Hey folks. PlanetKLX was an amazing resource which structured a lot of information scattered across the forums. Unfortunately it's in "archive" mode and mostly relevant to older KLX. I've learned a lot for the last year and want to put things together. So I've started PlanetKLX2. The engine section is more or less done and it would be great to hear your feedback/corrections.

Also if you would like to contribute articles there - let me know!

 

Very nice.
Some thots:

IN the "ECU tuning" section, you left out the fact that to get 28.5 hp, you must remove the secondary throttle plate. Please add this to the mod list for 28.5 hp. Here is the text that needs this addition:
"With correct air-fuel mixture(controlled with piggyback), free flowing exhaust and open airbox (removed airbox cover and snorkel) KLX300 can produce about 28.5hp @ 7500rpm (pink line on the chart below).

Replacing the injector is a problematic mod that, perhaps, should not be listed or mentioned. The reason for this is that injectors require a detailed parameter setup, within the ECM, in order to be properly controlled/operated. Since we cannot provide the ECM with the correct injector data, the injector will be operated with the parameters/tables of the stock injector - meaning that the new injector with be operated "out of spec" , which causes a myriad of problems.

Perhaps you should provide more details about the operation of your piggy back fueler. Maybe some screenshots of the app's interface and how to modify parameters..

 

The reason the BDSB chart does NOT show the same effects (power losses) of the soft rev limiter, compared to all other charts, is quite likely due to their FAULTY dyno testing .. They actually admit this - but probably assume we are too stupid to know better ...
You DO NOT dyno test a KLX 250/300 in 4th gear !
Doing so skews all power levels higher than they should be.

Below is a snip from their website - admitting to the erroneous testing and, therefore, results.

 

@Klxster Thanks for review, really appreciate your time! I will add subthrottle plate removal to the mods list to get 28.5hp.

As per my understanding injectors are really simple devices with a single variable - flow rate. Which is how much fuel it can spray per minute while being always "on". ECU operates injector sending on/off signals. So if injector with 20% larger flow rate will be "on" the same time as original injector, it will spray 20% more fuel. And I've as discussed here it works well after 250->300cc upgrade. So I think still worth to know about this "poor man" solution.

Will do a video!

But 4th gear doesn't explain the shape of the dyno curve... If it just inflate numbers it's one thing, but curve shape is other animal.
Also I've heard that 3th / 4th gear numbers might be higher than actual. But can't find explanation why. Any hints?

 

The explanation as to why a dyno operator must ALWAYS choose a gear that is 1:1 or as close as possible to 1:1 is due to the dyno sensing roller acceleration and speed for its' power calculations. A lower gear gives the bike more leverage to accelerate the roller/drum and maintain roller/drum speed, therefore creating inflated power numbers AND CURVES. Let me try to explain - When the engine loses power due to the soft-rev-limiter, it slackens off roller acceleration rate ( due to the dyno "loading" the roller with resistance) , this causes the dyno to register a power loss. If the bike is in a lower gear, and therefore has more leverage on the roller, it will not slacken off roller accel rate the same as if it were in a 1:1 gear ( 5th on the KLX)..

Injectors ARE CERTAINLY NOT simple devices. They have up to half a dozen parameters that must be entered into the ECM's injector control panel - I say up to half a dozen as ECM injector control tables vary in their size and scope.

Slapping in a "bigger" injector, and calling it a day, means the new injector WILL NOT be operated properly. There is very little chance the engine will run properly ( especially idle ) ,or be fueled properly from idle to WOT - but stranger things have happened.

 

I will put forth that Doug Pippin has a really good KLX250 site for carbureted models, not sure if he has anything on EFI since I don't believe he has an EFI model. KLX250S Home Page

I was on the KLX planet back when, because I had a KLX650. I don't know what all was there, but I will say the KLX sub-forum here probably has as much or more overall in all the threads covering so many different things KLX related. But it never hurts to have more places even if it is the same information, continuity. I have some of Pippin's stuff on a google doc ln my signature. Feel free to make copies to keep the stuff continued for future KLX riders, old models and new.

I've already seen how the demise of information hurts. The Yahoo KLX650 owners group had great information until it more or less disappeared courtesy of changes at Yahoo. I copied some of the files to post in google to prolong the availability of stuff like fitting a DRz400 shock to a KLX650 and installing a braided cable using a wrap around like a Honda CR had on the KLXs with the forks that had the brake line run under the axle to go from front to back.

Good luck on keeping the planet spinning.

 

Added fuel controller video -

 

Review of the AHL "299" kit. @klx678 Do you think there is something else which needs to be covered? I still have spare AHL kit and standard OEM cylidner+piston on hand.

 

People comment about the coolant holes not matching up on the AHL gasket, but I didn't worry about it. In learning about fluid flow I've understood that too smooth a path can allow coolant to flow in a faster laminar flow than is ideal. Coolant must be reasonably slow enough to pick up the heat from the cylinder. The surfaces and openings must create some turbulence in the coolant to pick up heat the best. Too smooth allows a laminar flow, creating more of a layer effect in the fluid, turbulence mixes the fluid so it will transfer more heat through the turbulent fluid flow. So I left the overhang. I'm sure there is plenty of opening for coolant.

We built the top end without altering any gaskets.