Had my rm250 for awhile now. Owning ktm's prior, I wanted that bottom end pull back. I added an fmf gnarly, reed spacer, jetted, adjusted powervalve and added 10oz fww. Good but not there yet. So.. I lowered the cylinder with a thinner base gasket! Squish came in at 1.2mm. Base gasket came in at .44mm. Went to a .1 base gasket. I had to make it, but athena does make different thickness base gaskets such as .1 .4 etc. Cometic aslo make a .2mm. Squish came in at .66 to .7mm. I was a bit cojlncernednbecause that is pretty tight. Crank and everything is new and dial indicator showed. Less than .005 play. Could have been less or more but it wasn't enough for concern. Buttoned it up and went for a ride. Long story short it runs awesome. Throttle response is crisp. Motor sounds cleaner. I can now open the throtle and pullna nice wheelie. The powerband trwnsitions smoothly from top to bottom. Midrange hitch is gone. At idle I can get on gas and bike responds. No burble or spool up. Best mod I have done to the bike. I didn't want to cut the base of cylinder yet. I wanted to make small change that can be reversed. As hours rack up I may have to cut head or keep crank fresh. This is a worthile mod for anyone looking for more linear and torquey power. Simple mod that really changes the personality of the rm250. I based the gasket and build of this based on the stock limitations. SomeSomeay have to resort to milling cylinder or head. A gasket can also be made for the cylinder head, but there is mixed opinions on this. Fun mod and rewlly got what I was looking for. Hope it helps. I see it uas heen done before but wanted to share my experience for new members and to share another opinion on port timing and squish mod review.