Ok, Jeff, I decided I'd better make sure you know something - the KLX250S induction system is designed with/around a 34mm throttle body. The 40hp KX250F induction system (for 2020) is designed for/around a 44mm Throttle body. There is no way to make a KLX250 intake tract flow the same as the KX250F's - and 40hp requires the flow rates of the KX250F induction system.

This will be a limiting factor for your peak HP numbers regardless of porting/cams/etc.. On the bright side, you should be able to create a TRQ curve with a shape and at levels we have never seen before.
So, generally speaking, porting and cams aimed at producing high RPM power (9000 rpms +) should be avoided as such mods trade off Trq for more HP - and top end HP is something your induction system won't allow you to fully capitalize on..

 

Definitely some things to think about. I definitely would like to go with the big cams to see what kind of power the KLX can dish out. I spoke with Bill about cams before and he said not to do them. He said someone in Asia did cams and got slower lap times with them. However, I think there are more factors than just the cams. We'll see how it does with the ported head, I plan on getting the map that the tuner finished with. I've heard a lot of people overseas have gone with a Ninja 650 injector. Kind of curious myself about that. So, I might test that out before picking up the Beet injector. Looking forward to the results!

Also, I don't think the KLX will peak out around "uncorked" KX power levels. The KLX should be able to get close to 35, which is similar to a stock KX. But yes, the torque should be pretty wicked

 

Go carefully on choosing an injector. We have no way of re-calibrating the ECM data fields that pertain to driving the injector. So any replacement must have very similar, or identical, latencies, scaling, fuel pressure table/expectations, Voltage table, etc... The ECM will drive any new injector the same exact way it did the original injector - which absolutely won't work if the new injector has significant differences in its' operational characteristics from the original.. The scenario to look for, on such a mismatch, is a loss of idle capability/quality and the low/mid is horribly overfueled. BTW, using a "biggy" injector that's overfueling your bike can create a "cylinder wash" that will destroy your 351 kit.

If "everyone" is using a particular injector in their KLX, perhaps try it - but you should only try out an injector while the bike is hooked up to the dyno with AFR sensing in operation ! That way immediate changes can be made to the fueling curve without running the engine very long with dangerous fueling..

If the PCFC interfaces with the Dyno like a PC5, you can just start tuning with the stock injector.. If duty cycles hit 90+ , slap in a SLIGHTLY larger "best choice" injector and continue tuning.. Create a "straight line" 12.8:1 at wide open throttle (WOT) for best compromise between component protection and max power production. Do this regardless of whatever "expert" is telling you (probably) that 13 to 13.2 to 1 is best..
Remind the "expert" that your cooling system is designed for a mild 20hp ,250cc engine, and you need a little component protection built in to your WOT fueling. I would tell you to explain that 12.8:1 makes more power than 13 - 13.2 to 1 , but explaining flame front speed, flame propagation characteristics, etc, of various AFR's is just too tedious.. If "component protection" gets a blank stare, tell em to google it, but to do-up 12.8:1 @ WOT..

P.S. One of many "pet peeves" of mine is idiots leaning their WOT fueling, thinking that they will get better gas mileage or that MPG is a "concern"... Morons !

 

Why yes, of course. Let's not forget that I am doing this to be able to experiment with the platform. Before I go into the dyno session, I will have a plan worked out with the tuner for the duty cycle. So, if a bigger injector is needed, I will supply one.