1981 Kawasaki GPz550: Restoration

Well, that stinks! Looks repairable for sure, but it sure isn't what you had in mind. How does the cylinder wall look? Hope it's still good. Ray

[Fjbj40]

Machine the valve and seat, then measure. If it is within specs you are good to go. Piston damage looks negligible.

Damage on head can be blended easily.

Pictures are high quality, but diagnosing the parts as junk or serviceable cannot be done from them. Measure after they are cleaned up and then go from there.

Personally I would step back, throw a cover ver the bike and parts and cool off for a few days, your emotions will feel better for it. Then get the machining done and go from there. Sometimes we get too caught up in things and a little break goes a long way, it works for me anyways.

Cheers brother and persevere.

[chuck hahn]

Looks like 1 valve is junked for sure.

If NGK denies anything but full compensation for the failure of their product and the resulting consequence I'd be very surprised. Itemize everything, they have a budget for this kind of thing.

On a side note, GPZ550 was the first bike I ever rode.

That seat is done for, unless going oversized.

[Nessism]

Wow! Bummer!

Steve, some dings in the top of the piston won't hurt anything. Same goes for the head. Can't you just replace the valves that are damaged and kiss the seat with a cutter as necessary?

[srsupertrap]

All bad news when I did a compression check on Friday, my setup



#1 cylinder is where the spark plug insulator failed


Rest were like this . . . 5300Ft




NGK forced my hand had to have a look inside, it gets worse





Looks like insulator residue, valves seemed to be straight but that needs to be verified





Not a catastrophic set of photos but its loosing 30+ psi somewhere.



Although I didn't buy the plugs, I contacted NGK and they sent me a claim form for the damage. They want the spark plug for a failure analysis investigation ( I am sure they will find a way to deflect the claim ). Regardless, I will submit a claim for a cylinder head, gaskets and piston but the Wiseco 615 piston in the photo are the XC type which were discontinued long time ago so there is no hope of finding one of those. I will probably have to replace all the wiseco pistons with new or find a new cylinder and run stock Kawi pistons.

Either way its a total mess & money pit too.

Wow! I have never seen that before. I second Ed's vacuum cleaner suggestion, ceramic in the ring area could be very damaging. Sorry to hear that. Ray

[Nessism]

Steve,

You only ran the engine for a few mins while in your garage. No way a fault in your engine caused that plug to break.

[srsupertrap]

I found this on the NGK site but no guidance about what damage occurs

The combustion temperature can rise to an abnormally high level so that heat transfer from the interior of the plug is unable to keep pace, leading to trouble such as cracking of the insulation and melting of the electrodes.

1)	Breaking of the insulation Type 1 (See Photo 1) When selecting a plug, make sure that the standard plug will not go outside the optimum temperature range while engine combustion is normal (refer to the "Plug Temperature and its Effects" chart below). If for any reason (water leakage, oil leakage, etc.) the engine starts knocking or detonation occurs, the temperature of the combustion gas will rise sharply and the plug, piston and valves will overheat. Overheating of the plug causes the center electrode to expand, and this can break the insulation.	Photo 1: Breaking of the insulation
2)	Breaking of the insulation Type 2 (See Photo 2) This is the situation where deposits (products of combustion of oil, etc.) penetrate into the gap between the center electrode and insulation at the firing end, expanding the center electrode and causing the insulation to break. Normally, deposits do not penetrate into this gap. If the engine overheats, the engine's cylinder head may distort. This means that cooling of the combustion chamber will fail which in turn means that knocking will occur more easily. Repeated knocking leads to abnormal pressure and vibration in the combustion chamber. This abnormal pressure and vibration causes the deposits that have accumulated in the combustion chamber to scatter as fine particles and enter gaps in the plug.	Photo 2: Entry of deposits

[Nessism]

Steve,

You do not need to remove the tensioner, just the spring cap. A 17mm socket on a long extension will allow you to reach the cap. Pull off the cap & spring and then pull back on the cross wedge just enough to make sure it's not jammed in tight. Do this just before you reinstall the valve cover, not while working on the top end. You need the tensioner in place while rotating the engine and so forth.

