Friday, 26 August 2011

THE ROOT OF ALL EVIL

Stripped the top end of the chop (again) the other day and while looking for possible sources of noise decided the pistons had a bit too much slap in the bores. Took 'em off and had the bores measured, i did it when i first built it but this time i took them to a local engineering company to have them measured properly. Fully expected them to be way oversize but max 2 thou wear on standard they said, pretty good. Took them the pistons, negligible wear they said and both the same but...they are undersize by about 6 thou ! these are standard original Triumph (Hepolite AE) pistons that the bike left the factory with. Couple this with 2 thou wear and we have the whole reason the thing has always blown a mist of oil out of the breather.
There are probably lessons to be learned here but when you have a totally standard size motor that has quite possibly never even been apart before and done very few miles (remember it was hung up in a bar for 15 yrs then has sat unused for another 18yrs since imported to the UK) and the bores and pistons look fine.....


New pistons and a rebore and we continue....

1 comment:

Huguilena said...

Ohh , the good old British tolerances... Bless them.