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Old 06-28-2015, 12:09 PM   #1
keener OP
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Intake valves leak?

2004 950 adv, 87,000km

I was going to do a valve clearance check just now and noticed when I turn over the motor there are tinny bubbles around the intake valves. I made a video:

http://smu.gs/1FIKklO

Is that acceptable?

Also, the clearance dor the intakes are so low that I can't even put a 0.04mm filler in!!!

Bikes is running fine, except I have a ton of back firing on decel. But That could be just a jetting issue that I'm working on.

Let me know what you think.
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Old 06-28-2015, 01:45 PM   #2
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I can't watch your video because of crappy slow and ultra expensive internet here. I'll try after midnight when it's cheaper.

Anyway, at 87,000km you're doing nicely. Can you rotate the bucket on the tight valve to see if you've got any clearance at all? I'd start by setting your clearances first, then do your bubble check on that intake again. Could be it was just a closed up clearance and you may have got away without damaging the faces.

If it still bubbles and was tight then I would run it for a few days and check it again. Thinking if you can get another 30,000km or so then you could go for a proper re-furb including timing chains, rings, valve surfaces if reqd.

If it still bubbles after a few days then I'd go inside and lap that valve only and fit a new valve stem oil seal. Leave the rest for another 30g km, but check for Pyndon Syndrom at the cylinder base while it's off.

Have fun!
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Old 06-28-2015, 01:54 PM   #3
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Thx. Just trying to get them the correct clearance right now. I've done several valve checks before, never had the clearance change by so much.

It's gone off by about 0.12mm !!! The front cylinder is exactly the same. Except I see less carbon built up over the valves in the front.
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Old 06-28-2015, 05:05 PM   #4
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Not a good sign if clearance has changed so quickly. I would do a leakdown test. I have a friends 990 in my shop now. It whistles air through the intakes when performing the leakdown. Theorizing that he got it hot, really hot, and cooked the seals and damaged guides and valves. I am sure you know, but the clearance typically changes as the valves tulip shape and sink farther into the valve seat, pushing the valve stem, bucket and shim up to the cam--reducing clearance.

FWIW
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Old 06-28-2015, 06:48 PM   #5
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Quote:
Originally Posted by renogeorge View Post
Not a good sign if clearance has changed so quickly. I would do a leakdown test. I have a friends 990 in my shop now. It whistles air through the intakes when performing the leakdown. Theorizing that he got it hot, really hot, and cooked the seals and damaged guides and valves. I am sure you know, but the clearance typically changes as the valves tulip shape and sink farther into the valve seat, pushing the valve stem, bucket and shim up to the cam--reducing clearance.

FWIW
That's a good description, the tulip shape, so one can see how wear accelerates once past a critical point. True.
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Old 06-28-2015, 06:55 PM   #6
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Back firing indicates a lean condition most likely jetting I would do a leak do a as mentioned to be sure that the vales are indeed leaking enough to worry about.

I dont know that anyone has really looked at valve leakage this way, at least ive never seen it on a 990, if the clearance has changed quickly then that does show cause for concern. What did the clean side of the air box look like or are you running a CPR/ Rottweiler intake?

Normally bad or worn intakes are affiliated with hard starting and also show ware on the cam buckets and cams

If you cant get a 0.04 mm feeling in then yes they are tight but when was the last time they were done?
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Old 06-28-2015, 07:36 PM   #7
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Hi Keener, I just got in from a 250 mile ride to the coast.

ICERIDER gave you good tips. It could be that you just have some tight intake valves. Adjust them to the loose side of the spec, about 0.006". Then run it for a while and check again.

In general the intakes will tighten up and the exhausts will loosen up. You may have just got a little quicker wear than before.

If you are running a foam air filter, these will pass dirt if you don't service them regularly. Two days of riding in dust can fill them up. Dirt = quick wear on intake valves. I've worked on an SE with a 'teddy bear' air cleaner and it had NEGATIVE 0.002 to NEGATIVE 0.012" of clearance on the intake valves. Yet to see if it had a permanent problem. Nothing works as good as the stock paper filter and airbox.

