Hi guys

I am struggling to get the power I need from my N21R limited.

It's fully broken in now (about 5L, maybe 6-ish).

initially I ran it with a 9901+41030, and it was a disappointing. I thought this was due to it being still not fully broken it but it didn't really wake up, even when broken-in. If I wanted to get some power out of it I would need to lean the HSN, but then it would collapse after 3mn from heat. This was very obvious as it simply wouldn't restart, you'd see the fuel being vaporized when reaching the carb and pushing back in the tank. when it would work (read be stable but slow), it'd do about 9mn30s.

I thought this was due to the clutch (brand new mugen carbon clutch, new springs, new shoes, new bell), grabbing at too low rpm. I replaced it with a brand new (shoes, springs, bell) alum one, initially with 1.0mm springs, then going to 1.1mm which slightly improved it but not much. we're talking a man's clutch here...

Then I tried a 41021 just to see if the header shape (41030 curvature is "narrow") would change anything - nada.

Then I put a brand spanking new 086HS on it today - a bit better, but still if I want it to weeeeeeeeeeee down the straight it will soon overheat. LSN is a bit more tolerant, the sweet spot seems pretty wide, to a point only, after a while the idle simply becomes very erratic if leaned a bit too much. Temps are an issue again (vapor lock as described above + spit vaporizing instantly). Runtimes have dropped to 8mn30s...

That wouldn't upset me so much (I mean, it's a $150 mill...) if my best buddy wouldn't have a N21BF from last year which litterally puts every $400 mill at my track to shame... and clocks 10mn+. We run the same fuel (CRF 25%), same plugs (Nova #6), same exhaust (41021 + 9901), and I've run his mill in my car before, I've pulled it apart, I've cleaned it and so on so forth, I mean there's nothing special to his nova... and it rips like a bat out of hell.

And by the way, this is a new tank too

So:
1- What am I doing wrong with mine????
2- what has changed from last years N21BF to this years N21R Limited?

I'm really beginning to loose my temper at the track and use dirty cusswords... would welcome any help

Thanks

Paul