CB750 Makeover Cafe Style

[Potbellied Yeti]

Brethren,

So I'm new here of course, I'm not new to forums however. Pictures will follow. 8) I am starting my build log of a 1975 CB750K. I picked up two of these beauties for 700 bucks. However as I dive into this project its feeling likg more of a boat than a speedy road legal race bike. Let me explain, as you'll see below I acquired these bikes as they are in the first photos one complete the other missing a gas tank and a seat. Which coincidentally I am working on the one without a tank and seat so that at least one less item that will go to the trash bin. :

I will also state that opinions and suggestions are welcomed throughout the build and I will also be asking advice on specific areas where I lack expertise.

I decided I was going to rebuild the top end as it had previously sat outside for a number of years though it had great compression and the ability to turn over I found rust goo on number 4 piston. Up one removal of the jugs I found the number 3 piston had a frozen ring. Upon checking the clutch I found further damage as a bolt had previously spun loose and made bits way into the cover revolving a few times before someone noticed. I also found a broken ear on the plate for the clutch springs. Further along now I have completely disassembled the cases and I'm glad I was talked unto it as I found two broken gear teeth that fell out of no where, yet not a single tooth is missing on any of my gears. Upon closer inspection of the journals and crank bearings I found scratches in the bearings and two of the journals have the slightest steps in them. Just barely enough to catch a fingernail.

Well that's as far as I have gotten so far. I need a front brake caliper assembly sometime in the future as this bike didn't come with one.

OK a little about me before picture time. I'm 26, a single father of two little girls, I'm also in a machining career. I do everything a machinist does just without the title since I didn't go to school for the degree. I'm very good at my job and am very familiar with tolerances. Mostly the only time I have to work on this project is in the evening after the kids go to bed and on the weekends. I expect this build to take about a year with hopes of riding by next summer. The biggest challenge for me will be the motor as money is tight but I want the best bang for my buck without cheap junk.

Anyways cheers I hope some have input for me down the road. The main color I'm going to focus on is A) Burnt copper or B) Baby Blue Metal Flake (the real flake) opinions are welcomed though I extremely love the copper/orange burnt color wheel.

Take care,
The Yeti

 

[Potbellied Yeti]

I apologize in advance. I only have my phone camera. Sorry guys I'll do my best.

 

[Potbellied Yeti]

And lastly for the moment the two gear teeth that the motor shat out from nowhere.

In hind sight typing this, the only thing I haven't taken down after removal from the case was the oil pump. I don't know what that looks like........

 

[Potbellied Yeti]

Update***

Stuck studs. Please help. I've triple nutted the studs and to no avail have they loosened. I'm going to runHD studs anyways so I decided to try bending one like someone posted and that only twisted the stud without breaking it loose. How bad will I mess it up by applying heat and try again?

Regardless they have to come out now since I bent one.

Thanks,

The Yeti

 

[Hoosier Daddy]

Congrats on the bikes. Being a machinest apprentice will help you on this engine. With you knowing how to read a mic and understanding tollerances is a major benifit, you're ahead of most Noobs.
Download yourself the FACTORY service manual. They are available on line from many sources for free if you search.
If that crank journal is the one you can catch a nail on it looks pretty good in the pic, I'd be tempted to scuff it with some fine crocus cloth around it's circumfrence and call it good, you don't want to remove material, just clean it up. Measure it with a Micrometer / caliper and see if it is withing service specs. Then Plasti-gauge it when you get your bearings. That rusty goo on top of #4 almost looks to be oil that was contaminated with water. Much better than a cylinder that was left in the elements with a valve open and filled with water.
I would lightly heat the head to remove the studs, propane torch hot, not oxy/acetelyne. Also a pair of parrot jawed channel locks works wonders on removing round parts, Excellent addition to your tool box. The jaws are curved and actully bite in harder the more you turn. Grip the stud down low close to the head.

Bummer about the gear teeth, I would definately check the oil pump as long as you're in there..., regaurdless if you don't see them missing anywhere else. "Ounce of prevention is worth a pound of cure".
Oh and those "Mag" wheels on it look to be Lesters, They are worth a small fortune! Do not damage them, be very careful when you are replacing the wheel bearings, seals, and tires. If you don't like them clean them up and list them on E-bay... it would probably pay for your bike build.
One m

 

[Potbellied Yeti]

Congrats on the bikes. Being a machinest apprentice will help you on this engine. With you knowing how to read a mic and understanding tollerances is a major benifit, you're ahead of most Noobs.
Download yourself the FACTORY service manual. They are available on line from many sources for free if you search.
If that crank journal is the one you can catch a nail on it looks pretty good in the pic, I'd be tempted to scuff it with some fine crocus cloth around it's circumfrence and call it good, you don't want to remove material, just clean it up. Measure it with a Micrometer / caliper and see if it is withing service specs. Then Plasti-gauge it when you get your bearings. That rusty goo on top of #4 almost looks to be oil that was contaminated with water. Much better than a cylinder that was left in the elements with a valve open and filled with water.
I would lightly heat the head to remove the studs, propane torch hot, not oxy/acetelyne. Also a pair of parrot jawed channel locks works wonders on removing round parts, Excellent addition to your tool box. The jaws are curved and actully bite in harder the more you turn. Grip the stud down low close to the head.


