Ive got a 87 250R bored 60 over with an old as the hills PT race pipe and open air box with a uni filter. I am wondering if I would see any gain by going to a 38 or 39 mm Carb to replace the stocker. I have been thinking about doing it just to get rid of the wore out 34mm. I am also wanting to upgrade to a 330 or 350 Cyl and ESR pipe for next summer. But for now would I have any adverse effects by running a 38 or 39mm?

Thanks

 

I dont think that you would notice very much of a difference at this point. The engine can only flow so much. After the big bore and upgraded pipe I would def go to a larger carb though.

 

do you have any porting done to the motor. If not you should seriously consider just getting that stock cylinder done instead of going big bore. Unless money is no issue. properly matched pipe and porting, and 39mm carb can yeild over 55 hp on stock cylinders.

 

<div class="FTQUOTE"><begin quote>Originally posted by: Fulltiltrider

do you have any porting done to the motor. If not you should seriously consider just getting that stock cylinder done instead of going big bore. Unless money is no issue. properly matched pipe and porting, and 39mm carb can yeild over 55 hp on stock cylinders.</end quote></div>

thats pretty good power from a pipe, carb and port work. who did your porting?

 

well not just that, VF3 reeds, 01CR250 ignition, C-12 race fuel for the 208 psi. The cylinder is pretty much a copy of a MacDizzy 270 sleeper. Great for MX or woods. Wide powerband! Im getting another 250r that is going to be strictly drag. I'm seriously considering a Sabre racing 500 kit. But its ALOT of money. Maybe a 425 PSI motor. Thats a little cheaper

 

My other little issue is that it has to run on pump fuel 93 octane. Race fuel is just too hard to get for me. The only reason I ask this now is that I can get a good deal on a new carb.

PS there is no port work done on it .

Thanks

 

If there is no port work done you are not going to notice the difference. The motor is choked up internally. A carb will not help. Porting is not that expensive. Probably could get it done for 180 bucks. Porting a 2 stroke is the best bang for your buck. Hope this points you in the right direction

 

Do you think that using the bigger carb on the stock motor until I get some work done to it will cause any problems? Will it be over carbed?

 

no as long as it is jetted correctly. You may have a little hiccup when you are off the pipe and in low gear if you just stab the throttle open. This is caused by your factory reed cage. V Force 3 reed cage will solve that and give you a broader power range