Compression Test Failure

[Mike A]

My 2019 Tracer GT ran perfectly, parked it, week later it turned over but would not start. Checked battery, fuses, etc. Still no go. Took it to the dealer who eventually did a compression test.  One cylinder showed leaking thru intake valve, the other two had leaking thru exhaust.  I'm baffled.  Bike has 36K miles, serviced by dealer including valve check at 26K ( I do oil changes).  Faulty fuel pump replaced by dealer under warranty last year.  No other problems, always ran perfectly.  Dealer is tearing into it next week to look for valve damage at my cost.  When issue is found, they submit it to Yamaha for warranty repairs (I took out 5 year extended warranty).  Yamaha approves, they pay everything, they don't approve  I'm stuck.  How can the bike run perfectly one day and have major valve damage the next?  I've never noticed any Tracers having valve issues! Any ideas? Thanks

[ZigMerid]

Did the dealer make any adjustments at the 26K valve check?

 

Any possibility of overheating or oil-feed starvation?

It seems pretty bizarre that all three cylinders *suddenly* have compression loss. Unfortunately without a previous compression test, it's only speculation that compression has been lost very recently. It may have been slowly getting worse over time.

[GTO MIKE]

Wow ,my question how do they know what valves are leaking.  No way! No start can be a number of things . How about spark , fuel. Switches. .for it to just not start out of the blue. And maybe that replaced fuel pump give out? Lots to consider before  valves.      Mike

[skipperT]

1 hour ago, GTO MIKE said:

Wow ,my question how do they know what valves are leaking.  No way! No start can be a number of things . How about spark , fuel. Switches. .for it to just not start out of the blue. And maybe that replaced fuel pump give out? Lots to consider before  valves.      Mike

They would know if a leak-down test was performed along with the compression test:

when a compressed air source is fed into the combustion chamber of an engine at TDC compression, the piston is all the way up and both valves should be closed. 
By measuring the air loss, and determining where it is leaking from the engine, one can establish whether the air is coming past the piston and rings, cylinder, intake valves or exhaust valves on the cylinder being tested. 

these results are why a leak-down test is ALWAYS more valuable information than a compression test when performed correctly. Compression tests also have their merit, esp on a 2-stroke. Less so on 4 stroke engines. 
HTH,

-Skip

[RaYzerman]

Let's hope for a better diagnosis....... meanwhile, it will be very interesting what the actual cause is.  I'm following this with great interest and want to know if the valves are bent, burned or carboned up..... each will have its own cause.  Odd that exhausts are leaking along with an intake.... makes me think clearances are too small.  HOwever, the real story is yet to come.

Edited October 16, 2023 by RaYzerman

[Mike A]

Thanks for the input.  Sorry, yes a leak-down test was done.  They told me numbers that I did not write down, but will get from them this week.  That's how they determined what valves did what.  I recall the numbers were less than 50% of the excepted compression on the leaking valves.  Old age has moved in on me, so maybe the bike has been running poorly and I did not realize it.  Hope to find out this week.

[Lone Wolf]

17 hours ago, Mike A said:

 How can the bike run perfectly one day and have major valve damage the next?

Sometimes a burnt valve will lose a "chunk" resulting in sudden loss of compression. 

But it is odd that it ran OK when parked, then later it wouldn't start.

[etex]

I might ask the dealer, who adjusted the valves, how a valve could have burned with a correct valve adjustment?

[GTO MIKE]

I'm only questioning why the valves all of a sudden are leaking when they had supposed to have done the last valve adjust. Seems odd . Will for sure follow this post to see the outcome.  Mike

[GTO MIKE]

12 hours ago, skipperT said:

They would know if a leak-down test was performed along with the compression test:

when a compressed air source is fed into the combustion chamber of an engine at TDC compression, the piston is all the way up and both valves should be closed. 
By measuring the air loss, and determining where it is leaking from the engine, one can establish whether the air is coming past the piston and rings, cylinder, intake valves or exhaust valves on the cylinder being tested. 

these results are why a leak-down test is ALWAYS more valuable information than a compression test when performed correctly. Compression tests also have their merit, esp on a 2-stroke. Less so on 4 stroke engines. 
HTH,

-Skip

Oh I know how it works . I'm  just questioning this dealer's results,!  Mike

[duckie]

Just thinking out loud here…. It’s important to get the numbers of the measured valve lash gap on each valve. 
 

If adjustments was performed, it’s important to know which valves were adjusted and the shim sizes used.
 

It just might be those valves that are leaking were within spec when checked but in spec toward the tight side and finally went too tight causeing the valves to be open at TDC.

Or the valves sunk into the head which would also allow the valve to be open at TDC.

[larolco]

Or the new kid did the valve adjustments... That's a real possibility. 

I once had a valve burn on an old XS650 and had to ride it a couple hundred miles back home on one cylinder. Kinda struggled on the highway. There was a pretty significant chunk out of that valve once I got it apart and had a look. All was good until it let go on a hill climb. 

[Mike A]

Got the answer...sort of.  Dealer called me yesterday to come and look at my Tracer.  Walked in to see the Tracer engine on the bench, head off to the side, etc. (actually looked pretty small).  Cylinders were in good shape, but excess carbon build up on top surface.  Couple of valves were pulled and cleaned showing the difference between the major carbon buildup on others.  Definitely pretty bad.  Enough carbon that some valves were not seating causing the compression leaks.  Dealer thought bad gas was the answer.  I actually go to some effort to use non-ethanol premium gas and unfortunately usually the same small station.  So I guess that could be the cause.  Dealer said to use additives in all gas to keep carbon away.  He recommended BG 44K or Star Tron, which I used years ago. Since the aging process has caught up with me, I can't help think that I don't scream this bike like I did previous ones.  Did that contribute?  Dealer said they would try to get Yamaha to contribute under warranty.  I'll update the outcome next week.

[etex]

Take a look at this thread RPM's and carbon buildup.  Do you usually ride at rather sedate RPM's?

[Mike A]

Definitely feel my riding manners have changed since I got the Tracer.  On a typical 200 mile ride I probably take it to 9K a couple times.  Previous bikes, Triumph 1200 Explorer, Concours 14, I would take to red line multiple times on a ride.  I had a serious crash 5+ years ago on the Triumph and am certainly older, and my fast friends no longer ride. All leads to me slowing down.  Seems I need to crank up the revs more.