hi ive been on a trial on the 348 today in 1st gear it makes a grinding scraping noise and when dropping the oil it is more like glitter not good.

so i was wondering does anybody have any advice on this engine common problems

i have never split a crankcase so im a bit scared

is there some kind of workshop manual for this bike

thanks

There would be quite a good manual with exploded parts diagrams supplied with the bike. Try Jim Sandiford - type sandifords montesa into a search.

There were a couple of things that could cause gearbox problems

Chain too tight - some people misjudged tension because chain hidden in tubes

Gearbox sprocket is on taper and with wear or overtightening can move too far onto the shaft putting side pressure on the bearing.

When I first bought mine there were no shims in the gearbox at all, previous owner was a clump. that meant that while he was riding it the gears were all rubbing themselves to bits. no permanent damage but a lot of work to make shims and build it up carefully from scratch. search this montesa forum there's a few links to free download manuals. send me your email address by PM and I can email you a copy.

the other failure is the brass thingy that transmits pressure to the clutch basket in the outer casing, in my case previous owner lost it so clutch spider was rubbing directly against the operating fork.

I made one easily from brass but i have a lathe and mill. they do turn up on ebay now and again when someone breaks an engine. but they are a wear item.