38 or 40.5 carb

[albertp86]

Ok so I went to the dunes this week with my new esr 310 pv, 9 port,3 mil stroke, 38 as, running pump gas, 13/38 gears, 8 paddle haulers. I noticed that my top end could be a bit better. So I thought, what about a 40.5 carb. People tell me that I will lose bottom end. Can someone chime in on this. I think that because I have a pv that I will still be able to keep bottom end power.

The type of riding I do is duning with a little bit of draging.

I am also switching to a v force reed as well from the rad valve and am thinking at going with a 14/38 gearing and 7 paddle haulers. Any good info would be great.

[Honda 250r 001]

i would try a 39 pwk if i were you, plenty of top end without the sacrifice of bottom. In fact i have a pwk 39 that i will trade for your 38 air stryker because im wanting to do mx.

Let me know

[250rPRIDE]

no way go with the 40.5 if you dune and drag only thats what you NEED.. dont waste your time with a 39.. i run and 40.5 on a 250cc r and it still pulls good. dont go with a 14 front untill you try the new carb also i always did better with a rad over v force and use a k n N for more top.. also make sure the rad is ported it helps a lot.. goog luck..

[Honda 250r 001]

Originally posted by 250rPRIDE
no way go with the 40.5 if you dune and drag only thats what you NEED.. dont waste your time with a 39.. i run and 40.5 on a 250cc r and it still pulls good. dont go with a 14 front untill you try the new carb also i always did better with a rad over v force and use a k n N for more top.. also make sure the rad is ported it helps a lot.. goog luck..

You can always get the 39 bored if you dont like it. Plus you will loose a bunch of bottom end with a 40.5. Duneing takes a lot of power and u need a little power out of the powerband or its hard to get around.

[albertp86]

I have a rad valve now. It's been about 7 years since I replaced the reeds. How do I port a rad valve or who will do it. I have just always heard so many great things about the v force 3.


The reason why I ask about the carb is that I got my butt kicked by a regular esr 330 with a 40.5 carb and no stroke. His bike ran great with good bottom end power. I know cause he let me ride it. I just purchased this 38 a/s and thought that I would lose all sorts of bottom end power. Bit then again I have a power valve and 3 mil stroke

[250rPRIDE]

ftz or fzr i can remember who but they port the rads update the reeds and get it ported and go with the 40.5 with a big k n N and you will see a huge differance i promise you will be happy with the 40.5 by the time you pay to get a 39mm bored and pay shipping twice you way better off selling your new 38asw for 150ish and go buy a new 40.5 for 200-250 range that way you know its new and right.. this is what i would do you can take it how you want it,, goodluck

also how much do you weigh??

[albertp86]

I weigh 185 and also run pump gas. The 38 as is at 185 which I might drop that down to a 180. What's your thoughts on that set up

[250rPRIDE]

oh well thats good new on the weight, i am 165 and can afford to give up some bottom end and you sould be in the same boat, but ya on my 250cc bore i run anywhere from mid to upper 170's to a 185 main if its cold, thats when it works the best. but you should be richer than this with the bigger bore and stroke, also my elev. is about 2700 ft.. im telling you with a well tuned 40.5mm you will be very pleased..

the pump gas is also ok for top end you dont want a lot of compression. i run about 165lbs and use 94 octane with amsoil 50:1 i tryed 180lbs 200 210 ect.. and this lower compression run the best time at the drags..

[albertp86]

So I guess I would not lose alot of bottom end power based on all of the feed back that I'm getting and that I would gain some more top end power. Am I correct??

[250rPRIDE]

i am not claiming no lose of bottom end.. but if you can gain a lot more top and keep the bike in the mid to top power range, then you will get huge gains. but i can still trail ride my bike and its only a 250 so a 310 pv with stroker you should not have any problems

but in short you will loose bottom but make up for it on top.

[machwon]

No question, run a 40.5mm carb. Even the stock cylinders will make more power with this carb. As for losing bottom end, its down where you don't use it anyways, expecially at the dunes.