CB750F 1983 Tracker-ish build

QupiX

New Member
Time to introduce myself and start my own topic!

I'm Joost, a 24-year-old guy from Holland (so don't pay attention to my bad english ;)), living in Kamperveen (little village nearby Zwolle). Tried 2 studies, didn't work out, and now working two jobs (dad's company and supermarket). About a year ago i got my drivers license, and since then i owned 3 bikes. Suzuki Bandit 600N, first bike, really loved it though it was old and started like crap. Didn't care, first bike so to me, it was the best bike there was. After that, i got myself the Honda in this topic, while keeping the Bandit. September last year i sold the Bandit (i was surprised someone wanted to have it because it really looked like crap) and then bought a nice 2004 Suzuki SV650. Light twin-engined bike, very much fun to ride, so that's gonna stay for a while. But, it's not a custom bike, and that's boring, so that's the reason for the Honda build :D

Bought a Honda CB750F a while back, had big plans to tear it down and build it up again, without any experience. Got inspired by the Guzzi build a friend of mine did, so, went searching on the web, found an old bike for a reasonable price (350 euros). See below. Went for a Honda because they are reliable and i liked the look of it.
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PO didn't drive the bike for over a year so it was just standing there, outside, in a poor condition. Made a test drive, ran fine, only thing that had to be replaced was the battery.
After visiting the PO, I decided to buy it. 3 weeks after that i went down there again (with new battery) to drive it back (start of winter, so freakin' cold!). Surprisingly, it ran perfectly all the way and we came home without any problems! So far, so good.

The same day, i moved the bike to my dad's company (big place, shitload of space, perfect for a bike build at that time). Got a bit short on time after that so took me over a month to really start tearing down the bike. Had to start it again to move it, after a month it started instantly with the first push on the button, so, no reason to take the engine apart. Nice ;D
Before, ready to be taken apart:
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After doing some hard, hard work :p
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End result:
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Right, time to get some parts:

Found a nice front-end of a kawasaki ZXR 750:
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The front wheel is one of the two wheels i got from a cb900. Really like them, weren't expensive at all and they are a bit smaller and wider then the original comstars. The comstars also weigh a ton, so that's also an advantage.

Also bought a cb750 tank from an sohc, had better lines, and less huge then the original one. Still not sure which one to use, have to decide that when i put all the parts together.
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Just had to get myself these, not very original but i really like the look of them, and i'm very curious about the sound:
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Don't want to post a picture of every little piece i got myself over time so here's a quick mock-up picture:
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Already chopped the frame in that picture, cut the end off, welded a new piece of tubing in between (with corners, not the smooth half-circle you see a lot)
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After this, the project became on hold for a looong, long time. Recently i met Bert Jan and his girlfriend Jene again and he told me he started a motorcycle building shop not far from where i live (for info and pictures, take a look at his cb550 cafe endurance racer topic: http://www.dotheton.com/forum/index.php?topic=39773.0) Visited a few times, really loved the place, so when Bert Jan asked me when i would bring my bike-in-pieces into his shop, it didn't take too long before we moved the bike to his place. So, very pleased about that!
Picture with parts laying down (quality sucks, i know ::))
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So, there we are. Now, the regular problems with building a bike with different parts. The front axle ofcourse didn't fit the wheel, so at first, i decided to make a new axle myself. A lot of work, but fun to do, so no problem. The more obvious solution, to get myself new bearings, did just recently kick in when Bert Jan (cb550 build) made clear that that was a lot easier. So, problem solved. I also want to use the original kawa brake discs and calipers so have to make myself some spacers (already made some in solidworks, now have to machine them).
Next problem: Triple tree axle is too short, so, have to make it longer. Cut the axle in half last week, going to insert a steel bar in it, get a short piece of tubing, weld it all together and then it should hold. Also found new bearings to fit the axle so when it's all done, it should fit without any problems. Will post some pictures about that proces in a while.

What's the plan?
I really like the wrenchmonkees style, less is more, clean bikes, etc. So that's the way to go with the design. Build it up again with the new parts, get the motor in, try to fabricate a new wiring system, and when it all works, tear it down again and send it to the powdercoater. Engine is going to be ice-blasted (no sand or dust in the engine, very nice) and then will get a nice new layer of engine-paint.
Didn't have the time to do much more until now so i will keep this thread updated with new stories and pics whenever there's something new to show. Also, when there are some big problems even Bert Jan can't solve :)P) i will ask for some help here! Hope you liked the (long) read ;D
 
Welcome to the the site, Joost. Looks like a fun project you have going on there.

