So, I Gave It A Shot.....

Adjusting the valve clearances, that is.
We had a bunch of 650 engines going in the scrap bin at work so, since I'm off for the winter, it's a good chance to try my skills with valve adjustment.....especially with a scrap motor.
The first candidate I picked was a 77 or 78 engine...but it turned out to be seized, so that ended that. The next candidate was an 81 or 82 engine that turned over nicely....too nicely, in fact.
Turns out that it had 3 really tight intake valves with very little/no compression on those 3 cylinders. All went well, although the sprockets for the cam chain are marked differently starting in 1980 compared to the earlier ones. Fortunately my FSM has the 1980 supplement incoprporated in it so that made everything a lot easier.
So I learned how to set the clearances which was a lot easier than I'd been lead to believe. Patience and the FSM are mandatory.
I understand from a veteran tech at one of the local Kawi dealers that the 2 valve KZ's all had relatively soft intake valve seats and this caused the demise of a lot of these bikes because owners weren't willing to pay for a valve adjustment when the bike got to be 15 or 20 years old and scrapped the bike instead. What a shame....

H2RICK wrote:

...I understand from a veteran tech at one of the local Kawi dealers that the 2 valve KZ's all had relatively soft intake valve seats and this caused the demise of a lot of these bikes because owners weren't willing to pay for a valve adjustment when the bike got to be 15 or 20 years old and scrapped the bike instead. What a shame....

Interesting.

Yeah, I've found that valve adjustment is one of the first times a novice mechanic is faced with going "inside" the engine (depending on the type, of course).
I guess it can be so intimidating to somebody that they'd just toss the bike. Weird. I mean I understand the intimidation, since I was nervous, too... but toss the bike? Again, weird...

Yeah, even if i KNEW i would kill the engine...what the hell the other option is scrap the bike.

So i would dig in, try to fix it and win or lose at least i tried to hold onto my bike.

People are odd... but those same folks make it easy to find a nice bake that is easy to repair

Well, gents, working at a bike wreckers like I do, I see this kind of thing all the time. That's what keeps US in business. When we get a KZ in the repair shop that has valve problems we quote the owner a fair price for trying to resurrect his bike. We start off with a compression/leakdown test to get an idea of what we're facing and then go from there. Unfortunately a lot of folks are just not into spending any kind of money at all on a bike that's 25+ years old.....unless the rest of the bike is almost mint, and that's a pretty unusual situation.
And, of course, a lotta people don't have the knowledge, tools or place to work on a bike either.

However there IS the odd happy story. A guy brought in a KZ750 twin in not bad condition but she wouldn't start on the button. We check it out and it has something like 60 PSI compression on each cylinder. So, the tech pulls the cover off and, sho 'nuff, the intakes are tight, tight, tight. He shims them properly and, presto, now the old girl has 130 PSI on each side and starts/runs like a dream. It had probably never had the valves set from the time it left the factory cuz it only had about 20K miles on it, IIRC. Another KZ rescued from the torch.

H2RICK wrote:

However there IS the odd happy story. the intakes are tight, tight, tight. He shims them properly and, presto, now the old girl has 130 PSI on each side and starts/runs like a dream. It had probably never had the valves set from the time it left the factory cuz it only had about 20K miles on it,

I hope I get that lucky with mine. It has a little over 20K so it sounds like it may be possible. I'll know more this weekend if I can get a compression gauge.KEEP YOUR FINGERS CROSSED FOR ME !

1982KZ1100D1 wrote:

H2RICK wrote:

However there IS the odd happy story. the intakes are tight, tight, tight. He shims them properly and, presto, now the old girl has 130 PSI on each side and starts/runs like a dream. It had probably never had the valves set from the time it left the factory cuz it only had about 20K miles on it,

I hope I get that lucky with mine. It has a little over 20K so it sounds like it may be possible. I'll know more this weekend if I can get a compression gauge.KEEP YOUR FINGERS CROSSED FOR ME !

Just a reminder that acceptable compression test figures do not mean valve clearances (gaps) are within specs.

Gaps should be checked (the easy part), and adjusted if necessary (requires special tool and shims), regardless of compression test figures.

A compression gauge is of course not needed to check the gaps. Nor to adjust the gaps.

The gaps reduce as engine warms. An insufficient cold gap further reduces to the point where valve cannot fully close, and becomes a "leaking" valve (loss of compression at operating temperature). And which can ultimately result in a burned valve ($$$$).

In essence, proper valve clearance (gap) is required to allow complete closure of the valve at normal operating temperatures.

Your bike is beautiful. And with only 20k miles barely broken in. Here's hoping it's soon running as good as it looks.

Post edited by: Patton, at: 2007/12/01 01:27