01 mm700 oil squirter location/melted piston causes

The picture of that piston, looks like it did a 4-corner seize. Usually caused by lack of lubrication, or some failure to warm up that particular cylinder, causing the piston material to expand faster than the cylinder sleeve, causing a cold seizure.

As well as the other tips the guys gave, check your thermostat for proper operation, and good luck!
 

i agree stanage it does look like lack of lubrication.

i did bleed the pump prior to testing it but i will do it again tonight just to confirm before i order a new pump.

anyone know what other pumps i can use from other sleds? ie srx, sxr, vmax, sx etc...? years? is the 01 different than the early ones.
 
Ok so I bled the pump and tested it again, I got a little out but I'm still not convinced its working right, I'm just gonna snatch a used one off ebay if it ends up not being the problem I'm not out a whole lot of cash.
Checked for any coolant blockages and the bottom end checked out ok. Supposed to have my gaskets on Friday, will just be waiting for the oil pump then. Will update then.

Thanks for the help guys
Robbie
 
crankcase oil lines

Not familiar with this red head motor but the srx cases have a couple oil lines feeding two places which is what yours is sounding like, if you have the engine out you should see two lines running to the bottom case. They add oil to the crank at those two locations.
 
That looks like a lack of lube which I doubt on a yamaha oil pump, my guess is it is detonation which super heats the piston and makes it swell to a point where there is no more clearance for oil and it then it seizes,bad fuel-ethanol is also bad jet up for it.
 
that four corner seize i would be checking the crank seal on that side and if it were me crank seals are cheaper than another motor job. i have had the same problem on a vmax4 race engine 4 corner cold seize cause leaking crank seal . on pto side and yes stagger jet it , i have allways jetted one size higher on pto side and other 2 the same i do run tripple pipes on my mountain max 700
 
rlbock said:
Not familiar with this red head motor but the srx cases have a couple oil lines feeding two places which is what yours is sounding like, if you have the engine out you should see two lines running to the bottom case. They add oil to the crank at those two locations.
Click to expand...

thanks for the input, pretty sure they are factory lines, but most guys that know anything about these red heads tend to have experience with pre 01 motors and i think these lines are an update in 01 or around then.


sxr1000 said:
That looks like a lack of lube which I doubt on a yamaha oil pump, my guess is it is detonation which super heats the piston and makes it swell to a point where there is no more clearance for oil and it then it seizes,bad fuel-ethanol is also bad jet up for it.
Click to expand...

Yea this could be it also and i will say the pistons defiently look lean, this guy definetly ran the motor too lean that or they are fresh pistons with barely any time on them.

How do i go about checking the crank seals properly, can i do a leak down test with the piston at very bottom center and using a low psi?
obviously i know i can visually inspect for oil leaks but even a small hole/split could cause a vacuum leak without spewing oil.

extremelyfastmax4 said:
that four corner seize i would be checking the crank seal on that side and if it were me crank seals are cheaper than another motor job. i have had the same problem on a vmax4 race engine 4 corner cold seize cause leaking crank seal . on pto side and yes stagger jet it , i have allways jetted one size higher on pto side and other 2 the same i do run tripple pipes on my mountain max 700
Click to expand...

I will defiently be checking everything before and after its put back together. I have to wait another week for parts becasue dumb *** at yamaha ordered me rings for a 600.

Thanks you tons for info on stagger jetting, perfect info i was looking for, this might be the reason it leaned out.
 
Send me a pm with your e-mail address and I'll send you the PDF of the shop manual. It covers everything, including overhaul and leak down testing of crank seals
 
I am not familiar with your particular engine but many of the later Yamaha 2 stroke engines have the oil delivered to the fuel pump to be mixed with the gas AND deliver oil to a gear "house", the cavity where the gear on the crankshaft drives the gear on the water pump/oil pump shaft. The oil then gets transferred from another fitting from this cavity to a fitting directly below the PTO section of the crank. The only way the water pump/oil pump bearings and the drive gears get lubricated is from the delivery of oil to the fitting. This gear cavity is sealed off from the rest ofthe engine.

Also, the gear ratio from the gear on the crank to the gear on the oil/water pump shaft is something like 1.3:1 (meaning the oil pump spins pretty fast) so testing the pump with an electric drill is not going to result is a large quantity of oil being delivered. I have not tried it yet but I suspect you would need to run the drill with the electric drill for many minutes to see any effect. I have a brand new out of the box oil pump that I will be installing on my rebuilt SRX 700 engine. I an going to use the drill technique to prime the oil system.
 
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