high rpm miss

[help]

i have a 1999 banshee that i just recently purchased it has a weisco crank and pistons. it has been punched a 100 over and it ran great when i baught it. now it has a high rpm miss. as soon as it gets in the power band it just falls off. i'v checked the reeds and reed cages. they look great. i cleaned the carbs and the fuel filter. my coil and plug wires ohlm out good. i also did a compression test it had about 130 psi on both cylinders. i've been turning wrenches for a long time and im all out of ideas. if any one can help i really need it.

thanks :verymad:

[CMAC]

Is it a miss like its leaning out(running out of gas) What kind of carbs, air filter set up, stock heads? Did you check the screens in the gas tank? does it do it through all the gears or just a few?

[dajogejr]

How do the plugs look, is it fresh gas?

Check the pickup gap on the flywheel, then pull the flywheel off and shake it, see if it has busted magnets inside.

Gap should be .015 to .018....

.100 over? You're on borrowed time, my friend.

[jack24piper]

mess with the carb settins and richen it up

[dajogejr]

mess with the carb settins and richen it up

 

That's a good point....

When did you buy it, and how much have temps dropped since you bought it and it ran fine?

[help]

i put new plugs in it and it ran the same. they look good after it runs awhile. im running ngk9es. i was running8s but it seems to run better with 9s. it has stock carbs with k@n filters. the head is also stock.the fuel is good im running amsoil at about 40 to 1. i havent checked the screen in the fuel tank or the fly wheel. thanks for the input. i've had the banshee for about a year but i've only put about 15to20 hours on it and i havent checked temps. i havent done any mods on the bike it is the same as it was when i bought it. this is kind of a stupid question but is the a high and a low fuel mixture adjustment. or is it just jetting. it has a 310 main jet in it but it looks like someone has ran a drill bit through them at one time. but that doesent explain the miss because it ran great when i got it.

thanks guys i need all the help i can get

Edited January 11, 2007 by help

[CMAC]

Not sure what your trying to ask with the high low question. What Daj means is being the time of year it is you probably bought the bike when it was warm out and know its cold. cold air is more dence(more oxygen) so your fuel mixture is leaned out. More O2 than fuel to burn. Add more fuel richen up your jetts. I think thats what you were trying to ask. If not just ignore this.

[sheefreak]

Some snowmobile carbs have a high low adjustment on them. The banshee carbs do not. The airscrews only adjust the pilot ckt. As daj brought up, if it is colder out then last time it was running well, you may need to richen it up and would exlain that problem. But if not, you need to look at anything that would restrict fuel flow. Once you have eliminated all that, it is time to start thinking electrical.

[J-Madd]

I had that problem and tried all jetting combinations, different carbs, checked everything, and finally replaced the stator just to rule that out, and it fixed it. I think your problem is electrical, since it ran fine when you got it. High rpm miss exactly described my problem, and it was worse when it got hot.

[87sheerips]

When my CDI was taking a shit, it would die at high RPM's under load. If you can try out a buddies, try that. Or buy one for 50 bucks on here to keep as a spare none the less.!

[help]

yeah if worked on alot of polaris jet ski's and they have a high low setting on the carbs. and i also swapped cdi boxes with a buddy and it did not make a difference. so ill probably look at the stator. thanks for all the help guys i really needed it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1