KX Guru Racing

I'm going to try drilling a main to 250 and going down on the slow jet back to 50 from 55. See what that is like.
Just for something to try before I go.

Quick and easy as well

https://youtu.be/tiqW3OcX3kM

That's about as successful a run with the bike boosting as I have had, it's still going lean with boost though. It's a 40 slow jet and a 250 main. The gauges are from left-: fuel pressure, inlet pressure, pitot pressure. It goes lean at any revs if you just go straight to WOT, you can get it up to about 5-6000 and I did see 12psi on the pitot gauge before it started misfiring, I'm assuming due to being lean although I could be wrong about that. There was a fresh plug in it, one number cooler than stock (a 9 instead of a 8).

I'm going to look at the video a bit more and see if I can get some more inspiration from it.

This screen shot from that video shows the fuel pressure at 15psi the pitot tube at 12psi which also feeds the float bowl.
The inlet pressure is at 5psi. The water injection and the ignition are still fed by the inlet pitot tube, the original one. The ignition is maybe not retarding enough when the boost rises or maybe not enough water spray?

That's when it it misfires or knocks or whatever it's doing.

I can't remember... Are you running the stock ignition?

I'm running the programmable ignition but the pressure sensor is fed from the inlet manifold which lags behind the pitot tube in pressure but really the inlet manifold is what the engine sees so that's right. I think?

I put in that fresh plug and tried a coil on plug coil I have had for a bit, all with the same misfire.

Ordered this today. Hoping it helps with tuning the bike.

Hmmm... What's the scoop on that carb?

It's the jet sticking in through the rear of the carb body, it's a thunder power jet from a place called thunderproducts.com on its list of recommended uses is turbo applications. So I'm hoping this will be a help with the fueling under boost. I'm guessing that the over pressure from the pitot tube that feeds the float bowl will push extra fuel up this jet and richen with boost.
I looked on YouTube for videos of them in operation and it looks the part.
It occurred to me also that this is what the accelerator pump does to a certain extent but at least this is adjustable, well unless the knob on the end is just for show?
What comes with the kit is the jet the tubing the one way valve and I also got the optional deep well nut for the bottom of the carb. I also paid for the prioritity mail, which nearly doubled the price, but never mind. I get home on Monday so I will be keen to get on. I do have some other pressing issues though. I don't know whether I said or not but I burned out the fan motor I had. The fan was too heavy for it and it cooked the motor, the fan has adjustable blades though so I can alter the pitch to suit the motors power, the new plan is to belt drive the fan. This way the motor will get to its intended speed the fan will be at a more ideal speed and I also have a little fan that is for exhaust extraction that I will put on the main shaft off the motor, I got it a while ago but I was in too much of a hurry to get the fan done when it came to that time to do it (or so I thought). Once it's all running, I will put a ammeter on it to check the motor is not over loaded, if it is I will back pitch of the blades, I can also make it a 3 blade fan, there is 6 on it now but the blades can come off.
I'm also going to try to fit the adjustable wastegate I have. Plenty of time for the power jet to arrive.

Wow...
You do have a lot to do.
It will be interesting to see if that carb solves your issues..
I'm going to go to their website and do some looking .
You never know what else I may find there...