I recently bought a 2006 klx250. I found it for a good price even considering the fact that it needed some work. The sprockets were worn and the chain was missing a number of o-rings, needed a new rear wheel bearing and rear tire, the forks needed rebuilding as well as the rear brake caliper. I've just about got that all finished then I'll start working on some cosmetic issues. I did verify one thing that seems to be common knowledge. When I poured out the old fork oil I was expecting sludge but it was like new, the forks must have been recently rebuilt with cheap aftermarket fork seals which leaked. Comparing them to my new oem seals was night and day, the cheap ones were only rubber and had no structure to them where the oem seals were reinforced with steel and were rigid. In the past I've considered aftermarket seals but always went with oem, now they won't even be a consideration.
When I bought the bike I noticed it had a FMF pipe on it, later I realized it also had a pumper carb so that was a cool surprise. It also has a K&N filter and the air box lid is removed. I've heard not so great things about the K&N filter in the dirt, should I replace it with a foam filter or is that over reacting? I also am not so sure about not having an air box lid, seems like if I were to drop it during a creek crossing it would be more likely to ingest water, what do ya'll think?

 

Welcome to KF and nice find on a 2006. Let's see some pics when you get a chance.

A pumper carb is a surprise. Any chance it has a big bore too? There's some controversy with the K&N, but some guys swear by them. Many of us run with the air box lid removed, but sure, a drop in the creek with the lid off may be more likely to ingest water. How quick are you with the kill switch?

 

Wish mine had the carb...

As for the K&N FWIW... they claim greater flow making more horsepower. How do you get more flow? Less restriction. How do you get less restriction? More porosity. Fine on the street, but questionable if exposed to too much fine dirt/dust. I don't know about the water thing, seems to me the water might penetrate the K&N filter, but wouldn't it do the same with foam too? I'd think so. Still I'd think the design of most filters would simply have the water drop below the carb mouth and eventually drain out the bottom.

You don't see many - if any - motocrossers running K&N. They go with oil wetted foam. You also don't see K&Ns without the precharger foam filter covers when they are on dusty flat tracks or desert racing. That alone really sums up my point - even K&N uses foam when the going gets dusty/dirty.

I'd run K&N on my street bike or truck/car, but I don't on my dual sports or off roaders. I'm sure there are many others who might feel I'm wrong, that's fine. I'll continue to use oil wetted foam, they can do what they prefer. I hope they remember the precharger foam cover on the bad days.

 

Thanks for the welcome. I wondered about the big bore kit too. I couldn't find anything to indicate one way or the other except for a old registration from a previous owner where it was registered as a klx300, I don't know what to make of that.
I don't guess there is any way to know without taking the top end apart? I'll get pictures when I get a chance. The plastics are faded and ugly right now, I'm looking forward to having before and after pictures.
My other bike is a klr650, I'm really looking forward to my next off-road trip with my new bike. I wouldn't be surprised if I end up selling the 650, but it's a lot of fun in it's own right, especially for long days with mixed on and off-road, so we'll see.
I think I'm going to use the k&n for now and have a close look at it after a dusty ride to see if I can spot signs of dust getting through, and keep the kill switch in mind when crossing creeks.

 

ZombyWoof here runs K&N I believe. Maybe PM him if you have particular questions, or maybe he will pop up here. I've read the same Mark described above, and also the critical importance of making sure it seals correctly against the mating surface and that it is properly oiled. The foam cover makes sense when very dusty (I've seen pics of K&N on KLR650 completely plugged with dust while the other KLRs on the ride with foam filters were not plugged).

I found this recently. Unfortunately, he doesn't test a K&N. Air filter test | HBR

The KLR650 is a great compliment to the KLX. I have both, but if I had to get rid one, it would be the KLR.

 

I believe Bill Blue marks the cylinders he does. That should be present at least on a BB 330 or 351.

But I'm betting a run against a standard 250 with the jetting done and maybe a pipe would tell the tale. The big bore should pull it all around.

 

Thanks, I looked for marks or a stamp but didn't find anything. Regardless, I'm looking forward to trying this bike out.