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DSS .25 pistons not correct size

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eight0:

--- Quote from: ka-ja on November 04, 2020, 04:36:04 PM ---I always had rebores done to suit already purchased piston sets, with each bore machined to match a chosen/numbered piston, even a matched new piston set each piston can vary in size to each other,  micrometer wise

--- End quote ---

Yeah the guy at the machine shop said he was happy to go back and do this if I sent him the rest of the pistons. As long as all the pistons are larger than they should be and not smaller!
Learnt a lesson here  for next time I guess.

taysidedragon:

--- Quote from: eight0 on November 04, 2020, 04:59:35 PM ---
--- Quote from: ka-ja on November 04, 2020, 04:36:04 PM ---I always had rebores done to suit already purchased piston sets, with each bore machined to match a chosen/numbered piston, even a matched new piston set each piston can vary in size to each other,  micrometer wise

--- End quote ---

Yeah the guy at the machine shop said he was happy to go back and do this if I sent him the rest of the pistons. As long as all the pistons are larger than they should be and not smaller!
Learnt a lesson here  for next time I guess.

--- End quote ---

Fingers crossed 😉

K2-K6:
There's a need to be careful here particularly around the tolerances they bore too.

Many places just will not accept the Honda specification for clearance and leave them with excess. Have they told you what they are aiming for clearance wise?

It's generally good practice when boring to first measure the pistons that are going to be used,  rather than bore without checking.

Laverda Dave:
I agree with the advice of others here, each piston should be measured and the barrel bored to suit. As Nigel states, you need to be careful of who does the rebore and the tolerance they use. Did you supply them with the Honda tolerance for piston to bore size? Do they do motorcycle rebores and do they have a good reputation?
Having been on the recieving end of an engineer who thought he knew best regards CB250RSA clearances and who ignored the Honda specs without telling me making the clearance far bigger than it should have been (in case it seized with it being air cooled!) and having the bike subsequently blow up on the motorway at 70mph (the wife was riding it and had only just passed her test), I learnt my lesson the hard way!
I can recommend SRS in Sutton, Surrey. Make sure you advise them of the correct Honda specs though.

eight0:
Thanks for the replies and advice. They do seem to have a good reputation (SRS engineering engineering in Sutton) and the guy said he went off the Honda workshop manual. He said really to be accurate he prefers to have the pistons. so it's my fault they don't fit . As I said, SRS said if I supplied them he would bore each cylinder individually to the manual specs .

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