hi everyone.

am beginning to consider a big bore kit for my Yamaha DT50MX (1990) but would like to know the facts before i do.

i already have an aftermarket exhaust can (original expansion chamber though) and will be fitting a performance air filter soon.

so far i can only find 60cc big bore kits but i was wanting to get at least 70cc or possibly 80cc (which i cant seem to find the kits for) so does anybody know a good UK supplier that does them?. and because of the extra power would i need a new crankshaft? (if so, where can i find them?)

and also, to cope with the extra capacity im going to need to re-jet the carb which i can do no problem, but would i need a bigger carb aswell?)

aint easy finding good mods for this old bike

- Steve

you can port the 50cc barrel and get the cylinder head skimmed and the squish recut and put a bigger carb on the 50cc engine and also open out the reed stops on the reed block and port and flow the reed block and this is the same process

when running a big bore also you can put a dt80mx engine in and this is the same process of tuning as the 50cc and the 60cc big bore then you can put a big bore on the 80cc engine and the tuning is the same process