TOPIC:

I don't of course.

This was an Email from a mate of mine I kept.

Hi Neil,
From my memory and bearing in mind ive tried to blank it out the following was done to the Z13

Initial Rebuild:
Stripped top end of motor found bores badly worn and from what I recall only oversize pistons were available so the barrels were sent to SEP for re-boring with supplied pistons
Cylinder Head was stripped replaced valve stem seals and gave a light lapping in to valves everything thoroughly cleaned and re-assembled
Everything re-built and we had a tapping sound which got worse as the rev’s were increased, re-checked cam timing with nothing found out of manufacturers spec for year of bike
Re-Checked all gears to water pump and cam timing again with nothing found
Bike returned to Neil’s for further investigation at a later date

Z1300 – The Return
Bike came back to myself where after speaking to Oz suspected tapping noise was because of piston being oversize and now hitting cylinder head, upon further inspection with endoscope “witness mark” could be seen on one area of piston which was consistent across all 6 bores, after much swearing head came off again and edge of combustion chamber was chamfered all the way round by couple of millimetres the on all 6 combustion chambers.
Engine was put back together but was a pig to start with various things tried including different ignition timing position, by-passing fuel solenoid etc but made little difference, I do recall having an issue with getting the advance retard unit to line up with the factory marks 100% but Oz’s finding of partially sticking unit would explain this.

Also:
A number of times I checked cam / valve clearances and all was fine as I started to get more concerned I also removed the cams and measured distance form top of valve to top of cam follower bore to ensure we didn’t have any significant difference which may have indicated a stuck / bent valve but nothing shown that was not consistent with the others so it was put back together.
My area is Ducati Bevels so it is a bit of an unknown to me and doubt very much that I would have found half the stuff Oz has Neil, happy for Oz to give me a call to see if I can shed light on anything else, only thing I can suggest is that the heads not chamfered enough but I’ll be surprised if it isn’t or there is a problem with the re-bore and a piston is slapping in the bore but doubtful failing that maybe a small end??? But im guessing now and wouldn’t like to say without seeing it stripped again.

Cheers mate and give us a call and we can chat through this
Martin

Hi Neil
Not sure of the email address you are using tonight.

I have had another good look inside, there is some wear on the cam chain sprocket and cams themselves but no more than most z1300.
The inside of the engine has a couple of vertical marks on a couple of the bores but are showing mainly the honing marks.
You did say that when you last cleaned the combustion chamber the noise was reduced, maybe we will have to have a go and see if this will help again.

To go on to the next stage we will have to lift the head off and investigate the combustion chamber, pistons, piston to pin movement, valve cutouts on piston crown, cam chain waer, cam guilds and cam guide wheel, upgraded cam tensioner.
The pics show the wear on the cam chain sprocekt and cam guide sprocket.
If you let us know what you wish us to do on this matter please.







Regards
Oz
Director
Zed-parts Ltd
Company Reg 08877151

Website www.zed-parts.com
email This email address is being protected from spambots. You need JavaScript enabled to view it.
pictures to follow. Its also had the zzr1100 camchain tensioner fitted.
Neil.

A few details came into the picture, and the first thing that popped up in my head was 'bend valves'. They are good apparently, but are they? The bend might be very minimal and hard to measure, but there.

Vertical marks on the cylinders? Are the pistons-sleeve clearances right, and the piston pins not too much play in the pistons and small ends of the connecting rods?
Hard to say without looking. And that would require top end disassembly.

Hard to advise without first hand look. Depending on what I would see and hear, I would probably do a full top end disassembly and check ALL.
You have a beautiful machine. If that's all what is not working, I would even source parts for another top end overhaul, or rather even build a brand new top end spare with all stock sizes. (pistons, rings, another block honed and deglazed to regular size, set of new valves, new head correctly machined)

Hi Neil just an idea, do a cold compression test because my thinking is if you have evidence that your pistons have been hitting the combustion chamber there is a good chance the valves have been hit which will make it hard to start as your combustion gases going pass the valves .If you do decide to take you head of again put some fuel in the combustion chamber and see how long it takes for the fuel to soak through IT SHOULDN'T just my thoughts

Sounds like the problem started with the replacement of the new oversize pistons. The crown of the new pistons to the center of the wrist pin is taller than the stock pistons and that caused interference with the cylinder head, So the remedy was to chamfer the cylinder head? Did anyone check the valve to valve pocket clearance? My money goes on this being the problem. A clay impression can be taken and measured. Typical clearance should be around 2 -2.5 mm. There's Youtube videos regarding this check.
You should also check the squish band area to piston clearance as well now that we know the pistons were a problem. That clearance should be between 1-1.5 mm.

Somebody really messed up when the new pistons were selected. Nothing wrong with going in this route when you know what you're doing. You just need to realize that now you need to follow all of the standard procedures for blueprinting an engine.