how far can you advance the ignition without starting to overheat etc

on a rev3270 2006

Depends on fuel octane, jetting, compression (rings, cylinder condition, carbon buildup), riding style, air temperature... Like any other tuning technique the only way to really know is to try it and measure the results in your specific application. I know that's not the answer you wanted but it's safer then giving an answer that causes you to seize your motor. Try gradually increasing the advance a small amount at a time and note the results. Soon you'll know more about how that engine responds to ignition advance then the guys who designed it.

cheers,it was very timid i thought for a 270 when i got it,since i got the stator rewound,i moved the timing forward about 1 mm! feels a lot sharper now,gonna have to see if it overheats quickly now though!

One thing you might want to consider is before '07 the 270s had an additional flywheel weight on the primary drive side of the crankshaft. The 250s didn't have that and as a consequence felt quicker. The '07/'08 bikes are reversed with the additional weight on the 250 and not on the 270. If you feel the need for a little quicker revving then you might want to take a look to see if yours is equipped with the weight. You can see it through the gearbox oil sight glass.

Edited September 19, 200817 yr by Dan Williams

" You can see it through the gearbox oil sight glass. "

Whaa? Isn' the flywheel on the other side? My understanding is, there is a spacer on the flywheel cover to make room for the flywheel weight. The sight glass is on the clutch side which is the primary side.

Check out

http://www.betamotor.com/system/attachment...evisione_03.pdf

page 5 POS 23 part number 29-07314-8 scroll down to footnote at bottom of list.

If you look at the 00-06 parts manuals you'll see the extra weight is on the 270

Yes I can see it through the sight glass on my 05 270.

No I can't see it through the sight glass on my 08 270

No I couldn't see it through the sight glass on my buddy's 05 250.

Not the first trials engine I've seen with an additional weight on the primary side of the crank. My old Bultacos also had an additional weight on the primary side of the crank.

Edited November 9, 200817 yr by Dan Williams

funny you say that dan,my old 250 does feel sharper!

and yes its an 06 270!

i shall take a look in there romorrow

Looks like that is especially difficult to get rid of.

i gues that is to balance the weight on your crank!

My two riding friends and I all have 2007 270s. We each advanced the timing by placing a 4mm drill bit in the slot at the top. The bit was touching the right side of the screw (screw on left) and the right side of the slot. Two of us noticed slight improvement in quickness off the bottom and the third didn't. Two of us ride the local Expert class and the other the local Pro class. The guy in the Pro class didn't notice the difference. We run 2-stroke oil at 80:1 and fuel at 20% C12 to 80% pump gas. I have V-Force reeds. The other two don't. The only difference between our bikes that is a noticiable "setup" difference is that my bike requires substantially leaner carb settings (27.5 pilot at 2-3 turns out, need clip one down from the top and a 135 main). My hunch is that the difference in carburetion is due to the reeds, since it is the only material difference. By the way, the reeds substantially smoothed out the engine compared to my friend's bikes.