MX 470? Good? - Snowmobile Forum: Your #1 Snowmobile Forum

Rayce13 · 05-04-2009, 02:50 PM

I had a guy give me (yes free)

a '94 MX 470 (467) yesterday. It is in perfect shape, no cracks, tears, dents or bends and has a nice clean engine. Of course there is one problem one cylinder has no compression (brake side)

. The clutch side cylinder has 125 and it turns over easy so it doesn't seem to be a crank or other issue. I was going to part it out but after getting it home it is so clean and such a nice sled so I'm debating to just fix it. Two questions 1) how are these engines and the sleds in general; and 2) what process to go through diagnosing the cause of no compression on one side? I can get a new piston/rings but want to be sure I'm fixing the problem that caused it. Let me know if you think its worth fixing or if I should just part it out like I originally intended.

Thanks!

**RJ Gleason** · 05-04-2009, 03:18 PM

You need to see why there is no compression.
Look inside through the plug hole and see of there is a hole in the piston.
Pull the exhaust manifold and look at the sides of the piston too.

Rayce13 · 05-04-2009, 03:21 PM

Thanks. I planned on pulling the cover to check it out, I have a feeling I'm going to have to do that no matter what so may as well start with that and see what is going on.

**RJ Gleason** · 05-04-2009, 03:35 PM

If it's that good of shape, I'd fix it and run it. Those 470s are surprisingly quick.

Rayce13 · 06-30-2009, 02:02 PM

Well I am reviving this thread, I finally pulled the cylinder head and jugs and took the pistons out last night (been busy with my MXZ rebuild). The bad piston had pretty bad carbon buildup on it and it looks like the ring disintegrated with pieces of it smashed into the cylinder head. The jug isn't too bad surprisingly so I'm going to have it bored over which should be fine. Is this generally caused by it just wearing out or what makes a ring go bad like that? Also, I know I saw a chart somewhere saying how many CCs you gain with overboring but can't find it back, any ideas on what I would gain going .02 or .04 over on this?

**smallengineguy** · 07-01-2009, 07:18 AM

If it's just the rings that went, it could have been a number of things. How many miles on it?

Rayce13 · 07-02-2009, 11:51 AM

There are 4200 miles on the sled. It looks like the pistons are original.

**smallengineguy** · 07-02-2009, 07:06 PM

Check the carb boots for cracks, and clean the carbs while it's apart.