Removed downpipes looking for Oil loss clues - photos!

[vonny232]

Hi Folks,

Ive posted a few messages over the last year about my elusive oil leak (more specifically oil burning issue).

Finally got round to removing the downpipes to see if there were any clues inside the 4 exhaust portals.

The only takeaway I got was the two inner exhaust portals had considerably more carbon buildup than the two outer ones. I wasent sure whether this was because the inner cylinders get a bit hotter or whether this was a clue worth investigating.

I took a flat screwdriver and gently scratched the area where the downpipes attach and a decent amount of carbon could be scratched away (the two outer portals were coated black, but without a buildup).

See pictures below, you can see a decent buildup of carbon piled up after gently scraping the area. Lots more could be removed if I had wanted.

Also see picture of one of the outer cylinder portals as an example (cant remember which side), where the metal is "coated" but theres no thickness to the carbon. Both outer portals are like this.

I also noticed the colour of the valve stems were different one each of the valve pairs for the inner cylinders. Please see my next post for picture of this.

Any thoughts?

[vonny232]

Hi Folks,

As I mentioned from my previous post, I also noticed the valve stems were a different colour for two of the inner valves.

Both pairs of outer valves were kinda white/reddish, but one each of the two inner valves were more dirty looking.

See pictures below. It was really difficult to take decent pics, but I think this does a good job of representing what I saw.

The first picture shows what the two outer valve stem pairs looked like (i.e. reddish/whitish not sooty).

The second picture shows what one of each pair of the inner valve stem pairs looked like (i.e. one white like the others, but the other distinctly more sooty).

Is this a clue or am I over analysing this?

[vonny232]

My final pictures is the paper test.

I started the bike (with the downpipes off) and put a couple of pieces of A4 paper in front of the portals.

The first sheet of paper captured some definite spots of Oil (Note I deliberately smudged the spots so you can see the Oil).

the second sheet of paper was when I revved the bike. There were also spots, but not black oil. It looked more like diluted oil mixed with petrol but am open to other thoughts.

Its worth noting a serious amount of heat and fire came out of the portals, and lots of blue fire which was very pretty to look at but I dont know if thats normal.

Any ideas or feedback welcome

[Andre]

Probably leaky valve stem seals. What does compression and leak down test show?

[vonny232]

Cheers for the reply.

I had a compression test done earlier this year. Apparently each cylinder was 130psi.

I suspect the mechanic did not perform the test properly because 130psi is on the low side, but it was interesting that all 4 cylinders were very consistent with each other, which I inferred as meaning the piston rings are probably ok.

I have not had a leakdown test done yet, but I will probably need to do this if I cannot identify the problem myself (which I admit is optimistic lol).

I was thinking it might be the valve stem seals, but am open to other ideas.

Do you think the thick carbon buildup + dirty valve stems on the two inner cylinders is something worth investigating further?

[Andre]

You think you are burning oil. More carbon on the inner cylinders. On these there is one stem each  with carbon build up while the other seems to be fine. Leads me to believe that the darker valve stems have leaky seals.

Oil spitting out the exhaust. All of them or only the inner cylinders?

130 PSI is on the low side. Ok, the compression test might not have been done correctly or the compression gauge is not calibrated.

Proper oil changes throughout life? Mileage? Usage of engine/bike?

Does the oil you use have a high NOACK? If the is high you will see a drop in oil level without a oil burning issue.

Checked for a vacuum leak? If you have one on 1 or 2 cylinders the other cylinders will run rich which causes carbon build up.

Heat and fire is normal!

[vonny232]

Hi Andre,

Regarding the stems, yes that's my interpretation.

Hard to tell where the oil is spitting from but it tends to cluster around the middle of the paper so that points to the middle cylinders. I may have another go to confirm.

I only bought the bike 2nd hand 18 months ago so no way of knowing how well it had been maintained.

It's got 27,000 miles and I use Motel 5100. I previously bought Halfords "own brand" oil and I burned a litre in a few months of use.  The 5100 gives me around 600 miles per half litre top up.

No idea how to check for a vacuum leak lol.

