36MM Carb or 240 KIT ??

[Eddiet]

Which one of these mods would be my next best investmenet? I have an 01 220, rev pipe, Boyseen reeds, with the air box removed. I'm looking for more top end without sacrificing the bottom torque. I have a damaged 220 cylinder to work with or I can send the carburetor to be bored. I'm looking for the best bang for my bucks since I have to keep myself and two sons racing.

 

[Mac]

Since you have a rev pipe you need to let the bike breathe to get more ponies and that stock 33mm carb is gonna be too small. The stock carb will be even more of a restrictor with a larger 240cc bore.

IMO, I would get the RB carb mod first then overbore when a top end is due.

 

[Kaw_Boy_5]

Have you ported that cylinder yet. That really made a difference on mine. Fredette did the work and did one great job. When he did it he also bored the carb which was pretty cheap.

 

[Dr. Dirt]

I had my carb bored at a local machine shop for fifty bucks. Off the top of my head I think iI went to 152 main, stock pilot and not sure which notch on the needle I ended up with. I had the torque pipe when I made the change so that might make a difference but no doubt about the increase in the top end . Before it seemed to signed of way early but now it revs out nicely. For a guy on a budget I think it was money very well spent. If you give it a try let me know what you think.

 

[for]

Go for the carby job mate. I've got a 240 and they add low- and mid-range, but not top end. This is to be expected given that the carby and porting, etc, is designed to feed a smaller cylinder. Boring any engine out usually just shifts the torque curve lower down the rev range unless other mods are done to improve the breathing too.

If you've already got a 220, the increase in capacity moving to a 240 (which will not be a full 240, but 23x) is negligible and not worth upsetting the engine design so radically. The iron sleeve and (reputedly more expansion-prone) Wiseco piston both seem to make a 240 run hotter with a tendency to seize, and it's hard to get them jetted to idle nicely. It's not worth it unless you are desperate.

Craig