[stay_upright]

I guess that 38hp is quoted by GG? You would need to compare to other dyno'd GG 200's. 27 may not be an unreasonable rear wheel horse power for claimed 38hp at the crank.

Is it noticeably slower than other GG 200's in a straight line?

The KTM200 probably makes more power but mime was very on/off, For tractability you have to trade ultimate power which I believe the GG does and KTM does not.

Also the UK magazine TBM ran a test and said while the bike felt slow it was faster than both a MX250 and a KTM400 around a special test (surprisingly since it felt much slower to ride) and much less tiring to ride.

As I remember when TBM dyno's bikes say the current crop of 250 4t's which claim 35hp+ (I think - check this) the power on a dyno is around the 30hp mark. I think a knobblie tyre costs about 5hp over a slick alone.

Other factors - O ring chains use power

Manufacturers will test at optimum conditions so usually a cold day when the air is more dense but regardless they have probably claimed BHP so without an engine dyno the best you can do it to try and match other known good GG test test results to see if your bike is down on HP.

Did you check if the bike was revving high enough and who was doing the jetting - how do you know it was set up spot on for max power.

I've been told 2t oil mixture affects power and something like 16:1 gives max power because of better ring sealing and increased compression - you would be better speaking to 2t kart tuners or possibly MX tuners to confirm this though Enduro tuners aren't too bothered about max HP. I don't know if manufacturers do this for their dyno runs but obviously you would have to re-jet for this and then it's only to produce a number from a machine.

Have you checked the basic compression on you bike - how many hours do the rings have on them - this can make a big difference and even aftermarket pistons may change the compression ratio and timing.

If I remember I'll try and look through my TBM mags to see the GG 200 dyno result - PM me if you haven't heard anything for a bit (I may forget) if you really want this.