Revs too high

[Dan Bennett]

Well, i just got my bike together but it's not running right. It idle's perfect for as long as I let it run, but as soon as I touch the gas it quickly revs up really high, and I just barely touched the gas, maybe 1/8 throttle if that. Fourtunatly I had my thunb on the kill switch so I got it shut down quick. It does this every time I start it and I can''t figure out what it is. The carb boots look good, no cracks and they're on tight. Any idea's? I know the main jet its way too big for my set up, but I didn't think that would cause this problem.

 

It's a 97

Stock cylinders no port or bore

fmf pipes

no air box lid

340 mains

25 pilots

Cool Head with 21cc domes

 

I just put the cylinders on with new pistons and all new gaskets, I'm getting about 135psi in both cylinders.

[njbanshee]

Sounds like you have a problem in your carbs. Try taken them off and cleaning them. I would definitly rejett if you know it wrong. Good Luck.

[TWILES]

My 500 Quadracer did that once but it was pulling air from the back of the cylinder. Too big of a main jet won't do that. It should just flood out. I'd bet you have pilot circuit problems. Clean the carbs out good and use a 280 main and stock pilot. I think the air screw needs to be out 1 and 3/4 turns with the needles on the 3rd or 4th clip or do what I did and pay $80 for the Dynoport kit.

 

My Banshee never did idle with aftermarket pipes. I set the carbs the way the paper said and left it.

Edited August 15, 2006 by TWILES

[dajogejr]

My 500 Quadracer did that once but it was pulling air from the back of the cylinder. Too big of a main jet won't do that. It should just flood out. I'd bet you have pilot circuit problems. Clean the carbs out good and use a 280 main and stock pilot. I think the air screw needs to be out 1 and 3/4 turns with the needles on the 3rd or 4th clip or do what I did and pay $80 for the Dynoport kit.

 

My Banshee never did idle with aftermarket pipes. I set the carbs the way the paper said and left it.

 

 

TWILES...that's three posts in a row I've looked at where you've given inaccurate advice.

 

If you can't get a banshee to idle with aftermarket pipes, you did something wrong, that's not just the way it is.... ::

 

Dan,

The best thing you can do is this. Either you do have an air leak, or your carbs are sticking...

remove both carbs, and clean the bejesus out of them. The stock carb slide configuration sucks.

 

Any tiny bit of sand or dirt passed through the filter can cause one or the other to stick.

Remove the float, needle and seat, pilot and main jet. Clean all jets and passages real good.

Clean the inside of the carbs where the slides go very carefully...

Unscrew the choke, clean that as well.

 

I normally use brake cleaner because it cleans great and dries very quickly.

 

Remove each of the needles from the slides, and roll 'em. Make sure they're not bent at all, a bent needle can cause a stuck throttle, too...

 

If you clean the crap out of both carbs, and this still happens, you may have an air leak.

 

Have you sync'd your carbs properly too? That can cause erratic idle, but normally won't cause it to sky rocket RPMs.

 

Start out with 300 mains, but...as TWILES said, you'll probably end up with 280 (ish) on the mains.

This is if you're at or around sea level, 65 to 90 degree temps or so.

You're gonna have the carbs apart, might as well change the jets now instead of later.

Do NOT buy the DYNOJet kit...it's a waste. You can get better needles from Toomey (made by dynojet) or Vitos. These aftermarket needles will eliminate the lean spot in the middle of the RPMs. However, these wont' solve your problem at hand.

 

Do you still have the TORS adjusters on there, by the way?

 

Lastly, since you have the lid off, you do have a pro flow kit or other means that seals the carb to the box, right?

 

Good luck!!

[Shee-Male]

did you just wash it?, if they're stock carbs, theier famous for sticking.

Give them a good cleaning and make sure you don't have the slides in backwards.

[Dan Bennett]

Ok, thanks everyone for all the insite.

 

I took out the carbs and cleaned them then cleaned some more. took everything little screw needle and jet out and cleaned all those, put it back together and I THINK it's better now. This bike is new to me and didn't really run when I got it, so it's kinda hard to tell if its right. I went up to about 1/4 throttle and it seemed to rev up to it instantly and then went back down to normal, going to have to wait until the am to actually ride it so I don't piss off the neighbors. Do these bikes rev up that fast? I only ask because I have a tecate-3, it revs quick but not nearly as fast as this did.

 

Oh yeah, there is an air filter on it and the plate says pro flow, just didn't come with a lid for the air box.

Edited August 15, 2006 by Dan Bennett

[dajogejr]

JUST gotta ride it now, be careful. Those stock carbs can be a pain once they get a little dirt in 'em, but..they're actually very efficient.

 

They rev pretty quick in nuetral.

 

Don't forget, you have two small pistons working together...not one big one...