Hi I am new to the group. My 2007 KLX250SF seems having spark or power loss issues that I think related to spark, ignition or CDI problems. Bike is carb type, rejetted, removed snorkel and now using open pipe. Used to run great. A month ago, bike starts, idle normally, runs on on 20-30KPH (low rpm) but will run out of power and die on the highway if pushed to revved higher.

I've since replaced spark plugs and ignition coil. Same problem, it runs but when pushed hard to high speed it seems to misfire and exhibit loss of power similar to overheating and then engine sputter and die. After 2-3mins engine can start again, can run at low speed for 5mins then misfire, sputters and die.

Appreciate your help on this mates...

 

Do you let your bike sit for a month between rides?

 

Thanks for the kind reply....the answer is yes. I seldom ride and the bike just sit there sometimes 1 month or two without rides. I just start the engine to maintain the battery. In my last ride of Sept 2022...I've changed spark plug twice and then replaced the ignition coil at home because of such problem. The problem happened during my last 500km ride. sputtering, misfire, loss-of-power but otherwise, starts okay and idle okay. When engine got heated and running for about 3-5km, this problem occurs.

 

Have you ever cleaned your carb? IMO, you may be looking at the wrong place for your problems.
Do you run the carb dry everytime you ride?

 

Things to Check:

Clutch Switch
Tip Over Switch
Kill Switch
Kickstand Switch