valve job

Well, I was all excited that I successfully did the starter clutch repair on my 1978 KZ1000, only to be blown out of the water by some scary compression readings for the motor. I usually do the compression reading first (before I spend a $%#@load of money fixing up the rest of the bike:)) and for a couple of different reasons that did not happen this time around. Anyway after doing the usual stuff, valve adjustments (twice actually) carb cleaning, etc, I did the compression check. 145psi on number one, 140psi on two, 130psi on three, and then it goes rocketing all the way down to 90psi on four. I poured some oil in number four, re-checked it, and it only came up <5 psi. So I did a leak down test on it, started with number four, and the air was just *flying* out of the exhaust...you might not have thought there was a valve there at all for the exhaust. I stopped right there, as it was obvious that I was looking at some valve work, at the very least.

I think I know where to get all of the parts, but I have a question. On my 1978 KZ1000, are there any other years of KZ where the head (and possibly the jugs) will fit on my motor?

Is it running?
Steve

Check clearence on #4 exhaust valve? I would do that before janking a head.

How many shim sizes down did you go on 4E? If you had to go more than one the valve may have some carbon on the face which is keeping it from seating properly. Running the bike for a few hundred miles should clean off the carbon and may restore the lost compression. It's worth a try anyway considering the alternative.

@swest---That is the weird thing, not only is it running, but except from the fact it seems to be a little noisy on the top end, it starts right up, and idles nice, and just running around my house, pulls like crazy from first to second gear, no smoking with the engine. I checked the timing when I got it back together, it was right on. I bench synced the carbs, have not synced it while running yet.
@Z1Driver-- Two times.. it was perfect from the get go, .07mm
@Nessism--Never had to adjust 4E, it measured out at .07mm. Yeah, I'm thinking maybe some of that Ring Free treatment (Yamalube?) and then just take it out, and ride it like I rented it.

You know, I just had one of those D'OH moments; I was in a hurry yesterday when I leak down tested #4 yesterday, and I suppose the possibility exists that I was at TDC on the exhaust stroke instead of TDC compression. Im going to re-test it tomorrow, and see about something to treat the motor with. Any suggestions? Ring free, SeaFoam?

Why do you say it's noisy? How many miles? Sat long?
Steve

Skiprrdog wrote: @swest---That is the weird thing, not only is it running, but except from the fact it seems to be a little noisy on the top end, it starts right up, and idles nice, and just running around my house, pulls like crazy from first to second gear, no smoking with the engine. I checked the timing when I got it back together, it was right on. I bench synced the carbs, have not synced it while running yet.
@Z1Driver-- Two times.. it was perfect from the get go, .07mm
@Nessism--Never had to adjust 4E, it measured out at .07mm. Yeah, I'm thinking maybe some of that Ring Free treatment (Yamalube?) and then just take it out, and ride it like I rented it.

You know, I just had one of those D'OH moments; I was in a hurry yesterday when I leak down tested #4 yesterday, and I suppose the possibility exists that I was at TDC on the exhaust stroke instead of TDC compression. Im going to re-test it tomorrow, and see about something to treat the motor with. Any suggestions? Ring free, SeaFoam?

Seafoam? Sure. Put whatever you want in there. It all does just as good of a job cleaning out your wallet. It's pretty much impossible to clean exhaust valves with any of that stuff, because by the time the exhaust valve is open it's burnt up anyway. If it is carbon holding the valve open, then riding hard may compress it/blow it out. More likely, the valve/seat is just worn or the valve is burnt. What usually happens when carbon builds up on exhaust valves is that they pit badly, and nothing in a can will fix that.

@swest--I have only had one other KZ, a 1996 KZP, with similar mileage as this one, 48K, and that bike, while it seemed, noisy to me at the time, IDK, this one seems a tad noisier. I have already done the cam chain adj twice. How long did it sit.. good question. Probably up to a year, possibly longer.
@jackleberry--I would tend to agree with you on the snake oil, I guess considering it is a safe way for my brain to NOT have to consider dropping another $400.00 to $500.00 on the bike in the form of a valve job

I was thinking the cam chain rollers may be coming apart. They are "rubberized",get hard and brittle then fall apart. A broken cam chain can be the result. I'd check them.
Steve

Skiprrdog wrote: Well, I was all excited that I successfully did the starter clutch repair on my 1978 KZ1000, only to be blown out of the water by some scary compression readings for the motor. I usually do the compression reading first (before I spend a $%#@load of money fixing up the rest of the bike:)) and for a couple of different reasons that did not happen this time around. Anyway after doing the usual stuff, valve adjustments (twice actually) carb cleaning, etc, I did the compression check. 145psi on number one, 140psi on two, 130psi on three, and then it goes rocketing all the way down to 90psi on four. I poured some oil in number four, re-checked it, and it only came up <5 psi. So I did a leak down test on it, started with number four, and the air was just *flying* out of the exhaust...?

Been there, seen that. I took the head off, laid it upside down and poured light machine oil in and watched it pour out past the valve. You probably will find a crud buildup is keeping the valve from seating.

FYI: the machine shop that did mine also serviced the cop bike fleets (KZ1000 cop bikes) and he told me the standard service interval they allowed between valve jobs was 18,000. I told him I had 42k on mine and he couldn't believe it went that far on the factory valve job.

I expect to get at least that much out of mine.
Steve

18,000 miles between valve jobs? That doesn't sound right at all. I have about 60,000 miles on my KZ650 and the head has never been pulled. I wonder if he was mixed up and was talking about adjusting valves? Ed