Newb needs help with 600 Grizzly

[Bigblockorwalk]

Hey guys, just bought a 1999 600 Grizzly with a bad motor, 4700 km on the bike. I've got the motor out of the bike, just getting ready to split the cases. The previous owner had it bored out and a new piston installed, shortly after it started making noise and quit running. Not sure if this failure is related to the rebuild or not. The oil filter is full of aluminum, the head and camshaft are scored up pretty bad. Once I get the cases split I'm sure I will find more damage than that by the ammount of metal in the filter. I have found another motor for parts. My questions are:

What are the known weak points of this engine and what can I do to make it live longer?

Is there any way to get some extra power out of it? I figure since it is apart already now is the time.

How are these bikes overall? I paid $800 for the bike so I can put abit of money into it but I don't want to go crazy. What are some things to watch for?

Thanks for any help you can give.
Chris

 

[maim]

well. i would check the head for damage as from the parts fiche, the cam runs in the head with no bearings or bushings. if the aluminum is discoloured, odds are it is scrap.

could always throw aftermarket cam from these guys http://www.webcamshafts.com/index_blank ... earch.html and the piston they spec while you are at it. only other thing i found for that quad was a clutch kit for larger tires.

 

[Bigblockorwalk]

Thanks. Yeah the head and cam are scrap. I split the cases last night and it seems all the metal came from the timing chain that was rubbing the front of the case... untill it jumped and the piston hit the valves. Good news is I found a parts bike for $350

 

[Bigblockorwalk]

Well it looks like I finally got to the bottom of this one. Whoever did the top end on the bike did not put the front timing chin guide back in, that led to the chain rubbing on the case and making a bunch of aluminum filings go through the engine, which scored up he cam and the head. Finally the chain got lose enough to jump a few teeth which pounded the piston into the valves.

 

[maim]

sounds like it had a back yard hack job. might have had the tensioner go as well. cost me 2 custom intake valves, piston, timing chain, guies and lower case on my xt whe my tensioner failed.

 

[grizztracks]

Well it looks like I finally got to the bottom of this one. Whoever did the top end on the bike did not put the front timing chin guide back in, that led to the chain rubbing on the case and making a bunch of aluminum filings go through the engine, which scored up he cam and the head. Finally the chain got lose enough to jump a few teeth which pounded the piston into the valves.

How do you forget to put it in. I've done several motor jobs and always keep my parts together and organized. I guess when he got done he figured those extra parts weren't needed.

 

[Bigblockorwalk]

Yeah, I have a hard time seeing how you could overlook that. Even if the guy found it on the bench after the job was done, he should have taken it apart and put in. I kinda feel bad for the guy who sold the quad to me.