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Discussion Starter · #1 ·
Ok, I've been hearing about people having problems with the JE pistons, specifically the 10:75. I have the 11:1 and haven't had a problem with it. I had the motor work done when I got the trans upgraded about a year ago. Mike at Ripper Racing recommended the JE 11:1 in a +2mm size. He said that it is a quality and reliable unit. So what gives? :3question: :unsure: Is it just the 10:75 that was crap or are all JE pistons crap? I don't think Mike would steer me wrong though.
 

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Unless there has been another production run they were all 10.75:1. If you've truly got an 11:1 then you might not have the same piston but I doubt it.

They're not guaranteed to fail or anything, but they're significantly less reliable that the other alternatives on the market.
 

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Discussion Starter · #3 ·
Should I seriously consider replacing the piston with a better unit? If I would have known about that at the time I would have never got the JE. Kind of sucks that JE was recommended to me when it was known to be an inferior product :mad:. Everything else he told me was right with what people are saying on here, except about JE.
 

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In a perfect world yes it'd be best to pull it. But realistically if you make sure your jetting is not lean and you're running enough octane for your build and of course not revving it to the moon you should be able to get some good time out of it. But instead of re-ringing it I'd replace it at that time. I wouldn't run that piston in a high rpm build even if someone gave it to me but if you're just going to trail ride with it for a year I think you'll be ok.


*Mandatory disclaimer: You'll be at less risk for a problem if you used another piston. I'm just trying to reassure you by explaining that in the right conditions the odds are with you. I make no guarantee one way or the other.
 

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Discussion Starter · #5 ·
Damn that's bullshit! :mad:. I spent good money upgrading weak links just to end up paying to add a weak link! Well, I guess getting mad isn't going to make it right so my question is: Do i have to take it to a machine shop and have the bore matched to the new piston or can I just install it no prob? I've been riding with that piston for around a year or so now, which has me thinking about it letting go.
 

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Before you get too worried or worked up I'd take a weekend, buy a head gasket, and take a look at the piston. If it doesn't show any signs of wear on the wristpin or cracks near it and it's still got a solid deck from the top and bottom then I would let it be until you start losing compression. They had a habit of cracking or breaking apart in the center on the underside near the wristpin. JE claims they fixed the problem a few times but every time they do someone comes along with a busted JE and it's hard to take their word for it.

However if you're ready to replace it and your cylinder is in good shape you could probably get away with the same size piston and hone. You'd need to check the dimensions of the cylinder to know for sure.
 

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Discussion Starter · #7 ·
I blew my head gasket about a month ago or so. I didn't even think about checking the wrist pins. The top of the piston looked fine but since that's not where the problem is it really doesn't tell me anything. The cylinder is slick with no scratches. Bottom line is that I really don't have the money to fix it right now but, I really don't want to blow up my engine. I do run 92 octane gas in it and I've never hit the rev limiter. I do like to run hard and fast though. I top it out every now and then. It's been bored +2mm also. If I can get buy with a new piston and no machine work that would be great! If I have to get a new sleeve installed too then it's going to be a while.
 

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Well if that's the case then I'd just save up for a new piston and possibly a new sleeve and replace it when it becomes financially viable. I wouldn't be in a rush if you've run it for that long already. If there were no signs of a problem on the deck of the piston then it's probably not going to blow up tomorrow or anything.

Sorry, guess I should have just said "JE is great" and not have you worry about it. ;)
 

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Discussion Starter · #9 ·
Mad Dog Beyond Thunderdome said:
Sorry, guess I should have just said "JE is great" and not have you worry about it. ;)
:lol: Naw man, I'm just ridiculously anal about stuff like that. I've half-assed projects in the past because it saved me a few bucks and it cost me 10 times that to go back and fix it right. I'm also a mechanic by trade and know what will happen if that piston ever lets lose. I'm back to the 10 times more thing again.
 

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I'd use a JE in anything EXCEPT a Raptor. I've seen 3 motors with grenaded JE 10:75 pistons but the 12:1s seem to hold up fine. There just isn't enough wrist pin material on the 10:75s

Probably your best bet is to buy a stock jug off ebay and have it bored to fit a new Wiseco 102 11:1. The used jug will be far cheaper than the cost of a new sleeve and installation into your jug.

I'd figure 375 total to do the job on your existing jug but about 250 if you bought the used one (plus whatever the used jug costs). You have the cost of the piston, bore and gaskets in both cases.
 

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Discussion Starter · #11 ·
I can't seem to find a Wiseco in a 102mm bore. I know they make them I just can't find them. I was thinking about going to 100.5mm or 101mm so I'll be able to bore it a few more times. How much power will I lose by going back down to a smaller bore? My guess is that the main power increase came from the bump up in compression and not from the extra 2mm bore. Is this right? Also, since I've been riding it for a year or so already do you think it would be ok for a while longer, or am I asking for trouble? The only reason I don't want to run out and do it right now is, of corse, no gottie no money! :p
 

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You'll probably be fine for awhile, but like Maddog said, don't bounce it off the rev limiter. You should be fine if you know when to shift.
 
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