1980 CB750F for $180, modern suspension and upgrades for a cafe racer build

I can look in my shop tomorrow evening or Saturday, whenever I have a chance to get out there. I might have one. I know I have a few tanks, but I am not sure if they have the cap and locking latch.

Just curious here...

Are you dead set on keeping the stock tank? Just my opinion that a different tank would look cleaner on it if you're not keeping the side covers, being as your stock tank is designed to marry to the side covers to keep the body flowing from tank to tail.

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Thanks for looking. I actually would like to keep the tank, I love it's lines even without the sidecovers. I've sketched uo a concept idea, and some other tail ideas. There's also a guy who's done a brat style overhaul on his DOHC that looks clean as Fuck, personally the tank matches the lines of the engine well.
 

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Cool. Well, I'll try to get out to the shop tonight or tomorrow to see if I have a good locking latch and cap. I think I do, but I can't be for certain. Is there anything else that you might be looking for? I've got a lot of random parts lying around, and I'm trying to.clean out my shop. I'd rather them go to someone that can use them rather than the scrap yard. Haha.

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Let's see, I'm in the market for a CB900F oil cooler, lines, oil pan, and pump. Also gonna need a front fender that isn't all wobbly, and that's in good enough shape for paint... as far as I know, that's it for OE parts. Unless you got a timing and pulse generator cover that isn't scraped up. Oooo also, exhaust. If you've got a complete DOHC exhaust that's in good shape for super cheap I'll entertain that, but otherwise I'm thinking of doing Carpys Yoshimura replica style or the Delkevic ebay stainless 4 into 1. If you've also got the rubber airbox boots/velo stacks I'll need a new set of them. Other than that, I think I've already gotten all the parts I needed shipped and set aside.
 
helped a buddy with his 79 he ditched the side covers but kept the stock tank.. not the best pic but you get the idea.

Psy
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Interesting, that must have been a K or a C model right? I thought all CB models went to comstar rims in 79. Maybe just the F models then. Mine has discs front and rear with comstars. My seat design will have a step in it, a shy a away from the flat brat seats more common on the sohc models. The F is going to be a blend of brat with streetfighter stunt bike feel. I want the small step in the seat to cradle my ass when lifting that front wheel off the ground. Found out my frame is gonna wait until the local bike show here concludes, hope I see or meet some of you guys at the Salty Bike Revival show coming up! I'm gonna enter this bike maybe next year if it's finished by then. Fingers crossed
 
Its a K model as far as we can tell. However it has the spokes and origionally the "boat tail" .. ? apparently they are rare in the states... a little more common here in Canada even tho these options were only avaialable one year. I have seen other 79's with the regular K tail and comstars.

Psy

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I love how there's so many differences. Well my project has been placed on hold for the moment. I've got a new used front wheel on its way from NY, and the rest of the parts just sitting till after our local custom bike show Salty Bike Revival.

I'm also putting it on hold until I fix my transmission on my daily rider, my 85 Honda MAGNA VF700C had its 2nd gear dogs take a shit on me so they skip and chunk under load. I NEED this bike to have all the gears especially 2nd while living in the city, and due to the fact I have no garage so it's a high priority so I can ride in the winter. Doing good research on interchange ability between models, and finding a good transmission I can salvage gears from.
 
Should be working on the frame this week. The guys at my local custom shop offered to teach me what to do and how to weld so looks like I'll personally be fabricating my bike.

Also ordered a Delkevic exhaust header that will be paired to a Yoshimura RS3 muffler, decided not to go scrambler route but more of a good reliable daily rider brat with a nice aggressive angle using taller shocks in the rear. Will be disassembling the engine soon and seeing what fuckery if any there is that the previous owners did.

I also found a 80 cb750k locking fuel cap latch, ignition switch, and helmet lock matching with one key on ebay for 50 bucks. Picked that up too.
 
I see you're on the 1100f site. Its a good site with a lot of knowledgeable people. Working on these engines is fairly straight forward. I rebuilt mine in feb and dropped in bigger cams and an oil cooler. I have a 750. I would also look at all the mods. Relay, starter clutch, shifter mod and cbr coils and look into getting a better charging system. I got mine from cycle x. You may be able to find the same system a little cheaper. Hit me up if you want more info.
 
esmoojee said:
I see you're on the 1100f site. Its a good site with a lot of knowledgeable people. Working on these engines is fairly straight forward. I rebuilt mine in feb and dropped in bigger cams and an oil cooler. I have a 750. I would also look at all the mods. Relay, starter clutch, shifter mod and cbr coils and look into getting a better charging system. I got mine from cycle x. You may be able to find the same system a little cheaper. Hit me up if you want more info.

Yeah those guys have been very helpful. I was considering cams, and I wanted to pick up a CB900F oil cooler setup but might opt to wait until my motorcycle is apart. There's a local Boneyard that has CB900 engines lying around but I have to disassemble them to get to it. Might wait overall. The shifter mod is planned, I've got CBR coils already, I've diagnosed the charging system and it's got the proper charging voltage, but I did have to get a new pulse generator. At least the oil cooler and the cams are something I can change later without having to pull the whole engine again. I've got a brand new starter solenoid, what's the relay mod you're talking about? Signal relay? I'm planning on picking up an LED electronic one because all of the lights will be LED when I'm done. What's the starter clutch mod?

