engine experts? why losing power at high rpm

[puttputt]

200m runs great down low. Is flat, and runs out of steam at full throttle, higher rpm.

Mixture is the obvious suspect, but the problem has been consistent with no air filter, then a homemade, and then a stock
replacement. It was there before I cleaned the carb and after.
It's there with different main jet settings ( moving the clip on the needle ).

So, I'm wondering what the next suspect would be, if it's not a mixture issue ? Valves are in adjustment. Carb is PROBABLY ok.
It makes great power, and good throttle response, at low and mid rpm. Plug is clean - runs the same with different plugs, in different heat ranges.

Should I try advancing the timing one tooth ? Do coils deteriorate over time. Any ideas ?

[Dirtsquirt]

Losing power during high RPMs? How so? All engines will fall off the power curve when the higher RPMs are reached, maybe it's just the nature of the honda 200's

[ATCnut]

Have you read the plug? That would tell you if a main jet change is in order.

[84200s/m]

afther reading this i find it funny because my 200m has all topend
no bottom end (wont spin the tires in first in mud) but it i get it reving up some it will spin them in third

[Fuzzy]

How is the gas supply coming from the tank?. Is it possable that the supply from the tank is not keeping up with the engines demands. Like a clogged shutoff valve.

[puttputt]

haven't done a plug chop, but probably should ( I can't ride
at my house in town, so doing plug chops is a hassle, but
I should do it anyway - need to be somewhere where I can
run full throttle in 5th for a little ways . . . )

Fuzz - fuel supply seems fine - the fuel line into the carb flows
very solid when disconnected. I'd been tinkering around
trying to clear this up, and hoped when I got a stock air
filter and a replacement muffler on it, it should clear up but
it didn't.

[Fuzzy]

It sure does sound like mixture. Have you tried moving the clip on the needle down one notch to give it more fuel at wide open?.