No you havenīt misundrestood . In itīs original position the ACR opens one exhaust valve at about 90 - 100 degres before TDC and closes at about 50 BTDC , releasing some compresion , therefore making the engine easier to turn . Shaving the ACR lobe will not modify itīs angles , it will make it open less or not at all . Instead of shaving the Jesus out of it you are better off removing it . Then , if you latter change your mind , you still have a good , working ACR to install .
Ahh , and yes , it works only from 0 to 500 RPM , therefore it does not have ANY influence on how your engine itīs running .

 

YES , YOU DO !
If you do only one cam , you may have better results , I just donīt know if itīs 15% or 50% better . Whatīs certain is that you need to rejet .
If you then choose to do the other cam as well , you need to rejet AGAIN .
You see the trend , more work , ***** footing and less results .
The only ones who donīt need to rejet are the owners of EFI bikes that still have the O2 sensor connected ; The ECU does all the corrections for you ,so you donīt have to , like mine .

 

The stock KLX has more like 19 HP .
You can gain 1- 1.5 HP with a KDX snorkel or removing the air filter lid .
Before the cam mod I could not use the bike with the lid off , it was grawling like a hungry lion .
I gained another HP by removing the butt plug , itīs an exhaust mod , it consists in changing the original end pipe with a 1 inch one , look a few pages back .
On itīs own the cam mod accounts for 3-4 HP on a 250 .

 

Itīs an engine mod , it does nothing to your gearbox , if it feels better in one gear it feels better in all gears .

 

Has anybody yet done the mod the way it was supposed to be done ?
Do the mod the way it should be done , donīt touch the carb just yet . give it a ride .
Then move the needle up one position and repeat , then down one position and repeat . I know the needle only affects your midrange but al least you get a clue if you need to go richer or poorer ; if it works better with the needle higher you need to go richer ; if it works better with the needle lower you need to go poorer .
You donīt want to be bothered with the ACR just yet , fine , you need to let the bike cool down between runs anyways so you can play with the needle , it will start cold no problem , even if you leave the ACR where it was , instead of 1 sec. cranking you may have to push the button 2 seconds .
Have a cool beverage of your choice in between runs , it allows you and your bike to cool down .
Iīve used the bike 2-3 days before I did the ACR .

 

Marcelino, I did the camshaft mod and the 351 kit at the same time and I have 128 Dynojet main jet and needle with the clip third space down with two washers on top. Do you think I need to bump up to 132 main jet since I did both at the same time? Bill Blue recommended bumping up jetting two spots with the 251 alone. It's just I can still distinctly hear that intake grawl from the air box.(I have the lid off). I also removed the spark arrester from my HMF slip on to try and get more flow out of the exhaust.

 

Hoffy, did you do both cams?

 

Dynojet 128 DOES NOT MEAN A THING TO ME , I donīt know their sizes , what you supposed to have etc . So those numbers mean something only if you go by Dynojet nomenclature AND you are familiar with it .
Do the needle thing as I said before , check it the middle position , then raise one or two positions , then lower one or two positions . Monitor midrange , this is what the needle influences most .
The bike will tell you herself what is better , at least you will have a clue what direction is the right one , richer or poorer .
Idle and up to 25% acceleration are the pilot jet responsabilities , if the pilot jet is close enough you can adjust the mixture screw ( you do have the tool , donīt you ? ) . From 75% to 100% is main jet alone , thatīs why I say the best spot to start with a carb jetting is top acceleration .
You can also look at the plug :
In between runs ( if youīre doing main jet or needle ) DONīT let the bike idle , shut it of right away , then take the spark plug out and look at it : the cermic insulator should be white ( ish ) and the ring ( the portion of the thread thatīs inside the combustion chamber ) should be covered with a little dark gray soot . If itīs light gray or none at all you may be running too poor , if itīs almost black you are running too rich .
Of course nothing beats a O2 sensor , you can use ANY generic cheap aXX sensor you can find ; You just need to connect a cheap digital voltmeter and see if the voltage is below 0.5 volts ( poor ) or above 0.5 volts ( rich ) . I preffer the 4 wire ones ( the extra 2 wires are for the heather , 12 volts )
Itīs the most accurate , when youīre done you can take the sensor out and put a short screw in the bung . Save the O2 sensor for the next time when you ( or your friend with a hot barbeque and cold beverages ) need rejetting .

 

Man why are people only doing one camshaft? Just move them both. I like this mod alot but i would like to see it compared to new aftermarket camshafts before i dive into it.

 

This was the morning ride I wanted to do that I mentioned in my earlier post about the intake side (only) cam mod.

Conditions were virtually identical--wind speed, direction, etc as yesterday but it was only 80 degrees temperature instead of 101. Road course was the same, too.

Was able to ride against the wind with 3/8 throttle versus 1/2, as with yesterday. Apparently ~20 degrees temperature makes a difference!

With the intake-only part of the mod, you can definitely tell that something is going on, but to use a semi-pun, it takes the exhaust side of the mod to let it out.

So I did the exhaust mod today and the test ride, too. That will be the subject of my next post, just to keep things separated.