I read somewhere that with the mcm mod you have slightly higher consumption. So my question is, is there anyone that encountered any issue when going for a vehicle inspection, like higher emission or something?!
And just to be sure, is there any special tools I need? Should I replace to a new gasket also?!

 

Consumption of what? I haven't noticed any changes, but then again the KLX is so easy on gas I never check mpg. I don't know about the emissions, not in an e-check area.

No special tools needed, just some hand tool thread locker (blue LocTite 242 I think, Harbor Freight carries 242 as well). From there follow directions. I will admit it took me three or four tries to get the cams right on the chain. I kept moving one too far or the wrong direction, but it was obvious. See the instructions I have in my signature. Let me know if it doesn't work.

One thing I did, I was re-shimming valves, so I had to wait to get shims. Some models of the 250 had gasket issues with shrinkage or the like. So when the bike had to sit I put the cam cap back on, just snugging down a couple of the bolts, barely tight, then put the cam cover back on so the gasket was held in place and couldn't shrink or expand.

Important note when taking off the cam cap make sure you know which bolts go where. There are two different lengths. Make sure the alignment pins are either in the head or in the cam cap, don't lose one in the engine without knowing it. Most important is how the cap is removed and how it is reinstalled. On removal tap the cap with a plastic screwdriver handle to loosen it enough to lift it off, never pry on it. When reinstalling the cap put it on, making sure the locator alignment pins are in place then fit the cap on by hand until it fits flush around the surface, tapping lightly with a screwdriver handle if needed. Do not force the cam cap by hitting with a hammer of any sort or try to pull it down with the bolts, you may crack and break it. The cap comes mated to the head, so that would require a new head assembly. You can get the cam cap off and on easily enough, if there is a problem look around to figure out why. You don't want to break that cap.

 

Thinking to do it those days that i have some free time. Some more questions, do i need to empty the tank?(i just topped it damn, efi version). Can i reuse the old flange or i have to use a new one? Can someone give me more details of how to remove and put back the cam chain tensioner?!

 

Not sure what you are talking about reusing a "flange". In doing the work there was nothing I had to replace. I don't remember how much gas was in the tank, but I'd run some out or syphon it out into a can, just to lighten up the tank for removal and so that when I'd sit it on the floor or wherever, that it won't leak out of the cap or breather.

If you still have the OEM tensioner you need to remove the big bolt, which holds the spring in place, to take a load off the plunger, remove the tensioner, and once out, reset the plunger all the way back. You could put the tensioner, minus spring and bolt, back in place to get it out of the way. Then when you're all done with the work you put the spring and nut back on, pushing the plunger back out to take up the slack.

While the tensioner is out you should look to be sure it is still good. If there is a kind of wear pattern on the teeth over about four teeth and the underside has a length of the shaft polished, the tensioner is failing. Replace it with a manual tensioner. If you already have a manual tensioner, has a thru adjuster bolt with a lock nut against the body you can simply crack the locking nut loose and back the adjuster out a few turns to allow some slack in the chain to do the work.

I am PMing you about the tensioner and a shop manual

 

Flange = gasket.

 

So did it today, but im not 100% sure i havent mess things up, i got confused at one time while puting back the left one. Is there a way to see if i have it right?! Bike works though, maybe with slightly hesitant throttle response sometimes. Havent notice a power different really but its difficult to tell because its snow here two months now. But indeed started faster i think!

ps just read it has a different at 6.5-7k, i think i havent went that high in rpm
PS2 opened it again and took photos, looks ok to me, someone to confirm?
PS3 if I want to go back to normal, do I have to put the spring back on the kacr?

 

Hot Rod Engine Masters did a video on cam lobe separation angles (LSA) using three identical lift and duration cams only varying the cam LSA. This is what is done with the MCM. It may or may not feel stronger, but the fact is with the cam LSA narrowed doing the MCM the power range from around 3500 on up will have some gain. There will be no change in the redline, which is not tied to LCA, It is controlled by lift and duration I believe. Here is the article, but can't find the video anymore. click here :

Many people said the MCM increases low end, but it actually decreases low end, but realize low end is in the 1000-3000 rpm range. No one is riding around on a 250 at even 3000 rpm unless puttering along in town. Low end in the case with cars is in that low range where most cars operate. Bikes like the KLX250/300 get reved much higher and harder than car engines. But with both being four stroke, the science is the same. The narrow LSA increases torque in the middle range to top end, 3500-8500 rpm. It actually may cost a couple HP at the very top, but is better everywhere else.

So you may or may not notice the power pick up , but it is stronger. Improvements like that may or may not be noticeable. It won't be earth shaking either. It's just stronger.

 

I see, thanks!
Any idea if I change it back if I need to mount the kacr spring back on?

 

I haven't had the KACR spring on my 250 since I first got it. I did actually wire it fully disengaged, but running without the spring does the same thing. I think the KACR is a left over from the pre-2006 kick start KLX250/300R models. I've never had a moment's issue without the compression release.

 

You had it removed even without the mod if i get it right?