MBD Race-Tour piston

[celt]

Received today a 'B' grade race-tour piston for my TS1 from MB Developments.

I did request an 'A' grade piston to compliment my 'A' grade barrel, but unfortunately they were out of stock on 'A' grades.

They said that it would be ok to use and that a 'B' grade piston will fit in slightly tighter. I thought it was the other way around and that it would be slightly looser.

I know we are only talking microns but will this piston grade be suitable to use.

I have done less than 1000 miles on the barrel

[sean brady scooters]

yes i,m sure thats good to go also.if MB say so.

ideally another grade A would be good,but if you cant get one........... ,what can you do..?
just fit and use the B,and take it gently for a few 100 miles to be on the safe side...

[Ian Hepworth]

yes i,m sure thats good to go also.if MB say so.

ideally another grade A would be good,but if you cant get one........... ,what can you do..?
just fit and use the B,and take it gently for a few 100 miles to be on the safe side...

Ideally you match the grades but you can go up or down a grade, it's only microns.

This info was got from AF ages ago.

[sean brady scooters]

how many microns is the difference exactly Ian,
i,ve always presumed that the grade b was to take up some slack and wear from an A...etc.

[celt]

So to re-cap 'A' grade pistons have the slackest fit in microns compared with B, C, and D grades which have a progressively tighter fit.

i.e you can use a 'B' grade in a slightly worn 'A' grade barrel and 'C' grade piston in a worn 'B' grade barrel etc

But not an 'A' grade piston in a 'B' grade barrel as it may be too slack

Is this correct

[Ian Hepworth]

So to re-cap 'A' grade pistons have the slackest fit in microns compared with B, C, and D grades which have a progressively tighter fit.

i.e you can use a 'B' grade in a slightly worn 'A' grade barrel and 'C' grade piston in a worn 'B' grade barrel etc

But not an 'A' grade piston in a 'B' grade barrel as it may be too slack

Is this correct

You can go up or down one (i.e A piston B barrel) but no more than that (A piston C barrel).

If in doubt ring the shop, 01709 869756.

[celt]

You can go up or down one (i.e A piston B barrel) but no more than that (A piston C barrel).

If in doubt ring the shop, 01709 869756.

Ok cheers

[Wayne Miller]

Hi Celt,

I put a 'B' grade Racetour into my ts1 cylinder after porting and new nicasil, it worked a treat.

As was said above just take it easy first couple of hundred miles and Sean's right if MB says its good to go then its good to go