How Much Power Gain With Big Bore Kit?
- Thread starter CWDHUNTER
- Start date
- Jun 29, 2005
- 443
- 0
My guess by just looking at the displacement increase is in the neighborhood of 1.5-2 HP, roughly 5%. I believe when we discussed this with Eric his comment was if we did an overbore and port job that 75% of the gain would be due to porting, 25% to displacement increase. The moral, spend your money on porting now and save the overbore for a worn cylinder.
robwbright
Member
- Apr 8, 2005
- 2,283
- 0
from a prior post:
I don't have a '98, but I do have Eric's 265cc setup on my '01 CR250, with low-mid porting. Horsepower/torque were 45/32 at the rear wheel, with the hp. peak at 6500 rpm. Very nice smooth curve, with almost no hit at all...just smooth progressive power.
Basic setup at dyno time:
EG 265 cylinder w/ low-mid porting
Stock pipe/silencer
Stock carb, 370 main, stock needle in 3rd clip, 25 pilot jet
VP C12 mixed 40:1 with Maxima Castor 927
Dyno runs were done this summer, around 80F/80% humidity or thereabouts.
Just a data point...hope it's helpful
http://www.dirtrider.net/forums3/showthread.php?t=68152&highlight=dyno+265
I don't have a '98, but I do have Eric's 265cc setup on my '01 CR250, with low-mid porting. Horsepower/torque were 45/32 at the rear wheel, with the hp. peak at 6500 rpm. Very nice smooth curve, with almost no hit at all...just smooth progressive power.
Basic setup at dyno time:
EG 265 cylinder w/ low-mid porting
Stock pipe/silencer
Stock carb, 370 main, stock needle in 3rd clip, 25 pilot jet
VP C12 mixed 40:1 with Maxima Castor 927
Dyno runs were done this summer, around 80F/80% humidity or thereabouts.
Just a data point...hope it's helpful
http://www.dirtrider.net/forums3/showthread.php?t=68152&highlight=dyno+265
