97 VMAX 600 XTC runs great till warm then get TIGHT

K

Kenora

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Nov 13, 2012
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55
Location
Kenora, NW Ontario
It was running like a top, I ran 3 tanks of ethanol free gas (Shell 91 in Canada). The oil pump is working properly as I had to fill it after the third tank (each only got down to 1/3 or 1/2 before refuel).
I was on the lake running around at 7000 rpm max but varying the throttle and never pinned it at all (I saw a max of 65 mph or so)...the temps were -25c so I was careful not to run it too hard. (I ran it at 7000 rpm for no more than 30 seconds then back down to 5500 or 6000 or so)
Whn I rolled to the garage I let off the throttle and it died without me needing to shut it off (that has never occured before)...I tried to start it up (elec) but I couldn't turn it over with the starter (I got real worried here) I also couldn't pull it over with the rope starter so it was TIGHT.
I pulled the plugs and both were WET and BLACK; there was no metal.
After it cooled (4 hours) I was able to start it with the elec starter and it ran/idled perfectly for 10 minutes however it suddenly siezed up again and like before there was no turning it over with the key or rope :(
I let it cool overnight and pulled the plugs again, same as before. I was able to pull it over with the rope and with the starter (I disconnected the plugs so it wouldn;t run)...
Can someone please tell me whats going on...
fyi... 5400 miles
compression in Sept was 125 psi both sides (I can't tst it now as Im at the lake)
It had the top end (new pistons/rings and hone) done last winter and about 200 trouble free miles since...I broke it in over 100 miles as recommended, lots of heat/cool cycles/no more than 1/3 throttle, then 1/2 throttle then 2/3....I have never had it WOT since the rebuild.

I am thinking its in the bottom end....ideas...PLEASE?????
 
I doubt this is the problem but the vmax and the viper to my knowledge have a smaller pump to reduce the waste. On my 98 vmax 700 i sometimes have to give it a little bit of gas while trying to pull it over. It may have been because of that but i highly doubt it. Just some background info for you.
 
Air/fan cooled twin right? If it were botom end I would suspect it to seize back up ALOT faster than the ten minutes. Oil pump may have just failed or some other problem stopping oil and your pistons are swelling as they heat up
 
No these are liquid cooled twins, basically the same twins in the old vmax's.
My best guess would be the oil pump is gone, but with these sleds when it goes it runs wide open. Thats probably the reason your getting a lot of black on the plugs. The reason it may be hard to turn over could be due to the oill pump dumping tons of oil into the cylinders which fouls your plug then hydro locks the engine.

It was a safety feature built into the oil pump so they would melt a piston. It does sound like your using a lot of oil, I ran 3 tanks last year in my 97 600 xt and I still had 1/4-1/3 oil left.
 
I have run sleds in the past with the oil pump zip tied wfo. Never had any problems, its like mixing at 16 to 1.


My guess is that the sled was soft seized and now its smearing aluminum from the pistons to the cylinders every time it gets hot.
Fhen locks up.

Fyi, Hydro lock is not going to keep you from turning the engine over unless its almost full of oil or gas.
Did you check fhe tolerances before you out it together?

What type of pistons are fhey?
 
I have run sleds in the past with the oil pump zip tied wfo. Never had any problems, its like mixing at 16 to 1.


My guess is that the sled was soft seized and now its smearing aluminum from the pistons to the cylinders every time it gets hot.
Fhen locks up.

Fyi, Hydro lock is not going to keep you from turning the engine over unless its almost full of oil or gas.
Did you check fhe tolerances before you out it together?

What type of pistons are fhey?
 
Although rare yes its possible oil pump quit pumping or line broke fell off as well as I beleive they are a gear driven pump. Were gears/busshings serviced? Is coolant circulateing?
 
