Z1OwnersClub GB

I have had new valve guides fitted to my head and the guy re-cut the seats while he was about it. the problem I now have is that he smallest shim I have is 2.45mm which is too big for three of the valves, so I am unable to determine what shims to order for these valves.

I suspect that the valve stems are too hard to turn down a tad in the lathe so I am a wee bit stumped.

Any one have any bright ideas?

Ralph, you can trim a bit off the stems, not sure wot the max is, but someone will

I know that if one has an external grinder in ones workshop it can be done ... but I don't. Actually I have some spare valves from the head that turned out to be a lemon that I got off flea-bay, so I could experiment with trying to clamp the dremel to the tool post of the lathe I spose, though I don't think that the bearings of the dremmel are man enough for the job.

Any one tried that?

I think they have to be ground rather than turned down. Can't remember how much is safe to take off before you are through the hardened surface but I know its not a lot.

I'm thinking of making myself a toolpost grinder in a similar fashion. Just take light cuts.
You can take 0.3 mm off std Kawa valves if they are unground and you need to leave a minimum of 4.2mm from the top of the collet groove to the tip of the stem.
Good engine fettlers will be able to skim them for you but make sure they are square before putting them back in as the bucket will slap if not.

shims go down to 200 so I'd suggest you get one of these and measure from there - you may not even need to touch the valves.

I would say that the guys who cut your valve seats are the same guys you will need to grind down valve stems if required. I do not know how much can be removed, but I may need to find out myself.
I too have just rebuilt top end (Z1B), new valve guides, seals ect. It was many years ago I last rebuilt an engine, but then I turned down a Test Shim to minimum thickness and used this to calculate required shims. With the new shims put in the valve clearances worked out to be spot on.
With the engine I am now building, my concern is that what do I do if a valve stem does need to be ground off a little. Will this mean the top end comes off again to remove valve and will I have to put on another new head gasket? I am presuming that I will have to bolt the head back onto engine with gasket in place before measuring valve clearances.

The shims are case hardened as they take a hammering you can't grind them down and use them as they'll break. The smallest available is a 200 as chrisu says. You can use smaller ground down ones for measuring to find out just how much clearance you need. If you haven't clearance for anything in the proper range you can have the top of the valve stem ground down the factory manual will tell you how much you can take off but I'm sure Rich is quoting the right figure for what needs to be left.

I think I'll machine a 2.00mm shim from mild steel to measure with. As Z-Power want ?6.85 / shim I don't want to buy any I don't necessarily want. This bike restoration has gone wildly over budget as it is!

That should do the trick. I made my one from stainless, turned and then surface ground on both sides. It is probably best to get it as flat as possible. Keep us posted.

Sadly I don't have a surface grinder, so my cheap lathe will have to do. Thinking about it, a 2mm slip guage would be fine for measuring ... not that I have one of those either! But it might be easier to mill a bit ol flat bar as a slip than bugger about trying to turn a piece of 36mm bar 2mm thick. When I'm finished doing paid work I may have a crack at that later.

If you only have access to a lathe and not a surface grinder then there is another way to sort out how much to trim off the valves ( if any ) by making yourself a valve stem height gauge.
Basically it is a piece of ally bar the same diameter as the shim bucket with a hole through the center to fit over the valve stem and counter bored at one end to fit clear over the valve guide and a step milled out of one half of the top face of the bar.
To give you an idea of what you need to make APE have a picture of the same type thing on their tools page http://www.aperaceparts.com/tools.html

Handy tool to have in the box.

Hope Jerry's reading this, as we could do with one in the CLUB vaults for loans purposes

I appriciate that this does'nt realy help you with getting a smaller shim, But if you need shims for a z1000 i went to my local Yamaha main dealer and bought 3 shims for a yamaha FJ which fitted my Z1000 a treat

Hope this helps

Cheers

Chris