I really like the squared off rear hoop, looks good.

Looking forward to seeing where you take this thing.
 
Have to say I'm interested to see just what a DOHC 750 tracker would look like. Any inspiration pics, or are you kind of winging it?
 
Thanks y'all!;) Curious myself what it's going to be like, for now i don't really have a clue what the end result will be. Can't decide about the colors, parts i'm going to use and which parts will end up on Bert Jan's bike:p Want to make parts myself too (have access to a big-ass cnc cutting table, which i'm going to use to mill alu parts soon) so that's pretty sweet when it all works out as planned.

Have to say I'm interested to see just what a DOHC 750 tracker would look like. Any inspiration pics, or are you kind of winging it?

Same here, just like the tracker style, but i haven't got a clue how it will turn out. We'll see, i just want to build myself a nice bike:) Inspiration comes from watching a loooot of pictures online (bike-exif, wrenchmonkees, etc) and just decide what i like about a particular bike and what not.

Today i put 4 new bearings in the honda wheel, smashed two seals by accident so they had to be removed. Have to get myself some o-rings to seal them off, shouldn't be a problem. Still, it sucks quite a bit.
Also installed the triple trees into the frame, didn't have an axle yet so had to do it with a piece of threaded bar (really don't know the english word for it) through the axle pieces to hold the trees together. Worked great, so ended up installing the kawa fork. Feels great, getting some shit done. Tomorrow i'm installing the wheel, and maybe at work going to fabricate some spacers to fit the brake discs.

Pictures of the current state:
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Made a solidworks model for my frontwheel spacers. Took some measurements yesterday so when i machine the spacers and order the bolts, washers and nuts it should fit perfectly. Planning to put the brake discs on with M10 socket head bolts, should hold fine i hope.

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make the holes smaller and put bearings in them, just because it will be even stronger.
 
Been a while.

Have been busy looking for new/old parts, ways to fabricate parts, etc. Got the welding equipment in our shop working so that's nice, welded once before so that was a bit exciting. Went allright, have to practice a lot to actually weld things for my bike.

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Planning to fix the piece of tubing at the lower part of the frame to make the frame more rigid. Only downside is that i have to take some parts of my engine at the bottom to fit it into the frame, but that's allright. Also want to weld some steel between the downtubes and beneath the seat.

Fabricated the spacers i showed earlier from wood on our CNC table. They aren't perfect, but doesnt matter, they just have to hold my brake discs for the moment, had to know sure my measurements were correct (they are:p). Also the first part i made with G-code so quite proud of that. Some pictures below:

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Have to decide now if i'm going to make them myself out of aluminium or let a professional take it from here. Quite an important part, when they aren't balanced properly the whole bike will be shaking, don't really want that:p

I'm also thinking to replace the original rear-fork with a '92 square one from a sevenfifty. Has anyone any idea if that one will fit without any problems? Want to use that one because it's supposed to be less twitchy and I got myself some guzzi shocks that would fit perfectly. I found one but that's quite expensive..

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Maybe I'm missing something but wouldn't it be easier to put a spacer behind the calipers and move them in? I have to use spacers like you designed since I have radial calipers.

Seriously jealous of those wheels, I don't see those around here.
 
Would be easier indeed but then the calipers would hit the wheels, those boomerangs are quite wide. So this was the best solution.
 
Makes sense. Seems like as long as your discs don't bolt directly to the spacer you should not have too bad a balance problem. The weight is close to the axle anyway and your design isn't crude. If anything have your tires balanced with the spacer installed.
 
JoostS said:
Just had to get myself these, not very original but i really like the look of them, and i'm very curious about the sound:
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They're loud. I'll post a video some time...
 
I couldn't love those wheels much more for an awesome 80's build like this. I just think they're great, and remember seeing those on lots of flat track racers when I was younger. Even the 883 class Harley guys rocked those rims. So cool.
 
Quick update: Had the opportunity to buy a nice CBR blackbird swingarm, so the concept of the bike isn't exactly what it used to be. Doesnt matter, it looks pretty cool and i hope it drives like that too. Mounting it wasn't that hard, just had to grind off 2mm from the swingarm to fit it into the frame. Some new bearings and it should work fine. Tank looks a bit tiny now so i'm thinking about using the original tank again. Bike has been torn down, going to weld the mounting brackets for the new suspension and some other stuff on the frame and then it's making his way to the powdercoater. I hope:p

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