98 Mxz 500 fouling plugs - Snowmobile Forum: Your #1 Snowmobile Forum

Gary46055 · 01-24-2008, 11:23 PM

I've got a 98 MXZ 500 LC. and occationally fouls the plug on the right side from if you are sitting on the sled. Also when R.A.V.E. valves are cleaned the one on same side always has a lot more build up on it than on the other side nd sometimes enough that it is a little tough to remove. Ussually clean carbs and r.a.v.e. valve every 400 miles or so. Sled has about 2,600 miles on it. Bought it about 5 years ago with about 649 miles on it and it did this back then also. Seams to foul more plugs on that side when running at slower speeds and never when running at a good click. Thanks for any help.

upersleder · 01-25-2008, 12:25 AM

do a compression check, you may find that side down alot. that would be the first step.

**RJ Gleason** · 01-25-2008, 03:33 AM

Time for a spark detector.

**smallengineguy** · 01-25-2008, 07:24 AM

Or a sticking choke plunger.

Gary46055 · 01-25-2008, 08:32 AM

Thanks for the info. That gives me some places to start. Will let you know what I find out.

Gary46055 · 01-26-2008, 02:54 PM

Checked compression. left side is right at 100 and right side is 110. This is a primer only machine, so bought a new primer to put on.

**smallengineguy** · 01-26-2008, 09:42 PM

COmpression is a tad low, should be 120 or higher. Might be why it's fouling plugs.

Gary46055 · 01-27-2008, 11:06 AM

So time for a rebuild or at what compression do you recommend for a rebuild? and what do suggest just go thru the top end?
Thanks

Kellan_723 · 01-28-2008, 12:30 AM

Before you rip it all apart, try smaller jets and what are you runing for plugs.

Kellan_723 · 01-28-2008, 12:34 AM

Before you rip it all apart, try smaller jets and what are you runing for plugs.
Is there bubbles in any of the gas lines going to the carbs?

So did it runn good before at all?

Gary46055 · 01-28-2008, 02:31 AM

NGK, I believe they are BR9es. The sled runs great. Just a little problem with fouling the right side plug(Primer Side)and the rave valve having a lot more build up on it than the other side. I live just northeast of Indianapolis, we are heading up to Traverse city to ride for the week. We are staying at Ranch Rudolf. Hope every thing runs great.

Gary46055 · 01-28-2008, 02:32 AM

Oh, no bubbles noticeable

**smallengineguy** · 01-28-2008, 07:01 AM

Let us know how it ran for you. Buying new rings, a top end gasket set, and a general honing of the cylinders will put compression over 130.

Gary46055 · 02-01-2008, 12:59 PM

Ran good. Rode about 360 miles and no fouled plugs. Was a little hard to start before, do to flooding starting first thing in the morning or leaving a restaraunt. But this trip no issues. Will do some work on it though. On another note. I have a 1980 Scorpion Sting that was given to me several years ago. It starts and runs okay but seems to die when it warms up or just doesn't seem to run long. Just like it will just cut out.