Hello everyone. I just did Marcelino's cam mod on my 09 klx250s and after reassembly it won't start. I even repositioned the ACR to almost exactly where it was originally located.

Everything is set exactly like the picture in Marcelino's thread and I quadruple checked that the crank was at TDC. Now, for some reason when I tried to start it the first time (without repositioning ACR) I had gas pissing out of my carb bowl overflow and when I pulled everything apart there was a significant amount of gas in the carb to filter boot. After pulling my carb and cleaning it, it no longer flooded. However, I still can't get the bike going.

The plug is wet after I crank it. I tried a new plug, nothing. I do have spark. I left the rear of my carb open just to see what is happening and when I turn it over, it seems as though my carb is blowing gas back out?

I will admit that I'm not the most knowledgeable person when it comes to four strokes, although I am familiar with it and I've rebuilt many 2 stroke engines...There are no cams to deal with in that situation though.

Do you think I screwed up the mod, or is there something else related to my carb problem that coincidentally happened after I finished? The cam sprockets are exactly as pictured, with the cam shafts in the same position at TDC. Hopefully someone can help me with advice. I wanna ride!

 

Does it suck in the exhaust?

David

 

No, the exhaust is discharging light puffs of smoke as it turns over. But I am not actually getting ignition. The back of the carb is arbmost like it is pulsing in and out. I also see the carb moving back and forth with each stroke.

 

Do you have any intake valve clearance? Sounds like one or both of them is staying open or opening at the wrong time.

Ride on
Brewster

 

advice, take it apart again, check everything over very very slowly, and reassemble it as it was stock.. if you are lucky, it will run again.. get a big bore, forget the cam mod

 

+1 on putting it back the way it was. I don't think there is much to be gained with it and if you have an issue it could be major. I never considered it for myself.

 

+2 on back to normal. I haven't seen much good come out of it.

Just spend the $550 on the big bore and get your thumb outta your butt.

 

Cam mod is essentially free. -1 on putting it back to stock. Post some pics so we can see your cam timing.

 

from what i read a few months ago on this cam mod, the acr must be repositioned .. also, did you modify the exhaust and intake.. if so, you need to ofset the acr.. like in the writeup. have u gotten it started yet?

 

+1 big bore