[Andre]

Motul doesn't mention the NOACK for this oil. At worse they use the upper limit for this specification. That wouldn't explain 1/2 liter over 600 miles though.

Skipped oil changes are the most likely cause.

Give that paper test another go. I would do it without the fire and heat though. Have a fully charged battery, disconnect the fuel pump (leave the spark plugs in) and hit that starter button. Oil pressure will build up and you "should" see the result on the paper and/or feel/see oil on the stem.

Not much can be done wrong when doing a compression test. One of the things is not to warm up the engine. On a cold engine I'd guess 130 PSI on each cylinder is good enough. You may want to ask the mechanic if he did the test on a cold or warm engine. If he has done it on a warm engine then ask him if the compression gauge is accurate (calibrated).

On an engine with valve stem seal leaks I would want accurate compression readings. A 27000 mile engine should not have leaky seals and low compression. I would want to know as much about the engine condition as I can before throwing lots of money at it. Not doing the work yourself can add up quickly, especially if you don't do the work yourself. IMO if you do it yourself, changing the seals is not a difficult thing. Can check the stem guides, cam journals, valve clearance at the same time. I don't know (and don't want to know - heart attack) how much it would cost to have this done. Here they charge 110-140 € / hour.

I am a bit paranoid regarding undetected vacuum leaks (guess why). It is an easy test. Usually carb cleaner is used for that. I have used that as well as cigarette lighter gas. You spray it on the suspected areas and if there is a leak you will notice a rise in RPM. Mine was at one of the rubber intake pipes (specifically the o-ring embedded in the pipe) that are connected directly to the head. Other possible places are the rubber tubes connected to the throttle body. Unlikely that you have a vacuum leak but it is good to check for it every once in a while.

[T 24]

I had very sooty exhaust ports in my K2, and I think it came from injection control from stone age.
Now with turbo, extra ECU and water methanol injection the situation is much better. The engine is still "stock", 143 000 km riden.
Exhaust ports are now cleaner (sorry about bad quality of phone pic) and you can see same "shiny" result
on piston tops.

[vonny232]

IMO if you do it yourself, changing the seals is not a difficult thing. Can check the stem guides, cam journals, valve clearance at the same time. I don't know (and don't want to know - heart attack) how much it would cost to have this done. Here they charge 110-140 € / hour.

Can you change the seals without removing the head?

I know its possible with some bikes (provided the valve doesent fall into the cylinder).

Would I need to buy a new valve cover gasket or could I reuse the existing one?

I will try disconnecting the oil pump and running the splatter test again. If im lucky I will see/feel evidence of oil around the two inner stems once they are extended.

[Andre]

Oil pump is a typo I guess

Usually the valve cover gasket can be reused. You'll need to clean off the Three Bond though (and apply new Three Bond or alternative).

When removing valve cover be extra careful so the PAIR "pins" don't fall into the engine.

You have to remove the head to change the stem seals as valve assembly has to be disassembled for this.

[vonny232]

Cheers for the reply.

Not sure I am confident enough to lift the head, but first things first ill try dry running the bike to find any evidence of oil spots or leaks around the valve stems and take it from there...

[grog]

Mate, one way to check stem seals leaking, mate following, a big downhill run, throttle closed, gives high vacuum, open it up & your mate should have visible smoke. Very low mileage motor to be using oil. Id be checking all your vacuum hoses, not kinked or one on wrong connecter.

[T 24]

Mate, one way to check stem seals leaking, mate following, a big downhill run, throttle closed, gives high vacuum, open it up & your mate should have visible smoke. Very low mileage motor to be using oil. Id be checking all your vacuum hoses, not kinked or one on wrong connecter.

It will give visible smoke if INTAKE valve stem seals are leaking, but it won't tell you anything about exhaust stem seals.

[grog]

T24, good point, ill agree with you. I find this subject interesting but working out the answer is difficult. I just cant see how a 14 motor can need seals or rings with low ks. Hard to overheat, hard to flog to death, 2 reasons that could shorten its life. Can the pairs set up leak oil into motor? It also only goes to exhaust side? What about making up a temporary crankcase breather, oil filler, just to see if it stops oil use? Weve had similar story on this couple of years ago, dont think i saw a result.