Trying to cook up a good recipe for my 2007 klx250s, without using a slip on muffler.

I've got most of it sorted out, keeping with the dynojet 2125 recommended settings and running the Dial a jet per instructions. What I'm curious about most is the MCM.

Is there any reason why it wouldn't work with the stock exhaust? It's just a timing advance/retard no?

Maybe someone who has done the MCM with stock exhaust could lend some advice?

Cheers

 

it should work fine with the stock muff

 

It works perfectly on a totally stock bike and really should be the first mod done to a new/stock bike. You'll notice the power increase the moment you wick the throttle in first gear. A big stupid smile is guaranteed.

MCM works on any KLX, with any mod combo..

 

If you use the Dial-A-Jet you want to jet in close, then back off two main sizes. I'm running the Kiehin jetting and instead of going to a 128 I stayed with the smaller 125. Lets the Dial-A-Jet work over the range from lower to higher elevations.

 

I'll be using the Dynojet kit, so my main jet selection will be limited to the contents of the box.

I know that the jets aren't exactly the same between different manufacturers, but the equivalency chart on jets-r-us gets me close enough.. and if that Dial a Jet does what it's claimed to- there shouldn't be an issue if it's not perfect.

The DJ 120 Main Jet is close to the Keihin 128 Main. I'll start there. It's the recommended main jet for the stage 1 dynojet upgrade, so obviously a gain over stock but not nearly as rich as most guys run the bikes without Dial A Jet. Should make trouble shooting a bit easier too. If for whatever reason the DaJ fails, I could delete it and still ride on with good safe jetting.

Call me crazy but all this being said- I'm tempted to run the main a bit higher... since the DJ kit is already a proven formula and the DAJ is only marketed to sort out lean spots in the operation of the engine.

It wont add fuel if the engine is running fine, and I may want to do something crazy like pull the airbox lid.. just to see how much the stock exhaust is really holding me back :P

Should the Dial a Jet be able to compensate for something like the lid being pulled? Or would that be outside it's range of adjustment?

 

Bike is joining up for dinner tonight, in the dining room. It's goin' down and my shop is full/ wont fit 2 dual sports at the same time :/

I'll post if I get lost :P

 

On the 650 I cut the lid out bigger - too loud without it - and put on an exhaust, the DAJ compensated for the original leanness plus the freer flow No jetting what so ever. Then the big bore. Still good. The bike has been over roughly 5000 ft without noticeable leanness or richness. Just the same all the time.

Not quite so lucky on the 250, I had to richen the main to the 125. Not gotten up in elevation, but I'm pretty sure it is right at the edge of lean.

 

Based on what you've said klx678, I think I'll start with the DJ 120. I ride between sea level and 2000ft (max). You mentioned in a previous post that your bother rides with the 128 keihin main, what elevation do you guys ride at?

 

We are at around 900-1000 ft. He jetted his bike in first without the DAJ, then added it. So his running the 128 was because it worked fairly well. He found adding the DAJ smoothed out some flat spots in the jetting from slide - needle - main. I just went a size leaner than he did. Seems to have worked okay.

I will say once you do the pilot jet, if you do the drilling of the starter jet (use a pin vise drill to hand drill it with grease on the drill bit to pickup any chips, it's too easy to drill too far and possibly break the drill with power), the bike will start near instantly and warm up way faster. I disabled the compression release with a wire holding it disengaged and my bike will spin and start at 8°F. It will start on a normal day and be warm enough to drop the choke in less than a minute or so. That bike was serious lean on the start and idle. I did the cheap mods stuff in my signature. Jetting was in Kiehin brass, but Dyno Jet does the job too, just different numbers.

Disabling the compression release is in the MCM link in my signature too. Pretty simple and easily reversed.

 

Please stop advocating putting a coat hangar on KACR's.. Household items have no business on internal rotating assemblies.

Coat hangar aside, regardless of the metallurgy of the "wire", the bending required to fit it to the KACR creates weakened "points of failure" within the wire..

Pulling the spring off the KACR is all that is needed/required.