The Friendship Bike - NobleHops restores a 75 Z1

Alright, we all know what this photo means! Yesterday was "Engine Disassembly Day".

Things went well, I had a single cross head screw snap, having used heat and penetrants and the impact driver to extract them all, so that was a decent average I thought . at the moment I am down to the crankcase, which I hope to get to split today if i can finish up some other chores and get back to it. I found a few gems along the way, which I'll post now just for fun, along with some other disassembly photos, and I will be back likely next week with a bunch of questions for those of you that have rebuilt these before.

Was puzzling why I could not extract the clutch pack in a stack. Took the plates out one by one till I found one of the fiber plates, broken into three pieces:

Oil screen was pretty funky. Nice hard coating of tar was on the engine sump too - that's soaking in the parts washer today.

There was evidence of leaking at both the head and cylinder base gaskets:

I don't seem to have photos of this, but the non-toothed cam chain tensioner at the rear was pretty chewed, and the steel chain guide at the front was snapped clean through. Replacements are inbound, along with a cam chain.

The pistons and valves look suspiciously good, like the top end was done, which accounts for the numerous leaks. The pistons look cheap to me though, can't quite say why I say that, but they don't look strong or well made.

Valves in #2

#4 had some minor crusty carbon, and more evidence of a leak

Cams and bearings seemed fine, no particular wear, big end and wrist pin bearings have no discernable play up and down, cylinder bores are lightly scuffed near the bottoms, no visible honing crosshatch is in the bores. Once I get it all the way apart I will measure stuff like the ring end gaps and see where I'm at with the bore and piston clearances, see where that leads me. The head will come apart so I can inspect the valve sealing faces and replace the seals at minimum, will lap those valves while it's apart, check the guides, etc. Gasket surfaces seem too smooth to me, thinking of skimming them. Going to vapor blast them all too, and that might help evaluate the flatness of the sealing surfaces.

Thoughts on all this stuff? Would appreciate your accumulated wisdom on these and other items, potential service I ought to do to the oil pump etc.

More photos, just for grins:

More to come...

Measure the bores. Looks like Wiseco pistons. 10.5/1? Use Liska cam gears. 1/2 the price of OEM. That's a early Z1 oil pump. (a good one) Open it up and measure between the gears. You can sand the face plate with #600 paper on a sheet of glass. By the oil around the pistons, it looks like the cylinders weren't honed. Measure the clearance top, middle and bottom with a feeler gauge.
More pics. :woohoo:
Steve

swest wrote: Measure the bores. Looks like Wiseco pistons. 10.5/1? Use Liska cam gears. 1/2 the price of OEM. That's a early Z1 oil pump. (a good one) Open it up and measure between the gears. You can sand the face plate with #600 paper on a sheet of glass. By the oil around the pistons, it looks like the cylinders weren't honed. Measure the clearance top, middle and bottom with a feeler gauge.
More pics. :woohoo:
Steve

Priceless intel as usual Steve..

Cam gears looked fine, is it best practice to replace those along with the new chain?

I'll look more closely at the pistons, see if I can find any markings, no clue about the compression ratio just yet.

For sure the cyls were not honed.

> Measure the clearance top, middle and bottom with a feeler gauge.

What are you referring to here - the ring end gaps?

There are a few more engine photos in the Smugmug gallery beginning here, but I'll shoot some more as I go too.

noblehops.smugmug.com/Motorcycles/The-Fr...1975-Z1-90/i-wTHcqzm

Thanks Steve!

N.

Nice Job! Those are not Wiseco's. Do not have their mark underneath. The 11th picture shows the detent head was off before, it is hammered back on, The lock washer shows that. And that is a Heavy duty cam chain. You have to use a bore guage for the cylinder bore measurement per the manual. Could have been cheap replacement pistons. But are higher comp.
Good Luck!

Put the pistons in their respective bores without rings and measure at the piston skirt. Those are high compression pistons. The 903 piston is in the front.


Cam sprockets last a long time. Mine are 40 years old. I'll bet you have 70mm pistons making it a 1015 or even a 1075. :woohoo: They look good.
More questions? Ask away. :whistle:
Steve

Nils, will you adopt me? I will live in that garage! :laugh: :laugh:
Nice shop!

If you get into engines like that you should pick up a dial bore gauge or a set of T gauges. I prefer a micrometer for tool setup but you can get away with a set of digital calipers, depending on how accurate they are. Micrometers are the way to go IMO.

Kidkawie wrote: If you get into engines like that you should pick up a dial bore gauge or a set of T gauges. I prefer a micrometer for tool setup but you can get away with a set of digital calipers, depending on how accurate they are. Micrometers are the way to go IMO.

Kid, all, would you help me choose a set? I was on Amazon today looking at those very things, but I don't know what's good and what's Chinesium crap. (and I am NOT against purchasing a Chinese set, per se) I am totally up for owning a bore gauge and a larger micrometer then the wee one I have. I do have digital calipers but I can see that a big mic would definitely be better.

www.amazon.com/b?node=15708741

TIA for your thoughts fellas,

N.

z1kzonly wrote: Nils, will you adopt me? I will live in that garage! :laugh: :laugh:
Nice shop!

C'mon down man, we'll set you up a little hideyhole for sleeping in the loft

I LOVE my shop. LOVE it. So thank you. It is a major dream come true to be doing what I am doing in this shop. This was it on May 1 or thereabouts.



N.

swest wrote: Put the pistons in their respective bores without rings and measure at the piston skirt. Those are high compression pistons. The 903 piston is in the front.
Cam sprockets last a long time. Mine are 40 years old. I'll bet you have 70mm pistons making it a 1015 or even a 1075. :woohoo: They look good.
More questions? Ask away. :whistle:
Steve

I'm gonna have a million Steve, thanks in advance. I'm busy prepping for a swap meet this weekend so unfortunately this was all I was able to do on the Z1 today, but it shore is purdy!

N.

swest wrote: I'll bet you have 70mm pistons making it a 1015 or even a 1075. :woohoo: They look good.
Steve

Just for fun I did go measure one just now, and I came up with 69.5mm across the very crown of the pistons. So it looks like I've got me a hotrod here. Odd that it was paired with the 26mm carbs.

Back to this next week lads, but not before one more little shot of eye candy, I did my valve cover while I was at it

N.

Very nice. Check out your transmission dogs while you are at it.
Steve