One cylinder possibly ran lean. Damaged engine?

[Speakas]

So in the middle of testing out my charging system which was not working after wiring my bike up, at some point whilst I was playing with the throttle cable it seemed the right cylinder slide was stuck open.

I had the bike running a few times no more than 1-2 minutes each whilst i was trying to work out the electrical gremlin

Now having issues kick starting the bike back up. It kind of feels like I'm low on compression. I Can hear the left cylinder puff but right one seemed like nothing was going on... Am I up for a rebuild?

 

[Signal]

I doubt it. Try testing the basic stuff, spark , fuel , compresion. I would start with spark as you were working on the electrical system.

 

[Speakas]

I

I doubt it. Try testing the basic stuff, spark , fuel , compresion. I would start with spark as you were working on the electrical system.

Ive tested spark with the plugs out sitting on the engine and had it. Not sure how to test fuel since it's gravity fed. I'll do a leak down test soon, don't think I can kick hard enough for a meaningful reading on a compression tester.

Also tried spraying the easy starter fluid

 

[gggGary]

Kick compression testing works fine. And I'm not a heavy weight.
Years back I did some AB tests and found I could coax higher numbers with (say 8-10 strokes of) the lever than the E start would give.
I think this has to do with being able to arrange the kick start so highest effort is applied as the compression event occurs. The motor is constant current and slows through the compression stroke. I have a much harder time kicking though a high compression 750 like Madness or a Norton....
I'm in the won't damage an engine with a couple minutes of lean camp. Tea leaves experience says it takes an hour or more of high speed lean to hole a piston. Getting some loose carbon on a valve seat causing compression loss IS a thing that happens.

 

[Speakas]

I

Kick compression testing works fine. And I'm not a heavy weight.
Years back I did some AB tests and found I could coax higher numbers with (say 8-10 strokes of) the lever than the E start would give.
I think this has to do with being able to arrange the kick start so highest effort is applied as the compression event occurs. The motor is constant current and slows through the compression stroke. I have a much harder time kicking though a high compression 750 like Madness or a Norton....
I'm in the won't damage an engine with a couple minutes of lean camp. Tea leaves experience says it takes an hour or more of high speed lean to hole a piston. Getting some loose carbon on a valve seat causing compression loss IS a thing that happens.

Did a compression test.. the supposed lean cylinder came back at 110-115 psi whilst the other is at 90psi.. not sure what the standard numbers are but is this enough for a non start? Supposedly the PO rebuilt the motor less than 5k km ago. I'll try give the valves a spray with throttle body cleaner?

 

[Speakas]

Might add I left the slides closed as is when I did the compression test

 

[gggGary]

Throttles held open, the slides have a big enough bottom gap that they don't matter for compression testing.
that's low, but should be enough for it to run (and usually improve)
Ideal would be 140-150

 

[Speakas]

Yeh it's quite strange.. I'm hoping cleaning up the valves will do the trick. It did sit for 2 years before I got it started the few times for short periods.

I was hoping I'd get my build done by end of the year but it's looking like I might need to add a few more months to it

 

[Speakas]

After further testing

Compression test
Dry
Left 100-110 (was 90 night before)
Right (90-100)

Wet with about 5ml of ATF
Left 120-125psi
Right 110-115psi

Leak down test which I kind of rushed, as far as I could tell loss is around 40-60%
I want to say most of it through the rings but probably some through the intake valves as well?

Looks like I'm up for a tear down? Question is what am I expecting that needs to be done to head and cylinder?
Head - clean up the valves and lap the seats?
Cylinder - best case just the rings and hone, worse case next size up


I tried starting her up and got a lot of smoke presumably coming from the atf burning, sounded like it was about to start before she gave up. I want to say this definitely rules out fuel and spark.

 

[Raymond]

FWIW might be the e-start not doing its thing. I've had two engines in my XS - the first engine, the starter was slow and there was a horrible mechanical noise, so it was like kerrchunga-kerrchunga-kerrchunga-BRmmm. So I gave up using the starter and just kicked. Works fine, first or second kick from cold. The newer engine, the e-start is even worse. I've only tried it once or twice but I doubt it would start the engine. Made a mental to take a look and see what it needs, probably worn brushes, but it's never become a priority. Good luck!

 

[Speakas]

FWIW might be the e-start not doing its thing. I've had two engines in my XS - the first engine, the starter was slow and there was a horrible mechanical noise, so it was like kerrchunga-kerrchunga-kerrchunga-BRmmm. So I gave up using the starter and just kicked. Works fine, first or second kick from cold. The newer engine, the e-start is even worse. I've only tried it once or twice but I doubt it would start the engine. Made a mental to take a look and see what it needs, probably worn brushes, but it's never become a priority. Good luck!

I'd love to say it's the e start if that was even working in the first place! Pretty sure the retainer clip on it went or something because it doesn't engage with the crank last time I tried a few years ago before taking the bike apart

 

[xjwmx]

Make sure your battery is charged when you try to start it, better yet have the charger attached to it. I'd also try brand new plugs. If you do lap the seats pay attention to the manual -- the ring where the valve should make contact is narrow. Wider means more opportunity for something to get stuck between. A motor that was supposedly overhauled so recently that's doing so poorly, no telling what you might find in there!

 

[650Skull]

Thing i'm looking at is both sides are close together, compression wise and moving at about the same rate That isn't common. Usually one side is way down. I would do some more diagnotics before commiting to tearing down the engine...............I your compression tester the type that crews into the park plug hole??

 

[Speakas]

Make sure your battery is charged when you try to start it, better yet have the charger attached to it. I'd also try brand new plugs. If you do lap the seats pay attention to the manual -- the ring where the valve should make contact is narrow. Wider means more opportunity for something to get stuck between. A motor that was supposedly overhauled so recently that's doing so poorly, no telling what you might find in there!

battery voltage was good and i was monitoring it on the m unit, freshly charged too but ill try putting it on the charger. it is the pamco e ignition though so i didnt think battery would have been a heavy factor. I had unplugged the wire to the regulator so no power to brushes.

ill probably send the head to a shop for a once over for a valve job. valve did look a bit shit from peaking at it from the spark plug hole (wait am i even suppoed to be able to see it from the plug hole?)

My compression tester and leak down screw into the plug hole yes.

 

[Speakas]

Thing i'm looking at is both sides are close together, compression wise and moving at about the same rate That isn't common. Usually one side is way down. I would do some more diagnotics before commiting to tearing down the engine...............I your compression tester the type that crews into the park plug hole??

are you in any of the Australian xs650 groups on facebook?

 

[650Skull]

Sorry no. Used to be in the 650club till it went full on facebook.