Piston to bore clearance

[dirtyhandslopez]

.003.
If the rings are correct for the piston, a .003 clearance will give a 9 something something something thou ring gap(pie equation, not the eating kind) and all that. 9 something something something-10 thou ring gap is on the money.
Breaking in will still be neccesary though.
If ya don't want to break it in much , go large on the clearance, but ring issues will happen.

[Adam_Winstone]

IMO - 4 thou starting point. Too much will cause rattle/slap, which also increases heat build-up.

You say standard... if you mean 66.0mm standard then you have a chance to use the + 0 - incriments that are available for the standard 66.0mm factory bore, which might just be sufficient to take up some of the play/wear on your bore. In this case I would look to use the standard Mahle Indian GP piston. These pistons are actually very good when compared to Asso pistons and many of the aftermarket brands; stronger, less likely to seize (better alloy), less likely to crack (better radius on transfer window cutouts), better on ring wear (top ring is chrome plated). HOWEVER, whilst these are promoted (for mild road tunes, incl. his Stg IV) by one of the UK's top tuners, he choses to only fir the top 2 rings and to leave off the bottom/3rd as it adds wear/drag/heat but doesn't actually do much else. Aslo, you would need to consider exhaust port width as traditionall thick ring pistons don't like the early TV200 'ring breaker' ports much (especially if exhaust duration is increased).

Adam

[lamblast]

thats the piston i use now with 4 thou ,no problems now

[hatch]

Af Rayspeed Mahle pistons are the best ive found / always use now, standard type and there beefed up to stop cracking on the skirts , with 200 careful miles running in on flat roads you can do these at 2-2.5 thou , with fully syn at 2% , never had any problems

[Darrell Taylor]

Ive found the bore clearance requirement for poor quality pistons and forged pistons to be quite big 3.5 to 4.5 and good cast pistons 2.5 to 3
some pistons grow and distort more than others so quite often the piston manufacturer will quote the required clearance based on there own data quoting air or liquid/ cast or alloy / low or high rpm and bore size adjustments

[soosh]

Af Rayspeed Mahle pistons are the best ive found / always use now, standard type and there beefed up to stop cracking on the skirts , with 200 careful miles running in on flat roads you can do these at 2-2.5 thou , with fully syn at 2% , never had any problems

Ditto. Some people laugh when you tell them that but i was told they are the best "standard type" on the market by the guy who did mine.Cheap as well,cant see why you would spend more unless you had something very revvy or had massive exhaust port.

[bristolmod]

ditto- always used Mahle and worked down from 3 1/2 thou to 2 1/2 thou clearance now, with no issues whatsoever. Mix at 3% semi. Loads of short, reasonably hard cycles on rebores and well run in by 300 miles.

Chris

[Muppet]

feck it i is goin for 1 1/2 thou an 1% think im winning this one now

[Adam_Winstone]

This thread was never about what clearance you would start with on a rebore, rather, it was about how big is too big on a used bore.

TS1-200, how are you getting on?

Adam

[Muppet]

This thread was never about what clearance you would start with on a rebore, rather, it was about how big is too big on a used bore.

TS1-200, how are you getting on?

Adam

+1 wood be nice to find out,