Yamaha big bear 350 NON RUNNER

[Wolf Studios]

Hi guys so I'm looking for any help or advice with a yamaha big bear 350 1997 (i think) it's fairly dirty and just been say for many years, boss says it's a non runner and I've tried and it will not start, ideally would love to do it up and get it running but have been told the engine has gone, cannot find a new engine anywhere. Anything I should check first before just taking the entire thing apart? 

[Frank Angerano]

Wow that’s filthy !!!! I would wash it down  as best possible and start checking things out. Make sure there is oil and the fluids are good.

1. See if the engine turns by pull starter or crank. If the engine cranks then that’s a good sign.  Pull the spark plug to make it easier, and spray some WD 40 into the spark plug hole. If it’s  seized up then it’s a problem and the heads going to have to come off at the very least. 

2. Drain the oil and inspect it for metal particles that could be from a blown crank bearing. 

3. Take a compression reading (if possible)

4. Pull the carburetor off and rebuild/clean it and put it back on and see if it will fire up. (But this only applies if the motor turns) 

You can connect a battery and jump it If you want so you can  really crank it over as well. 

If the previous owner said the engine is dead it could be from a blown piston or a main crank bearing or the transmission is blown. So the engine may run but the bike does not move or vice versa.