Z1b Top End Strip

[Spunky]

Decided to dismantle the top end of my Z1b. Not stripped a Z before so trying to learn from all the great info on this website. The bike was burning oil and there is a broken fin on the head that needs repairing. I did a compression check and they were 100 115 100 105. Squirted some oil in and readings were about 10% higher. . Anyway, I started taking out the cams and checking all the markings for the camchain, I counted the pins on the camchain from the first one above the mark on the exhaust camshaft to the 28th pin mark on the inlet camshaft( all as per manual) and..... only 27 pins !!!.
I checked it again and checked the manual again and defo only 27 pins. I am assuming that someone has put it together wrong.

Now for the probably silly question, but would this have affected the compression readings ?

Kev

[kev edwards]

Not 100% sure but possibly no to affecting compression,power probably down due to different cam timing.

[Steve S]

I would have thought that as long as both inlet and exhaust valves were at some point both closed together during rotation the compression for that cylinder would always give the same reading obviously taking piston rings,bores into account.

[Pigford]

Spunky, compression test will be the same as its MAX pessure thats recoreded, regardless of cam timing +/- 1 tooth.

Did you do test with hot engine & throttle wide open

[Spunky]

I did the compression test with throttle wide open but on a cold engine.
The bike had always been down on power and with it smoking a bit I thought it would be the rings. When i took off the camshafts there were pools of oil by most of the tappets except 1, 2 and 3 inlet valves. I am guessiing that the stem seals are b*ggered. I think I'll take the barrels off anyway and check the rings while i'm at it. Is there anyone down our way that could sort out the fin damage and advise on valve guide wear and stuff like that ?

[PAULJAC47]

You are on the service limit on 100 psi would go for rebore and pistons as for the valve guides get hold of a good unworn valve and push it into the valve guide upside down, there should be little if no movement,if there is would get new inserts put into the old guides,dont be tempted to use pattern stem seals go genuine,
the bike would have run one tooth out but obviously cam timing would be out,you are counting pins not links are you?
If loads of wear cracks, across combustion chamber,plus your broken fin would go for better head, i just let one go for £35! Good luck Paul J...

[Spunky]

Thanks for the advice Paul. Looks like I'll be spending a bit more money than I thought. But doesn't that always happen when we delve into the unknown ?
So far it looks like I'll be needing correct carbs, replacement barrels or rebore, pistons and possibly another head. Just missed barrels and pistons from padders. I also need a 4 into 4 exhaust system so will be raiding the piggy bank I fear !

[PAULJAC47]

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT
THese look ok for the money and are correct for a B.....PaUL j,,

[Pigford]

The compression readings are only valid on a HOT ENGINE

You'll find those readings go up a fair bit when done properly - inless the engine really is shagger

[Spunky]

Thanks for all your advice.
Know what i will do now. Spend some dosh and get it well sorted, after all it is a great bike and deserves it.

[prowlerz1]

before forking out on a rebore get the bores and pistons measured may only need rings