Looks like on the 250efi the sub throttle plate is easy to remove. The shaft and actuator remain so the no trouble code from the ECU. Depending on how much that thing is throttling it will impact fuel to some extent.

 

Nigel, there can be no doubt that ecm controlled throttle manipulation is occurring - ICE motorcycle engines do not have "double hump" power curves unless forced to.

Removing the secondary throttle valve will NOT unleash the missing power and would, no doubt, be dangerous to the engine. The existing fueling and ignition programming will still be "in effect" and completely inappropriate for the "new" throttle scheme. You would end up with a severely leaned out midrange combined with a improper ignition scheme.

I and many, many, others have seen this on many models of the Indians and have identified the programming causing it. In this case, Polaris has artificially detuned almost all of the Indian lineup, to some extent or the other, via ECM throttle manipulation and the supporting ignition and fueling schemes. This detuning can be resolved thru complete reprogramming of the Bosch ECU running on the Indians, via the DJ PV3 and a very, very, lengthy dyno session (From one of the few shops capable of such on the north American continent.) Sidebar: Work-arounds to this have been put into place in order for owners to easily create good (not max) power levels..

Unleashing the 300 will require the same. Someone will have to "break into" the ECU, create new programming, flash the new programming onto the ECU.. The performance increase will be profound, so the tool and new programming would command a high price.. GO FOR IT !!!

 

Remember Nigel, the reason behind all this is to get the engine to pass EURO 5.
Kawasaki and its' engineers spared no expense in creating the components and programming needed to get the engine to pass EURO 5.. Since none of the emissions testing protocols in any country delves into sustained WOT engine operation, Kawasaki ( and all other manu's) are free to allow their engines to produce max power in the top end. This is why there is the secondary huge rise in TRQ and HP culminating in a second peak - giving us an idea of what the engine is capable of.

 

Klxster, that all makes sense. My short term goals are some simple mods and have fun this spring/summer/fall. Maybe next winter I will try to figure out a little more. The extra the 300R has in the 6 to 7k rpm range would be nice to have.

 

I watched some youtube videos. When I do it, I'll post what happens.

 

Will be interesting to see what you find out.

 

Klxster - good call on the ECM limiting power.
Tooter - you are correct on the sub-throttle.

I rigged up a voltmeter to read the sub-throttle position sensor, taped to the handlebar and used an iphone to record sub-throttle vs rpm with a video capturing both the dash and the voltmeter. Not perfect but close enough to see what it was doing. I assumed 4v as full open per an earlier 250 efi manual. I did a quick plot of % open vs rpm. Main throttle was 100% open when I recorded. It was pretty cold here today (20F), so I only did one run and parked it. Good thing because the iphone did not like the cold, went dead right when I finished recording. EDIT: Refined the chart a little, downloaded the video to my computer to get better resolution reading the points plotted.

 

A gent from another forum sent me the dynojet map for a stock KLX300. I did not have a stock klx300 map because I bought the euro version for the 250, and dynojet does not have it available from the website. Anyway, at WOT conditions, the stock bike is fairly rich if dynojet is accurate. The only thing is they are not pulling any fuel around 7.5k rpm at WOT, so with any mods and no fuel tuning the bike is likely to be fairly lean there. At least now I have a baseline to start tuning from.

 

I overlaid the sub-throttle on the dyno plots.

 

Remove the secondary throttle plate, put bike on dyno, instruct the shop to provide a12.8:1 AFR across the board at WOT - and keep part throttle ops synch'd correctly for load and RPM with a range of AFR between 13.2 ( for higher load/rpm/throttle opening) to 13.8 ( for cruising ops)..

Off the top of my nead, I can't remember if your PCFC has ignition tuning capability on the KLX300 - if not then you are stuck with stock ignition programming, which means you have an issue whose effect will range from "no apparent consequence" to "show stopper". Once fueling is completed, the shape of the curves will show the effect of the ignition scheme on power levels..