Has anyone played with cam timing??

[bison head]

I had an adventure with my bike and I wonder if any of you have tried different cam timing settings. When I initially set my cam timing according the the clymer manual I have I set the number 1 mark slightly below the head surface. I also noticed the #1 mark was half a tooth above or below the head surface. I set it up with the cams advanced the half tooth because thats what looked right according th the manual. I was repairing a butchered engine thats why I had cylinders off, picked up bike cheap. Any way in my quest for more power and better high end riding I tried changing it. I had wicked low end driveability and torque and no high end power. The high end power loss was attributed to air flow trouble, but I was experimenting because symptomatically it seemed cam timing was over advanced. I tried moving cams 1 tooth retarded and found a lot better top end and the #1 mark was now slightly above the head surface. The engine takes off not bad now but the real power doesn't seem to kick in till around 3krpm, but on the other hand it pulls real hard all the way to 9krpm now. The bottom line is I have fixed my carb problems now and I am wondering if the cam timing is in the correct spot or should I try the other setting again? I think that this engine would really benefit from variable valve timing like on the modern cars after moving the timing and seeing the difference it makes. Do any modern bikes have variable valve timing nowadays?

 

[flyingace]

The power band sounds about right, there isn't a lot of power below 3K on my bike either. I would guess the cam timing is OK. You could scratch in some additional marks to make sure you can put it back exactly as it is now.

IMO, just advancing/retarding the stock cam on the cam chain is not a way to performance. You'll just lose power on one end or the other. The engineer has to find the best average cam timing for a particular engine, and moving that around isn't the answer.

 

[Guest]

Plenty of good reading and info on this site...look in the 'mods' section..... I think he's a member of the GS Resources too.

http://medlem.spray.se/biker661/index.html

As far as I know, bikes do not as yet have the VTEC systems seen on the newer Japanese cars....Honda's VFR 800 has a system called vtec, but it alternates between using 8 valves at low/mid rpm and all 16 past 7000 rpm ....not really variable valve technology, IMHO.

Tony.

 

[Jethro]

Talk to member "Pano". He degreed his cams last winter and says it made a huge difference. I'm gonna do the same this winter.

 

[KEITH KRAUSE]

I had mine degreed at 106. Greater low/mid-range punch.
I don't know exactly what I've lost at top end (3-5 mph?) because I had other mods done at the same time, but the power is so much more usable now. The bike is much quicker.
It doesn't matter if I can go 125 or 130. I need to stop doing that stuff anyway. I really like it the way it is now.