In Other news, I've finished pressure washing the bare frame, now it's time to chop and weld. Going to have a perforated rear hoop to integrate the LED tail light with signals, and fabricate a easy removable sissy bar for when I camp out.
 

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The relay mod uses a 40a or 50a horn or gen purpose relay. It charges the coils faster to avoid voltage drops. It’s on the performance tech link at the top under Mod/Fixes on the 1100 site. The starter clutch mod uses an r6 starter clutch. Here’s a link to how to go about it. https://www.youtube.com/watch?v=sYJSUiXDim8 I picked one up on ebay for about $40.

Are you sticking with the stock carbs or going with a mechanical lift? I ended up with Mikuni vm29 smoothbores. No problems running pods. I may switch to cr29’s. We’ll see. If you do stick with the stock there is also a mod for the carbs. The RSC. I did do an LED flasher relay. It was the only way to get my lights to work. :)
 
esmoojee said:
The relay mod uses a 40a or 50a horn or gen purpose relay. It charges the coils faster to avoid voltage drops. It’s on the performance tech link at the top under Mod/Fixes on the 1100 site. The starter clutch mod uses an r6 starter clutch. Here’s a link to how to go about it. https://www.youtube.com/watch?v=sYJSUiXDim8 I picked one up on ebay for about $40.

Are you sticking with the stock carbs or going with a mechanical lift? I ended up with Mikuni vm29 smoothbores. No problems running pods. I may switch to cr29’s. We’ll see. If you do stick with the stock there is also a mod for the carbs. The RSC. I did do an LED flasher relay. It was the only way to get my lights to work. :)

Ill check those mods out. My starter actually fires very quickly and powerfully, i might leave it as is.

Yes, im sticking with the stock carbs too. Ive rebuilt them fully disassembled, polished the diaphragms internals, all orings replaced, all air cutoffs replaced and a new accelerator pump. After i got the valves adjusted, cam chain tensioner set, and the ignition sorted out the bike fired up immediately. Theres a video earlier in the thread of its first start in 11 years. I got a used airbox and will be running that with a UNI foam filter, and ill have to get new airbox boots. I figured that would be the absolute most reliable and now i understand the carbs really well i feel comfortable keeping them. Ive decided I want to keep the bike mostly stock as I want it to be reliable over performace. Except of course aesthetics, rear shocks, and ill be buying progressives for the front forks.
 
That's dope! I think my next build I'll keep it close to stock. I love my street fighter but I kind of prefer an upright position for extended riding. I can't wait to see you project complete. Good luck with everything. If you need anything, feel free to hit me up.
 
esmoojee said:
That's dope! I think my next build I'll keep it close to stock. I love my street fighter but I kind of prefer an upright position for extended riding. I can't wait to see you project complete. Good luck with everything. If you need anything, feel free to hit me up.

Yeah I was playing with ideas of having rearsets, but decided against. I actually like long distance rides, and my girl likes to two up along, so.id need the passenger pegs anyways. This F model will be a bit different because I am planning on fabricating an easy removal sissy bar for packing bags on trips, or as a backrest for the girl, but also be able to take it off for when I'm just cruising the city and local canyons. In the beginning of this thread I was looking into a monoshock conversion with CBR or gsxr upside down forks, but it just wasn't gonna fit into my budget. I figured with adjustable air shocks in the rear (15-16" which is 1-2" taller than stock), and progressives in the factory forks I'd be able to have a nice and comfortable ride for distances, not necessarily for aesthetics but for comfort. Upside down forks and a monoshock might be on my next sport build, but I've decided my next build is going to be a hardtail chopper twin.
 
Frame is still sitting in the shop, my CL175 forks got ruined while attempting seal replacements, and my Jeep contracted Death wobble... next step? Begin the engine disassembly on my CB to keep positive.


So, I've started the engine disassembly. Everything's looking pretty solid so far, I got the cylinder block off last and called it a night because I hit a mental wall. Taking a day or two break before I tackle the clutch, oil pump, and then splitting the case.

I'm feeling really good about my organization, labeling and stuff, but distractions aside I think I made decent time.

I've also heard some naysayers in other places spouting about Marvel mystery oil and seafoam being nothing but snake oil, I'd like to refute this with photos of my cams which used to be glazed and brown which are now bright and clean. I ran a whole quart in the crankcase of marvel during my first engine start to see if I could unstuck the clutch (which it did after a week of on and off running), so I'm feeling pretty good about the internals being scrubbed as well.

So far I'm not seeing any pitting in the cylinders but there's a lot of carbon build up on the valves and piston. Some of the valves looked tan, I'm guessing they got cooked pretty good. Splitting the head and the block wasn't too bad, just light tapping for about 10 minutes each with a rubber mallet pulled it out. My big mistake was when I finished taking the cylinder block off, I decided to start disassembling the starter, and accidentally dropped a screw down the open crank hole. Whoops, I'll get to it sooner or later.
 

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Maritime said:
If you worked on the floor instead of the ceiling it would be easier on you I bet. ;D

Ha, thats how i keep the floor clean! LOL i have no idea why the pics got flipped when i uploaded them
 
Papinbrew said:
Then disassembled each carb one at a time and...

I rebuilt the carbs on my '75 750 a few years back. Doing one at a time with much patience and a good cleaning mine went well and the bike ran like new afterwards

Patience and keeping each carb's pieces organized and separate from the other carbs is key. Great project!
 
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