I have a montesa 242 I was very lucky to find parts I fit a new baral and piston but now I carnt get it to run the timing is spot on thair is a grate spark and loads of compretion no nasty noises I carnt fathem it if anyone has any ideas please let me know

Well the only thing you did not mention is if you are getting fuel. Here is some other posts that may help. http://www.trialscentral.com/forums/topic/43781-my-new-1975-montesa-cota-247-pics-hot-starting-problems-its-my-first-two-stroke/

Edited February 17, 201313 yr by lineaway

was it running before the work .have you checked with a compression gage to confirm enough , if ok next check with a strobe light to confirm sparking under compression ,if that ok is carb been cleaned out ok ( is fuel fresh ) or try putting fuel down plug hole and it should go ( is there a wrong way to fit the piston ) as ive seen them fitted in 200,s wrong way but still ran , has all gaskets and manifold sealed ok with no air leaks ,is there any cloths left in anywhere causing a blockage if all fails it could be crank seals

I think it will be crank seals as eveything else is new and I have dubble checked everything else and it ran but not for long as I found a crack in the piston so far I have 550 pounds in the bike so if it costs a copple more quid to sort out the expens wont be spared as I have a few montesas thankyou for you help