been very busy between being away with work and being a good husband and father.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 18:12:49
It ran! my mate who bought it rode up and down the street but it didn't have front brakes and the rear was not working great either. I do have a short video of that moment (maybe I will upload it to youtube and post a link)
After letting me have a quick turn it was time to start work on it. Because my mate lived in an apartment and my wife is very understanding it was decided it would be built in my garage.
So first thing we did was park it up on the center stand and strip it down.

If you look carefully there is a CD250 in the background that belongs to my brother that I had my first go at tinkering with. Also my other mate used my compressor to spray his tank and it was still hung up.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 18:20:26
After taking the rear springs off my mate chucked in a dirt bike shock just to have a look, he wants to modify the swing arm and frame and put in a mono shock set up.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 18:38:37
The project paused here. I moved house then my mate and I went away for work, I went home after only a month and he had to stay for another 6 months and because he is a top bloke he said I could have the bike!
When I got home I put the donk in my trailer and took it to get soda blasted. You can see it was painted with a brush and if the duct tape wasn't holding the valve cover on you could see it was not painted down the middle because the brush the PO used wouldn't have reached in that far.
Also the carbies are in need of a clean.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 19:16:21
Next job is to grind off the rear and all the extra tabs from the frame. I got a piece of pipe bent for the hoop and welded it in, also built be a sand blasting booth in the backyard and cleaned up everything ready for paint.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 19:22:34
I got the foot peg brackets powder coated as well as the rear brake support and the shift lever and brake lever re-chromed.
Also bought a new bit of rubber for the shift lever.
Title: Re: 1980 CB900F Build
Post by: The Limey on Jan 16, 2018, 19:29:30
I'm on board.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 19:32:41
The engine after soda blasting was great! it did however reveal that the bike had an accident at some point in its mysterious life because there was a crack that had been metal puttied up on the bottom of the front left engine cover. (not pictured)
I painted the motor except for the parts that I would be polishing.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 19:43:20
Forgot to mention that I welded in a bit of flat steel for seat mounting.
Paint was done using POR15 in UV stable black.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 20:01:38
I got new tyres, shocks, headlight, front indicators, fork seals, clip-ons and somewhat reassembled the bike. I built a seat pan out of a street sign and duct taped some foam to it. I also welded on a tab to the rear hoop to mount the number plate
I then built a box for the battery to live in and promptly chucked my cheap stick welder in the bin as I'd had enough of shitty looking welds.
My lovely wife decided I needed a good mig welder for my birthday.

Bike is starting to look pretty damn good here if you ask me.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 20:14:58
I'm not really confident in my wiring abilities so I took the bike into a mates workshop and he helped me with the spaghetti monster, unfortunately he was all about just getting everything hooked up no matter how messy or what length wire was used. He didn't even get the Acewell gauge working properly! So after getting it home and doing some research I decided to rip all the wiring out and start again myself. I just had to buy some Moto gadget products so it was a bit easier.
I got the M-Unit, M-button, and a 3 Button switch for each handle bar. The wife wasn't really happy with how much all that cost until I did a price comparison with getting an auto-elec to build and fit a custom harness that wouldn't even have as many functions or as nice minimal controls.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 20:39:24
Ok, we are nearly live with this build. I moved house again and started the most intense employment I have ever done including non stop 7 days a week of 16 hr days doing physically demanding work. So there was absolutely no progress on the bike for a solid year as I ran myself into the ground and as I watched all my mates getting divorced from this ridiculous new job I got super lucky and snapped my femur into 3 pieces. Now I've had some time off and when I was able to walk again I started working on the 900 that had been so neglected.

