Oil in #3 Intake Runnner - Opinions **pics added**

In my other thread I'm battling an oil consumption problem and was almost completely sold on needing new rings. I pulled the carbs off today and here's what instantly caught my attention:

1. Carb holder had small pool of engine oil in it, intake runner covered and almost black inside. All other intake runners bone dry and looked normal.

2. #3 carb was the one I was having sync issues with. So to my surprise when I pulled the carbs off, #3's slide was almost completely closed (intake side), while the other's had roughly 1mm or so of gap.

To refresh, compression in this cylinder was about 120 dry, 150 wet. Any thoughts on this? Should I proceed with the rest of the tear down? Leakdown test (poor man's) revealed minor, I mean I could barely hear it, air leak through the oil filler.

I searched and found that valve seals could possibly be the culprit if it's on the intake valve side.

Pics show the oil build up on the intake valve, second is shot through the spark plug hole

From what I read in the other thread, sounds like you ran it hard then shut the throttle under a decell. This would get the highest intake vacuum possible, which would stress those old stem seals.
Could be worn valve guide also, but stem seal would be check able without a head removal, although removing the head makes it easier with common tools.
There are several threads on stem seals, there are tools just for the purpose of removing the springs while the head is in place. It must fit down into the lifter bore. You need to hold the valve up so it doesn't drop inside. This can be done easily as well.
Depends on your skill, but stem seals are something that you can change with the head on.
If you pull the head, look to do rings and a valve job.

Motor Head wrote: From what I read in the other thread, sounds like you ran it hard then shut the throttle under a decell. This would get the highest intake vacuum possible, which would stress those old stem seals.
Could be worn valve guide also, but stem seal would be check able without a head removal, although removing the head makes it easier with common tools.
There are several threads on stem seals, there are tools just for the purpose of removing the springs while the head is in place. It must fit down into the lifter bore. You need to hold the valve up so it doesn't drop inside. This can be done easily as well.
Depends on your skill, but stem seals are something that you can change with the head on.
If you pull the head, look to do rings and a valve job.

Thanks for the reply. As I look through the spark plug hole and lower the intake valve, I can see oil on the seating surface. Is there a way to tell if the seal is bad or just plan on replacing it? I read threads on using soft rope into the spark plug hole and raising the piston to hold the valve up.


Is this the tool that's commonly used while the head's on?

That looks like a valve spring compressor for a flat head, can't imagine how it would work on a KZ.

Yeah you're right. Has anyone ever performed this without removing the head? How's it done?

I'm trying to get another month of riding in before I tear it down completely this summer. I could pull the head but I'm saving the gasket set.

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

DesertKZ wrote:

Motor Head wrote: From what I read in the other thread, sounds like you ran it hard then shut the throttle under a decell. This would get the highest intake vacuum possible, which would stress those old stem seals.
Could be worn valve guide also, but stem seal would be check able without a head removal, although removing the head makes it easier with common tools.
There are several threads on stem seals, there are tools just for the purpose of removing the springs while the head is in place. It must fit down into the lifter bore. You need to hold the valve up so it doesn't drop inside. This can be done easily as well.
Depends on your skill, but stem seals are something that you can change with the head on.
If you pull the head, look to do rings and a valve job.

Thanks for the reply. As I look through the spark plug hole and lower the intake valve, I can see oil on the seating surface. Is there a way to tell if the seal is bad or just plan on replacing it? I read threads on using soft rope into the spark plug hole and raising the piston to hold the valve up.


Is this the tool that's commonly used while the head's on?

Attachment ValveSpringCompressor.jpg not found

NO, that is not going to work. You need something more like this.


Do you have the service manual for your bike? It will be the first thing to buy if you don't. It will show how to remove and then re-install the camshafts. How to adjust the valve clearance while your there etc.

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

Motor Head wrote:

DesertKZ wrote:

Motor Head wrote: From what I read in the other thread, sounds like you ran it hard then shut the throttle under a decell. This would get the highest intake vacuum possible, which would stress those old stem seals.
Could be worn valve guide also, but stem seal would be check able without a head removal, although removing the head makes it easier with common tools.
There are several threads on stem seals, there are tools just for the purpose of removing the springs while the head is in place. It must fit down into the lifter bore. You need to hold the valve up so it doesn't drop inside. This can be done easily as well.
Depends on your skill, but stem seals are something that you can change with the head on.
If you pull the head, look to do rings and a valve job.

