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Buell Forum » Knowledge Vault (tech, parts, apparel, & accessories topics) » Engine » Big Mechanicals: Head, Cyl, Piston, Rod, Crank, Flywheel, Cases, Bearings » Archive through October 22, 2006 » Oversized pistons « Previous Next »

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Jimmytwobuells
Posted on Thursday, April 07, 2005 - 08:13 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I've got a X1 motor with a Zippers 88" kit on it. I'm on my third set of pistons (3.8325 dia.) and now I find the front piston needs replacing.
My question is.....does anyone make a Thunderstorm style piston in a 3.8425 dia.? Is that size making the liner to thin?
I'd rather not have to buy another set of cylinders if at all possible.If anyone can point me in the right direction I'd appreciate it.

Jim
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Blake
Posted on Thursday, April 07, 2005 - 06:01 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Are you seeking to treat a symptom or the root problem that is causing the trouble.

Don't you first want to diagnose what is causing your pistons to suffer ?

Are they scuffing or are they having problems with the ring groove integrity, or something else?
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Jimmytwobuells
Posted on Thursday, April 07, 2005 - 06:33 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

piston pic
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Jimmytwobuells
Posted on Thursday, April 07, 2005 - 06:38 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I'm thinking it might be a breakin problem. This motor is in a roadrace bike and it got little to no breakin after the new pistons were installed. I can't afford the dyno time to do a proper breakin and once I hit the track I can't exactly pooch it or I'll get run over! Or it could be something entirely different
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Pammy
Posted on Thursday, April 07, 2005 - 10:58 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

What is your cyl wall to piston clearance? Cylinders are cast iron or nik? Carbed or injected? Or it could possibly be the lubrication film failed under thermal load on the exhaust side of the piston. What type of oil are you running?
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Jimmytwobuells
Posted on Friday, April 08, 2005 - 08:13 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks for the reply!

Aluminum cylinders with liners and carborated. I had it dynoed for jetting purposes and it was 12-13/1 AF ratio. Hal's set the wall clearance and ring gap. Not sure what they were but I could call and see if they keep that info on file. Oh yeah, I run Mobil 1 15-50. Also have a Jagg oil cooler.
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Pammy
Posted on Wednesday, April 13, 2005 - 05:40 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Are you flushing the oil tank and lines, etc... after each catastrophe? Have you checked your oil pressure? Just how many times (total) have you had this failure? Even before the upsize?
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Blake
Posted on Saturday, April 16, 2005 - 04:47 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Pammy,
Are you having a Capt. Pete flashback or what? I am. crazy
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Pammy
Posted on Saturday, April 16, 2005 - 05:44 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

You betcha.
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Pammy
Posted on Saturday, April 16, 2005 - 05:49 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I would be curious to know how many miles before blast off as well.

I would think a proper set up(Dyno tune or such) would be considerable cheaper than many rebuilds. Also, heat cycling is most important on a new build. Unfortunately, some motors are never going to do the right thing, no matter what the preparation.
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