M91 250, I'm Going In!

[miketaco]

Ok I've had my m91 250 for a couple of years now and after two trips to the French 4 day she is deffinatly ready for a rebuild. Just wanted some advice on the piston, my dad has a 340 and says to go for a mahle just wondered if anyone had tried anything else and with what result? Also going to replace the carb, is dellorto the carb of choice and if so would I stick to a 26 or up to a 28? Also would anyone happen to know the standard shock length on a m91? It seems I bottom the rear end out more than expected and as the shocks aren't standard I wondered if this could be a factor.

[lorenzo]

I believe Mahle was considered the best available in the day; I'm not sufficiently familiar with what others use nowadays to say whether this still applies.

This possibly raises two other questions, though : would a Mahle item be unobtainium?.......or simply unaffordium ?

Suspension spring rates will have more influence on the tendency (or not) of a shock to "bottom out" than its length.........

Edited February 3, 2013 by lorenzo

[pschrauber]

I believe Mahle was considered the best available in the day; I'm not sufficiently familiar with what others use nowadays to say whether this still applies.

This possibly raises two other questions, though : would a Mahle item be unobtainium?.......or simply unaffordium ?

Suspension spring rates will have more influence on the tendency (or not) of a shock to "bottom out" than its length.........

NOS Mahle piston with rings and piston pin was around 145 € in 2011, as I know still available.