Max Camshaft Lift

[sambo]

Hi, I just picked up a used set of cams for my 78 GS1000, they are russ collins rc151. I can't find specs for them anywhere, so I measured the lift and it is around .41in (my calipers really suck). I heard I might have to dremel the head a little at the bucket, so the lobes clear the head, I was wondering if anyone knows the max lift a cam can have for a gs1000 before you have to machine the head? If anyone knows the specs for these cams or where to find them? And is this engine going to streetable, or am I going to lose all my bottom end with cams this big? Thanks in advance, Sam

[BadBillyB]

Hi, I just picked up a used set of cams for my 78 GS1000, they are russ collins rc151. I can't find specs for them anywhere, so I measured the lift and it is around .41in (my calipers really suck). I heard I might have to dremel the head a little at the bucket, so the lobes clear the head, I was wondering if anyone knows the max lift a cam can have for a gs1000 before you have to machine the head? If anyone knows the specs for these cams or where to find them? And is this engine going to streetable, or am I going to lose all my bottom end with cams this big? Thanks in advance, Sam

Two things you will need for sure.....
Hi-perf valve springs and "shim under" buckets. Anything near .400 lift will spit out the stock valve adjustment shim at high RPM, destroying the head. You will need to remove the valves and test fit (rotate) the cams in the head to check for clearance. There is no specific lift that dictates whether the lifter bores need clearancing not knowing whether the cams were ground at the factory or a smaller "basecircle".....Some high lift cams, that were ground at the stock "basecircle" will require grinding releifs in the valve cover for clearance also......The specs for these cams can probably be found if you ask in the right place. Look on the end of the cam for a grind number to be sure you are looking for the right thing. I would suspect that those cams are designed for road racing and should be streetable, but thats just a guess. Maybe do a search on the Kawasaki forums as the grind number may be the same....Jay at APE may be able to help you with specs, buckets and springs.......BadBillyB

[sambo]

Thanks for the info, I'll check out some kaw stuff. They do have a stock base circle.

[sambo]

With a shim under bucket set up, I need to buy new buckets and then new smaller shims? And to change the shim you have to pull the cam and the bucket? I imagine that is how it works, it seems like this is going make valve adjustment a pain in the butt.

[Big Jay]

I looked in my RC catalog, but it is so old it did not have Suzuki cams listed. Altho the GS1000 has a larger bucket than a Kawasaki, I believe they take the same diameter shims.

We sell .410 lift cams for the Kawasaki that work with the shim on top arrangement. I wouls assume that GS1000s would also work. You do need high performance springs.

How did you come up with the lift? Did you measure from the heel to the nose than subtract the base circle diameter?

Jay

[sambo]

yeah that is exactly how I came up with the lift, is that correct?

[KEITH KRAUSE]

Suzuki shim diameter is 29.5mm and Kawasaki is 29mm.

[Frankenzuki]

Cams

Sam,

With a lift that large you should be using a shim under bucket set-up. Jay's right the Kaw stuff is smaller. Also you will probably have to clearance the head to fit the cams. Usually anything over about .375 lift is going to be really close to the edge of the valve spring bore. To use those in your motor you will need different springs and retainers, buckets and shims. The retainers for the shim over bucket are different. You've got my number, give me a call when you get a chance.

Dennis