I got the wiring sorted and kicked the bike in the guts and it coughed to life! ...then died. I took out all the spark plugs and cleaned them up with some wet'n'dry and tried again and it worked so much better! The valve cover wasn't torqued down so some oil dripped out the top and ran all down the motor.
The battery isn't charging and after taking it into a shop yesterday the bloke said "its dropped a cell" he put it on charge and I will go check it after lunch today and if its still cactus I will buy a new one. Meanwhile I checked the stator and reg/rec with my multi-meter, checked the brushes and all the connections for continuity and they all seem fine so I really don't know why it not charging. Thats what led me to modify a wiring diagram of the bike to try and work out what else it could be and I put it up on this site in the electrical section and some one has already pointed out a few problems with the diagram and my wiring for me to address.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 20:52:46
POD FILTERS!!! The only thing my mate bought for this bike before he gave it to me was the pod filters, that led me to throwing out the air-box in one of my house removals. Little did we know what fun getting a bike with CV carbies on it to run well with pod filters would be. Talk about a can of worms! anyway my "solution" was to put rubber boots on the carb intake and drill holes for a balancing pipe between them so it acts like an air-box and lets the pressure level out between the 4 carbies as well as making a velocity stack shape similar to what was in the factory air-box so the turbulent air from the pod filters goes into more of a laminar flow. What ever the outcome is i'm not claiming anything and i'm not trying to shave tenths off a second on any lap times. I want to ride and enjoy this bike. If I wanted to go fast I would buy the S1000rr that I have been eyeing off....
Title: Re: 1980 CB900F Build
Post by: crazypj on Jan 16, 2018, 21:06:42
Find a stock airbox or fit different carbs, The $200.00 (US) Dynojet carb kit may work (never tried one) but without some serious modification to carb bodies it will never run right. It isn't that tey are CV carbs but the specific type of CV carb.Even Honda knew tey screwed up when the couldn't get factory race bikes to run properly with 'stock' carbs for Superbike series in the 1980's. As your in Oz you may find someone who understands CX500 carbsand knows how to mod them.  mods won't be the same but will be similar.
BTW, any 'job' where breaking femur,  in 3 places is deemed 'lucky' is probably not a good place to be, no matter how well it pays (16 hr days, 7 days a week you better be a millionaire after a year)
Oh, is rear tyre fitted properly now?
The cheap pods are more trouble than they are worth (you have the cheap pods, looking at pics)
K&N 'oval will be a lot better, those actually restrict airflow at high rpm
Usual reason for bad charging is bad earths (ground connections) You'll ave to fit extra leads from crankcase to frame and probably from frame to forks to make sure headlight gets full voltage (even with all te ground leads Honda fitted)
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 21:14:31
so the bike starts and runs (even if its not charging yet) the only thing stopping me doing a test lap of the block is a complete lack of brakes. Old me would have done it but you should ask how I broke my leg... anyway I'm not getting on the bike until the front and rear brakes are working at 100%
I bought some nice braided lines to get rid of the old rubber ones. I've heard that is the best thing to do. (other then a modern fork conversion which is a future job)
When I took the front calipers off I did notice that the mounting threads had stripped out, I drilled and heli-coiled them to good as new.
I pulled apart the front master I got from the wreckers and checked it and put it back together, I couldn't get pressure from it even though it looked good! many frustrating hours later I pulled it apart and figured out I put the piston back in the wrong way! Idiot!
The front calipers will need a rebuild new pistons as they are super mega pitted.
The rear calipers are good but the master cylinder needs a rebuild and I couldn't get the piston out. It was stuck solid! I managed to hammer it in further to try and free it up but that didn't work so I tried 150psi of air shot into the return hole. That also didn't work because the piston had been hammered too far in by some idiot!
I soaked it in apple cider vinegar over night and it still wouldn't budge. so to get it this morning I drill a hole in the piston, tapped it with an M6 and put a bolt with washer and nut on it to screw it out. I found this solution on a forum last night but didn't find any vids or pics so I thought I would share mine.
Title: Re: 1980 CB900F Build
Post by: crazypj on Jan 16, 2018, 21:22:51
Back in te day........'they all do that sir' then collapse laughing around the corner. I moved to Suzuki deal across the street and ended up working on Honda's again ;D
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 21:29:15
1: stuck piston
2: 5mm drill bit
3: 6mm tap ready to go into the new hole
4: bolt long enough to screw into hole with thread sticking out for nut and washer
5: success! I twisted the nut and there is piston sticking out. (nut and washer removed for picture only)
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 22:08:40
Find a stock airbox or fit different carbs, The $200.00 (US) Dynojet carb kit may work (never tried one) but without some serious modification to carb bodies it will never run right. It isn't that tey are CV carbs but the specific type of CV carb.Even Honda knew tey screwed up when the couldn't get factory race bikes to run properly with 'stock' carbs for Superbike series in the 1980's. As your in Oz you may find someone who understands CX500 carbsand knows how to mod them.  mods won't be the same but will be similar.
Oh, is rear tyre fitted properly now?
The cheap pods are more trouble than they are worth (you have the cheap pods, looking at pics)
K&N 'oval will be a lot better, those actually restrict airflow at high rpm
Usual reason for bad charging is bad earths (ground connections) You'll ave to fit extra leads from crankcase to frame and probably from frame to forks to make sure headlight gets full voltage (even with all te ground leads Honda fitted)

