Problem after trying the lidless setup
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Junior Member
Joined: Jan 2017
Posts: 9
Really good job finding and fixing the diaphragm issue @fordtruck..
As you probably know, the lidless setups are not experimental - If the bike doesn't run right after the carb session, something was done wrong..
Also, as you know, the lidless setups unleash power that leaves "normal" KLX builds in the dust..
The MCM is an enhancement of volumetric efficiency through valvetrain retiming. It is proven very effective thru dyno charting. As such, it does the same "goodness" regardless of what size piston is in the bore.
The MCM is not experimental. If it is done correctly, it works.
As you have found out for yourself, if you want enhanced low - mid TRQ with little-to-none HP loss in the top end, you do the MCM.
As you probably know, the lidless setups are not experimental - If the bike doesn't run right after the carb session, something was done wrong..
Also, as you know, the lidless setups unleash power that leaves "normal" KLX builds in the dust..
The MCM is an enhancement of volumetric efficiency through valvetrain retiming. It is proven very effective thru dyno charting. As such, it does the same "goodness" regardless of what size piston is in the bore.
The MCM is not experimental. If it is done correctly, it works.
As you have found out for yourself, if you want enhanced low - mid TRQ with little-to-none HP loss in the top end, you do the MCM.
Now the lidless setup is a different story. I'm very impressed with it. I already had the Stage 2 Dynojet kit in mine and it still added quite a bit over that.
Senior Member
Joined: Jun 2013
Posts: 3,315
From: North Texas
1st Gear Member
Here is the comparison chart - DO NOT make the mistake of looking at the HP curves, that is useless information. ONLY THE TRQ CURVES have useful information.
This comparison chart is imperfect due to the MCM bike (blue lines) not being fully/final tuned at the time of this dyno run AND due to the run not being started at a lower RPM - but the two bikes are outfitted identically otherwise.
Differences between MCM and Stock can be deduced - but the slight losses, for the MCM, in the upper end are probably due to the incorrect carb tune.
In a nutshell: You are looking at significant increases in throttle response and power ramp-up below 6500 rpm and, basically, parity above.
This comparison chart is imperfect due to the MCM bike (blue lines) not being fully/final tuned at the time of this dyno run AND due to the run not being started at a lower RPM - but the two bikes are outfitted identically otherwise.
Differences between MCM and Stock can be deduced - but the slight losses, for the MCM, in the upper end are probably due to the incorrect carb tune.
In a nutshell: You are looking at significant increases in throttle response and power ramp-up below 6500 rpm and, basically, parity above.
Last edited by Klxster; Mar 30, 2022 at 03:39 PM.
Thread Starter
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Junior Member
Joined: Jan 2017
Posts: 9
Well after fine tuning the idle mixture screw to halfway between idle drops and putting a few hundred miles on the bike, I've changed my opinion on the MCM. Adjusting the mixture helped the flat spot off idle. The bike really feels responsive above 4.5k rpms. Doing the MCM and lidless setup really woke this bike up.
Senior Member
Joined: Jun 2013
Posts: 3,315
From: North Texas
1st Gear Member
Now that you've properly set the idle mixture screw - and I hope your idle speed it also set correctly - you have fully "fleshed out" your build - great job!
For the record, an integral part of the lidless recipes is the proper setup and selection of the pilot jet and pilot system - this information is included and specified in each of the lidless recipes.
As @fordtruck found out - a lidless recipe is not complete - and the full performance benefit is not available - until the directions for the pilot system are followed.
This is doubly so for lidless builds that include the MCM. The proper setup of the pilot system is vital in order for the CVK to provide an enhanced "shot of fuel" every time the throttle is snapped. In the case of lidless builds that include the MCM, this allows for the "full effect" of the enhanced TRQ, and enhanced TRQ ramp-up offered by the MCM.
For the record, an integral part of the lidless recipes is the proper setup and selection of the pilot jet and pilot system - this information is included and specified in each of the lidless recipes.
As @fordtruck found out - a lidless recipe is not complete - and the full performance benefit is not available - until the directions for the pilot system are followed.
This is doubly so for lidless builds that include the MCM. The proper setup of the pilot system is vital in order for the CVK to provide an enhanced "shot of fuel" every time the throttle is snapped. In the case of lidless builds that include the MCM, this allows for the "full effect" of the enhanced TRQ, and enhanced TRQ ramp-up offered by the MCM.
Last edited by Klxster; Apr 25, 2022 at 04:11 PM.
Senior Member
Joined: Jun 2013
Posts: 3,315
From: North Texas
1st Gear Member
Replacing the pilot jet with a #38 or #40 is not always "mandatory" with lidless setups ( I will explain below) .. But, properly setting the fuel screw is mandatory.
About replacing the pilot jet:
When the MCM is included in your lidless build - the pilot jet should be replaced with a #38 or a #40, along with proper fuel screw setup. Use the #38 only if your bike stays above 3000 ft above sea level.
If the MCM is NOT included with your lidless build but you are using the stock header, a new pilot jet is recommended.
If not using MCM and using a full performance exhaust, pilot jet replacement is totally optional.
About replacing the pilot jet:
When the MCM is included in your lidless build - the pilot jet should be replaced with a #38 or a #40, along with proper fuel screw setup. Use the #38 only if your bike stays above 3000 ft above sea level.
If the MCM is NOT included with your lidless build but you are using the stock header, a new pilot jet is recommended.
If not using MCM and using a full performance exhaust, pilot jet replacement is totally optional.
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Klxster
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