Author Topic: compression check  (Read 5707 times)

Offline harleymike

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compression check
« on: November 04, 2008, 08:14:00 AM »
Just baought a 97 yamaha vmax 600xtc...compresssion is 118 and 120.Does this sound alright for this machine.
What would be considered low, and time for new rings....
thanks for the help
Mike

Offline DaJudge

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Re: compression check
« Reply #1 on: November 04, 2008, 10:37:32 AM »
That is not too bad, I always liked to see 135 to 140, but the '97 600 twins had a bad set of pistons in a lot of them. The pin that holds the rings in position would come out and take the cylinder with them when the go. It would not be a bad Idea to change both pistons and rings. You also may want to use a thinner head gasket to increase the compression. All of these 600 twins liked fuel and didnt get very good fuel mileage, but when properly set up they ran pretty good.
DaJudge

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Offline harleymike

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Re: compression check
« Reply #2 on: November 04, 2008, 05:21:46 PM »
You say bad pistons, how do I know if I have the bad pistons you are talking about...
Thanks mike

Offline DaJudge

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Re: compression check
« Reply #3 on: November 04, 2008, 10:25:34 PM »
You wont know it until the locating pin comes out and the rings twist and hook the intake ports. By then its too late and you will be replacing the pistons and cylinders. This USUALLY happened before 3500 miles, but I had one do it at 4500.
DaJudge

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Offline harleymike

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Re: compression check
« Reply #4 on: November 12, 2008, 09:22:13 AM »
talked too yamaha , they said it was the 500 twins that had some bad pistons. Not many. The 600 was fine, and there are no recalls on them...
They said my compression is ok,,,,

Offline DaJudge

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Re: compression check
« Reply #5 on: November 12, 2008, 10:15:59 AM »
They lied to you. It wasnt the 500, it was the 600. I know because it happened to one of my sleds and a bunch of other people that I know. Yamaha never recalled any of the sleds. If it happened to yours while it was under warranty, that was good for you. Yamaha would fix it. Some happened out of warranty and the owners had to pay for a fix unless the dealer went to bat for them.

Here is a link to a thread on pistons on the TY site. Unfortunately it doesnt go further than 2003 but some of the guys mention the "updated pistons" for the '97.
http://www.totallyamaha.net/forums/showthread.php?t=680&highlight=pistons
« Last Edit: November 12, 2008, 10:33:34 AM by DaJudge »
DaJudge

It is your $$$ Buy what you want and enjoy what you ride.

Offline harleymike

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Re: compression check
« Reply #6 on: November 12, 2008, 12:42:19 PM »
interesting.
Well i was planning on pulling it apart next summer and do the top end. I guese new pistons are in order.
I can't do it now.My wife will kill me , I just boaught it and I dont think she would appreciate it...
I will hope too get throught this winter then fix it.
thanks mike