HAHA! yes the tire is fitted the right way now.  Thanks man, that's some interesting info on the history of those carbs with the whole superbike thing. I didn't know any of that (prob because I wasn't born then). And yeah they are the cheap pod filters and I had even written that they were cheap shitty ones in the build thread but then deleted that part because I want to show my mate this page without pointing out the only thing he did was shit.

Earthing you say? I do have a solid connection for my headlights and all my switches by running the earth leads back to an earthing block under the tank (pictured) the only reason I haven't got a more updated photo of that is because i'm a bit embarrassed that I have tech-screwed that block to the frame. And only because one of my other mates kept my tap and die set (except the M6) that I lent him and an M6 bolt is too big for that application. I will go pick up my new battery now and put it in and check if its charging, if its not I will try adding some more earth straps to the crank case. I just really want it to look neat and to not have to take any paint off my beautiful frame or motor.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 22:18:50
Also I will need everyone that reads this to help me convince my wife I need new carbies, because the bike technically is running and the Mikuni or Keihin carbies are between $1300 and $2000! Considering how much I paid for the bike I don't know how I will justify that...
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 16, 2018, 23:27:55
Work has been slow because my garage has no A/C and it was bloody 45 degrees! (if your in the Bahamas, Belize, the Cayman Islands, Palau or the United States that's 113)
But, I have the new battery and its filling with delicious electricity water as I write this. Can't wait to see if the charging problem magically fixed itself!
Also this battery has 20 less Amps or cranks or something? The bloke at battery world assures me that it wont matter. Is he full of shit? I only agreed to buy it because I also figured a smaller battery would be easier to charge.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 17, 2018, 00:28:38
Nope. Installed the battery and checked volts, 12.79V so far so good. Turned bike on to idle and it dropped to 12.38V held the revs at 3000 and it stayed on 12.38V. So no magic fix today. The reg/rec has its own earth bolt to the frame to make sure its grounded good and proper. The purple wire that shares that ground is the oil temp sender earth. I checked that its getting some AC current to it but don't know how much it should be getting so that doesn't really answer anything.
There is a pic of the earth for the crank case, big thick wire straight from the neg terminal of the battery.
Also last pic is of the earth block for all the front lights and switches. As I said, not really proud that its just tech-screwed in but its a solid earth that doesn't rely on the bearings in the head stem to be making contact.

