Hey guys. Im trying to get my 600 grizzly back together but right before i started reassembling I noticed that the piston end of the Rod has some scoring inside... I was not real thrilled about this. If I slide the wrist pin in, it is very smooth going through, no catches or anything, and spins nicely in the rod. Im thinking since there isnt a big range of movement at that end of the rod that it may be ok, but I went ahead and quit assembling for the night to try and gain some info on what would be best for me to do about this issue. Not sure why i didnt pay attention to this before. The reason for the tear down was piston scoring/low compression. Bored it .5mm over with new piston and all that is good, so this is my only hangup. The rod shows no signs of being hot, and the crank side of the rod is nice and tight and feels smooth. Im really hoping to not have to split the case... Any info or help is appreciated. Sorry the pictures arent great...

 

even though the piston pin is case hardened and tougher than that rod- that rod looks pretty bad to me. Problem is, as that clearance between the pin & rod gets worse, it'll start "slapping" or "knocking" - the weakest point is where the pin goes through the piston skirt- that's what will break first.

so- gotta ask yourself- is it easier & cheaper to replace the rod now while you have it out and the top end off the motor, or when you poke that rod out the side of your jug or crankcase after it gets worn to the point of failing and it breaks the piston skirt- and letting all that crap fall into your bottom end?

I think you know the right answer, go with that feeling in your gut

 

Thanks for the reply.

Yes, its a little worse than I would like for sure. I may have went on and assembled it if it werent as bad, but there are a couple grooves and i thought it would be a good idea to get some opinions.

Im still not sure what to do though. There is virtually NO play between the rod and wrist pin. It is a very snug, and smooth fit. My thoughts are that it may be just fine since there is no binding and it will have oil lubing it obviously. If there were play in the wrist pin and rod, I wouldnt be here asking this question, but since the fit is still nice and snug, im thinking its possible to still last a very long time?

Im going to have to think on it a little for sure, and anymore input is appreciated as always.

 

Ok, thanks to you and OPT I have had a reality check... lol

Off to order a new Rod and work on splitting the cases after work tomorrow...

 

it's still an uneven surface- which means the pressure is not equal across the surface of the pin and the softer rod- saying it has "virtually no play" means nothing- that piston is slamming up & down thousands of times per minute- even .001 of an inch of play will create enough slapping to greatly stress that aluminum piston skirt which will eventually wear out and fail.

if it were my engine- I'd replace it. that's the best advice I can give you.

 

opt is a wise old man

happy to hear you're fixing it right!

 

Yep, the rod is ordered and I will be splitting the case as soon as I get the time. I did it on my old suzuki quadrunner. I figure this one may be easier if anything since it doesnt have a 3 speed sub transmission with 15 forward gears and 3 reverse.

Worse thing is I didnt want to have to haul it to the dealer to have them pull the magento, but I really dont have a choice other than spending about $40 on a magneto puller.

You are right though, I would not have had peace of mind riding it had I left the old rod in it. I would have always been worried about it. Should be good for a good long time once I get it back together.

I gotta get this thing going. Riding season is almost upon us!