help with 97vmax 500

TTT any further Ideas? I hope to get it back together in a week or so. Compression test and attempt to fire her up. Cleaned and check carbs all looks good. I am wondering if she wasn't Ice'd up the morning she went and a ring got to hot and welded to the piston loosing the seal. The sled would not idle verry good and was smoking alot too. Oh well time will tell, Thanks
Blue
 
Hard to telll from this side of the puter blue,things sure look normal,just take your time pay attention to detail and should be ok..OEM parts...

you said rings were free when you took it appart right??
 
I'd just slap a complete set of Yamaha pistons, rings, pins and clips in her. Put a new set of gaskets in. You can thin the head gasket if you want while you have it out.

If you are really cost minded and since you live in Maine anyway JR Graham has complete sets of pistons for about 1/2 the cost of Yamaha pistons. I have them in my 600 and they work just fine.
 
I wonder if a leak down test before you tore it apart would have better pin pointed what was the real cause?

I did a 500SX a while back that had an oil pump go but there was compression on one cylinder still.
 
just a thought .The sides of both pistons seem a little brown to me {compression blow by } When you first removed the cyl's were the rings stuck even a little bit will give you a loss of compresion.Also both crowns are different colours check those seals oily drule indicates leakage,If the carbs haven't been drained check for water.
 
Tim, Thanks for the reply. The rings were moving when removed but I did poor oil down the plug holes so maybe they freeed up? I wiped the crowns to check for abnormal heat or cracks. Seals look good, plugs have a real good color so I don't think it was running lean. Carbs have been cleaned and found no ICE only gas ( but it was warm in the shed.)
Blue
 
Update on Vmax 500

O.K, Pistons replaced, rings, gaskets complete upper rebuild. Compression is 120psi per cylinder. Carbs have been cleaned , airbox cleaned,reeds are fine sled builds compression and will run below 4000 rpms and no power! CDI ? I check spark is there on both cylinders but appears weak. Plugs are really wet due to extra oil for upper rebuild. I am back to square one! I think the CDI is not sending the timming signal ? Please help, I am open for Ideas! Thanks Blue
 
Run it to try and burn the oil out, because I know my sleds act sort of funny after they have been fogged. Once the oil burns out they run fine.
 
bluebullet said:
O.K, Pistons replaced, rings, gaskets complete upper rebuild. Compression is 120psi per cylinder. Carbs have been cleaned , airbox cleaned,reeds are fine sled builds compression and will run below 4000 rpms and no power! CDI ? I check spark is there on both cylinders but appears weak. Plugs are really wet due to extra oil for upper rebuild. I am back to square one! I think the CDI is not sending the timming signal ? Please help, I am open for Ideas! Thanks Blue
Click to expand...

without confusing the issue any more than one has to, but, by-pass T.O.R.S. and check that off your list... you did have the carb rack off and if the free-play isn't properly adjusted, you might get similar symptoms as described.. try to elliminate things one at a time...
 
Spark seems ok just seems a little weak, yes it is blue hard to tell with all the extra oil. I did not unhook the throttle or oil pump but how do I bypass Tors? Can I just unhook? It does act like it is being dampened by something, I thought of that last week. Throttle cable acts fine gap is correct as per the manual and also carbs are syncronized. Thanks I plan on playing with it some more tonight after work. Please keep the Ideas comming! Thanks Blue
 
Time to check out electrical,coil,stator,wires,boots..

i don't think you have a tors problem,if you did you couldn't
get over 3,000 rpm,and it would sound like a rev limiter..
 
daman said:
Time to check out electrical,coil,stator,wires,boots..

i don't think you have a tors problem,if you did you couldn't
get over 3,000 rpm,and it would sound like a rev limiter..
Click to expand...

pehaps it's a good idea to get this out of the way first?... he didn't mention if he was driving around or not, so maybe, he may have been mistaken on the RPM's...

why rip into a pail of other issues before he elliminates others first? systematically!...

An intermittent TORS, will allow the engine to rev past 3000... then limit it, when TORS is activated....



many, many issues like this get lost in the multitude of suggestions... just trying to see things elliminated in a systematic fashion... this time!...
 
TJ500 said:
pehaps it's a good idea to get this out of the way first?... he didn't mention if he was driving around or not, so maybe, he may have been mistaken on the RPM's...

why rip into a pail of other issues before he elliminates others first? systematically!...

An intermittent TORS, will allow the engine to rev past 3000... then limit it, when TORS is activated....



many, many issues like this get lost in the multitude of suggestions... just trying to see things elliminated in a systematic fashion... this time!...
Click to expand...
he can do what he wants and filter through the info just throwing things out thats what he asked for..


NONE of my yamaha's will rev over 3k when tors is activating..thats how
it's set up to act(2,800 to 3,000rpm's).
 
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