Sooo.... why isn't it charging?
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 17, 2018, 06:45:17
So I have done some reading and followed everyone's fault finding guide and I'm starting to think my Reg/Rec is not working. I pulled apart the only 3 original plugs from the wiring loom and cleaned the male and female connectors up with emery paper and pinched the female sides closed a little bit more with my long nose pliers. (pictured) After that I reassembled the plugs and was even a little bit happy with how well they clipped together, but after starting the bike and getting nothing but battery voltage out of the Reg/Rec output side i'm pretty sure that's where the problem is.
I did check the resistance of the stator slip rings and the continuity and they were all good. Seeing as its only a $25 part i'm just going to see if the one motorbike shop in this town has one in stock. (pictured)

Also I have to look into what dielectric grease is and where to get it.
Title: Re: 1980 CB900F Build
Post by: cxman on Jan 17, 2018, 07:42:40
check the resistance on the charging rotor

and inspect the brushes if they do not have good continuity thet reg cant energize the rotor

make sure they meat left and are not sitting at the replace mark

what was the resistance of the rotor?

if you are stuck i probably have a few airboxes from where i swapped carbs on mine
Title: Re: 1980 CB900F Build
Post by: crazypj on Jan 17, 2018, 09:55:42
It's a long time since I worked on 750/900 (mid 1980's) Pretty sure the earth is under one of the rear case bolts then onto frame either on a tapped hole in lower rear engine plate or under a bolt head? ( I would have to dig out a manual to check)
Generator rotor could be suspect, they are very reliable but don't like being smacked about (do any of us?  ;D )
 I only read about the cover damage this morning (it's 8.54am in Florida)
Did you get correct instructions with battery? Let it stand a minimum of 1 hr but preferably 24 hrs, check voltage  and charge at 1/10 of capacity for 12 hrs or max charge rate printed on it somewhere for 1~3 hrs (may be on instruction sheet.
SLA has a slightly 'more acidic' acid than conventional 'wet cell' ( from memory I think 1.32sg instead of 1.26~1.27sg)
Title: Re: 1980 CB900F Build
Post by: jetmechmarty on Jan 17, 2018, 10:47:14
Also I have to look into what dielectric grease is and where to get it.

Dielectric grease is an insulator.  It can not make your connections better.  It can make them worse.  I know there is controversy over the stuff.  It's good for lubing o'rings, otherwise, I have little use for it.
Title: Re: 1980 CB900F Build
Post by: jetmechmarty on Jan 17, 2018, 10:56:53
CXMAN asked the resistance of the rotor.  Good question.  It should be about five ohms.  You'll have no field if it's shorted, just a dead battery.  I'm not familiar with your Honda, but from my chair I'd ask if a shorted rotor could damage the regulator.  Measure slip ring to slip ring. 
Title: Re: 1980 CB900F Build
Post by: crazypj on Jan 17, 2018, 11:25:51
It's an EMF system, so shorted rotor could damage reg/rect as it will try  to power field coi,l not get  expected~14v so allow full battery voltage. As it's voltage regulated not current regulated it shouldn't be possible to overheat windings with a dying battery. If you connected a car battery  up with engine running, that could easily supply enough amps @ around 15v to fry things.
I'm guessing $25.00 is price of used part?
Title: Re: 1980 CB900F Build
Post by: jetmechmarty on Jan 17, 2018, 15:36:11
If the rotor is bad, the best option is

Custom Rewind
2014 Pratt Hwy, Birmingham, AL 35214
205-798-7282
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 17, 2018, 19:13:32
Thanks for the help fella's, to answer a few questions the brushes have a fair bit of meat left on them as seen in the pic and there is no resistance between them and the bolts holding them in. I know the pic I put up here says 4 Ohms but thats because I was holding it in one hand to take a pic and couldn't get a great connection, but with two hands it was definitely 0.
The resistance between the slip rings on the generator rotor is 4.3 Ohms and from memory that within range?
Also resistance between the stator coils is 0.4 Ohms which is inside the allowable 0.4 to 0.5 range. and I checked all 3 yellow coil  wires not just the one pictured.

