I really like my klx 300, (in town and in the dirt), but on my two longer trips it's too wound out on the highway. I spoke to my dealer about an extra tooth on the front sprocket but was told that there's no space because there's some kind of safety doohickey that would have to be removed to accomodate the larger sprocket. And if I put on a rear sprocket with less teeth the chain would end up too long and i would run out of length on the swingarm once i put it where it wouldn't touch stuff. I was told i could have a sprocket manufactured with less width but that seems kind of dicey. I really want to keep the bike but it's not fun on the highway after a couple hours. Any thoughts out there?

 

You can fit a 15 T front sprocket without hitting anything in there. You can also go as small as either a 38 or 39 T rear sprocket, Kawasaki has them on the Supermoto version. Geared 15/38 is too high, I ran it. I found I couldn't shift to 6th without being out of the good power until around 60 mph. The 250 engine is just not powerful enough to do that, a 300 might. I could cruise at 70, but would have to downshift if I got on any sort of rise, not talking hill, talking a rise in pavement. I wouldn't recommend the 15/38, but definitely the 15/42.

I'd say order a 15T and get a good dealer who will do the job for the road, it might become marginal in off road riding though. If you go to a smaller sprocket on the rear, have them take a link or two out of the chain.

By the way, the 250 will rev all day long at 7000 rpm, no problem. Small engines have less stress in running, because of smaller lighter parts. I have no problem running my bike at 6000-6500 no problem. It's more psychological than fact that the engine is reving too hard, it is that the rider thinks it's reving too hard. If you ride in any kind of tougher off road riding I'd leave the 14/42 or even go to a 13/42 and just let the bike rev on the open road. You have to realize the engine has a redline of 10,000 rpm, if you're running 6000 rpm you still have 4000 more to go. You are only at 2/3 the engine's peak capability.

Funny thing about it, the scooters made these days run around at virtually full throttle all day. Honda's Reflex 250 was spinning around 6500 rpm at 60 mph and had a bit more to go. Just sayin' if a scooter can do it no reason the full size higher performance bike can't. I am almost never under 4000 rpm on my KLX250 and not afraid to wind it up running around 8000 rpm on open roads. I will say I have a street bike that is far more comfortable to run highway speeds, but that's expected. Again if a scooter can take it for mile after mile after mile, why can't a 300? . Rev it!

 

Dude! Thank you so much! this is extremely helpful!

 

No problem I have run a 13/45 riding in Michigan in the sand. I also figured I'd try the 15/38 for the road. Right now it's a 13/42, when I finally replace the chain I'll go with a 14/45, which is about equal to the 13/42, but less wrap with the larger front sprocket = less wear, probably marginal, but what the heck. It also allows me to gear lower or higher with a 13 or a 15.

As for the rpm, think about this.... The new Kawasaki 400-4 has a redline around 16,000 rpm. I don't know, but I'm betting it's probably going to push higher than our KLXs at 60!

Regardless, have fun. The sprocket is listed by JT. Click here to see the page, shows a 14 and a 15, plus the Kawasaki part number indicates all years of KLX liquid cooled 250/300 use the same counter shaft sprocket, and I can vouch for the fact that a 15 T fits.. I don't know why JT doesn't show the 13 considering they do show it for the KLX250S and riders are fitting them to their 300s. They also aren't showing the 38 and others for the 300, in spite of the fact that the same part number rear hub is used. Kawasaki shows that hub to work on everything from 2009 up. Probably fits the earlier ones too. Chain size is 520 as well. So it sounds like your dealer was blowing smoke up your tail.