WTB: CB750 Piston and sleeve & CB125 Crank (Big Bore for my CB100)

Dirty Dan

Dirty Dan

Tasty waves and a cool buzz.
I'm wanting to give my CB100 a little more grunt. I plan on using the CB750 piston/sleeve + CB125 Crank.

I know it's pushing it, But It'd be awesome if someone had a 65mm 836 with a high CR forged piston... Factory is just fine, Though.
 
Re: WTB: CB750 Piston and sleeve & CB125 Rod (Big Bore for my CB100)

Still lookin'... Anyone have anything laying around?
 
Re: WTB: CB750 Piston and sleeve & CB125 Rod (Big Bore for my CB100)

I've got some NOS pistons, will check and see if I have any liners that could fit
 
Re: WTB: CB750 Piston and sleeve & CB125 Rod (Big Bore for my CB100)

I have a NOS cb750 piston
And a used forged xr200 piston
 
Awesome! Sounds good guys. Who's going to give me the best price? How about a bare knuckle fight to the death, Winner gets my money ;)

I'm thinking I'd like to go the 750 piston/125 crank route as that's what I've read the most about. I've seen people using entire XR200 top ends though... That seems like it could be fun. Decisions, Decisions...
 
XR200 needs a lot of work including boring crankcase mouth
You also need an XR 200 or XR/XL185 crank as it's longer stroke
 
Ah, Gotchya! I read that CB550F article you told me about, That was good stuff. Getting the head flycut doesn't sound like it's something a shop would have trouble doing, I just need to hunt down a shop around here that's willing to.

I'm also thinking a Mikuni VM26 would be a nice addition (per your 26mm recommendation!)
 
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Yeah the XR piston is a tone of work and probably not worth it for a street bike.
 
Well, I'm definitely interested in picking up the parts... Figure to be fair I'll give PJ first crack at the sale because he posted first, That and if he has a liner too I can kill two birds with one stone.

Whatever ends up happening, Thank both of you for taking the time to look for stuff!
 
I only have 0.75mm over pistons
The liners I got rid of when I sold the CB350 stuff I had (sorry, I forgot I gave them away)
CB550 liners will work but can only go to stock CB750 piston size, you need CB750 liner to go 0.75mm over (maybe CB650 would work, can't remember)
CB125 cylinder will bore to 61mm spigot gets too thin to go further (I used to do a few 145cc conversions in the 70's)
 
No worries, PJ! I think I'd like to stick with stock sized pistons for now. Curious, Do you remember what sort of speeds you were able to achieve with the 145 setup?

Surffly, Feel free to shoot me a PM and we can work out the details :) You wouldn't happen to have any liners too, Would ya?

Thanks again guys
 
We had a long gradual downhill past Sarn Services, friend had about 90mph on his XL'125' (aftermarket exhuast and Suzuki GT250 left carb on it as well)
He was 'wrapped' around the tank though
 
Not sure... Entire crank assemblies are pretty cheap on ebay I'll pick one up and report back!
 
I really want to do this on my CB100 but I'm having a hard time google'n the process for this conversion. You have any links? Is it as simple as getting a 750 piston/sleeve and 125 crank? Does the stock 125 crank stroke work? Do you have to get a shorten/elongated rod?
 
loser said:
I really want to do this on my CB100 but I'm having a hard time google'n the process for this conversion. You have any links? Is it as simple as getting a 750 piston/sleeve and 125 crank? Does the stock 125 crank stroke work? Do you have to get a shorten/elongated rod?
Click to expand...

You got to be joking ::)
If you need a step by step, it isn't for you
You machine top of piston and use as much stock stuff as possible.
It's the kind of thing I used to do because people said it wasn't possible
 
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