I havent had the time to call or research this yet, but have any of you guys running the aftermarket carbs found a smaller lighter tension spring to replace them with? The two 35pwks together is killing my thumb. I even made a practice set of bars with a strong mocked up thumb throttle to strengthen it. But I have the new cable and everything works fine, just too much for me on long rides. Maybe my older age is making me into a wus, but I figure that a set off of maybe the 29pwks or something else would work better. Thanks for any help,Bubba

 

I dont remember which website did it, but they properly jetted Keihin Pwks from 28-35 mm and found that on anything less than a 400cc banshee, the 28mm made the most horsepower. I got the 28s bored out to 29.5 and I love em. Im sure theres someone out there who would trade you the 35s for 28s...

-nick-

 

Read it again please. I am wandering if a set of slide springs off another carb will work to reduce thumb fatigue. Does anyone know here? Thanks again

 

The springs are needed with that tension to push down the slides which cut of the air supply to the engine, with weaker springs you risk the quad staying WFO after you release the throttle, so DON'T RISK IT. Now what you can do is loosen the screws that hold the thumb throttle and turn it down some so it becomes a more natural push on the thumb, this will make a big difference.

 

i cut part of the springs off on my 35 nearly in half it still hurts a lil but its better then it was

 

If you do clip em keep the slides clean and smooth. The part about 28s working fine on a motor under 400 is right but only if you keep the revs down. Size or RPMS are the main things that call for a bigger carb.

 

ive always cut my springs in half on my mikuni 35.5's..... it might not be the best way but it works for me!

 

I have had people tell me that they cut them down, although I dont like the idea. I have adjusted the throttle every which way and nothing is to my liking. I am a high maintenence person and I wouldnt have any worries about them not coming back to idle position if using a lighter spring. In my opinion a longer lighter spring would be better than a shorter stiffer one.

 

I have to say no on that one Jakal, the reason they explained why they worked well was because of velocity. Sure the 35s can suck more air, but they suck it in slower. 28s suck it in much faster into the engine, thus more power. Its kind of like the high velcity porting your 4 stroke idea. Smaller intakes = more power.

-Nick

 

You are correct, but once the RPMs of a motor reach a certain level then the velocity is increased enough in the larger carbs to make the better power increase. Fact is smaller carbs will only feed so much and there is always a point where the motor needs more.