Yamaha TRX850 Enthusiasts Forum

About the only thing left to do to my motor is to change the cams for increased valve lift and greater duration.

My understanding has always been that camshaft mods are more about changing the engine power delivery characteristcs to provide more useable power rather than adding more hp.

I would have thought that increased lift and especially extended duration would result in power increase for the simple reason that more fuel/air mixture is able to enter the cylinders. Probably would not compare to the benefits of an 878 kit or FCR's.

Also wondered whether altered cam duration would influence the true compression ratio?

If anyone has a better understanding of this topic than me I would welcome some guidance (comparative dyno charts?) before I spend >£200 on a camshaft regrind.

Thanks

misterdimwiddy wrote:About the only thing left to do to my motor is to change the cams for increased valve lift and greater duration.

My understanding has always been that camshaft mods are more about changing the engine power delivery characteristcs to provide more useable power rather than adding more hp.

I would have thought that increased lift and especially extended duration would result in power increase for the simple reason that more fuel/air mixture is able to enter the cylinders. Probably would not compare to the benefits of an 878 kit or FCR's.

Also wondered whether altered cam duration would influence the true compression ratio?

If anyone has a better understanding of this topic than me I would welcome some guidance (comparative dyno charts?) before I spend >£200 on a camshaft regrind.

Thanks

Here´s a quickie: http://www.lunatipower.com/Tech/Cams/CamSpecTerms.aspx

Thanks Killerwhale

An excellent explanation of camshaft terminology and general effects of changes to spec.