Yammy's first overhaul

Batwolf

Batwolf

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Joined
Jan 21, 2015
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113
Location
Minturn, CO
Well, I ran the odo past 4k recently on Yammy and figured it's about time to give the ole 600 some love instead of gambling and pushing through this season. I pulled the head and removed the cylinders for a top end job; once I got the pistons off I found a cracked skirt on the mag side. Guess it was 'bout that time anyway. Really glad I caught it now because the cylinders look great still; had them honed to sure things up. Cylinders spec out nicely: both at 74.81mm. Contemplating a total overhaul; cost isn't an issue and I just want to have piece of mind. What do you guys think?
 

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Pistons and rings if one is cracked who knows when the next one will crack and maybe break and realley mess things up 4000 miles isn't a lot if money's no object you could pull the crank and have it checked too. Good luck
 
I was thinking just that as a matter of fact. Already got OEM pistons/rings/bearings/pins coming in the mail. As for the bottom end, I have the measurement spec for rod free play but don't have the means to check myself.. I've already yanked the motor and going to pull the crank tomorrow to send it out. This light 600 loved to rip before so I can't wait till this thing is running like new again!
 
I just had a piston failure on my '97 Venture 600 which is the same engine. Piston broke right where your crack is, glad you caught yours before it broke.
 
I lucked out. I was at idle and fouled a plug. When I went to change them out I noticed that one was slamed shut as if some thing had hit it. I still had good compression.

When I tore it down a huge chunk of piston skirt was gone. I split the crank case and only found a tiny piece so it must have exited the exhaust. No damage to the head, and damage to the cylinder wall was minimal.

I think we both lucked out! My clutch side piston was cracked in the same spot ready to let loose too. 2100 miles on mine.
 
I was concerned about the crank bearings but flushed them out and couldn't find any problems. I will know more after my pistons arrive. 1997 was a year of bad pistons in the 600 twin engine
 
Yea thats what I understood about the original '97 600s too. Did you buy new OEM's or something else?
 
I bought aftermarket pistons SPI I believe, which I have read mixed reviews about. I didn't want to buy OEM and have a repeat performance.
 
Let me clarify and say that they did update the design so I am sure you will be fine.
 
Yes I did. Had a heck of a time getting that flywheel removed. Actually broke the first puller. Finally let go after soaking it with PB Blaster all day.
 
I don't think that I would be sending the crank out, those bottom ends are pretty reliable. I have a redhead that has gone through 3 piston failures and still original bottom end. I just replace the pto bearing because it has the seal and the mag side seal. You never had any pieces go into the bottom end so I personally wouldn't worry about it especially with only 4000k on it. I know you have a different motor but that bottom end is pretty stout. JMO
 
I recently did a top end on my 600 and I used SPI pistons and everything has worked out well.
 
Sxr700, ya know I've been reading other guys' stories and that seems a common assessment. Guess I could be a little over worried about it. I need to figure out how to get a good measurement on side2side wiggle at the top of the rod so I can get a read of the bottom bearings. I see movement now but not sure if it is okay. I don't have the proper tool to measure but I do have the tech manual. I do have both seals on the way.
 
Haha, I just love this sled even tho it's not a big ole powder hound. It's outright fast! And light so I can toy around in the mountains behind my place. Have thought about a tunnel extension next year and down sizing the drivers so I can fit a 1.75 maybe.. Not totally justified tho since my 1.375" can break trail with 600lbs gross wt., just not up the mountain side! Haha!
 
Still waiting for a couple parts to arrive.. Aaannd its snowing. Just might have a Viper in my possession in near enough future to have fun with it this season!
 
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