Backfire!

[CrazyJa]

Hi!

I have a blaster which i bought from some guy that he modded and used kx 200 parts. Well what happened is that i broke the piston and replaced it with a Pro-X piston and since then it does not want to start. I had it at the local guys and was advised that it is the reed valves as there is no suction on the reeds infact it blows air back into the carb. I bought ner booysen reeds and fitted them but still no luck. I need serious help as i know a bit about bikes but this one has me baffeled. Please help!

 

[yb200]

check the compression did you take the cylinder to a shop to see if you needed a hone/bore or both

 

[phragle]

If the reeds are good, do a leak down and compression test. if it passes that and has spark, its a jetting issue. Turn the airscrew all the way in, back it out 1 1/2 turns and try and start it with the chocke and no throttle.

 

[YZ Otis]

sounds reedy but if that ain't it, when you broke the piston could you have sheared the flywheel/crank key? Have you had it off?

 

[CrazyJa]

I replaced the reed valves to the standard blaster reed box with booysen reeds, as I mentioned the previous owner had kdx 200 reeds in. It started with those reeds but with effort and just would'nt rev up. Now with the new reeds it just wont start. I took off the exhaust and turned the motor but there was still air coming out towards the intake. I took off the barrel so that I can take it to the engineering shop so they can check the clearance for me. If they give the green light and confirm that all is ok then i will do a compression test. It was 0.5mm oversize and I bored it to 1mm oversize. The crank key was damaged trying to get the flywheel off but had been replaced. There is feul that gets through as I saw it on the crank but will check the carb jets aswell. But It still does not make any sense!