Here it is:

 

I have spent hours reading this 35 page thread and no ones talked about the 250 cam mod doing the intake seperate then doing the exhaust. Does the exhaust really help that much in the 09 klx250 carbureted?
And im at 600 above sea level with the 132 dj jet no airbox lid with full exhaust seems to run a little rich right now, maybe just doing the intake cam will help?

 

The modified exhaust is more a matter of aesthetics or performance actually weight.
The maximum increase in power you can expect is 1-1'5cv.
With the complete modification of the cams is more noticeable increase.
To get an idea, the increase in power with the exhaust is equivalent to half of the modification of the cams, only on admission. Approx.
Do not expect miracles with an exhaust pipe.

 

I hope you know I was talking exhaust cam

 

No, do not know you spoke only of the exhaust cam. Sorry.
My English is not very good, so try not participate much.
Modification of the exhaust cam is a bit laborious, but the results do worthwhile. In my opinion you will not have to modify the carburetor.
Most of the problems of lack of power and drowning at the bottom of the rpm were because they were prior to 2009 models, with intake and exhaust cams different.

 

That's okay any help is appreciated. I'm gonna try out the cam mod this weekend and let ya know how it goes. My bikes running rich so we will see what the cam mod actually does.
Anyone have any tips?

 

This thread has been open for nearly a year now and has always intrigued me - today i sat down and read over the forum and double checked everything and set up my 2000 model KLX250 with Marcelinos mod.

It DEFINITELY makes a difference. My bike already has a 120 mainjet, straight through exhaust, removed airbox lid but after a little while it became dull this mod has livened up the bike something severe.

Before anyone asks - I did both cams the inlet and the exhaust. I did my valves at the same time as they were out. I did not press the ACR out, I am just starting the bike with quick turns as opposed to winding and I have drilled out the starter jet which helps richen the mix upon starting. As everyone else has said starting is an issue without moving the ACR although my bike still cranks just takes a little longer to fire up. Also note this is a carb setup not EFI like Marcelinos bike. I have not had to adjust anything although the fuel/air probably needs tweaking just a little bit.

I can now wheelstand just by rolling on in 1st gear and 2nd gear the bike will lift a lot easier than it did previously. As others have mentioned you can feel the bike "pulling" in each gear like it still has power where before it was just revving really high and felt like there was no power at all. I can climb hills with the throttle just quarter opened instead of wound out now.

Im interested if anyone else who has done this has noticed a shorter life of the engine? I would assume the advance would cause some drawbacks however since the power curve is now shifted and im not revving the bike out i would assume this is better.

 

No harm at all to your engine.
On the contrary. the engine suffers less wear because it is not necessary to increase the rpm to walk.
Less rpm = less wear = greater longevity.

 

I've read this thread a couple of times and have been following the posts for about a month.
I used to do a little drag racing (long, long time ago) and what I know of engines and cam timing, this should should be a good mod for low and midrange power, which is what I'm looking for, so I gave it a try.
My bike is a 2007 250cc with modded stock exhaust (basically same as Marcellino's, but 1 1/4" pipe), no snorkel, but lid on.

I made the changes to both intake and exhaust, but decided to see how the bike starts without the acr so I just removed the spring.

The results are about what I expected to see, but I'm having a little trouble with the carb jetting.
I was running a 38 pilot jet, and 128 main jet before mod, with a .030 shim under stock needle, and it was lean at WOT, so I went up to 135 on the main and added another .020 shim to needle.
The bike runs good, but giving it full throttle under 4000 rpm causes sputtering (for lack of a better word).

I ride at 300-1000 ft above sea level.
Could someone in this altitude level give me their carb jetting after making this mod.

BTW; I don't notice any difference in cranking speed by leaving off the acr, and it starts on 1st or 2nd revolution, cold or hot.

 

If your bike starts well in cold and hot after the modification is that the ACR is well synchronized.
Oddly enough, I have found no two bikes with the same regulation of ACR: all are different. It appears that the adjustment is performed by a machine factory is amazing. Rather it appears that the adjustment is done by a crazy drunk.
Usually he always starts well with the 250cc will also modifying Marcelino.
If your bike is lazy to boot up, get ready! then the displacement of the ACR in total security!