Phil,
I would agree with the replies that say you have it tuned, but, it you want
to experiment a little more, here is what the SU says:
The effect of mixture strength on exhaust:
TOO WEAK: Irregular note, splashy misfire & colourless
CORRECT: regular even note
TOO RICH: regular or rhythmical misfire, blackish
I would suggest that you check the mixture by performing the test in the
shop manual that involves carefully pushing up the "lifting Pin" on the carb.
The manual describes the process. I assume you have already syncronized the
carbs.
You could also try leaning the carbs, then try richening them, to see if
there is any change. Keep detailed notes so you can return it to the original
setting.
Finally, How did you set the 15 degrees timing? was it static, or at idle
(what RPM)? Was the vacuum advance line connected to the distributor? If you
know someone with a "dial back to zero timing light" (or you have one) it might
be of interest to know what the timing is at Max. advance. Disconnect the
vacuum advance line, warm up the engine & run it up to approx. 3000-3500 RPM.
With the timing light, check the advance by dialing the timing mark back to
zero & reading the degrees of advance on the timing light.
Or you could leave well enough along!
Gary Hodson
In a message dated 8/3/2008 4:32:48 P.M. Central Daylight Time,
PhilRitten@aol.com writes:
All,
I am still getting a "puffing" noise from my BN4/6 after I have driven it a
little. After warming it up, I take it up on the freeway a mile or two,
turn
around and bring it home. After that, every fourth or fifth sound out of
the
tail pipe is a "puffing" sound. Interestingly, the idle is still smooth (no
obvious missing). The only way you can tell there is a problem is listening
to
the tail pipe. BTW - when idling and warming up in the garage there is a
steady staccato sound from the tail pipe.
I'm rather puzzled. I replaced the plugs/cap/rotor/wires and set the timing
around 15 BTDC. I looked under the hood at night (in the dark) to see if
there was any shorting and didn't see anything. There doesn't seem to be the
same
problem with the rotor rubbing on the cap that I had before. By the way, I
have electronic ignition.
I'm wondering if it could be something like a bad coil or something that
fails once it has warmed up.
Thank you all,
Phil
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