Bummer about the gear teeth, I would definately check the oil pump as long as you're in there..., regaurdless if you don't see them missing anywhere else. "Ounce of prevention is worth a pound of cure".
Oh and those "Mag" wheels on it look to be Lesters, They are worth a small fortune! Do not damage them, be very careful when you are replacing the wheel bearings, seals, and tires. If you don't like them clean them up and list them on E-bay... it would probably pay for your bike build.
One m

Hey Hoosier,

Thanks a ton man, I was starting to wonder if I was sitting here talking to myself ;D

I'll run out and pick up a set of channel locks like that today and give it another go, they soaked all night in liquid wrench....

The gear teeth is the wierdest thing and I'd take a picture to show, however I don't think my phone would pick it up, I found the new gear. If the motor is sitting like it normally would on the bike it would be the lower rack of gears second from the right. Second biggest gear on that rack. I can still see the machining feed lines around the outside of the teeth were as the rest of the gears have smoothed out over the years. So I think I found the culprit but I will check the oil pump anyways.

On the wheels, I'm keeping them, I love the look and hope to repaint them probably to the original color. Funny thing though, the guy I bought the bike from said the same thing. He said 1k. Yet I look on ebay and the most expensive ones I found was for a BMW and that didn't break 350.....Like I said I plan to keep these, but what are they really worth? I really like the look of these wheels.

Thanks a bunch,

The Yeti

 

[Hoosier Daddy]

I doubt they are worth a grand... but definately a couple hundred a piece if they are in good shape. Search "Lester wheel" or add "CB750" or "GL1000" to it and see what you get.

 

[Redliner]

Throw a pair of short handlebars on and a seat-bump and you have a café racer. What a loose term. I won't even get into it so I'll disregard and talk about the things we did before this fad took over.

CB750's are pigs. DOHC, SOHC, they're big displacement bikes with equally wide or tall frames. Putting skinny components on it makes it showcase that huge block. On the other hand, putting larger parts on it will make it seem more proportionate. Giant bikes can be just as impressive as anorexic ones, if not MORE!

Here's a DOHC I had to fix for a client recently. He called it a café. Those clocks and the headlight are so large and high that it looks like part of the bike fell off somewhere on the way here.

So if you want to go the racing route, look to MotoGP. If you slap the loooongest tank you can find on it then you have a glorious look! Disassemble the entire bike and then put back the minimum components you need to run safely and perform well. Airbox or not, you're going to have the oil-reservoir taking up that space between the frame. You could replace it with a cylinder type to make the bike look even more naked, if you do remove the airbox.

Finally, if you do decide not to go the race route (recommended since turning a CB750 at speed feels like walking in heels) then go with a highway killer! The kind of bike that zooms by the traffic and makes drivers question their decision to settle down and become a minivan owner. Hell, you already have the mag-wheels!

Throw big fairings on it, add a bump or fender eliminator, leave the tank or find one that is not as wide and streamline the whole look. Now when people walk by your bike outside the pub, they keep a fair distance from it because it looks like it could single handedly kick their ass.

But I just make my living on bikes, and you scored two road-masters for cheep. There's a lot that can be done here

 

[Potbellied Yeti]

Hey Redliner,

Thanks for the advice man. I agree about stock components. This bike I'm going to try to keep a racey feel to it. Smaller gauges actually probably just eliminate the speedo altogether. As far as the tank id rather not spend 400 dollars on a tank. I would like to dent mine and add a fiberglass rear half for looks only to stretch it out. I am eliminating the stock air box. I haven't decided on how to do the intake but wouldn't mind splitting four intakes down to two. Whether it be with the carbs or just the intake side for filters. The oil tank I will build my own to follow the down tubes in the frame and hide it some with the same volume but more surface area to help with cooling. I'll be upgrading my suspension to the best that funds will allow. I'll also be making my own seat cowl as well. I'll probably try to machine up my own rear sets as well but that's a ways down the road. Tank and seat needs to be finished and mocked up so I can build rear sets for me on this bike. I'll also be doing some motor work obviously what yet ibhavent decided. I can't really afford an entire kit at the moment from cycle x however I may spend a little more but at least I'll be able to buy it piece by piece. The only thing I won't do myself is a powdercoated frame and possibly cylinders bored (big maybe) and valves recut. The rest is up to me. I like to build things. Not buy them.

I appreciate everyone's advice so far. Please keep it coming.