So, we are all on valve watch.
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Old 06-29-2015, 05:07 AM   #8
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Agree with previous posters.

I don't think you can tell much by looking into the intake manifold - adjust your valves and do a leak down test.

If you have a lousier reading - 10% or more - listen to see where it is leaking - out of the muffler or hissing into intake (also you'd normally check bubbling in the rad although that doesn't sound relevant to what you're describing). Even if the bike is running up into the 15% leakdown range but is starting normally it is probably ok.

Leakdown testers from motion pro are not expensive if you already have a semi-decent air compressor.
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Old 06-29-2015, 06:27 AM   #9
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Yes I have the ITG aka CPR filter. I clean it regularly and meticulously . In very dusty environment I use the pre filter. Inside of the filter is always very clean.

Rear intakes took about 0.20mm to come to spec range! My valves never won't that much. Exhaust valves are all in spec. Last valve check was about 12,000km ago.

I did have a situation about two months ago in Moab that I burnt the clutch. But the engine temperature didn't go up too much. Not sure if that could have had any effect?

I poured a tea spoon of rubbing alcohol into the intakes after changing shims and did not see any bubbles. yay! I will do the front cylinder today.

I really want to know what has worn that much and why. Gotta read on this tulip valve thing you guys are talking about. Is that common on LC8? Never heard of it.
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Old 06-29-2015, 06:50 AM   #10
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Leak down test is a blunt instrument. If you already see and know your intake valve is leaking as the OP does than that is what you have to deal with! Simple!

The tulip valve thing is referring to what happens to the valve face/cyl head contact area after it wears a lot. The clean angles are lost and it changes shape through wear. You can restore this if necessary by re-cutting the surfaces if there's enough meat. I doubt if you have that at your mileage and you know your filters are good.
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Old 06-29-2015, 11:04 AM   #11
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Quote:
Originally Posted by ICERIDER View Post
Leak down test is a blunt instrument. If you already see and know your intake valve is leaking as the OP does than that is what you have to deal with! Simple!

The tulip valve thing is referring to what happens to the valve face/cyl head contact area after it wears a lot. The clean angles are lost and it changes shape through wear. You can restore this if necessary by re-cutting the surfaces if there's enough meat. I doubt if you have that at your mileage and you know your filters are good.

All motors have leak down - 0% is not possible even in a brand new engine. The question is how much.

If the valve is tuliped, then it should be replaced and faces lapped.
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Old 06-29-2015, 11:58 AM   #12
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Quote:
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All motors have leak down - 0% is not possible even in a brand new engine. The question is how much.

If the valve is tuliped, then it should be replaced and faces lapped.
Absolutely, Just trying make suggestions to save the OP time and teardown expense.

He could probably check the faces with a little hooked device, looking for smooth faces without a lip. Just by opening the valve and inspecting down the intake.

Agree there could be accelerated wear here but depends how far you roam from home and can put up with it.
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Old 06-29-2015, 02:12 PM   #13
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I corrected the shims and I have no leak. No bubbles even when it's filled with alcohol.

I will check it again in 500km or so.

What does causes accelerated valve wear?

Can I just buy new valves and have them the heads cut? If I do that, would be wise to replace all 8?
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Old 06-29-2015, 02:14 PM   #14
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While I had the camps out I did a plastigauge test. Journals are all perfectly in spec but don't look as shiny as they used to.
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Old 06-29-2015, 02:30 PM   #15
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Quote:
Originally Posted by keener View Post
I corrected the shims and I have no leak. No bubbles even when it's filled with alcohol.

I will check it again in 500km or so.

What does causes accelerated valve wear?

Can I just buy new valves and have them the heads cut? If I do that, would be wise to replace all 8?
Good news! The theory of accelerated wear could happen with Dust getting in for example. Wrecking the designed face angles and gas seal so the valve wears it's way quicker towards the cam, reducing the gap. IMHO.

If you're going to pull it apart would make sense to do all 8 and yes you should be able to get head re-cut. You could also get the valves reground. Depends on a few factors. Take it to a Cylinder head expert. (Take it to a KTM workshop they may recommend new heads etc). See how it goes.
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