Hey KLXster -


Hi Klxster,

I have many mods on my '12 KLX250S including the F&R suspension rebuilds, MCM, the KACR removal and a Bill Blue TM33-34 pumper.

My son has a new (to him) Africa Twin so he is considering selling his '09 DR650 and getting a smaller bike, like the KLX. Our local dealer has a few 2025 KLX300 EFI (USA) models on display now (Mar 19, 2025) and the MSRP is under $5500. We all know that March is the month to buy new!

Before my son or I get serious about a new KLX300, I want to make sure that the MCM mod will still work well on the stock engine without any EFI tuning? I would also like your advice on the KACR and the starter issues post-MCM on the KLX300 EFI model. Thank you for your continued valuable advice regarding our KLX obsession. - David, Roanoke VA

Hi klxster ok after lots of reading the photos of the Acr mod dont exist anymore but on your setup with the mcm where did aling your Kacr to 6-7mm or marcelion's 8-9mm setting on kacr ???

Hi klxster would you know where i could find sum pics on the KACR repostioned for the mcm mod the marclino kacr postioning ( on my page doesnt come with any pics) reading his pages it looks like its sposed to have pics describing where it gets moved to iam a simple creature pics r always gooder 👍🛵
cheers jimbo

Thx klxster for the info do you run the mcm on your 351? I know on the 250 with bigger jets the mcm was awsum low down grunt, in your oppion is the mcm and kacr worth doing on 351 or just go back to stock timming with kacr? Bearing in mind i dont ride WOT iam more low down down torque i have thoudsans of forum blips and still confused about the mcm on 351 apart from yr post made sense to me so thanks for yr input 👍🛵 iasked bill blue he said not to from putting a valve into piston but i dont redline any motor but he did say that they was a couple that use the mcm on 351 with good results
cheers jimbo

Hi klxster do you have issues burning your starters motors out with the mcm mod and no kacr ? I have a klx351 with mcm and removed kacr tm33 pumper with 42.5 pilot and 142.5 main recommended by bill sumtimes it seems its hard on the starter bike has only done 2000kms and new high crank battery any thoughts ? I more for low end grunt iam not big on valve bounceing so is mcm worth it or go back to stock timming and fit kacr what setup do u run ?

Hey Klxster. You and I spoke on here about jetting some time back (2015). I haven't been on here in a long time, but I just wanted to say a big thank you for your help. between jetting and the MCM, it made a big differance. Again, thank you!!!

Hi there Klster, just wanted to say that I enjoy your posts[and knowledge on this site. I just try to give my opinion on what I have tried/learned playing with bikes[I'm 73] in the last long while. When I got my KLX in 09 it had 725 miles on it with the full FMF pb&Q4 open air box and jetted stock carb with a 12t cs. The local Kawa dealer told me to 351 it, but seeing I had the HP covered with 200sx, 505xc and a 520exc[KTMs] plated and didn't need a hopped up 250. Any way I still have the KLX[17500 miles] and the KTMs are gone.
I put the BB carb on first trying to get the front tire off the ground to clear small logs and limbs. The 351 was installed at around 4700miles. The only hiccup the bike has had is the ground thing[ex fix,eh].

Well sorry to bend your ear, take care down there in Texas.

Been in a mid life crisis the last 20 years and loving every minute of it.

Bought the 2012 KLX250S for 16 my year old son to ride on the street. A Lady bought it, wiped out on it, and sold it to me all in a 3 week period! It had 23 miles on it. She was still recovering from laying it over on a gravel road. The bike needed, and got, some new plastic. I was very lucky to have gotten first in line to purchase the bike.

Modding the performance with Forum knowledge has been very rewarding. I am hopeful that my efforts at increasing performance can be of benefit.