I would replace my JE piston. I already had one gernade. I had a little something to do with it gernading though. When you put a JE, Ross and weslico side by side the Ross stands out as a better choice IMO.

The reason for the problems? IMO Guys are really starting to make some HIGH HP. Up until now no one was finding the limits very often.

 

Hmm...now this is making me paranoid.

I'm looking into the 686, and plan on purchase at the end of this month, maybe early March. I was looking at a TRUE 11:1 JE. [img]i/expressions/face-icon-small-confused.gif[/img]

 

It doesn't sound very good all lumped together like that, but I bet broken down case by case it wouldn't look so bad. I bet a couple were from too low of octane/detonation, and some could have been caused by a defect from JE, and some could be........ect. Just think of how many times you have heard that an 11/1 will run on pump gas, we know fo show that this 11/1 will not with that small of a cam. Then throw in the problem with a built Raptor's carbs.

I'm not trying to argue that the JE is a better piston than the Ross, I'm just ....not really sure what I'm trying to say.[img]i/expressions/face-icon-small-confused.gif[/img]

RaptorFam, what kind of rod did you have when this happened?

 

I still had the stock rod. Check out the pics in my profile. There was no galling of the wrist pin from the rod. It was simply a weak wrist pin. I'm glad I stayed with a stock rod with the JE, I would have hated to have the JE ruin an aftermarket rod[img]i/expressions/face-icon-small-disgusted.gif[/img]

 

I would have to say 9 out of 10 is the operators fault,not the piston.You can't just slam a 14:1 or even a 10:75.1 in and expect it to endure the harshest punishment.Fuel and timing requirements must be maintained at all times.I'm willing to bet that more than half of those failures are from detonation(lack of proper octane) or improper jetting.

It just takes one bad batch of gas and a hard ride to destroy an engine like that.Not to mention the majority of the people out there couldn't identify spark knock if thy heard it.

Detonation can and will break wrist pins,believe it or not.Think of a hammer striking the top of the piston repeatedly,sooner or later something is gonna give.Theres no reason why it shouldn't be the wristpin.

11:1 is not a pump gas setup,neither is 10:75.1.I wouldn't go more than 10:1 period if all you wanna run is pump gas.
Quads are not like streetbikes or cars,they do not have computers that can alter ignition timing when spark knock is detected.This is what computer control provides,unfortunately,we don't have that option yet.

If your gonna run high comp,then take the necessary measures to prevent engine damage.

 

I must be one of the minority (1/10) cases. I'm one hundred percent sure it was not jetting or octane. Is 107 octane enough for a 12:1 piston, I think so. We've been riding high performance motorcycles, three-wheelers, and quads for the past 40 yrs and belive me it was a wrist pin failure. I've already sent it off to JE to inspect it. We've never had any piston damage on any of our bikes. There was no sign of detonation. BUT I do understand that is the majority of the cause.

[img]i/expressions/face-icon-small-happy.gif[/img]

 

Not compltely true. You can run pump gas on some motors that have an 11/1 piston (I.E.: YZF is what like 12/1 and runs fine on 93). It just depends on cam selection and timing.


"You keep on knocking but cha can't come in"[img]i/expressions/face-icon-small-wink.gif[/img]

 

Does putting in an aftermarket piston that is lighter than stock, change the balance of the engine. I have read when you balance the crank on a single cylinder engine you just move the inbalance above or below the operating rpm. If the engines balance has changed does this cause more wear on the piston pin and other internals? Just curious.

 

been racing with my piston since dec01 and n2o since around june 02 no problems yet. put new rings on it once, and melted 3 plugs and blew a couple of head gaskets.and 3 trannys

raptorboy673

 

Even if 9 out of 10 are operator error it seems to me that it takes too little error for them to fail. A quality piston should be able to endure a little abuse. I've heard from more than one person that they feel the top of the piston is to thin and possibly flexing and a little detonation that should not have ill effects on a different piston are catastrophic on this one.

And then there's the 1 out of ten, that's 10%. That is not a good batting average.

They've also changed the wrist pin size I think three times now. They wouldn't do that if there weren't problems.

660r02 You are correct for the most part. A crank assembly should be balanced with the parts used and changing one or more of those parts should technically require a rebalance.

It could be that it's not a bad design it could be something off the wall like vibration or even an incompatibility of components (bad harmonics) which could also be the cause of the rod failures there've been. Most if not all of the two types of failures have been JE piston on stock rod.