 

[Redliner]

Whatever it turns out to be, spend $100 or so to get at least a bikini for it. Half-fairings streamline the look and make it more proportional.

 

[Potbellied Yeti]

Well.

It's been a Monday that's for sure. I picked up a stud remover tool, pretty neat very simple design. I proceeded to heat up the case and stud with a propane torch, after I shut the torch off I dowsed the part with liquid wrench which with the heat and cold can create a vacuum and suck the liquid wrench in the hole. Worked great, but, two studs perished in battle. Case 1 Yeti 0. Now I'm at a loss, not really sure what to do or how to do it. Sure I could take it to work drill them out and use an easy out but if they can't come off with the remover tool and a breaker bar what the heck is a easy out going to do......

Hints, suggestions, name calling bring it on.

On another note Sonreir pointed me in the right direction for wire harness supplies so I can build my own. Holy monkeys there's a lot of wiring for a motorcycle! Just wanted to say thanks to him!

 

[legendary_rider]

subscribed

 

[surffly]

You should send me those wheels.

GL1000 wheels are different then the CB750s.
GL guys don't like the wheels, cb750 guys love them and pay for them.
18 rear is much more desirable

 

[Hoosier Daddy]

You should send me those wheels.

GL1000 wheels are different then the CB750s.
GL guys don't like the wheels, cb750 guys love them and pay for them.
18 rear is much more desirable

True that the GL wheels are different than the CB's... shaftie vs chain, apples vs. oranges. I was just saying for price referance for him to check.
Oh, and not all GL guys don't like 'em, probably just the aftermaket chrome do-dad lovers who strap Teddy Bears to their trunks. Over on Naked Goldwings (www.ngwclub.com) is where I was exposed to their desireability. But those guy are a different sort of GoldWing owners.

 

[Potbellied Yeti]

You should send me those wheels.

GL1000 wheels are different then the CB750s.
GL guys don't like the wheels, cb750 guys love them and pay for them.
18 rear is much more desirable

;D Faaaaaaat chance buddy. I like these too much. That is unless you wanna pay for my motor build. Then we could talk.

 

[Potbellied Yeti]

Welp, I might as well just get used to it now, seems every bolt in this danged motor needs drilling. Drilled off 4 exhaust screw heads this evening. The other 4 I was able to get with the hand impact driver. I plan to port and polish, it'll be my first time with this as well, tomorrow a friend hopefully remembers his valve spring compressor so I can remove those tomorrow evening as well.

I was thinking of ordering from cycle x with there new valves and valve guides, but their machine work is friggin outrageous.... not bashing just saying. I will also be making my own exhaust (not my first time thankfully) I'm currently planning a 4 into 1 megaphone style building everything myself. The last set of pipes have been through hell and back for the past two years and are holding extremely well for a first time job.

This evening look at the front forks trying to decide how to get them off....stupid question I know. With the covers that are on there to hold the headlight and the fork boot I am not able to slide them out....unless I need to remove the boot from the bottom fork? Regardless I really really dig the look of (don't hate) modern front ends, lets say something along the lines of a cbr600 or something. Just something about it that calls to me. I'm just not sure if my Lester wheels are compatible??? (This is one major are I lack, not knowing compatibility of certain parts) Regardless I didn't want to run a modern swing arm as I think it takes to much away from the bike in my eyes anyways.

Also got the last of the wire connections removed and the harness is finally free! Sorry no pictures this round, my garage is a disaster and the shop looks like I am a spokesperson for Ziploc bags. ;D It's the only way to remember where certain things go in a motor, like I said this is my first COMPLETE tear down since well High school on a mini Briggs 4 stroke mower engine.

Welp, thanks for stopping!
Yeti

 

[rockcitycafe]

if you're a machinist apprentice, you can cut your own valves, just use a surface grinder, dress a 45 on the wheel and hold the valve in a whirleygig... you could probably make a good project out of building your own valve seat cutter as well, not a particularly hard tool to make, but would take some careful setups

 

[Potbellied Yeti]

if you're a machinist apprentice, you can cut your own valves, just use a surface grinder, dress a 45 on the wheel and hold the valve in a whirleygig... you could probably make a good project out of building your own valve seat cutter as well, not a particularly hard tool to make, but would take some careful setups

Trust me I already thought of lots of things ;D only problem is the surface grinder is the one machine in the shop that isn't in working condition too many big and fancy expensive machines running to worry about surface grinding....

 

[rockcitycafe]

Ahh, you work at a *production* shop... Yawn

 

[Potbellied Yeti]

Ahh, you work at a *production* shop... Yawn

Amen to that brother. Yea were not massive but were not small. Production is the name of the game. The nice thing however is that if I have a project of my own we have plenty of manual machines that are just sitting for my usages. I'll probably do my own motor mounts and all sorts of things. Should be a very fun build actually.