Interesting Carb/rich running problem finally solved

[bhaycock]

Hi all, I thought this might interest some of you. Earlier this year I purchased an '82 GL1100i which was not running at the time. It was a low mileage bike that had been a bit neglected but seemed solid otherwise. Got it home, stripped it down, did all the usual maintenance stuff (belts, fluids, fork seals, etc etc) and also did a clean and inspection on the carbs. Previous owner said it wouldn't idle and he was right.. You couldn't have driven a nail through any of the jets. So it came apart, everything cleaned, float levels checked, carb slides checked for burrs/rough bores etc. Assembled and bike ran reasonably well. A bit sluggish, misfired under heavy load, sooted up #2 plug really badly. So I'm thinking 'what did i do wrong'? I'm not a mechanic, but am reasonably competent, and know the early wings quite well. Couldn't find anything obvious, so started looking elsewhere (ignition etc) but everything seemed to point back to carbs (I was thinking maybe a sticky slide etc.).

Anyways I finally took it all apart again and double checked my previous work - that's when i noticed something I missed the first time - the needle on #2 slide was really tight - no movement at all - when I put my calipers on it, it was a mm shorter than the others. Long story short - I removed the needle from the slide assembly and found a homemade shim that was jammed under the needle. Somewhere in the past, someone had attempted (I'm assuming) to get more fuel through it by shimming up the needle - I have done this myself on other bikes after modifying the intake and exhaust. Here's the funny thing - it was only done on #2, all the others were stock. Checked everything again, reassembled, installed, sync'd, took it out for a burn and problem solved - no misfire under load - much better acceleration. Finally had the performance I remember from my '78. I'm not ragging on the previous owner(s) here - I'm sure I've done similar ill-advised things in the past as I was learning, but I just can't think of why you would shim up only one of the carbs.. Any ideas?

Bud

[low-side]

The only thing I can think of is that they misdiagnosed the cause of a lean condition on that cylinder. They might have done that when they should have adjusted the float height or something like that.

[Bugdaddy66]

Or maybe the carb got swapped in the past without the PO knowing it had been modified? Hard thing about bikes this age, too many possible "fixes" through the years!