600 twin poblems

S

srvfan

New member
Joined
Sep 2, 2003
Messages
47
Location
massachusettes
Ok my brother has a 97 600 twin. it blew the recoil side piston at 3200 miles. It didn't burn down the piston just disintegrated around the top edge, took out the jug head etc. he rebuilt it with a Hauk 1200$ , 700 big bore kit. 1300 miles later same deal same piston. It looks like the top edge of the piston was pushed upwards by the ring??? Shattering it and gouging the liner. actually it's mildly scratched. Can a new liner be pressed in ? about what does that run? More importantly why does this happen and how do we stop it. :o| :o| :beer:
 
I am trying to work the bugs out of a 700 kit. Would you mind telling me what you guys are running for jetting, clutching, etc.. and at what altitude/temp? Also are you running a single or twin pipes?

Thanks, Ryan
 
1500ft ele 0f jetting We went 1 size under what Hauk said as it was big time Rich, pistons still fully black so still rich , stock pipe , boysen reeds. The clutching is all messed up. it's got ahauk kit so who knows? I know it has the stock ab weights and rivets. Has a diferent primary spring and has a hauk helix. It worked like crap until we put a Silver in the secondary. Basically the Primary was pulling it into high gear way to quick. turns around 7800 before it blew up. I'll get the jet sizes from him
 
right it's a 97 how do we stop this what is the fix?? the first time it looked like the ring turned. this time I'm not sure if it turned or just caught a port???? If he puts money into it how do we stop it from doing this??? :o| :o| :rocks:
 
I'm having a hard time getting enough fuel into mine. It's the 95 style cylinders (500cc) bored to 700 with some pretty heavy port work done. The heads have been cut, re-chambered and o-ringed. Guy I got it from said it was a motor that Yamaha's R&D department did back in the day. I've got about 15 miles on it so far, and it keeps wanting more fuel. Right now I am running abou 25% 110 race gas till I get a handle on it. The squish is bigger than the solder I had to check it with, but the compression is up around 175-180 psi(cold motor).
 
Wouldn't detonation put a hole in the piston or look lean on top? This piston is black ,oil ,light carbon even all across. anybody got a 600 PTO side jug so he could go back to the 98-99 set up? That's what he'd need the original jug was scratchted right through the nicasel. The 700 jug is scratched but not too bad. Maybe we could get most of the scratch with a hone? It's right at the port it doesn't go all the way up.
 
Your description sounds like detonation. It will do different things to different motors.

I have a set of jugs off my 98 600 twin. I might be interested in a doing a swap. My stockers for his 700's. Let me know.
 
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