Thanks for the reply. As I look through the spark plug hole and lower the intake valve, I can see oil on the seating surface. Is there a way to tell if the seal is bad or just plan on replacing it? I read threads on using soft rope into the spark plug hole and raising the piston to hold the valve up.


Is this the tool that's commonly used while the head's on?

Attachment ValveSpringCompressor.jpg not found

NO, that is not going to work. You need something more like this.


Do you have the service manual for your bike? It will be the first thing to buy if you don't. It will show how to remove and then re-install the camshafts. How to adjust the valve clearance while your there etc.

Yeah I have the service manual. I said F it and pulled the head. Everything looks in order and the cylinder walls look pretty good. I'll pick up the new valve seals today. Thanks everyone.

Now that you have the head off, I would send the head out to a competent machine shop for a valve job. One that does motorcycle heads would be best, as some are not used to the different tolerances for the bike. Rings can hold compression, but not oil. Its something that doesn't show up on a compression or leakdown test, bad oil rings. I'd pull the cylinder off for inspection. You will need to be able to make several measurements, if you don't have the tools for that. Then you may want to take the cylinders with the pistons to the machine shop to be measured. If to worn it will need a bore job, which with a valve job will result in a fresh top end with correct compression/ power.
Just need $$$$$ which can be a deterrent. You got to love your bike.
Before you remove the valves from the head, do a simple solvent check. Thats filling the port with solvent/ brakeclean/ gas or another such fluid and see if it leaks out past the valve into the combustion chamber.

Motor Head wrote: Now that you have the head off, I would send the head out to a competent machine shop for a valve job. One that does motorcycle heads would be best, as some are not used to the different tolerances for the bike. Rings can hold compression, but not oil. Its something that doesn't show up on a compression or leakdown test, bad oil rings. I'd pull the cylinder off for inspection. You will need to be able to make several measurements, if you don't have the tools for that. Then you may want to take the cylinders with the pistons to the machine shop to be measured. If to worn it will need a bore job, which with a valve job will result in a fresh top end with correct compression/ power.
Just need $$$$$ which can be a deterrent. You got to love your bike.
Before you remove the valves from the head, do a simple solvent check. Thats filling the port with solvent/ brakeclean/ gas or another such fluid and see if it leaks out past the valve into the combustion chamber.

Just thinking out loud here. If the rings were letting oil slip by there wouldn't be oil in the intake port correct? Due to the vacuum created?

I threw some solvent into the ports and I didn't have any leaks and did the flashlight test. The bike has over 50K on it but it was a touring bike (complete with bags, fairing, windshield, stereo, etc.) so I imagine they were verrrry easy miles. Thanks for your input. Local machine shops want an arm and a leg for head work/boring/honing. May need to pass this off for awhile, I take care of my parents and money is tight.

Everything is bagged and tagged on a shelf in my garage for now.

The way I see things if you are going to have the head off anyway I would go ahead and replace the valve seals and re-ring it. Or if needed bore and replace pistons. With that many miles you might as well just do the repair once. If you don't you will probably end up tearing into it again afew years later.

Before you tear it down, turn the motor over several times and watch the cam chain for stretched spots. You'll see them at the top idler sprocket. Sometimes the chains are so bad they barely touch the idler sprocket in sections. Now is the time to check that out.

Go completely through the top end if you're going to take it apart. Pistons & bores should be measured before you just order up rings. Hate to see you buy them and then find out you need a bore job.

Go completely through the head replacing whatever it needs and resurface it.

Thanks, I did what you said and checked the chain, nothing out of the ordinary. I know how everyone loves pics so I added this of the #3. There was literally oil dripping off the intake valve when I pulled the head. I'm going to fill the area around the seal with oil and somehow apply some compressed air to the area to see if that seal leaks (because I'm curious). I'm 99% sure this was the issue, and here's why...

I pulled the carbs and even after the mercury gauge sync the #3 just didn't look right. The slide was closed way more than the others. I think this is what caused that #3 intake valve seal to fail somehow. Once I get everything back together after the build I'll sync it up again and check it. For now I opened it up even with the other 3. Any thoughts on this? Maybe the mercury sync gauge had a hole or tear in the vacuum line that gave a false reading and therefor inaccurate adjustment.

I'm going to let these heads soak for a few days and tear them down.