Vacuum Test Reveals Worn Valve Guide Seals (Short)

[171apples171]

I ran my KZ1000LTD with a 4 into 1. It made the mixture really lean and i didnt have the money for a jet kit so i just rode the last 2 months of summer thinking it wouldnt hurt anything.. the plug on cylinder three is now fowled with wet oil whenever the bike sits for a night or more. and whenever i start it it has to cook off alot of oil before it starts to run like a monster. I have at least 130 PSI compression on all cylinders. Sound like valve guides to you? i do know what to do:(

[CorvusCasull]

Well, you said you've got good compression on all cylinders, so I would imagine that worn guides could be a possibility there. I'm not very familiar with motorcycle engines as I've only ever owned one bike (a Yamaha XS11), but is there any other way you could get oil seep in a single cylinder with good compression? Does the engine have any blowby? Have you used a vacuum gauge yet?

If you don't want to open anything up, you could always try running a hotter plug on that cylinder as a band-aid.

[171apples171]

@CorvusCasull Yea but im a perfectionist sorta when it comes to mechanical stuff, i could giva a shit less how it looks:D I have recommended running a hotter plug to others before but after they install it the oil burning seems to only get worse. im getting a leak down tester for Christmas from my dad. Ill have to use it and listen for blow by from the intake and exhaust ports, and the crank case oil fill area. the motor is getting overhauled soon anyways:D thanks for the reply.

[ansar68pk]

@1foxtrot70 You are spot on mate. Let the piston go to BDC and 80-100psi should about do it. If you don't have an air compressor then a crude method is the rope trick. Bring the piston at TDC and feed a rope through the spark plug hole until there is enough inside to fill the compression chamber and jam against the valves. Locking the crank helps. The rope should be of a type that doesn't shed fibers when pulled out. We don't want crap inside the cylinder.

[1foxtrot70]

I often wondered how to check for the valve guide seals leaking. It stands to reason since they are a rubber type component that they would harden from lack of use. That in mind, can these seals be changed without removng the heads? I was thinking of perhaps jogging the engine until both valves were closed then, pressurize the cylinder with an airhose via the spark plug port. Remove the rocker arms compress & remove the valve springs replace the seals and reassemble. Any thoughts?

[CorvusCasull]

As far as I know, you got it man. You know your stuff. That would be the only way I'm aware of without taking the head(s) off.

What I know to look for with bad rubberized guide seals is excessive blowby at idle, an occasional tiny puff of oil smoke on startup that lasts less than a second, and vacuum readings at idle like the ones shown in the video above.

[1foxtrot70]

@CorvusCasull definately saves a lot in labor for the DIY'er. I am sure the repair shops use this technique but still charge the Flat Rate for head removal and replacement, etc. I don't mind paying a mechanic and the shop for services rendered but, if there is a savings to be had the customer needs to have some also.

[smithraymond09029]

@1foxtrot70 That technique is a "Chilton Time Saver" in the repair book. Never tried that before.

[1foxtrot70]

@smithraymond09029 - As I said to CorvusCasull, this method definately saves a lot in labor for the DIY'er. I am sure the repair shops use this technique but, still charge the Flat Rate for head removal and replacement, etc. I don't mind paying a mechanic and the shop for services rendered but, if there is a savings to be had the customer needs to have some also.

[JAMESS30288]

My 85 regal is the same way and it is low miles as well. Guess it got that way from sitting up almost 9 years of its life

[CorvusCasull]

The Skylark was last owned by an older gentleman in Florida, and when he passed a nephew of his drove it out to Colorado, didn't want it and sold it to me. Since the car only had around 48K when I bought it, I reckon it sat most of its life too.

Oh well, doesn't seem to have too many negative effects. I change the oil more often, and run the blowby out beneath the front bumper.