Who would have known this would be so much fun!
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 17, 2018, 19:17:55
It's a long time since I worked on 750/900 (mid 1980's) Pretty sure the earth is under one of the rear case bolts then onto frame either on a tapped hole in lower rear engine plate or under a bolt head? ( I would have to dig out a manual to check)
Generator rotor could be suspect, they are very reliable but don't like being smacked about (do any of us?  ;D )
 I only read about the cover damage this morning (it's 8.54am in Florida)
Did you get correct instructions with battery? Let it stand a minimum of 1 hr but preferably 24 hrs, check voltage  and charge at 1/10 of capacity for 12 hrs or max charge rate printed on it somewhere for 1~3 hrs (may be on instruction sheet.
SLA has a slightly 'more acidic' acid than conventional 'wet cell' ( from memory I think 1.32sg instead of 1.26~1.27sg)

Instruction with the battery were "The instructions are inside" I read it and it said it only needs 20 mins for the electrolyte to flow in then its good to go. I did think there was more to it than that. Now I know for next time.
Title: Re: 1980 CB900F Build
Post by: crazypj on Jan 17, 2018, 19:35:53
Yep, that's battery sellers instructions.
 Doing things that way (seen it before) battery can fail in as little as 3 weeks.
 I doubt you've done any damage so bung it on a slow charge for 8~10 hrs at 13.7~14.2v @ 0.5amp max charge. If you only have a 'fixed' output charger, get a cheap timer (probably already have a few, most people do for Christmas lights, etc?) give 20 min 'zap' with 10 min cool down for a few hours
Title: Re: 1980 CB900F Build
Post by: jetmechmarty on Jan 17, 2018, 21:51:54
4.3 ohms on the rotor is good.   Each leg of the stator equal is good.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 18, 2018, 08:02:36
The local bike shop didn't have a rectifier and the guy said to go after market anyway because the OEM one was $439. But they did order the brake rebuild parts I needed.
So... its going to be a good ol fashioned thumb twiddling until I get me some more parts, but I will keep you updated.
Title: Re: 1980 CB900F Build
Post by: cxman on Jan 18, 2018, 09:13:20
make sure none of the stator legs have continuity to ground

same with each side of the rotor
Title: Re: 1980 CB900F Build
Post by: jetmechmarty on Jan 18, 2018, 15:46:52
The local bike shop didn't have a rectifier and the guy said to go after market anyway because the OEM one was $439. But they did order the brake rebuild parts I needed.
So... its going to be a good ol fashioned thumb twiddling until I get me some more parts, but I will keep you updated.

http://www.oregonmotorcycleparts.com/  Oregon Motorcycle Parts probably has what you need, plug-n-play.

(http://www.vintageyamaharally.com/uploads/9/3/2/7/93275084/published/ompround.jpg?1514577689)
Title: Re: 1980 CB900F Build
Post by: crazypj on Jan 18, 2018, 16:43:53
Who would have known this would be so much fun!

LOL, AS Benny Hill said in one of his comedy sketches, 'Learning All The Time' (while groping one of the almost supermodel actresses)

There are a few R/R that will work. Either get a brand new aftermarket (generally better than OEM as they use higher quality or MIL spec components) or get RR from Honda SOHC 350~7500F, Yamaha XS 650 or similar or Kawasaki.
Anything with 7 wires should work, stay away from 5 wire RR as it won't ave a control feed to field windings. I'm pretty sure you won't find anything from Suzuki as tey used car style alternators on EMS systems and of course, a 5 wire PMS won't work. have you tried 'full fielding' the field windings? (basically connect te white wires direct to battery, you should get around 17v at idle. Don't rev the engine as voltage can go crazy high (100+ before it all goes quiet and the magic smoke leaks out)

http://www.oregonmotorcycleparts.com/ (http://www.oregonmotorcycleparts.com/)  Oregon Motorcycle Parts probably has what you need, plug-n-play.

