hi! my step son has a 2004 gas gas txt 80 rookie. I am trying to get a little more bottom end power out of it. the bike runs really well and pulls like a train at full revs. This ok but steep hills have to be attacked in first gear flat out.. I have read the other posts about the carb mods. The carb slide is all ready modified. I was thinking about changing the front sprocket from a 12 tooth to a 11 tooth has anyone given this a try before and was it any better? thanks!!

Had the same problem with my sons i had the barrel ported and the exhaust port raised also added stuffer to crankcase to raise primary crankcase pressure a LITTLE also skimmed head to set squish to .6mm that fixed it !! was then a match for 2010 beta 80 !! just sold it as he has now moved upto a 125 but he was riding it on the clubman route all this made a massive differance hope this helps :-)

thanks for that who did the work for you? also what was the stuffer?

You could try adding length to the intake tract.

A bit of radiator hose will do the trick.

My son had one of these and a lack of bottom end was definitely noticeable.

I wonder if a flywheel weight is available...