So ive finished measuring up NSE.ONE's GG300 and put all the data through my software... glad i only have to do it once for each model bike cause it takes a bloody long time to measure and re-measure everything... There are a number of things that require you to get pretty creative in order to get a measurement and there is always the possiblity of human error so i try to measure everything several times to get a good average, but the results are usually pretty reliable... probably within 5% or so.
Theres no question that the bike does what its designed to do very well, power is very smooth and tractable, but its no mxer. Basically they have done this by using a small exhaust port, low compression, large squish and very little blowdown. Basically there is a lot more power to unlock out of the engine with some pretty easy porting changes... thats if you need more power!
The Black line is the stock engine, in this case 2.5mm squish, 11.9:1 comp, 1.3mm base gasket stack, piston level with port floors at bdc
The Red line is the cylinder dropped by 0.7mm to give a squish of 1.8mm, no further changes other than what occurs by dropping cylinder.... comp increases, exh duration drops, transfer duration drops
The Green line is the cylindner dropped by 1mm to give a squish of 1.5mm, no other changes.
The Blue line is dropping cylinder a bit but then doing some basic mods to the exhaust port to bring the top end power back... best of both worlds... better bottom without the loss on top. You can take this much further to get better top end if you want.
This engine has low exhaust TA and by dropping the cylinder to correct squish you reduce that further, making it fall flat up top... green line shows this. This is why its usually not advisable to use base gaskets to alter squish cause you can mess up port timing if you take it too far... with this engine though there is not enough blowdown TA and it could do with a larger exh port and lower transfers, particularly the boost port which opens 2.5 degrees before the others... so there is actually some beneift in droppping the cylinder on this bike, but its really only beneficial if you then raise the exhaust back up a bit to increase exh TA and blowdown TA.
Thread stolen from here ..... http://www.dirtbikeworld.net/forum/showthread.php?t=82850
Theres no question that the bike does what its designed to do very well, power is very smooth and tractable, but its no mxer. Basically they have done this by using a small exhaust port, low compression, large squish and very little blowdown. Basically there is a lot more power to unlock out of the engine with some pretty easy porting changes... thats if you need more power!
The Black line is the stock engine, in this case 2.5mm squish, 11.9:1 comp, 1.3mm base gasket stack, piston level with port floors at bdc
The Red line is the cylinder dropped by 0.7mm to give a squish of 1.8mm, no further changes other than what occurs by dropping cylinder.... comp increases, exh duration drops, transfer duration drops
The Green line is the cylindner dropped by 1mm to give a squish of 1.5mm, no other changes.
The Blue line is dropping cylinder a bit but then doing some basic mods to the exhaust port to bring the top end power back... best of both worlds... better bottom without the loss on top. You can take this much further to get better top end if you want.
This engine has low exhaust TA and by dropping the cylinder to correct squish you reduce that further, making it fall flat up top... green line shows this. This is why its usually not advisable to use base gaskets to alter squish cause you can mess up port timing if you take it too far... with this engine though there is not enough blowdown TA and it could do with a larger exh port and lower transfers, particularly the boost port which opens 2.5 degrees before the others... so there is actually some beneift in droppping the cylinder on this bike, but its really only beneficial if you then raise the exhaust back up a bit to increase exh TA and blowdown TA.
Thread stolen from here ..... http://www.dirtbikeworld.net/forum/showthread.php?t=82850