(http://www.vintageyamaharally.com/uploads/9/3/2/7/93275084/published/ompround.jpg?1514577689)

Two way shipping may be a bit expensive from 'Horsetrail-yee-haa'
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 18, 2018, 17:34:15
make sure none of the stator legs have continuity to ground

same with each side of the rotor

Yeah I checked that. cheers.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 18, 2018, 17:42:47
have you tried 'full fielding' the field windings? (basically connect the white wires direct to battery, you should get around 17v at idle. Don't rev the engine as voltage can go crazy high (100+ before it all goes quiet and the magic smoke leaks out)

Two way shipping may be a bit expensive from 'Horsetrail-yee-haa'

What? as i'm not 100% on what that is I will just wait until I work out a new rr. and yeah postage to this side of the globe gets a bit pricey... not to mention the AUD is only 80c to every USD.
you said there are a few 7 wire rr that work but mine has 8 wires, which wire can I not use/direct elsewhere?

Also 'Horsetrail-yee-haa' hahahaha! your killing me!
Title: Re: 1980 CB900F Build
Post by: crazypj on Jan 18, 2018, 23:25:47
I think original has dual grounds? I still haven't looked for manual. I 'll try and get a look at it tomorrow
I'm from 'old' South Wales, saw NSW  on number plate and knew it didn't mean
'Not Safe (for) Work'  ;D
Full Fielding is where you figure out which wires are going to the brushes and connect them direct to battery. That will make the electromagnet  ( the 'EM' in EMF) as strong as it's ever going to get. Your bypassing the regulator which is why I said only check at idle (generally OK to about 1,5~1,700rpm) It's so long since I had to do it on CB900 I can't remember results if you get over 2,000 rpm, maybe just the instrument and head/ tail light 'pop'? (that's the minimum damage)
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 19, 2018, 04:57:56
I think original has dual grounds? I still haven't looked for manual. I 'll try and get a look at it tomorrow
I'm from 'old' South Wales, saw NSW  on number plate and knew it didn't mean
'Not Safe (for) Work'  ;D
Full Fielding is where you figure out which wires are going to the brushes and connect them direct to battery. That will make the electromagnet  ( the 'EM' in EMF) as strong as it's ever going to get. Your bypassing the regulator which is why I said only check at idle (generally OK to about 1,5~1,700rpm) It's so long since I had to do it on CB900 I can't remember results if you get over 2,000 rpm, maybe just the instrument and head/ tail light 'pop'? (that's the minimum damage)

ohhhhh, that makes sense now. I'm still not gonna try it. My Brother lives a couple hours away in a bigger city and the motorcycle shop there had a rr in stock for $80. I'm going to his place next weekend because us Aussies celebrate "invasion day" next Friday. So when I get back if thats plugged in and things still aren't working I will look in to more drastic measures.
It was 40 degrees hear again today and its going to be hotter over the weekend. So I will be avoiding the garage for a bit.
Where is South Wales? Florida somewhere?
Title: Re: 1980 CB900F Build
Post by: cxman on Jan 19, 2018, 07:01:11
the wire bundle also carries the oil pressure switch wire and the neutral switch

