Motorcycle Repair: 1986 1100 Shadow V twin, bench test, v twin

Question
I just have some technical question here.

I purchased an 1986 1100 shadow with 17,000 miles.

This bike had been sitting since 2000 so, I have went through the carb's thoughly soaking them in some good gum out professional cleaner for approx. one week and have them clean with all new jets, and even a new air cut off valve.

You have to let it warm up forever to get it to run right, but after that it idles great anywhere from 600 rpm's to 1000 rpms and runs very nice in midrange to high speeds, but when de-accelerating it just pops and cracks terribly.

Sounds like it is out of time to me.

I ran a compression test on it thinking that I have some leaking valves, and came up with around 130 psi per cylinder with really no deviation between the two of them.
My book calls out 157-213psi for the compression?

This bike ran fine when the owner parked it back in 2000.
Could the spark units go bad from sitting or any other electrical components that could cause this kind of problem?

This is the only thing I can come up with that could be causing this.

I would appreciate any help you could be with this matter.

Thank you,

Jeff Eggleston

Answer
Hi Jeff.
 There is the distinct possibility that you have a couple of things going on here.

The fact that the compression is lower than what the book says, indicates that you may need new rings or the cylinders need to be rehoned.  There is also the possibility that the valves may need work.  They may not be closing at the correct time or may be opening too soon, or the valve springs may need replacing.  Double check your valve gap and timing as well as wear of the springs.  If the springs are compressed beyond or at limits, then this might also solve your compression problem.

This could also be part of the warm-up problem that you are having.

Ignition units do not tend to go bad from just sitting, but the manual should have some kind of bench test proceedure to determine if they are failing or have failed.  The fact that the bike fires up at all indicates, however, that this is unlikely.

Try all of that and let me know how it goes.
Good luck.
FALCON