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Author Topic: TS Pistons  (Read 7070 times)

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Offline carcrank

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TS Pistons
« on: 04 Oct 2010 at 07:47 »
After one of the bigend lock nuts fell off and the bolt loosened, the piston hit the top of the cylinder and shattered. So I need some pistons, unfortunately the piston skirt measures 62.5mm which is very oversize, so the JP pistons are out, does anyone know of anything that will fit? This piston is Cast Iron so maybe its out of something else or did they make oversizes greater than 40 thou in the old days.

« Last Edit: 08 Oct 2010 at 03:49 by Dave »
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Offline kmd

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Re: TS Pistons
« Reply #1 on: 04 Oct 2010 at 20:21 »
Hi Carcrank

KAWASAKI Z650 and Honda 250N pistons start at 62mm. I have seen Hondas at 62.75mm and I guess Kawkers do the same.

You will have to modify the inside of the piston for the off set of the con rod and make up collars for the standard pins to be used in the new pistons.

Regards
Kevin
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Offline Ian

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Re: TS Pistons
« Reply #2 on: 04 Oct 2010 at 22:52 »
JP do an 80thou oversize - base on I think a 61mm standard bore - so this should be enough ?
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Offline graeme

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Re: TS Pistons
« Reply #3 on: 05 Oct 2010 at 10:17 »
If you go the JP route, remember to allow a thou or two extra on the clearance that JP suggest, and don't under any circumstances use their circlips - make up buttons instead.
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Offline Ian

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Re: TS Pistons
« Reply #4 on: 05 Oct 2010 at 23:07 »
In addition to what Graeme said - you will also have to modify the rod very slightly per other recent postings on the subject - with kevins one he had to trim a but off the short side of the little end on the rod as well as ease the piston a bit to allow clearance. Seems to have worked fine - we will be doing the same for my sons one. Also, the buttons rather than circlips are really the way to go.
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Offline carcrank

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Re: TS Pistons
« Reply #5 on: 06 Oct 2010 at 00:10 »
Thanks for the replies, it looks like the JP pistons will be the go. My barrels are 62.5mm which equates to .060" oversize with about 6 or 7thou clearance or I have them bored out for the .080" but that will be the end of the road for them. What sort of clearance should the JP's run at? Or have I done the maths wrong?
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Offline Ian

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Re: TS Pistons
« Reply #6 on: 06 Oct 2010 at 00:32 »
From memory thats about right on clearance - don't use the 4 thou they suggest !
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Offline cardan

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Re: TS Pistons
« Reply #7 on: 11 Oct 2010 at 09:41 »
Found a 62.8mm Douglas piston in the shed - cast iron with rings and 3/8" gudgeon. It looks quite OK if you don't want to do the full rebuild thing.
Leon
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Offline carcrank

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Re: TS Pistons
« Reply #8 on: 12 Oct 2010 at 02:57 »
Thanks for the offer Leon, unfortunately the pistons have already arrived from JP so that's the way it will be this time although I would have preferred the keep the CI pistons. But it would have been od with 62.5mm and a 62.8mm if I'd used yours.

regards

Mark
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Offline cardan

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Re: TS Pistons
« Reply #9 on: 12 Oct 2010 at 09:26 »
No problem Mark - I should have done my SPring Clean a week earlier!!! Leon
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