Compression Test on Monster 1100?

[Howellerman]

Thought I would reach out to the members who may know!

Pre-FI, I would check compression by removing the plugs and turning over the engine with the starter. The cylinder(s) that was not being tested just chuffed empty air and no fuel was sucked into the cylinder. Since FI pushes fuel, I expect some issues with fuel vapor shooting out the spark plug hole when I turn it over. But, since I gave up cigars it should not be a problem, eh?

I expect the EMU will go berserk, but since I already have a "wrench code" I am not too worried about it. As long the Orange light goes off when everything is buttoned up I should be fine, no?

Why do I want to do compression test? Because lately only 1 cylinder fires on startup until things get moving, say about 3-5 seconds. I just checked the valves for the 7500 mile (actually, closer to 8,000) checkup and they were all within limits, although the take-up clearance on the #1 cylinder exhaust valve was essentially zero (shim would turn, but barely). But, since the service limits on take-up clearances are zero I should be good. Besides, a tight take-up clearance would try to pull the valve tighter and not create a compression leak.

Any other thoughts on 1 cylinder mis-firing at start-up? Power is unchanged, strong as usual, once things are warmed-up, but I think my mind is playing tricks with me as it seems to run a wee bit rougher.

Thanks for the help!

[Curmudgeon]

Never crank a bike with electronic ignition without grounding the plugs or you will fry the ignition.

If you have an M1100 with Siemens ECU, take it to the dealer and let him hook it up to the Ducati computer for that cold start. He can see what is happening to cause one cylinder to fail to fire. A compression test won't tell you much about that!

Your EFi is a whole lot more complex than a carb bike with points.  It's even possible, though unlikely, that half of your ECU is faulty. This is not a DYI diagnosis IMO.

[Armor]

The take-up clearance - you're referring to the closer clearance?  The closer clearance always increases (as the valve seat wears) and the openers always decrease.

[Howellerman]

Never crank a bike with electronic ignition without grounding the plugs or you will fry the ignition.

If you have an M1100 with Siemens ECU, take it to the dealer and let him hook it up to the Ducati computer for that cold start. He can see what is happening to cause one cylinder to fail to fire. A compression test won't tell you much about that!

Your EFi is a whole lot more complex than a carb bike with points.  It's even possible, though unlikely, that half of your ECU is faulty. This is not a DYI diagnosis IMO.

Thanks for the red-flag, Curmudgeon. While I have cranked over EI Kawasakis without ill effect, they did not have the ECU that the Ducks do.

Oddly enough after sitting two weeks (I have been restoring a 67 Comet, and the bike was buried in car parts) it roared to life on the first stab this morning and ran great. Almost took the long way into work it felt so good. But, you are right: I was thinking old-school, and with the ECU tracking everything it should log "something".

Thanks for the response!

[Howellerman]

The take-up clearance - you're referring to the closer clearance?  The closer clearance always increases (as the valve seat wears) and the openers always decrease.

Thanks Armor. What you say makes total sense, and must be why zero clearance is okay on the closing rocker.

Thanks for the response!