Thanks for the great pictures. I just oiled my stock foam filter today after putting on the edge taillight. The dealer prep must not have included fitler oil! Maybe some engine oil was applied but it was very yellow and dry. It is now green with bel-ray filter oil. What a greaking bugger to put the filter in the box. I am a lip greaser so my greased lip made a huge mess while trying to seat that filter. Is the twin air smaller?

I see you used a 2009/2010 DJ kit but your bike is the older series. Is the newer kit better?

 

The stock foam IS the best filter, from a filtering standpoint. It's thick and has finer pores than the aftermarket stuff. From a performance standpoint it doesn't flow too well. When i was testing I couldn't see much change in box lid on or off or shimmed up in back with the stock foam. Aftermarket filter big change.

With an aftermarket filter stay out of the silt and dust though, or make sure it's oiled with sticky filter oil.

 

The TwinAir air filter is actually the same size as the OEM filter. What I like about the TwinAir filter is that it is dual density foam. A course foam for rough filtering and a finer foam layer underneth for the smaller particles. As for applying greese to the lip, I didn't do it. The TwinAir sticky oil made a good enough seal, plus stuck to everything it touched.

Even thou I used a DJ kit for the newer KLX, the carbs are 99% the same. Except the older models had a throttle position sensor and the new ones don't. But the internals are the same. You can even use the DJ kit for the KLX300 (which most folks here run), but I recommend it for more off-road use.

 

Hey LearJet. Were you at the Urban Assault dualsport ride in OKC last weekend? There was one fellow there with a KLX, but was riding a bigger machine.

About the foam filers, whether stock or Uni or TwinAir, oil foam is in my opinion superior to all other alternatives, paper, or K&N, especially when soaked as in the photo in this thread, with real foam filter oil. Wonderful to see water flowing around the filter and not going in, and how pretty much no particulates make it in the engine. Unfortunately, way too many filters are oiled with motor oil (gravity pulls the oil down) or not oiled at all, which does not stop fine particulates.

 

No, I wasn't as the Urban Assault. But I will be riding here soon at CrossTimber trails near Draper Lake.

Cough, cough. Ya, I made that mistake of using motor oil on the oem foam filter. Did not make that mistake again on the TwinAir filter.

 

The only mod that really made a big difference to my fat 218lb **** is to increase the displacement. I did most of the others with no real net increase (slight at best on most). Put the money into a good big block kit with stock everything else (rejet) and you will get a real healthy increase in power.

 

I haven't been to Draper since the mid `80s when I lived in Norman. Draper was much bigger then. I should go back sometimes just to check it out.

I live ~ 40 miles West of Lawton up aginst the Wichita Mountains Wildlife Refuge. Be fun to hook up sometime with more of the local DS crowd. I'm going to see about setting up a DS class for trials techniques on the ranch. Camping, fun cookout, etc. That's better before it gets really hot, so it may not happen until fall.

 

Consider a Dial-A-Jet along with exhaust and intake modifications. I've been using one in the KLX650 for over 10 years. It compensated for an open air box lid (unless you ride where there's a lot of water and soupy mud, the snorkle is unneeded restriction, I've never had one in and I ride eastern Ohio), a full exhaust system, and a big bore piston. Never jetted the carb since it was very lean to start and the mods just made it leaner.

I know on the 650 and the 300 the tricks were always freer flow exhaust and intake. The 300 did well with a bigger carb, open intake, and a bigger headpipe if not the whole exhaust. My 650 actually gained MPG over stock! From 50 mpg to 60 mpg and much easier acceleration to 90+ mph. It's also worked without adjustment over a 5000 foot altitude and 80 degree temperature range without jetting change. Performance hasn't changed much in any of the applications, except thinner air does take some power, but jetting stayed optimum for whatever was there.

When it comes to the Dial-A-Jet most negatives come from people who haven't used it ever. The company is totally receptive to calls for any help, but I ran them in a Nighthawk S and already knew how they worked. The site has a page of media comments. Both Motorcyclist and Dirt Bike! have tested it with decent results proven on a dyno in the use on a GSXR. I have no idea why the product is so poorly received in the motorcycle market as compared to both ATV and snowmobile markets, other than that hard jetting has just been tradition in motorcycles. Read some of the articles and then read some of the testimonials. I'm just one of many who've had great experience with the Dial-A-Jet.

The fact is it works on the same fluid dynamics principles as that of the Mikuni powerjet used for max performance by Mikuni. The difference is the Dial-A-Jet mixes in a bit of air to get a tunable emulsivication of gas/air. It is a fuel adder and as such only works when the vacuum draw of a lean system is present. Read up on it, check it out. You'll only have the carb off one time to set it up, never again after that relating to it or jetting. It just flat works. KLX650 riders have gotten similar results, viewable in the Yahoo KLX650 group, and a good friend has done the same with his XT225.

The KLX250 is an ideal candidate for the Dial-A-Jet since it is so similar to the 650 and clearly is getting a lot of modifications. I get nothing from telling you guys this other than knowing I've given some of you a good tip for your jetting needs, based on my experience over the past 20 years with the product. It costs about the same as a jetting kit and actually if you used a fitting for the fuel drain screw you can install it without taking the carb off at all. (I drilled the float bowl for a fitting because I find if I don't run the bike for over about 5 days I have to drain the float bowl - high quality gas these days.) My guess is the 250 is lean enough to probably work as is.

If you want to know how the set up is for sure or just ask more questions, call them at Thunder Products. They're eager to help out. Mentioning my name won't do a thing for you though, they have no clue who I am. I'm just a very satisfied customer from about ten years ago with the KLX and 20 years ago on my old Nighthhawk.

 

Thanks for the info klx678. It sounds like an interesting system. I've already done the re-jetting to mine, but the ability to adjust the jet on the fly would probably be good for people that ride at extremes in altitude.

 

Trust me, you aren't missing much. Draper lake is currently draining. The water level has dropped so much, theres a 2 year ban on boating in the lake. And by the looks of things, will conitune to drain. If you want pictures, thats no problem since I live like 5 miles from the lake.