Weird misfire.... cured.

I thought I would throw this one out there as a potential cure for an intermittent misfire. I have been getting a misfire on my Commando for the last few weeks. It only happened after the bike was warmed up, and it was revving between 3500 and 4000 at cruising speed. The bike would "chuff" three or four times and it wouldn't happen again for another 5 km or so. Irritating but not a game stopper. Since it only happened when it was warm I thought coils... nope. I fixed the Boyer timing leads last year, not them. Even though a plug chop showed a good burn I fiddled around with needle height , not that either. Checked wiring, plug leads, plugs, no dice. While tickling the left carb yesterday I noticed the float bowl gasket got wet before any gas came out the tickler. I had tightened the float bowl screws... all but the one I couldn't really get at because of the fuel line. Loose float bowl screw. The right combination of vacuum, vibration, temperature and an air leak must have leaned out the mixture occasionally. Mick

I for one appreciate your devoted desperation thorough check list turmoil, especially what done on road side.

Alas this has happened to me so much last couple years I finally tried RTV on the screws and so far so goodie. I got in habit of trying to wiggle the bowl bottoms when tickled and lately tend to do twice as can't hardly believe they stayed sealed some weeks now. Once the screw threads get so they let go on warm use its useless to try to just tighten them and expect to last a long ride. My once new Amals took about 13,000 miles on two Combat before the screws became annoying issue to discover along ways away. If you try loctie expect to bugger the screw slots approached at odd angles trying to remove w/o heat first. Lost two screws with bad running intervals on my learning curves, but surprising how well they run on good throttle with bowl hanging loose on one half backed out screw and gasket sticking out.

I like these post's, Problems with corrective measures...another one logged in the old brain box.

Yes sir, I had put RTV out of my mind to use anywhere on bikes but maybe seat tears or water proof a twisted electrical connection, but someone on list mentioned it instead of loctite last season and has finally worked the trick I'd been missing out on. I'd though of paint on the screw threads but figured the gas would remove it too soon on the fly.

Hi Moorejm
Yes that happened to me just two weeks ago when I changed out my Amals after I got the slides redone from Bruce Chessell. I put in the new stay up floats and went riding. Parked it over night and was going to go for a snort again only to find when I tickled her the fuel continued dripping. On closer inspection I found that one screw was gone and the other loose. I replaced the screw and lock washer and all was well again. I found the lock washer for the bottom screw on the garage floor later on. That is an important item to miss for that screw that is somewhere down the road. :? I love the new stay up floats by the way and Bruce did another nice job. 8)
Cheers
CNN

I always fit allen screws on my carb float bowls and top caps, that way they are easy to tighten with a ball-end allen key where access is tight.