RM80 Timing

We just bought a 99 Suzuki RM80 and smoked the motor within a mile of riding it. The main jet is probably too lean, it has a 180 in and stock is a 210, so that will get replaced back to stock and then adjusted as needed. My question is can these things have their timing adjusted for racing, etc? When we pulled the head and the cylinder the top of the piston looked like it was starting to melt.

One other question, should I flush the bottom end for metal shavings, as the spark plug electrode is gone as well. It must be somewhere in that engine.

We just sold a CRF70 because he was too big for it, bought this and smoked it within 5 minutes.......:smirk:

There is a chance the electrode went out the exhaust, but it cant hurt to flush it. I believe the 80 is the same as my 125 in that the cylinder wall is plated any fracture scratch in the plating and you will be sleeving or replating.

Assuming the 80 is alike to the 125 if you take the left engine/stator cover off there should be three 8mm bolts holding the stator in place in an upside down triangle pattern. remove the bottom bolt completely and you will see an index mark on the stator and the engine case. loosen the other two bolts just enough to rotate the stator until the marks align. bolt everything back down and your timing issues should be ok.

If I read your post correctly you should have been running extremely lean. This could have caused some oilling issues and a very hot cylinder wich may have caused the melting of the piston.

GOOD LUCK

That makes me feel a little better. I want to make sure none of the metal ended up in the rod bearings. We are at 4000 feet so it will take a little leaner jet but I don't think it should be that lean. I am going to start at the 210 jet and go from there. Another thought may be bad gas and/or a bad mix ratio. We didn't drain the gas and refill with fresh before we rode it and I knew better than that! I will post an update on what we find. Thanks for the help with the timing, that sounds pretty cut and dry.

Jason

Is it worth not rebuilding the bottom end? If you fix the top and the bottom goes, you will end up replacing the top end again. I would rebuild the whole thing and know what you have. A new and good motor!

There is a chance the cylinder was so hot the electrode melted away and went out with the exhaust. Being that you are at 4k' I would think about stepping up to plug that has a little hotter range than the original plug. I don't know if its available in your area but I highly suggest running a non ethanol fuel.

I am pretty mechanically inclined, but have never been through the bottom end of a motorcycle engine and wouldn't even know what to replace. The cost of a shop to do it is way out of our budget right now, so that probably won't happen.

I am pretty mechanically inclined, but have never been through the bottom end of a motorcycle engine and wouldn't even know what to replace. The cost of a shop to do it is way out of our budget right now, so that probably won't happen.

If you can turn a wrench and read a manual, it's fairly easy. there is not much to a two stroke motor. I wouldn't be riding if I didn't do all my own work . Except the specialized stuff like re-plating the cylinder and changing the rod on the crank. ( I really need to get a press!) With the few special tools you need, it cost's less than a shop, and you have them to do it whenever you need to again.

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