2021 Kawasaki KLX300SM I’ve been having problems with my 2021 Kawasaki KLX300SM. It only has 3,658 miles on it. I bought it used last year with less than a thousand miles on it. I love Kawasaki, I’ve had five of them so far. An 08 250, 06 636, 08 & 09 600, and this KLX. The problem started with, whoever designed it should be fired. The stock rear right taillight was mounted directly in line with the exhaust port. So naturally after I rode it a few hundred miles the taillight melted off the bike and ended up somewhere on the highway. I didn’t end up doing anything about it and rode it as is the rest of the year, until about October. I did several track days, flat track, motocross, kart tracks - motard, Supermoto, MSF coaching for a dozen events, and even a race on it Riding home one day in the rain, the bike was extremely hard to start and stay running. Then on the way home going 50 MPH, it suddenly turned off. I believe it happened because the exposed wires got wet and caused an electrical problem I’ve done some work to the bike trying to get it working properly. I first replaced the battery, with a lithium ion, lighter battery. I replaced the stock taillight and rear signals with an integrated taillight. I’m embarrassed to say that the oil was extremely low. This could’ve caused damage. I flushed the oil then added more. I didn’t see any debris. I adjusted the throttle cables, I adjusted the idle adjustment screw to max then less from max. I checked a few easy to reach fuses, I replaced the spark plug. It does seem to struggle starting way more than it did before. But usually does start up. Air filter looks fine Coolant is good, topped off. Feels electrical or that the fuel/air mixture is off. Could there be something clogged in the air box before the filter? Could it be the starter? Could it be bad fuel if it runs with my hand using the throttle? Could it be the fuel pump? Could it be something electrical? Could it be a crack in the fuel or air lines? I don’t see any fluid leaks. Could it be the oil or fuel filter? I didn’t replace the oil filter when I changed the oil. Could it be the stator - alternator? Fuel Injectors? It is not carbureted. ECU issue? Even with clutch pulled in, it still sometimes stalls from going too low in the RPM. Even after being warmed up for 10 min with my hand on the throttle keeping 5% throttle to make it stay running. What am I missing? I’m confused. What would you do next? I’m not a certified mechanic. I’m a racer & coach who knows how to make the machines go fast while at the controls. It’s only happening while off throttle and rpm’s are low. Will rev high and shift gears just fine. Thoughts / Suggestions? -Eric Swahn EricSwahnRacing.com
I don't know if this will help. I have one with 2800 miles. There is a recall for something on these bikes...I think it was fuel line related. I didn't take mine back for it. I most likely won't. Perhaps that is part of your problem? The light melting was a poorly aimed exhaust
Exposed wiring, not repaired. Many venues of abusive riding low on oil...all on top of Factory issued recalls She's only crying for help ..lol Hard starting ....... perhaps look @ Compression, leak down , fuel pressure, , any oil consumption ???????
I would check valve clearances first, followed by compression and leak down test. A single cylinder dirt bike engine on a road coarse gets more stress and wear than your odometer might lead you to expect. Tight valves with your amount of track time wouldn't be surprising.
I do like your line of thinking that the guy that designed the taillight should be fired because you don't check your oil level. Close to zero chance a electrical issue is causing hard starting. Those are usually either on or off. Your issue is mechanical. Probably related to low oil. Take the bike to a trusted, competent mechanic. Right now you're just wasting money on stuff that doesn't have anything to do with your issue.
My KLX is much older, but it's still the same basic engine. I had similar issues, and it was valve clearance related. As soon as I shimmed, all was good.