Regarding that insulator chunk, I'd make a solid effort to try to find it, or at least clean out the cylinder. Take a piece of hose small enough to fit down through the spark plug hole and connect it to your vacuum cleaner and try to suck out the debris in the cylinder. That ceramic is hard so you gotta get it out of the cylinder. If you can't find it that means it's gotta be in your exhaust system.

Good luck

[srsupertrap]

After getting the Dyna S statically timed on Saturday 8/13, I hit the starter button and it fired right up. I only let it run for 30 seconds because the fresh engine paint, new rings etc. but the GPz was very responsive which is likely attributed to 1/4 turn throttle. I blipped it a couple of times to 3-4K and shut if off feeling good. Later in the afternoon I started it again but it seemed less responsive to the throttle & noiser. Didn't over analyze it . . . perhaps I should have.

Next day, I called over Ray (Ghostgs1) to take a video confident it would start but when we started there was a real loud knocking noise coming from the valve train but we couldn't make heads or tails which side the noise was coming from. So my assignment for this weekend was to remove the valve cover, check the valve lash and see if anything hand grenaded inside. Once you remove the valve cover on a GPz/Kz550 you have to remove the cam chain tensioner which in my case requires removing those Mikuni TM27 . . . Ugh

It didn't take long to find this, while removing the spark plugs I found the insulator on # 1 spark plug had broke off inside the engine while it was running. No mechanical contact with the spark plug. First time I have seen this and the spark plug was brand new NGK.



Here is a picture of a .022" feeler gage that I slipped in between #1 Intake valve .. . that's a problem because the OEM valve lash is suppose to be .006" to .01" for the intake & .004 to .008" for the exhaust



I figured I better fish out the remains of the porcelain insulator form cylinder #1. I found some real small threads of porcelain insulator but nothing really visible. I stuck a carb vent line down the cylinder to see if I could suck up the remains but no luck and not very tasty either. After a lot peering down the spark plug holes I could not find the remains of the insulator. What I could see of the valve appeared to be undamaged but no telling if a piece got stuck under the seat which may account for that huge .022" valve lash measurement




I then went back and checked the valve lash and this time all the valve lash measurement were within spec. I guess my question at this point is can anyone convey their experiences with a broken spark plug porcelain insulator? I know its brittle but I have not idea whether a sound approach would be install a new spark plug and see what happens. Otherwise I am looking at tear down to the cases and replacing all those gaskets again.

PS: I also found a couple of the Yosh Exhaust stud nuts were loose which may have contributed to the noise

[srsupertrap]

I will start with the good because there is some BAD to follow.

Regarding needle jet assemblies, I sent Chad Thompson @ Sudco a TM 27 needle valve assembly and he identified Sudco's P/N VM15/172 as an equivalent needle. No luck on the needle seat and each one cost about $25 and there is no returns. I have asked Jeff Tuttobene to see if anyone at Mikuni can help but no definite word yet.

Jeff saw my picture of my butchered Dyna S wiring connections below and offered to help . . . again just like so many others have. When one installs a Dyna S on 81-83 GPz550's you loose the IC Ignitor and the factory connector. Note the extra Dyna S wiring loop.



Jeff lent me his Super Crimper, gave me his extra OEM connector to make my Dyna S connections look professional





Much better

Any news Steve? Possibly cam chain adjuster loosened up? Ray

[Nessism]

Looking forward to an update...

[srsupertrap]

Thanks Ed for posting those pictures, that helps.

Ray, I reinstalled the carbs, the float bowls are full and it hasn't leaked this week. I will try to start it tomorrow. If you have time Sunday maybe we can try again and shoot that video?

Regarding the carbs, I contacted Sudco on Friday to follow up on my request for parts. Chad Thompson who has been at Sudco for decades was very insightful & helpful, I learned these carbs are actually called TM27s. Chad stated all Mikuni Flatslides are in the TM family even the present day RS 34-40 series. These TM27s were manufactured in 1986 & 1987 and were pretty quickly obsoleted. When I asked about replacement TM27 Needle Valve Assembly, he told me I was most likely out of luck because they couldn't find any with an OD of 8mm. He was more hopeful though they could find some replacement float needles. I have the action to create a drawing with the dimensions and email it to me on Monday.

That's the latest update. We will give it another whirl Sunday