Minimum valve shim thickness

[ROZZER]

Help please. Anyone run valve shims less than 2mm min stated for Z1b? If so what is safe minimum.
Currently refurbishing cylinderhead with new guides/valves and oil seals. Old valves were topped off 0.3mm so new ones will need the same, shims before refurb were all 2.5 to 2.6mm. As seats will probably need recutting or at least lapping, I am concerned that not enough metal left to work with to give adequate future valve clearance adjustment on completion.

Can seats be reliably replaced if so any recommendations on suitable company and approx cost.

[Jeff Saunders]

Although you can get 2.00mm shims, these are really too thin. Most of the drag racers I know running shim over buckets will not go under 2.20mm. I've never had it happen to me, but I do know of shims shattering.

NEVER grind the shims to get a smaller size. This removes the case hardening.

Seats can get replaced - we've obtained these for people previously. The seats themselves are not that pricey (I think around 30 quid or less the set), it's finding a good machine shop to do it that's the problem.

Another approach is to install oversized valves - going 31mm on exhaust and 37.5mm on intake.

[ROZZER]

Thanks for the advice Jeff, need to wait and see if machining seats leaves enough meat before doing anything drastic like getting new seats fitted. Padders (on phone) has suggested Debben, can anyone else confirm or advice others eg SEP @ Kegworth as they have again been mentioned to me in the past. Problem is I'm new to the Zed game so any advice will be gratefully received.
Will definately heed the not less than 2mm minimum, as I'm not drag racing, the old girl will have an easy life so will probably have to go to shims less than 2.2mm - thanks.

[london calling]

Hi John,welcome to the massageboard.
SEP at Kegworth can do anything you need doing engineering wise.Tel:01509 673295.They've done a good deal of work for my mates and me over recent years and it's all been 100%.
Just 10 minutes up the kermit for me,so i'm lucky to have 'em on the doorstep. :

[phil churchett]

As London Calling says, SEP are very good. They have done work for me and several mates, there doesn't seem to be much they can't do.
Even if you don't have the work done by them, it is worth calling them for advice.

[ROZZER]

Thanks lads for the info on SEP, they sound like the outfit I might need if my refurb work leaves no shim adjustment. Pity they are so far from me in Cumbria, well at least the couriers will be happy!!!!!

This Zed ownership mularky, when does it become a pleasure, all I seem to have had since buying mine is pain and a VISA card going into meltdown!
:p

[london calling]

They're common symptoms John and most of us have have suffered with them. :

[Ed Z1-R]

Aloha! John,Welcome to the site.It all becomes a pleasure on the maiden mile,more so takin it for the MOT,the blast when all the bugs are swatted n its pukka.Moe so,hittin n holdin 6k. Then when finally the motor beds itself n you can give it full bore
Chox Away!
Ed

[kiwiz]

I have just been thru a similar process when I had zero clearance with shims down to 2.00MM. I noted that the 2.00mm shim had started to chip which suggests to me it may have been ground! Fortunately I had not previously had the stems trimmed so recovered clearance that way. O.2 mm off. Fortunately the New Zealand peso means that outwork here is cheap to have done but the parts; well thats another question. My shop seems to think putting in new valve seats at the correct distance is actually possible, but fortunately haven't had to go there.

I seem to be about two paces ahead of you. Your next joy is when you try and put the carbs back on. The pleasure of connecting the airbox rubbers is beyond description.

What keeps me going is the nostalgic recollection of a Z in full song from 30 years ago. Lets go there again! Its a wonderful bike (well perhaps motor to be truthfull). Keep the faith!

[debben1]

Hello John, We can supply bronze valve seats at ?5.75 each, but as Jeff has already mentioned, fitting is a very labour intensive job. If the valves sink in to deep then 1mm oversize valves can be fitted. Another potental problem with the valves sinking to deep is that the valve seat pressure will drop as the top retainer movers further away from the seat base, you should measure the installed valve spring height and then measure the seat pressure of each spring pair to check the seat pressure, if the seat pressure is too low then we can supply valve spring base shims to regain the correct seat pressure, these are available in 0.15, 0.30 or 0.60" and are ?13.62 a pack, If the valve springs have polished along one edge, replace them, VS900K from www.debben.co.uk are ?47.95, Regards, Steve

[debben1]

Just another thought John, which valve guides diod you fit?

[ROZZER]

Sorry for delay in replying Steve, fitted APE oversize guides you supplied in exhaust and PMC standard ones in the inlets (cos' I already had them and now have 4 spares!!)
Fitting has gone well, the 4 thou over guides were ground to 2 / 3 thou for perfect fit, big thanks to Tom Lewthwaite in Whitehaven (real old school craftsman).