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ENGINE QUESTIONS


TORQUEDFORD

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To make a long story short, 2000 banshee, I bought it new and the engine has never been apart. It has chariot head - 18cc, T-5's, K-N with no lid, and the timing is bumped up 4.5 to 5 deg. I jetted it and it has been good for 10 years. I did put a piston in the right side last year after it almost burned a hole through it from running out of gas while pulling our drag hill about two years ago. I put a stock piston and rings back in and rode it till now. Our elevation is approx. 4600' and I am sure I am on the ragged edge for pump gas. My plugs have always been a touch rich chocolate color. Running a bowl last weekend it melted down on me good this time. I read the post on how to build/use a leak down tester and plan to do so and have not torn the engine down. I rode 15 GPS hard dune miles before it went down. Pulled the plug on the right side, the electrode is gone, melted away and the plug is full of melted aluminum.The other plug was still brown colored. After a few minutes the engine unseized and I was able to get it started again on one cylinder but could not get the bad plug back in because it galled all the threads in the dome from being melted. I got pissed off and worried, was getting dark and cold. It made it maybe 1/4 mile back and that was the end of it. My friend was on a yz 250, there was no way he could pull me out of there. It still turns over but there is nothing there.

 

I was curious on if you guys had any thoughts on what happened, if I lost a crank seal, or what I should be looking for on the pistons. I am planning on going all the way to the crank on this rebuild, I'm sure it was due anyway.

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To make a long story short, 2000 banshee, I bought it new and the engine has never been apart. It has chariot head - 18cc, T-5's, K-N with no lid, and the timing is bumped up 4.5 to 5 deg. I jetted it and it has been good for 10 years. I did put a piston in the right side last year after it almost burned a hole through it from running out of gas while pulling our drag hill about two years ago. I put a stock piston and rings back in and rode it till now. Our elevation is approx. 4600' and I am sure I am on the ragged edge for pump gas. My plugs have always been a touch rich chocolate color. Running a bowl last weekend it melted down on me good this time. I read the post on how to build/use a leak down tester and plan to do so and have not torn the engine down. I rode 15 GPS hard dune miles before it went down. Pulled the plug on the right side, the electrode is gone, melted away and the plug is full of melted aluminum.The other plug was still brown colored. After a few minutes the engine unseized and I was able to get it started again on one cylinder but could not get the bad plug back in because it galled all the threads in the dome from being melted. I got pissed off and worried, was getting dark and cold. It made it maybe 1/4 mile back and that was the end of it. My friend was on a yz 250, there was no way he could pull me out of there. It still turns over but there is nothing there.

 

I was curious on if you guys had any thoughts on what happened, if I lost a crank seal, or what I should be looking for on the pistons. I am planning on going all the way to the crank on this rebuild, I'm sure it was due anyway.

 

I would say your crank bearings went out of it. And im supprised your getting away with running 18cc domes on pump fuel with +5 timing! But hey learn something new every day. :confused:

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@ 4600 feet, 18cc domes on pump fuel with modest timing like you have should be fine...as long as your jetted correctly.

 

You ran it 10 years the way it was?

 

At that point, IMO...it was time for a total tear down to inspect everything. Could be a number of things.

At this point, just replace the crank...why mess with it.

I'm sure it'll need two new pistons and a fresh bore/hone.

 

After that, as said...test the leak down.

 

You probably had an air leak or just age/wear from the cylinders. That long on a stock bore...I'm sure you had some blow by.

 

While a lot of people think the only job of the rings is to seal the explosion, they also transfer heat away through the cylinders and let the cooling system do it's job as well.

 

You could spend a whole lot of time trying to figure out what went wrong...but to be honest with that much time on it...I say freshen it up completely and be done.

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Thanks for the info.

I bought it new and it is a 2000. I didn't throw all of the bolt on parts at it at once, they came here and there over the years. I have always been on top of the jetting on it, jetting it for the different parts and up and down for when I have gone to California to ride. This machine has been extremely reliable and ran hard right up until it let go. I don't know that it was all that worn out.

I am going to get into the crank, and might as well replace it, I am going to replace it with a 4 mil. What is the matter with the spacer plates under the cylinders other than the extra gasket? I don't want any porting. I may just clean the ports up myself. I like where the power spread is stock.

I was looking at a Vito's crank, I like it because it is already welded. Is this one pretty good and last a long time?

Has anyone done a 4mil on here without going all wild with the porting and carbs etc ?

I was curious as to what the difference just the crank would make to power and how it would run ?

 

Thanks

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I would tell you if you're keeping the porting stock and just throwing a spacer plate under it you'd be completely wasting your money on a stroker crank.

You'd be spending a few hundred dollars to get 2-3% performance increase if that...and you'd have less options on pistons.

 

If you get a 4 mil stroker crank and have it ported to match your riding style, you can get a LOT of power out of it and retain the stock power delivery...there will be just more of it.

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