I have a 97 big bear 350 4x4. On the way to the woods today the ol gal started losing power, I geared down and she finally coughed and died. The motor was smoking hot so I sat there for half hour, started her up and headed home ( less than a Klik away) where she lost all power and quit. I noticed quite a bit of smoke and vapor coming from the head gasket area. My first guess is a blown gasket. The old bird won't start, turns over good but no signs of life .
suggestions ?

 

Is there any oil in it? Check compression, my guess is there won't be any, check valve clearance first, in case it has simply lost clearance, but the head is probably going to have to come off and you will find out if the problem is a stuck valve, blown gasket or scored piston/bore, when you take it apart. Even if the problem is a valve or gasket, be sure to take the cylinder off and measure the ring gap of the top ring in the cylinder, more than about 0.025" and you need new rings, if the bore is worn, either check it yourself or get it checked, as excessive wear and you need an oversize piston and re-bore. If it is scored, again an oversize piston and re-bore.

 

Thanks for the great info, looks like I have a project on my hands. I'll be asking a whole bunch of questions be as this process unfolds -- I'm about as far from a bike mechanic as you can get.
Thanks again

 

Ok, so I've about convinced myself to tackle the head removal. Do I have to remove the front carrier and fenders ?

 

Don't think I have done a 97 Big Bear so can't say if you need to remove front plastics. On most ATVs you don't but it can make life easier. Have you checked compression, and what is it?

 

I haven't checked compression yet, I have to get to town today ( if the snowstorm isn't too bad) and get a compression checker.
Thanks Merryman👍

 

Compression - cold, if course cause it won't start ; just under 50 lbs.

 

[QUOTE=NSWhitetail;3447968]Compression - cold, if course cause it won't start ; just under 50 lbs.[
/QUOTE]

So......I'm guessing the compression should be about twice that
I'll have to take the bike to a real mechanic I guess to get a proper diagnosis.

 

Unless it is simply the valve clearances needing adjustment, the cylinder head and cylinder will have to come off, and all components inspected to find the fault. If you don't feel confident to do this, then best to take it to a mechanic.

 

Ok. Thanks for your help Maryman