oil

neutral

ground

3 stator

2 rotor trigger wires if i recall correctly
Title: Re: 1980 CB900F Build
Post by: crazypj on Jan 19, 2018, 12:22:07
ohhhhh, that makes sense now. I'm still not gonna try it. My Brother lives a couple hours away in a bigger city and the motorcycle shop there had a rr in stock for $80. I'm going to his place next weekend because us Aussies celebrate "invasion day" next Friday. So when I get back if thats plugged in and things still aren't working I will look in to more drastic measures.
It was 40 degrees hear again today and its going to be hotter over the weekend. So I will be avoiding the garage for a bit.
Where is South Wales? Florida somewhere?
You might be from Oz but I know your not that thick.  ;D
The rugby country.
 I'm still a British 'subject'. American's seem to like the 'south' Welsh, (Anthony Hopkins, Richard Burton, Katherine Zeta Jones/Douglas , etc - and Me  8) except I'm broke)
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 23, 2018, 17:46:59
Quick update: Mirrors arrived. I will have to grind off some rubber to fit them in the bars but im not putting them on until its time for rego because im likely to damage them while working on the bike. My brother picked up a second hand rr but its still at his place and I don't think I will make it over there so he will have to post it. Also the brake caliper rebuild parts should get in tomorrow.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 25, 2018, 04:55:56
I got brakes! I picked up my parts from the shop today and spent ages trying to bleed the front, turns out one of the bleeders was blocked with some gunk that I didn't clean out and with the help of a mates vacuum bleeder kit I got it done in no time. Now its all connected I'm looking at the nice braided lines I've bought to replace the factory rubber and because I've got clip-ons which are lower then the original bars the new hoses are a little bit too long. I'm thinking of taking them to a hose shop and asking them to cut them a bit shorter.
I haven't bled the rear and tested it because I am going to buy a new reservoir .
Also I put the throttle cables back on and they will need to be shortened a fair amount too, I'm pretty keen to have a crack at that myself. To get the throttle return cable to screw into the handle bar housing I had to drill a hole through a bolt and cut a slit into the length of it to replicate the original part that is missing, its not the prettiest but I will replace it down the track when I get other priority stuff done first.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 25, 2018, 05:35:47
pics
Title: Re: 1980 CB900F Build
Post by: crazypj on Jan 25, 2018, 09:48:15
File the bolt head to round, make sure to stick some grease  in the rubber boot o bolt will rust (unless you used stainless?) I probably have a couple of the correct fittings but as we know, shipping is killer to Oz
 If you pull top yoke it may be possible to change angles by loosening banjo bolts and routing so 'long' lines can fit better without excessive bends. That way you shouldn't av to re-bleed system or mess with getting lines cut. You will need to get some brass nipples to shorten throttle cables. Inners may be stainless steel which is a PITA to work with unless you can find some hard solder. In my experience, brazing makes the inner wire brittle and it's likely to break, 'soft solder' is just too soft and cable pulls through nipple. It's easier to use cheap zinc plated bicycle inner wire as solder sticks to it real easy. Keep it oiled and it lasts as long as anything else out there (about 15 yrs / 17,000 miles so far on my XS650)
 With the mirrors, junk the bar end mount as it will fall out.  Go to 'local' Home Depot / B&Q / etc and get some 6mm Rawlbolts (I think you get the same stuff we had in Britain?) You can tighten them enough to distort alloy bars from the inside  ;)

Be VERY careful tightening clamp screw, easy to crack the cast alloy.
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 29, 2018, 02:00:01
The new R/R arrived and so did my 3rd Chinese tail light. The bike charges now! I will try to finish up the wiring tonight but this heat is oppresive!
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 30, 2018, 17:11:24
stayed up really late wiring in the new tail light and thought i'd solved it turning off when I go to high beam by wiring it both the Hi and Low out put sides of the M-unit. I didn't really think that through did I?

Who else can see the obvious problem with doing it that way?
Title: Re: 1980 CB900F Build
Post by: crazypj on Jan 31, 2018, 11:13:21
You wire tail light to what was originally 'Brown' wire on Honda diagram (everything that needs 12V outside of coils, headlights, etc)
Tail light should be on same circuit as instrument lights
Did you 'blow' taillight when it tried to feed 5 amps back to headlight?
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Jan 31, 2018, 16:53:48
I was surprised I didn't burn it out,  but no what I effectively did was join Hi and Low beam together so they are both always on regardless of the switch position.
I will rewire the tail light so its on the ignition circuit, I just really wanted the option of being able to turn all the lights off with the engine still running (stealth mode)
Title: Re: 1980 CB900F Build
Post by: crazypj on Feb 02, 2018, 19:49:55
You should have wiring already in handlebar switch? Does it have ON-OFF position on right hand switch/throttle housing or is it USA type? (blanked off)
I know I'm going to have to dig out manual to check but tail light should be on handlebar switch input not output side
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Feb 06, 2018, 00:15:43
I dropped the seat pan off at the upholsterer, he put some foam on it and I chose a material to cover it in. He also quoted me $440 for the work, I was hoping for less but his work is reputable. Also haven't finished the wiring yet as I have been working on some other projects. I have a few fiddly jobs to do on the bike while I wait because I can't pick the seat up until next Tuesday. Hopefully I can do my first test ride then.
Title: Re: 1980 CB900F Build
Post by: 1fasgsxr on Feb 06, 2018, 13:16:17
OUCH...440 for a seat..your pan?
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Feb 14, 2018, 07:58:42
Got the seat but it didn't fit on the bike because I didn't allow for the thickness of the material when I made the pan, I bent the tab that sticks out the front down lower and now it fits.

