I have stripped down the yellow bike engine and i have found the problem with second gear. the second gear dog clutch is worn out so two new gears at 80aud each from suzuki will fix that and while i'm wating for the gears i have started porting and polishing the head.
I have messed about with heads on other engines before but i still have no idea what i am doing when it comes to porting so its going to be a steep lurning curve and an expensive one if i mess up.
Basically all i'm going to do is take out all the casting marks and smooth out where the valve seat meets the alloy then give it a good shine up.
So far on the intake tracts i can see that the casting is quite good the surface is very smooth compared to other heads that i have worked on.
but there is a rather large ledge where the alloy meets the valve seat.
on the exhaust side its not so pretty the actual hardend insert is machined in such away that it tapers in by 2mm from the initial oppening. then the port trac is very chocked as it turns the corner to meet the other port.
anway the plan is to open the exhaust valve seats up a bit and to make the port tracs more even and i'll polish them as well.
This plus the high comp piston should make a ktm killer out of this dr
i will take some pics and post next time.