nytoy
New member
Anyone do a headgasket on one of these? Seems pretty simple, it's a 300cc single cylinder, it got hot and now it won't start and I see coolant weaping around the headgasket. Anyone have any advice? Can I do it with the engine still in the sled?
Check compresion before removing head. Removing head can be done in sled, first drain coolant so to not get any in cylinder, check head for "flat" with a straight edge. It is also a good idea to check the cylinder for "flat" also. If head is warped it can be milled up to .020. good luck Al
Vmax540
VIP Member
Check to make sure the water impeller is not melted or loose on the shaft. Yes, I said Melted...... 
they were known for cavitation , overheating and melting the impellers like vmax540 said!
nytoy
New member
crap... well I tried to fire it up just to move it 10 feet down the hill (it's amazing how heavy they are when trying to push them!) and with starting fluid it didn't even cough. But I could hear coolant blowing by somewhere and the weaping around the head gasket. I assume the exhaust is pressurizing the coolant system.
This figures we get a foot of snow today and I'm stuck! The dealer of course would have to order the head gasket. I'll compression check it tonight and pull off the water pump, why Yamaha didn't make this thing air cooled is beyond me....
This figures we get a foot of snow today and I'm stuck! The dealer of course would have to order the head gasket. I'll compression check it tonight and pull off the water pump, why Yamaha didn't make this thing air cooled is beyond me....