The tail light comes on with the ignition and the hi low beam is back to normal. No stealth mode :( Only problem is with the rear brake return spring, its a bit saggy so it doesn't pull the lever back up so the brake light stays on even after my foot is off the brake. I will add that spring  to the list for the next lot of parts to order.
I am missing a bolt to hold the caliper on but the dad of all trades has already put one in the post.

Getting close to the end!
Title: Re: 1980 CB900F Build
Post by: Maritime on Feb 14, 2018, 09:26:08
Nice work, hop you put the fender back or a brace on the front, makes a big difference in handling.
Title: Re: 1980 CB900F Build
Post by: crazypj on Feb 14, 2018, 20:39:59
Those 'pods' are going to try and turn 'inside out' as they severely restrict airflow over 6k even on a CB/CM400
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Aug 03, 2018, 04:54:01
Ok, I am back to working on my bike as this place slowly claws its way out of winter and back above freezing. Also I am back to full time work so have been very busy.
I got got the bike running but not very well so I ordered and installed the dyna-jet kit and I could not believe how good the bike is running now! except... Its only running on the outside two cylinders. I put fresh spark plugs in and tested the coils and they both have good spark, I checked compression and it was good too. Fresh fuel and more carby cleaner with high pressure air gun to triple check that no fuel passage was blocked and also checked the bowls were full of fuel. I swapped the leads from the spark plugs around and it was still just the outside two cylinders that were running. Im thinking that the signal wires are around the wrong way, cant remember if they are coming from the reg/rec or the stator. I working through the weekend and next week but i have a few hours Sunday I can duck home on start digging through the wiring.
Title: Re: 1980 CB900F Build
Post by: crazypj on Aug 03, 2018, 13:37:05
If outside cylinders are running, signal /trigger has to be OK for 1:4. 2:3 could be trigger or ignitor. I think they are either under seat or left side panel. Alloy blocks about 1-1/2" square. Also check wiring from crankcase, I've seen it get damaged by exhaust when it wasn't routed properly. May be worth pulling sprocket cover, just in case something isn't right under there? (seen wiring cut be cover fitted wrong, foreign objects going around with drive chain, etc)
Title: Re: 1980 CB900F Build
Post by: cxman on Aug 03, 2018, 16:44:51
pulse generator test

the 4 wires are in pairs yellow and yellow with white trace

blue and blue with white trace

530 ohms plus or minus 60 ohms between each colored pair

no continuity on any of the wires to ground

check for 12v at both coils

swap coils side to side

swap igniters side to side
Title: Re: 1980 CB900F Build
Post by: crazypj on Aug 03, 2018, 21:44:23
That's what you've done so far? I'll have to dig manual out and take a look at wiring
Title: Re: 1980 CB900F Build
Post by: Tim of all trades on Aug 06, 2018, 06:18:36
White trace! On the wires! thanks CXman, turns out I had them backwards. My god I have awoken a beast, I got so used to it running on two cylinders that when I finally got it going on four I couldn't believe the noise and revs I could achieve.
Now I have to order float needles and a fuel tap to stop the two petrol leaks I have. Also I will look at getting some new cables custom made to fit.
Title: Re: 1980 CB900F Build
Post by: cxman on Aug 06, 2018, 07:55:39
they are a blast to ride just wait i love mine