i bought a yamaha yd 250cc bike,i m new for the this bike,but previous owner changed the cdi unit,black box.

bike start is serious problem,it allways backfires and engine going to highly heat.cant slow engine allways trying to stop and cant going fast.most people says yd 250 engine like sr 250 engine.is it a true? what is the suitable cdi unit for yd 250?previous owner changed cdi unit now it has yamaha mate 50 cdi unit.pls give me your answers.

Do you actually mean YD 250 or YZ 250.

A CDI Unit is pretty much manufacturer dependant and very bike specific. The ignition timing is dependant on a magnetic pickup on the flywheel and an RC (Resistror and Capacitor) circuit changing the firing angle at varying RMP's. YD's (as far as I know) still runs of points and aYZ would run off a CDI unit. I've cross fitted some CDI units over the years, but you have to consider bike types, i.e. two stroke vs four strokes and the rpm's the engines run at.

I would suggest getting a similar type CDI, IT 250 ar raptor 250, if it's a YD with a CDI retorfitted, you might be able to adjust the firing angle adjusting the points with a timing light.

i bought a yamaha yd 250cc bike,i m new for the this bike,but previous owner changed the cdi unit,black box.

bike start is serious problem,it allways backfires and engine going to highly heat.cant slow engine allways trying to stop and cant going fast.most people says yd 250 engine like sr 250 engine.is it a true? what is the suitable cdi unit for yd 250?previous owner changed cdi unit now it has yamaha mate 50 cdi unit.pls give me your answers.

i actually mean yd 250 ,4 srorke ,one silinder ,2 valve ,ohc ,double silancer bike, but in internet hasnt show this bike ,u tube has one video only,

do u mean it 250 ar raptor 250 cdi unit is suitable for this type,

but the problem is we dont have timing light tool.i couldnt find this one ,i went more workshops,how can adjus the firing angle adjusting points without timing light.if u know send me a link sr 250 full manual .thanks for u.

OK, I manufacture CDi units and see this problem with the SR500 quite regularly. With the SR there are several similar CDi boxes, but chose the wrong one and it will over heat the engine to the point where the header pipe glows red. The wrong generator can also cause this as well.

If someone has fitted an incorrect cdi unit, this could be causing your problem. The manufacturers go to great lengths to stop one box working on bikes it is not intended for.

Please confirm the year model and market of sale of your bike

please confirm either the yamaha or ND part number of the cdi box required (the correct one, not what is fitted)

please confirm the numbers stamped into the generator flywheel (IE 032000-xxxx)

I don't have much info on this model but will try and help if I can, it looks as if it could be similar to the SR250

thanks for u ,

this is the fly wheel number ,flywheel model mitsubishi, F3T370,

if u can find this model in u tube,it has videos,

this is the engine number 31G-002716,

in every parts can see the 31G number,

if u can tell what is the suitable cdi unit for my bike.