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Z1A valve shims

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garybrez
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Z1A valve shims

#1 PostAuthor: garybrez » Thu Jul 11, 2019 5:54 pm

I am in the process of re-shimming my 75 Z1.... most shim needs are between 2.60 to 2.85 …. except cyl 3 exhaust which is looking like it needs a 3.20 shim …….. cam looks ok …. I also have no compression on this cyl but before starting the job cyl 3 inlet had very little gap and no compression ( less than 0.05 ) so I suspect the inlet valve was slightly open all the time and popping back through the carb ….. can anyone give me some direction … I am desperate to get this resto on the road

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Pigford
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Re: Z1A valve shims

#2 PostAuthor: Pigford » Thu Jul 11, 2019 6:14 pm

The need for a 320 shim could indicate a sticky/bent EX valve, or just not seating properly causing lack of compression.

The gap for IN at 0.05mm is tight - best aim at 0.10 - 0.15mm for all - the clearance typically lessens over time.
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garybrez
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Re: Z1A valve shims

#3 PostAuthor: garybrez » Fri Jul 12, 2019 2:36 pm

does anyone know where I can get the cyl head removed and checked / repaired for bent valve(s) in the north east uk …. might be a bit beyond my skill level

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Pigford
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Re: Z1A valve shims

#4 PostAuthor: Pigford » Fri Jul 12, 2019 2:54 pm

Before you strip the engine down - do a compression check using your finger over sparkplug hole whilst turning engine over with kick starter as a basic indication.
And on the 7th day... Zeds were created!

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garybrez
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Re: Z1A valve shims

#5 PostAuthor: garybrez » Fri Jul 12, 2019 4:18 pm

thanks for the tip but I already tried ….. all other cylinders have good vacuum apart from cyl 3 … this cyl has 3.05 shim in and the gap is still too big, wanting a 3.20 shim but I feel this will cause even more grief as the valve moves closer to the piston crown

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rickm
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Re: Z1A valve shims

#6 PostAuthor: rickm » Sat Jul 13, 2019 7:54 am

Personally I would be very cautious about starting and running this engine if it were mine.
As stated above, the valve clearances don't tend to get bigger in a healthy engine, especially not at the rate that yours seems to be.
Z1000J ELR US style, S3 400 triple

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garybrez
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Re: Z1A valve shims

#7 PostAuthor: garybrez » Sat Jul 13, 2019 6:18 pm

I did have slight resistance when I turned it over by hand but assumed natural piston motion, but how could I have bent a valve turning by hand … either way it looks like a bent/sticky valve and a head off job ….. is this a complicated task ?? I really could do with someone just sorting it for me

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z1bman
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Re: Z1A valve shims

#8 PostAuthor: z1bman » Sat Jul 13, 2019 6:34 pm

if you have verry little clearance you need to go smaller on the shim size not bigger i would fit a 295

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rickm
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Re: Z1A valve shims

#9 PostAuthor: rickm » Sun Jul 14, 2019 9:54 am

z1bman wrote:if you have verry little clearance you need to go smaller on the shim size not bigger i would fit a 295


OP says the problem is too big a gap... and getting bigger, which is the more concerning bit !
Z1000J ELR US style, S3 400 triple

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z1bman
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Re: Z1A valve shims

#10 PostAuthor: z1bman » Sun Jul 14, 2019 10:39 am

rickm wrote:
z1bman wrote:if you have verry little clearance you need to go smaller on the shim size not bigger i would fit a 295


OP says the problem is too big a gap... and getting bigger, which is the more concerning bit !


in his post he states that the gap is less than 0.05 so its unlikely to be a bent valve otherwise the gap would have been a lot bigger unless someone has shimed it up after the valve was bent

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rickm
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Re: Z1A valve shims

#11 PostAuthor: rickm » Sun Jul 14, 2019 10:46 am

z1bman wrote:
rickm wrote:
z1bman wrote:if you have verry little clearance you need to go smaller on the shim size not bigger i would fit a 295


OP says the problem is too big a gap... and getting bigger, which is the more concerning bit !


in his post he states that the gap is less than 0.05 so its unlikely to be a bent valve otherwise the gap would have been a lot bigger unless someone has shimed it up after the valve was bent


Yes, that's true. I've just realised that the posts are a bit inconsistent as he states that the gap is too large in post 5 ?
Z1000J ELR US style, S3 400 triple

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garybrez
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Re: Z1A valve shims

#12 PostAuthor: garybrez » Sun Jul 14, 2019 12:05 pm

sorry did not intend to confuse ……. bottom line is cyl 3 exhaust gap was too big in the beginning and adding a thicker shim has only made the gap even bigger

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garybrez
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Re: Z1A valve shims

#13 PostAuthor: garybrez » Sun Jul 14, 2019 5:24 pm

OK breakthrough ………. took the head off and shone a light combustion chamber side ….. light shone through when valve should be shut... not sure if bent or just wants re-seating …. I need a local expert to decoke / re-seat etc

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z1bman
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Re: Z1A valve shims

#14 PostAuthor: z1bman » Sun Jul 14, 2019 5:36 pm

get a valve spring compressor & do it yourself

https://www.ebay.co.uk/itm/US-PRO-Car-V ... 0008.m2219

Philippe
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Re: Z1A valve shims

#15 PostAuthor: Philippe » Mon Jul 15, 2019 3:49 am

Hi Gary
was the valve stem grinded off too much? If that's the case, the bucket pushes on top of the two collets and not on the valve stem. In that case, grind off the two collets so that these sit lower than the top of the valve stem.
Or replace the old valve with a new one. Make sure you have the correct valve for a Z1B . The collets and valves of a Z1 are different from those of a Z1000 (square versus round)!
Good luck
Philippe
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