Coolant is definately circulating, the heat exchangers get warm to the touch, even hot if I let it idle long enough. I just started it up and it runs perfectly, this time I didn't let it get hot and stop on its own.
The oil pump appears to be working as it smokes like a beast at first start then settles down to what appears normal.
I shut it down every couple of minutes as it warmed up to see if if was getting tight by pull starting it instead of using the electric starter....no issues, it starts on the first chug! I restarted it 5 or 6 times before I chickened out as it was getting up to "drive-off" temps; well warmed up :)
There are no abnormal noises when starting or when running.
My wife tells me there was a squeek from what she thought was the belt but in retrospect may be something else when turning the handlebar hard left or right and manouvering in the yard...I suspect that may have been something getting real tight, mind you why it only happended when the bar was turned hard left or right is a mystery.
Anyway I didn't let it get hot enough to seize up his time since it can't be any good for the engine.
Can someone expound on what a SOFT SEIZE is and what I should look at next.
I never checked the tolerances, the pistons/rings/gaskets are all Yamaha. A friend assembled it and like I mentioned before it ran perfectly for a couple hundred miles since the rebuild????
 
I would be pulling the plugs and look down into cylingers/pull theexaust manifoldoff and try to get a look at the piston skirts. If all of this look fine I would suspect lower end. What you have stated in the past posts (it idled for 10 minutes) I would expect it to be much faster if problem was in the bottom ends. I wont recomend running sled anymore until you start poking around looking for a problem. What may be a cheap and easy fix might compound expontially if you keep putting the engine threw heat/cool cycles.
 
you check the waterpump belt??? their is a hole on mag side of motor that you can stick ur finger into and check belt tension. Id check that out. Belt may be broke or out of adjustment and therefore not cooling things properly. IM pretty sure thats right location. Havnt looked at by buddies twin in awhile but know there is a hole on mag side to check tension. Look around by recoil
 
I'd do what Devilin suggests, pull the exhaust and the reed cages and look at as much of the pistons as possible, get a light and look down the sparkplug hole and see what those Pistons looks like. Maybe even pull the head off and examine the cylinder walls.
 
Devilin AblueDress! said:
I would be pulling the plugs and look down into cylingers/pull theexaust manifoldoff and try to get a look at the piston skirts. If all of this look fine I would suspect lower end. What you have stated in the past posts (it idled for 10 minutes) I would expect it to be much faster if problem was in the bottom ends. I wont recomend running sled anymore until you start poking around looking for a problem. What may be a cheap and easy fix might compound expontially if you keep putting the engine threw heat/cool cycles.
Click to expand...


I'll be doing that next trip to the lake...I was posting from the local library so pretty tough to do anything
 
yami1 said:
you check the waterpump belt??? their is a hole on mag side of motor that you can stick ur finger into and check belt tension. Id check that out. Belt may be broke or out of adjustment and therefore not cooling things properly. IM pretty sure thats right location. Havnt looked at by buddies twin in awhile but know there is a hole on mag side to check tension. Look around by recoil
Click to expand...


Water pump belt is there and spinning...the entire heat fin system is getting hot, both sides (under foot rests) and back under snow flap so I know coolant is moving...I tried to TEST the overheat light but don't know how to do it. I removed the coolant elect plug from atop the heads and shorted the two wires at the plug; that got me three flashes of the water temp light but it doesn't stay on like I expected..??
 
You will have to stop running it and find the problem. If it is running tight something is being damaged. Do a compression check. Pull the jugs and inspect.
 
Sounds cooling system related to me. If the impeller on pump isn't missing any fins and everything is turning and functioning as it should, Then maybe take a look at the head gasket. That could also explain why the plugs are black and wet. I find it hard to believe if the pump stuck wide open that the engine could seize. It would foul out plugs and smoke good before it would seize.
 
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I dropped it off at Tony Pinter's place just east of Winnipeg; he is the local Yamaha guru and the same one that did the top end. I saw the work order and realized that the rebuild I was told occured was really just a top end :(

Tony had recommended that the bottom end including seals be refreshed since he was in there doing the top.... the guy I bought from said NO and the bottom end was not touched.

He checked it and relates that a crank bearing is getting hot and swelling causing it to seize; consequently out comes the engine and the work starts. He is going to call me for a look at it once the case is split.

Going to a dealer is not gonna be worth it so Tony seems the answer. I want to ride this winter otherwise I would just let it sit till summer and tear into it myself. However his rates seem reasonable so the next few days will tell more... I will post with pics and desc to assist others who may have similar experiences.
 
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