I have a friend who has a couple carbureted KLX250s, if I understood him correctly, his bike will not run over about 8500 rpms. My 2019 EFI model easily spins faster and possibly will reach the 10,500 mark or more.
I haven't been able to determine if this machine has a RPM limiter and if so where it's set at. There has also been some discussion about a "clutch switch mod". where bridging the contact in the clutch switch will either bypass some limiter, or change some settings in the ECU uncovering some hidden performance? Some said this isn't the case if at all with US bikes. Currently my KLX, again a 2019, clutch switch won't allow me to start the bike in gear. The switch appears to be intact, so guessing some break ion the lines somewhere. Not a big enough deal for me to pursue. I am just interested in knowing if there is anything to any of this.

 

My 2007 with carb goes way over 8500rpm, and I never messed with the clutch switch, it still works.

 

2019 US models do not have the fake rev limiter in higher gears. The clutch switch mod would have no effect on your bike.

When you say your bike can't be started in gear, do you mean it can't be started in gear even with the clutch lever being pulled in (in other words, witu the clutch disengaged)? Or just that it doesn't start with the bike in gear and your hand off the clutch lever completely?

 

The bike has to be shifted into neutral to start. I have checked to see if the switch is broken, appears to be all intact. As I mentioned it's not that big of an issue, that I want to start tearing into the bike removing stuff to access the wiring to determine if it is disconnected or damaged. I currently have a bigger issue. The bike is jumping in and out of gear in 5th possibly 6th gear. I suspect circlip has jumped out of its groove or engagement dogs are damaged. Bike has less than 2,000 miles so I suspect the former. I probably won't get around to pulling the engine out of the chassis and tearing it down till this winter.

 

At that low of mileage, is it on the factory fill oil still maybe? These transmissions seem pretty sensitive to oil degradation

 

Just changed the oil and filter, used 10W40 Quaker State, but it wouldn't be that expensive to drain and refill with a motorcycle specific crankcase oil. although I don't think that is the issue. Sure would be nice if it was. Back in 1975 had a Honda MR175, with a clutch that would slip with multigrade oil, A switch to straight 30 WT and some heavier clutch springs took care of that. Since that time I've been using Rotella 15W40, and most recently motorcycle specific synthetics, this was the exception.

 

You should drain it, you need motocycle oil if you plan on your clutch working when you fix it.
But your problem is not the oil, that will not make it pop out of gear. Slipping yes!!!!!

 

Yep, I've seen this before, just not in a bike with such low performance and such low mileage. Most of the transmission failures I've seen occurred with offroad 2 strokes, and these have been mainly in the middle gears. One would think this kind of failure in the upper gear range is most unusual. The draining of refilling will take place after the trans is broken down, expecting that I will have to replace matching gears and shift fork.

 

I broke a gear on a Suzuki 80, an 80cc. I was so surprised, I just couldn't believe it.

 

Been looking into have the dog recut, there are several companies that do that sort of thing. Guessing it wouldn't 'make a much difference in price.