TOPIC:

A little off the wall here but while waiting to decide what to do with what I think are galled up cam lobes....(I think due some improperly hardened, cheap, crap shims from China)....
I've been messing with my valves.
I removed them all and put a little valve grinding paste on the them and lapped the seats to valves, mostly to see how the margins are after less then 4000 miles.
All look pretty good and very very similar to correct art work in the FSM.
I did something else out of boredom...
I installed the spark plugs, flipped the head over with combustion chambers up, and filled one chamber at a time with mineral spirits and then used compressed air in the ports to see if there was any bubbles in the chambers.
Not a great way but I used small damp rags to loosely "seal" the port and shoved my air gun inside at about 110-120psi.
Well, no bubbles or valves leaking for 6 of them....
But, on one exhaust and one intake valve, of two separate combustion chambers, I can see an EXTREMELY small amount of VERY tiny little bubbles dribbling out... almost like a little stream of fine foam from a couple areas under the heads.
If I really seal up tight, I can get that one exhaust valve to "just" start doing this with about 80psi.
None of the other 6 valves do this.
Now, I took those two valves back out and looked at the face and seat with my jeweler's loop (4x) and I can see NOTHING odd or funny on the margins. Just smooth gray all the way around.
Spinning the valves at low rpm in my drill press, with a fixed needle point of reference at the head, doesn't show and obvious bends or warped valve heads.
That might be a lame test as the limits for a stem bend is stupidly small, like .001" to a > of .002", which I doubt I could really see.
I don't have a true plate or V blocks to set up to use my dial indicator so I can't tell well by eye if they are bent a few thous.
Questions.... is it possible that my air pressure is actually pushing these two valves open a bit and those two valve spring combos are weak?
Or, I'm delusional and those two valves are also bent a little.... ugh!
These are original not aftermarket.
OEM Kawasaki valves.
Although touched up, they are the original valves as supplied by Kawasaki when the bike was assembled in Japan in 1976.

I'd put in new valve springs. They are wierd critters. They can test good but do some strange things under load. The valves should be fine.
Steve

I took my 750 valves to a guy with a centerless grinder for a quicky clean up, and even though the engine only had 11k miles on it the guy noticed several of the valves were not true and required a fair bit of grinding before they were ready to go back in. The seats were also in pretty crappy shape. I was surprised. It seems that Kawasaki wasn't very detail oriented in 1981 because the valve margin was not even close to even around the seat until I recut them. Guess what I'm driving at is unless you have the valves properly cut they could very easily be out of round, bent, whatever, thus leading to the leakage you are experiencing. The seats could be a little kaddywampus too. All of the above was present on my engine anyway.

BTW, if you decide to throw in new springs per Steve's recommendation, be sure to get stock springs, not aftermarket designed with extra seat pressure. Using such will wear your cams/valves/seats more than necessary.

No eBay APP ID and/or Cert ID defined in Kunena configuration

swest wrote: I'd put in new valve springs. They are wierd critters. They can test good but do some strange things under load. The valves should be fine.
Steve

Like these?

Kibblewhite Precision Valve Spring Kit 40-1016

Looks like the ones I have. Package says 1.320" -1.340" Had this discussion in my Poser thread. Kibblewhite said no extra stress on the valves or cams. Everything changed. The noises at speed and start up was gone. The valve train sings like it did new. At least 20,000 miles and I've adjusted three valves. All three were still within spec but I brought them into the high limit.I ran my old springs way too long.
Steve
www.blackdiamondvalves.com

You are worried about something that would probably be normal. You are applying air pressure to the back side of the valve when it is made to seal off pressure from the chamber side. The area of (area being the total surface of the valve air is applied to) of the valve may be large enough to overcome spring pressure and slightly unseating the valve.

I think a better test is to not use air pressure and see if the mineral spirts leak out.

The valves will seat in with use.
Steve

Both my KZ1000 heads have original valve springs with way more then 20,000 miles.... the one I am using right now is closer to 42,000 miles. The other is around 28,000 miles as a guess.
Free length on the 28,000 is still at the mid service limits 39.2mm large and 35.5mm inner.
I didn't think to check the one with bubbles.... doing it later.
This probably doesn't mean squat if the tension under load is off.....

Z1Driver wrote: You are worried about something that would probably be normal. You are applying air pressure to the back side of the valve when it is made to seal off pressure from the chamber side. The area of (area being the total surface of the valve air is applied to) of the valve may be large enough to overcome spring pressure and slightly unseating the valve.
I think a better test is to not use air pressure and see if the mineral spirts leak out.

Yes I tend to agree.... why I said in the beginning that this whole event might be moot.....

I did do that the other test with something very thin, acetone and one cylinder at a time.
After about 5-6 mins under my 2x bench lens and light, dry on the combustion chamber side.
I also tried regular old carb spray cleaner with the little red spray tube shoved right in the ports at the valve seat.
Pretty much the same results.... no obvious leakage.

Killing time waiting for a new Wiseco head gasket and to decide on what to do with the cam shaft with mildly galled cam lobes.... and those two Chinese 240 shims that are also galled up ... which I still think is the real culprit in this galled up cam lobe issue.

I greatly appreciate everyone's input!!

You may be right about the shims.
Steve




I understand they aren't marked this way.