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. I am thinking also if kill-switch wiring and connector issues could be related to this problem.

Appreciate your help on this mates...

 

Have to drained the carb bowl just in case H2O is in there? I buy only ethanol free, but still get water in there with regularity.

 

Sounds more like a fueling issue.
Make sure that the petcock will flow and if that looks ok, then I'd pull the float bowl to check for debris in the main jet circuit.

 

Hi, sorry my reply is delayed. I brought the bike to mechanic to have the carb cleaned as I suspect dirty fuel as the cause. Problem seems solved after the carb-cleaning. Bike was good during testing. However a day after, engine was again sputtering and losing power when put on high-speed running of about 50-70% throttle. We did some re-jetting but same result. The problem is, the bike would easily start and run fine at first but lost steam and power after several kilometers of high-speed driving. I discovered today that fuel filter runs dry or that fuel scarcely get to the carburator during high-speed running. With engine sputtering, I had several stop to check the fuel-line and transparent fuel-filter. Filter indeed was sort of dried up. But after putting the engine to idle for a minute, the engine is again running normal. I confirmed fuel tank has fuel while fuel-**** is supplying enough gas to the carburator as seen thru the transparent fuel-filter. It runs dry though during high-speed running.

I must state that fuel-**** is bad and needs replacement. The off-position still flows and supply or drip some gasoline to the carb. There are two fuel-line lines coming from the tank to the fuel-****. Could this be carburator problem, or the fuel **** and the fuel feeding system? Please help...

 

Also, ensure the vent on the tank isn't plugged/blocked.

 

Hi, seems the old issue was solved. Fuel supplied to carb from gas tank seems too low or small amount because of bent fuel hose. The old owner relocated the fuel outlet much closer to the fuel ****. As a result the fuel hose was sort of 45 degree angle thus not enough fuel was coming in. I replaced the fuel hose with a longer one about 10inch long. Problem solved.

However, cold starting, when bike is not used for several days, persist. I had to remove the air cleaner hose to perform manual choke. Choke is no longer working. Motor wont start unless I perform manual choke.

Is it advisable to replace my carburator? Would you recommend it?

Also, are replacement carburators made in China for KLX250 a good buy?

Appreciate your opinions on this.