Engine Trouble Minarelli Possible Engine Seizure

[noah9988]

I reckon tuning lean is the number 1 way to blow up a 2 stroke. A lot of people think that 2 strokes need to be rebuilt all the time but I really don't think that's the case. A race bike being abused? Sure. Something like a Polaris ATV can go a decade with the same top end, those engines are not performance engines and they are tuned rich (as far as I can tell). The enduro/dual sport 2 strokes from the 70s can also go a long time without a rebuild as well. It's all about how you run them, imo.

 

[ImpulseRocket]

I reckon tuning lean is the number 1 way to blow up a 2 stroke. A lot of people think that 2 strokes need to be rebuilt all the time but I really don't think that's the case. A race bike being abused? Sure. Something like a Polaris ATV can go a decade with the same top end, those engines are not performance engines and they are tuned rich (as far as I can tell). The enduro/dual sport 2 strokes from the 70s can also go a long time without a rebuild as well. It's all about how you run them, imo.

It's because lean tuning runs stronger and revs up faster/better. The entire purpose of the power jet came about form 2 stroke racers who wanted the power and throttle response of a leaner tune from 1/2 to nearly full throttle, but past 7/8 the extra fuel would be added to protect the motor.

Being air cooled doesn't help matters either. Just by their nature, 2 or 4 stroke, air cooled motors are just happier when they are a little rich since they tend to be hotter by default. Try running the jetting on an air cooled motor like you would a liquid cooled and you will seize it up eventually.

These people will also run really light oil mix ratios with the lean fuel tuning as well, which just makes the problem worse. I have no issue with going a bit thin on the oil mix (I love 40:1 and even 50:1 with a GOOD synthetic), but doing that AND running lean is a really bad combo.

 

[CrispyLeaves98]

If it rev's high, you had a lean condition. When clutch is pulled in it should never rev to the moon, should always have a dirty rev. I know a lot of these guys love to tune it clean reving, but that is just not how a 2 stroke works. An also why you don't see them come back here after they destroy their engines they bragged about and talked trash to us long time members over. We warn them, then they do it anyway, and call these engines junk. My second engine still goes strong like bran new, and I beat the living snot out of it. Thousands of mile, beating the snot out of it like a redheaded step child in the 1700's. Trashed the frame many times, and the drive train, motor runs perfect. Always, always, always tune rich, you'll save a lot of money losing that 2mph than you will tuning it to sound clean and run with no 4 stroking. Always, always, tune rich.

I do tune rich. I haven't taken off my cylender head cause my friend has a very very limited amount of tools. I'm here now and I replaced the plug for a b8hs, is it possible that that plug is defective aswel? I doubt it. After installing that plug, I still have great compression, so if the rings were broken I still have compression. I can't take the cylender head off cause for some reason he doesn't have a 10mil ratchet. I have a new pz22 with me and the same jets, but brand new, in case the old ones were clogged. I can swap the carbuerator, but it's either spark or fuel. When I go to start the bike it sounds completely normal, it changes pitches when I give it more has like normal aswel, but it sounds like it's not sparking. I might pull the plug and check if it's wet to see if it's fuel delivery. If I did have an air leak somewhere, it would've at least sparked a little with choke on all the way. any ideas appreciated

 

[Karl Snarl]

I do tune rich. I haven't taken off my cylender head cause my friend has a very very limited amount of tools. I'm here now and I replaced the plug for a b8hs, is it possible that that plug is defective aswel? I doubt it. After installing that plug, I still have great compression, so if the rings were broken I still have compression. I can't take the cylender head off cause for some reason he doesn't have a 10mil ratchet. I have a new pz22 with me and the same jets, but brand new, in case the old ones were clogged. I can swap the carbuerator, but it's either spark or fuel. When I go to start the bike it sounds completely normal, it changes pitches when I give it more has like normal aswel, but it sounds like it's not sparking. I might pull the plug and check if it's wet to see if it's fuel delivery. If I did have an air leak somewhere, it would've at least sparked a little with choke on all the way. any ideas appreciated

Try a 7 or a 6. an have a buddy hold the coil while you turn the back tire, does he get shocked?

 

[CrispyLeaves98]

Try a 7 or a 6. an have a buddy hold the coil while you turn the back tire, does he get shocked?

I'll check for spark, today school got out so now I can be there as long as I want. We're gonna check for spark, fuel, and compression. I think his dad has a compression checker, I checked by seeing if it was hard to turn the rear wheel, and it was. But nevertheless, tommorow I'm gonna get some real tools from my house and come back