Good day, everyone. I am Aditya Trivedi, part of the powertrain department of Camber Racing, an FS team based at SRM University, India. We are using a KTM engine for this year's car, the one used for Duke 390 here (it's a single). The engine has been giving us trouble we can't quite figure out. Here is how it goes:
The intake system for the car is previous year's design, and features two throttle bodies, one just after the air filter for throttle actuation, and another just above the engine head to put the fuel injector in (we didn't have time to measure the fuel injector angle so this was a quick fix). As per the rules, only the outer throttle body is controlled. We are facing difficulty in getting the engine to rev; the engine doesn't rev beyond 7500RPM. Until then it seems to be running fine, but after reaching this engine speed it starts pulsing very slowly (somewhat as if it's hitting the rev limiter, but a lot slower). It goes as low as 4000RPM during these pulses, recovering to 7500RPM again before repeating. It randomly backfires as well, and if one lets off the throttle completely the engine stalls. After a lot of trying to modify the intake (it had a lot of leaks so we did our best to seal them) we decided to put on the stock airbox and remove everything else. The problem continued. Then we thought that maybe the MAP sensor wasn't functioning like it should (I read that it can be affected by backfiring), so we replaced that. The engine now starts pulsing at 6500RPM instead of 7500RPM, with no other change in operation even though the intake system is now stock, essentially. What would you suggest we do in diagnosing this problem? We have prepared the following possible list of faults:
1. Carbon buildup on the spark plug
2. Dirty fuel line/injectors (we are thinking of buying injector cleaning fluid for the same, what would you recommend?)
3. Low fuel line pressure
4. Incorrect exhaust length, leading to wrong resonance pulses.

We have obtained values from the MAP sensor, and I am listing down the max and minimum indicated pressure values at different engine RPM:
Idle - 37.875kPa, 101.41kPa
3000RPM - 34.6kPa, 95.71kPa
5000RPM - 36kPa, 100kPa
7000RPM - 37.875kPa, 103.62kPa
These are the peak points obtained, the graph reads almost like a sawtooth waveform. If anyone would like those, I'd be glad to PM you.
That being said, are these values normal for a single cylinder engine? Please keep in mind that the MAP sensor is in the throttle body mounted just above the engine head using the stock airbox, and the engine is being run without any load whatsoever.
Thanks for reading this through, looking forward to a positive response to my first FS forum post.

Aditya