Shim over/under bucket for racing

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   Thanks again for a very prompt reply!

OK, the lights are coming on, and the last post is going a long way toward progressing my Kawi engine education.

I know I'm in the right place, and the many years of performance and racing experience here are greatly appreciated!

Jay

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JSBIRD69 Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 06 February 2009 Location: Colorado Online Status: Offline Posts: 54	Quote Reply Posted: 20 February 2009 at 1:12am
	Thanks again for a very prompt reply! OK, the lights are coming on, and the last post is going a long way toward progressing my Kawi engine education. I know I'm in the right place, and the many years of performance and racing experience here are greatly appreciated! Jay
	Poverty Level Racing - 1981 KZ1100 B1 Drag Chassis - 1983 GPz1100A Drag Engine

sonicrete Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 18 November 2003 Location: United States Online Status: Offline Posts: 908	Quote Reply Posted: 19 February 2009 at 9:55pm
	The valve clearance is adjusted using these shims. Effectively the shim is a thick $.50 piece on top the bucket under the cam. By using shims thicker or thinner the clearance is adjusted. The KZ650 type uses a shim about the size of a dime located under the bucket. In this way it is a lot less reciprocating weight but more important the shim cannot get "thrown out" by over rev/valve float and the reason people do it. After a certain amount of "hot cam" it must be shim under or the cam will overlap and makes it a tiddly wink. It does a lot of damage to the head when it throws a shim so most people who drag race will not take the chance.

JSBIRD69 Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 06 February 2009 Location: Colorado Online Status: Offline Posts: 54	Quote Reply Posted: 19 February 2009 at 7:35pm
	Thanks for your prompt reply Bob. Can you tell me what the shim change is based on? Is it for needed room? Or is it having the shim weight suspended somehow desirable? I have a lot to learn about these engines before I can figure on having any kind of success running them. As soon as the trucking company calls to let me know my KZ1000 cop engine has arrived in Colorado, I'll go pick it up and then crack the cam cover to see what I have going on in there now. Thanks! Jay
	Poverty Level Racing - 1981 KZ1100 B1 Drag Chassis - 1983 GPz1100A Drag Engine

Bob Brooks Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 18 January 2008 Location: United Kingdom Online Status: Offline Posts: 246	Quote Reply Posted: 19 February 2009 at 6:20pm
	Hi Jay, All the early engines used the large shim on top of the bucket.Most racers change these for the Z650 style shim under bucket ( between the valve stem and bucket underside). Sorry but I don't know about your engine. Easiest way to find out would be to whip the cam cover off and have a peek and all will be plain to see. I definitely wouldn't ever consider running shim overs unless I had stock cams. Hope you have fun. Bob
	Bob Brooks Yellow Metal Racing Blown Alky Puma

JSBIRD69 Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 06 February 2009 Location: Colorado Online Status: Offline Posts: 54	Quote Reply Posted: 19 February 2009 at 5:24pm
	I know this will come across as the most rookie of questions (and it is!), but after 35 years in aviation, my recent return to Jap bike drag racing leaves me with a few questions I haven't been able to fully answer or grasp the concept. I have an 81 KZ1100 drag chassis already set up, and a complete 1992 KZ-Police engine on the way to me from California in the next week or so. I plan to install the KZ Police engine to familiarize myself with the set up and installation, and look for another stock engine to modify from the bottom up. I have an exploded view (Gawd, I hope I don't see that too often!) of the cylinder head, and will use that as my starting point. If I understand correctly so far, the stock Z1/KZ head uses a shim under the retainer. If the hot racing tip is to have the shim in another location in the stack, where exactly does it go, and what is the benefit? Thanks for any knowledge you can share. Jay
	Poverty Level Racing - 1981 KZ1100 B1 Drag Chassis - 1983 GPz1100A Drag Engine