GPZ1100 '82 HELP WANTED.

Kawboy wrote:

Compression testing will tell you if you have a problem. Leak down testing will tell you where the problem is and how bad it is. Leak down testing will also tell you how the engine is wearing down. A well sealed engine will read around 95% and an engine needing rebuild will read between 85-90%. One could argue that you should be able to tell this from a compression test but then you have to account for carbon build up in the head and on the piston crown, where the leak down test doesn't care about any of that. A reasonable leak down tester can be bought fora very reasonable price only a few dollars more than a compression tester. It's an invaluable tool and I won't be without one.

At least you're on the right track. It would be nice to get Eddie back up and running to give Christine something to look forward to.



 

When I was 26 I found a Benelli 750 sei in a barn find, it had been sitting for years, I bought it impulsively just thinking about its exclusivity.
I loaded it into my van and took it to an old school mechanic, an Italian living 50 km from my house who had been a mechanic for a Benelli dealership in Modena, his hometown, after his retirement he came to live in a small town near Barcelona and he made some extra money repairing Italian motorcycles in his garage with the door closed.

Well, just get the motorcycle out of the van before entering the motorcycle, he took out the spark plugs and using the kick start he checked the compression of each cylinder with a motometer.
The good man told me that the first thing he wanted to know was if I had bought a motorcycle repairable or a pretty useless paperweight.

The reading I make of that episode is that first of all I should have checked the engine compression before mounting it on the frame.

I asked Santa Claus for a valve spring puller.
 
I have to admit that it works perfectly, its use is simple.
 
The intake valve on cylinder 4 was slightly bent and did not close properly.
So I was forced to order a new valve, I took the opportunity to order more parts such as a head gasket, shims of various sizes, a valve seal set and a valve seat grinding kit.
Getor.de has been the supplier of these spare parts.
 
At the beginning of the year I received the parts and got to work.
I replaced the bent valve, the one on the left in the photo, its curvature can barely be seen.
 
With the valve seat grinding kit, a couple of YouTube tutorials were enough for me to understand how to use it.
 
I remembered later that if I had watched the movie "Quest for Fire" again it would have helped me improve the tactic of spinning a stick between the palms of my hands.
I don't understand my wife's anger when I had the detail of using a piece of cardboard while working on the cylinder head so as not to stain the tablecloth on the kitchen table.
 
After working on each of the eight cylinder head valves, I reassembled the springs and their seals.
 
Everything ready to reassemble the cylinder head on the engine.
 

Strange that just one valve was bent. If the cam timing was incorrect, surely there would be more damage.
I didn’t know that the engine had shell bearings for the camshafts. I thought all Japanese motorcycle engines had camshafts running directly in the cylinder head casting.

biltonjim wrote:

Strange that just one valve was bent. If the cam timing was incorrect, surely there would be more damage.
I didn’t know that the engine had shell bearings for the camshafts. I thought all Japanese motorcycle engines had camshafts running directly in the cylinder head casting.

The engine was completely rebuilt without being tested, I suppose that when installing the valve they did not notice the small curvature.

The Z 900, Z 1000 and Z1100 have seat bearings on their camshafts from what I have been able to discover.
My Z 650 and Z 1300 do not have them.

kawaBCN wrote:

biltonjim wrote:

Strange that just one valve was bent. If the cam timing was incorrect, surely there would be more damage.
I didn’t know that the engine had shell bearings for the camshafts. I thought all Japanese motorcycle engines had camshafts running directly in the cylinder head casting.

The engine was completely rebuilt without being tested, I suppose that when installing the valve they did not notice the small curvature.

The Z 900, Z 1000 and Z1100 have seat bearings on their camshafts from what I have been able to discover.
My Z 650 and Z 1300 do not have them.

This valve got bent when the previous "mechanic" was installing the camshafts and setting the timing of the camshafts. The GPZ1100 is an interference engine just like the KZ1300 and I'm sure that the Service Manual for the GPZ has similar detail for the installation of the camshafts as the service manual for the KZ1300. The Service Manuals for the KZ1300 covers this aspect in detail starting on page  66 and failure to follow the steps EXACTLY as written will cause you to bend ONE valve, where as having the cam chain jump a tooth when the engine is running will cause more than one valve to get bent.

I reassembled the cylinder head with a new gasket purchased at Getor.de.
I first installed the exhaust valve camshaft in its position with the crankshaft at its timing mark.
I then counted the 44 teeth indicated in the manual and mounted the intake valve camshaft.
I reinstalled the timing chain tensioner and rolled the crankshaft manually, everything was perfect.
I checked the cylinder compression again and none were below 110kg/cm3.

I assembled the cylinder head cover, reinstalled the coils, added oil to the engine, primed the fuel circuit and pressed the start button.
The engine made a soft purr, it seems that this time I did things right.
White smoke was coming out of the exhaust so I stopped the engine before filling the house with smoke.
I was satisfied, it was after 2.30 AM and I went to take a shower and go to sleep.
The next day I went out to test the motorcycle, first short trips from my house until after about 20 km, with no white smoke, I decided to take a longer route.
I entered the highway and without going over 6000 RPM I was traveling at about 150 km/h, the damn bike runs perfect.
I barely had to adjust the idle screw.
I decide to stop for a beer at a roadside bar, the gazes of other bikers are fixed on the ELR, you can count on the fingers of one hand the motorcycles of this model that there may be in Spain.
I leave the bar and when starting the motorcycle I hear an annoying Clack, Clack, Clack when starting the motorcycle through the cylinder head area, it is accentuated when accelerating and seems to decrease a little when cutting off the gas.
Damn, we already started again, what can it be now?
I travel the 40 km home and the noise gets a little louder until it becomes annoying with no intention of going away.

The clack, clack that is heard with a cold engine becomes click, click with a hot engine.
I leave the motorcycle in the garage cursing my luck and go up to eat.
I don't feel like going down in the afternoon to inspect the bike but my pride is greater than my laziness so I took out the tank again.
When I was going to remove the valve cover to check the adjustment of the shims again, I started the bike for the last time with the engine cold, ready to listen with the stethoscope to where the fucking noise is coming from.
Just when starting I see a little smoke coming out of the exhaust gasket of cylinder one, I put my hand and feel some compression escaping through the gasket, that is the cause of the noise!!!
I remember that when assembling the exhaust gaskets the old ones looked very crushed, the screws on the exhaust flanges are tightened all the way and they no longer give any more strength.
I take out the exhausts again and see the gaskets that have already passed away, so I order new ones and an improved model from the people at Getor.de.
These are the new gaskets.
 
On the left is the used one and on the right is the new one.
 
You can see the difference in thickness in this photo. 


Once the new set of gaskets was installed I have ridden the motorcycle for about 150 km without any problems, now I am satisfied.
 

Christine, get ready, you're next.