New member, new project, new problems.

[NKing07]

Hey guys, new to the forum and new to the world of CB's. Mostly an off-road background but decided I wanted to keep busy over the winter and found a 1980 CB 750C. Running (obviously not without the battery), and aside from pod air filters I'm not going to do much engine wise. The first thing I want to tackle is raising and flattening the seat frame rail. Does anybody have any info, advice, pictures of this being done? Appreciate the time.

Oh and here's the bike, not too shabby for $350 CD.
 

[rrgunslinger]

Welcome, Nice buy,  Your gonna have fun.  Can't help you with the seat issue but I'm sure there are others here who can.  Not sure if I would run pods on this bike.  Carbs need vacume from the airbox to work I believe.

[NKing07]

Yeah unfortunately I am starting to realize that. Has anybody figured out another option aside from running the stock airbox? I've heard mention of switching to the CR carbs but I'm under the impression that's not a cheap route to take.

[Hellbilly429]

You can run a K&N air filter in place of the stock filter, that's about it with out making sacrifices.

It can be made to run, but it'll take many different types of rejettting and fine tuning and a whole bunch of stuff cause each of these bikes reacts differently to the pods due to elevation and the changes in air pressure and yada ya... But you wont be able to regain the performance of the stock airfilter box and it's pretty much impossible to regain the throttle curve.

Best bet, run the box or change the carbs.

[seestheday]

I agree with Hellbilly.

That said, there are a few options for carbs.  Cycle-x even has a dual-carb setup with a custom manifold.

You'll probably end up paying more for carbs than you paid for the whole bike though, so.... it's your call if it's worth it for you or not.

[NKing07]

I appreciate the info guys, i realize this isnt the first time this question has been asked or answered, i just had my mind set on pods so figured i better ask before i moved on to plan B. I think i may just fab up a sheet metal housing for the original air box to give it a bit more of an industrial look and keep it running asthma-free. Next step is replacing that seat frame rail. Gotta find the tubing im gunna use as replacement. Ill post pictures next time anything significant happens. Cheers.

[slownugly007]

Hey bud, not sure if this is what youre talking about with your seat frame but I noticed your avatar and mimicked my seat after that exact bike. Heres a few picture to give you an idea of whats involved and if youve got any questions feel free to ask. Good luck on the build! Youre gonna love this bike when it done!

[NKing07]

Hey Slow, that looks great man, nice work. Thats definitely really similar to what im gunna do to mine. I really like that brat look. Did you raise the seat rails at all or is that stock height?

I was thinking fiberglass was the way i was gunna go with my seat pan too, how difficult was it? Cant be too hard, paper mache for grown kids.

Thanks for the post, might hit you up for some pointers if and when i get stumped. Cheers.

[slownugly007]

Nope, I just cut the fram rails about 1-2" behind the shock mount and welded the loop straight in. The kick up in the frame was stock frame, which I really like, it gives it another detail instead of being flat. As for the fiberglass it was an easy process but pretty time consuming.

I bought a sheet of bi axis cloth (i think thats what is was called??) It had chopped glass on one side and woven on the other, super strong and pretty easy to lay. I cut cardboad to fit it the opening between the frame, blue taped the entire thing so that it was all one level. I also added a raised are in the back for added strength, like a bead roll in metal.

After the blue tape I covered it in foil a/c duct tape, then rubbed a mold release over it (about 3 coats) You can use a type of car wax, but you may want to check on what kind works. This just allows the form to pull off after drying.

I laid 4 coats of cloth and resin, giving adequate flash time between coats, also my resin was a no sand resin so I didnt have to let it dry then sand before each coat, which made it a little easier. After it all dried.....VOILA! I had a seat pan that fit perfect...almost like it was made for it!?  Of course I had to cut and sand it till it was the exact shape I wanted but that didnt take any time with a 4" cutoff wheel.

Then I just laid some foam and cloth and I got what you see in the top pictures. Hope that helps ya some? If you have any questions just ask. Good luck bud!

Heres a link that shows how I did it with pictures to give you a better idea of the process:
http://www.customfighters.com/forums/showthread.php?t=22549

[NKing07]

Awesome, thanks Slow, once i get those rails where i want them and re-painted ill give it a shot. Should be fun.

[NKing07]

Could anybody tell me if the front wheel from a GS750 will fit my 750C?

Here is the wheel.

http://classifieds.castanet.net/details/suzuki_gs750_front_wheel/1195671/

Thanks!

[NKing07]

So I just got my tank back from sand blasting. I had noticed before I sent it in that someone had thrown rock guard on the bottom edge of it but didn't think much of it. Turns out the rock guard was thrown on to hide the fact that it was rusted right through all along the bottom edges. I managed to find a different tank that I actually like more, now the fun is getting it to fit. Heres the tank...


Now I have seen people with SOHC's cut off the two outside tubes that go over the engine and just run with the single backbone, is that do-able on a 1980 frame? Heres a pic, Tell me what you think.


Oh and I picked these up too :)

[Lucky 1]

The vacuum carbs get vacuum when the pistons go up and down, not from the air filters.

But with pods rejetting may be needed. Fuel mixture will be lean.

[Lucky 1]

Why would you want to raise the seat rail?

The seat height is already very high. 31,32 inches already.
IF you raise the seat platform your feet may not touch the
 ground and the seat will not interface with the gas tank


The step in that seat is to give you back support and also
the tail is raised to give the tire clearance.

[Lucky 1]

All the vacuum operated slides do is to compensate to atmospheric and altitude changes,
so the mixture can be right more of the time.

[Lucky 1]

The stock tubing thickness is only 1/16 inch!
By removing any tubes the bike front end can tweak
and twist. I would not do that.

Choppers have single tubes for looks, but the tubing is
larger diameter and twice as thick(.120) wall thickness.

[NKing07]

I wont name names, but I've seen people, who's opinions are quite respected on this forum, cut the outside tubes off. Is that really only possible on the earlier models? I'm raising the seat frame rails to achieve the look I want, I prefer it to not look so squat in the rear end.

Oh and I'm 6'5. I could sit on a Clydesdale and still touch the ground.

[NKing07]

Does anybody know what kind of trouble I'm going to run into with using these spoke rims? They are off of a 1977 GS750. Biggest issue, I'm sure, will be that they have rear discs. Possible? Nightmare? What am I looking at.  As  far as my research goes the rear axles are the same size, I havnt been able to find out about the front. Normally i would just trial and error it and see how it goes but the seller is in a rush to sell and I'm a little strapped for time. Appreciate any insight you guys have.

-Nick

[TOOLS1]

Unless you are going to be doing some high speed road racing I doubt that you would ever notice any flex in the frame with the tubes cut off. I know that Cycle one sells a hardtail, for the DOHC bikes that does away with the two tubes. The center one gets cut, and spliced right where the seat bracket is.
TOOLS

[NKing07]

Thanks Tools, I was hoping that was the case. Its only 1/2 an inch off on either side so I may try cutting those outside bars in half length-wise and welding  on a flat plate just so the tank fits.  Might as well give it a shot. If it doesnt work ill just cut them off.