valve timing

[mickalomaniac]

hey guys i've been rebuilding my 125 china motor, for any of you guys that have one, just check your valve timing. I have been looking into it really closely and have found that my cam was out almost 1 degree.. I know its not much and it will run well, but if your trying to squeeze all the performance you can out of your motor it pays to check.

To fix this i machined my cam sprocket bolt holes, to allow it to have a few degrees adjustment, it then locks in place when you torque up the sprokets bolts.

Also i found that the intake and exhaust valves were not in perfect sequence, to remedy this was a tonne of mucking around, but basically i cut the cam shaft between the intake and exhaust cam lobes and re joined them with a pin i milled to fit snuggly inside. I then drilled and tapped locking screw holes in each of the cam sides to fix it in place. After working out the pistons top dead centre and bottom centre i was abled to re-align the cam lobes to optimise the timing on the intake and exhaust valves... I guess it almost makes it similar to a twin cam now that i can adjust either intake or exhaust valves.

I know it sounds like a hell of alot of work but the difference is more noticable than any bolt on part you buy. The power and throttle response is fantastic. I highly recommend looking into it...

 

[sixeven]

good old chinas hey. They know how to copy stuff but can't even do that well!

 

[Mack]

Is this a stock cam your talking about?

 

[mickalomaniac]

no its a high lift cam.

 

[Mack]

Which aftermarket cam is it?

 

[PITBIKE_MULLISHA]

Second that from my end

 

[mickalomaniac]

i cant tell you the brand exactly, i got it off of the importer that i bought the bike off of. In saying that i'm keen to find out too, as for a brand name i'll get back to yas.