Tuning a yamaha dt250mx

[faz dt250]

As above does anyone know how to tune up an old yamaha dt250mx, i had one of these years ago and it was a little flyer, i have just bought another one to take to wales up the slate mountains but it doesnt seam to be as fast as my old one, any help would be great, ps i have only just signed up so am new to this, cheers.

[cheese]

I'd give it a good clean out and look at things like teh reeds adn check the exhaust packing. maybe well past due for a new piston.

[F5 Dave]

Without a doubt a 25yr old bike could harbour a million problems, but wise to replace the airfilter which will probably be disintegrating, clean out the carb & check for worn emulsion tube (that the needle goes into).

I would hope it was CDI ignition. New plug of right type, & take the pipe & muffler off & clean it out, do a search or Google expansion pipe cleaning. Repack muffler if it can be, might be worth cutting it apart & remaking it with some perforated tube & some new packing.

my guess is the pipe is most of the problem. But it could be well past time for a new piston/rebore & or Decoke too.

[Motu]

Ditto - and rings and crank seals,you need to do both together.

[faz dt250]

Thanks for the help guys, on close inspection after taking the cylinder head off i noticed the top ring was missing and the piston was all broken around the edge so i think i will totally rebuild the engine with new bearings and seals, thanks.

[wobb]

i Have a 1982 DT250MX. but the exhaust has gone. Have baffel but no epaintion pipe.
can not find one any were. dose any one no what other exhaust would go on and get it running? i do not have the expantion pip so i do not now what it looks like, or sizes. any help would be gratefull.
wobb