[MotorOilMcCall]

Hey guys, long time reader, first time poster... Did a search and nothing really fit my symptoms.

I have a 97 Indy 500 LC, clutched and geared. It was running fine at the start of the season. Went to a trail with some buddies, hit the first field got left in the dust. My sled hit about 45mph and that was it. After riding for about 30min it picked up, like the throttle rolled into place, ran fine the rest of the day.

Later that week, I rode about 80 miles from my house, and the thing ran like a top the whole time. Hitting 80mph was no problem.

Went out to the SledFest out here this past weekend, and the first 15-20 miles I could only hit 40-45mph. After that, it ran good about 85% of the time. But here and there it would still bog out and slow way down. Just fired it up in my yard to re-align the ski's and its still bogging. It grabs real good with the clutch and will still spin the track in the loose snow. But once it catches up to 6500rpm it just tops out... 40mph roughly.

My buddy said it could be the high tension coil, but I'm not sure it has one. Could it be the carbs? Ignition? Looking for some ideas without replacing a bunch of parts I don't need to. Just had to put about $1k into my truck to replace the injection pump, so I don't have cash to spend on this right now...

 

[DubIllD]

These are both good and might help:

http://www.motorcyclecarbs.com/carbs101.pdf - Look at fig 7 and try plug chop.

http://www.snowmobileforum.com/engine-drivetrain/26360-generic-clutch-cleaning-advise.html - Check out the clutch.

 

[palmrose2]

My first guess would be that you have fuel problems. Like a sticking float in one carb. Can you tell if it's running on both cyl when it bogs? I can easily, but I know some can't.

Do you ever drain the bowls? The little hose coming off the bottom of Poo carbs catches water. It should be dumped periodically. Ice in carb bowls doesn't work well. Sled cold runs bad. Sled warm runs good. Warm melts ice.

If you have never cleaned the carbs on a 14 yr old sled, I think it's time.

The first sign of weak spark is miss-fire under load @ WOT. The denser air/fuel charge is less conductive to electricity than low pressure air/fuel.

 

[MotorOilMcCall]

Its only missing on one cylinder, but when it bogs it seems like that cylinder is still sucking fuel, because my mileage goes way way down... I'll drain the bowls, gonna have to warm it up to do that, might have to take the hair dryer out to warm up the carbs...

I rebuilt the carbs a few years ago, but I guess it might be time again. Its just strange that its doing this intermittenly. And like I said, it runs bad even when its warm sometimes.

Its not mis-firing under load... Its not mis-firing at all actually, so I kinda figured it wasn't ignition unless its just weak spark, but then I would think it wouldn't run at all...