Triumphrat

HankQ

Seven hundred miles or so after my rebuild I've been experiencing trouble with my left side plug. It is carbon covered or over rich. I have balanced the carbs. The slides open and close evenly, with both sides running beautifully at tickover. When I start out for a ride the bike runs good until I hit about 4000 rpms, then kinda does a syncopated hesitation and then evens back out abound 6000 rpms with only an occasional hesitation blip if any. If the rpms drop back down the problem picks up again. Checking the plugs reveals an over rich left side. The following things have already been checked:

1) Timing. The timing is spot on with a light.

2) Valve clearances. Rechecked while cold as a matter of course. (I've seen off clearances foul a plug.)

3) Plug itself and all associated electrical.

4) As mentioned above the carbs were balanced and tuned, with both sides running well at tickover.

5) Compression is good.

I am now going to probe deeper into the left side carb. Anyone seen this problem? Suggestions? Thanks, Hank.

GulfCoastDave

Hi Hank,
I recently overcame a problem that had similar symptoms (sooty plug & hesitation). In the end, it was a combnation of a bad float needle and a leaking choke plunger. Granted, your Amals & mine are different but it sounds like intermittant richness of some kind.
The first thing I did though, was to SWAP CARBS. When I did that, I moved the problem from one cylinder to the other and ruled out lots of other potential problems.
Good luck!
GCoastDave

oilyboot

A worn needle/needle jet assy, maybe? A wise man once said:

" If an Amal ain't new, its worn........"

HankQ

You may be on to sumpin' there oilyboot, especially since the problem evens out in the higher revs when the needle should be out of the picture altogether. It is almost as if the worn jet needle (or needle jet) is letting too much gas in before it is supposed to. Also, I forgot to mention, the one time I took the bike out and ran it at high revs for a while the plug looked like it was beginning to burn off and turn that nice toasty caramel color. So once again, needle jet. Anyway gotta' take the carb apart anyway. Hank

HankQ

Cha-ching!!!!!!! Took the carb apart and the jet holder had come unscrewed. This would account for the over richness in the 1/4-3/4 throttle range as gas ran around the jet holder and past the threads when the needle was still trying to control flow. Also accounts for the evening out in the 6000 plus rpm range when the main jet takes over. Good call oilyboot, I imagine a loose or worn needle would present the same symptoms. Hank

GrandPaulZ

I love happy endings...

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