Backfiring: rich, lean, or timing: circuitbreaker springclip

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Backfiring: rich, lean, or timing: circuitbreaker springclip

Postby King » Mon Aug 09, 2004 5:44 pm

Yesterday I took the Pan out for a rather extensive ride, about 80 miles through the Shenandoadh Valley here in VA. At highway speeds it ran well but on acceleration it backfired between gears and "went flat" at about 2500 rpm.
It has a Bendix with adjustable main jet so I figured it was too rich and gave it a half turn in (clockwise from the 2.5 turns out "book" setting). That reduced the problem but didnt totally cure it.
I checked the plugs and they were not the good brown I expected to see but a very light tan, actually they had almost no coating at all. I looked at them with the hand lens and spotted some tiny shiny balls attached to the porcelin and the ground. Scarry, I though they could be vaporized aluminum but they crumbled too easily for that.
So I'm a bit confounded here, the bike is acting rich but the plugs look a bit lean. Could it be timing?

Thanks
King
PS: i just conducted Cotten's manifold test and it was OK, no bubbles.
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Re: Backfiring: rich, lean, or timing

Postby Sidecar » Mon Aug 09, 2004 7:40 pm

tiny shiny balls attached to the porcelin and the ground.



Sorry for choppin' up your post, but I've never seen this condition before.
Would this be caused by to lean of a mixture or incorrect timing or both ??

BTW. I wish I was there to ride thru the "Valley" also. You can't ask for a nicer place to be !!!

Randy
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Re: Backfiring: rich, lean, or timing

Postby King » Mon Aug 09, 2004 9:09 pm

Hi Sidecar

You sure are right about the Valley. It is a real beauty this year with all the rain we are having, lush and green. I was on the west side riding parallel to the Alleghany Front, great riding country. You know you are on good roads when you have to dodge the horse hockey from Amish buggies.

I too am baffled by the deposits I got on the plugs. Maybe with our modern gas we get some additives that cause such as i haven't noticed them before. But I was looking at the porcelain with a 10X lens so the naked eye probably would not have picked them up. They look like very small glass beads. The only thing I have seen similiar was a photo of a "blistered" plug from over heating but Im sure that they did not get that hot.

King
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Re: Backfiring: rich, lean, or timing

Postby Billy » Tue Aug 10, 2004 6:36 am

King,
Just curious, are your heads re-done with-in a year or so. & were they media-blasted, like the intake/exhaust tracts ??
I have seen what sounds like this, & the bike was done by someone who media blasted the areas, I won't do for this very reason. There are so many different types of material, Aluminum shot, aluminum oxide, glass beads, silicon carbide, white sand & etc... All embed in the aluminum & are released slowly & in time as the aluminum gets to full heat & it's pores begin to open.
This is why I won't do
ANY
internals with
ANY
media.

The Bendix: at 2500 you are still running on some of the low speed mix. That adj. should be checked also.
I have had bikes that get "on the Hi-way" & wind them up a bit, & the adjustments from vibration change the settings on the carb. I would re-check them both.
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Re: Backfiring: rich, lean, or timing

Postby King » Tue Aug 10, 2004 6:02 pm

Billy

Thanks about the warning on blasting any thing that will be internal to a motor. I made the mistake of having a set of Panheads glass beaded and was never able to get rid of the media on the outside so I can just imagine what the story was on the inside!!

In the present case the heads are STDs with about 5000 miles on them so I don't think the mysterious balls are from media.

I am going to go through the points gap and timing drill. I'll also check the pushrods to be sure they are turning free. Then I'll try dialing in the Bendix. As you mentioned the low speed may be part of the equation. It sure is touchy, 1/8 of a turn either way will kill my idle. I believe the low speed adjustment is actually on an air bleed.

King
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Re: Backfiring: rich, lean, or timing

Postby Billy » Wed Aug 11, 2004 12:31 am

King,
Maybe what you are seeing @ 10X is gas additives as previously mentioned. ?? Maybe.. ??

Interesting about your 'touchy' low speed adjustment.
Wonder if you are leaking air at the carb adjustment/s ?
Just a thought.........
Sounds like you have a thorough course of checking it ALL.
Please let us know when you find what spoiled your ride that day.....

The beading leaves a nice looking finish. & Some builders do the entire cases & then Glyptol them.
I won't use blasting on any internals. I'd rather Parts wash them. & use some elbow grease on them.
They have these Ultra-sonic parts washers supposed to be great & $$$ Out of my league. I have a friend who put his cases in the Dishwasher when the lil' woman was out. They came out Nice.. I don't think I'll eat over there for a while, though... ;)
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Re: Backfiring: rich, lean, or timing

Postby Sidecar » Wed Aug 11, 2004 12:34 am

Billy,

You may not wanna eat at my place either !!!
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Re: Backfiring: rich, lean, or timing

Postby Billy » Thu Aug 12, 2004 12:32 am

Sidecar you wash motor cases in the dish washer too ??
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Re: Backfiring: rich, lean, or timing

Postby DuoDave » Thu Aug 12, 2004 8:24 am

My wife came home one evening and said " That smells good, what are you cooking for dinner?" She wasn't too thrilled when she opened the oven door and found my Norton cylinder head warming up nicely! >:(
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Re: Backfiring: rich, lean, or timing

Postby Sidecar » Thu Aug 12, 2004 1:01 pm

Billy.

I haven't washed any parts in the dishwasher for a while, so you'd be safe. :)
I have washed a lot of bike parts and car parts in it though........
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Re: Backfiring: rich, lean, or timing

Postby King » Thu Aug 12, 2004 1:39 pm

I got busted just like Dave only it was a set of cylinders getting their paint baked. And once she came home to find a bunch of old Enfield rifile parts boiling on the stove, again not too happy.

I think I might have isolated the virus with the Pan. I checked the points, timing, and pushrods and all was spot on. Then took it out warmed it up and ran it briskly through the gears. Same flattening out at about 3000 rpm and backfiring during shifts.

Then i noticed two things. When I would let go of the left grip to shift, it being a hand shifter, vibration would cause the spiral to rotate and retard the timing (like a fool I replaced the cable recently as it was binding and then greased the new one when i put it in, result no resistance at all now). The second one regards the see through fuel filter. It is installed vertically just below the carb inlet and when I pulled over to adjust the Bendix I noticed it was totally dry.

Apparerntly enough fuel was getting through to keep the motor running but perhaps starving it at higher revs.
That combined with the "self retarder" may explain the problem.

Tonight I will check the filter for clogs, replace it with some clear plastic, and figure out a way to tighten-up the timing, then run her again.

Will keep you posted

King
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Re: Backfiring: rich, lean, or timing

Postby Cotten » Thu Aug 12, 2004 2:26 pm

It only takes a minute to remove the springclip from beneath the circuitbreaker cap, tweak it for more pressure with pliers, and re-install.
That should add the resistance you need, and is easily 'tuneable' without affecting your timing.
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Re: Backfiring: rich, lean, or timing

Postby VintageTwin » Thu Aug 12, 2004 2:42 pm

Make sure the breaker base retainer (spring clip) is actually spring steel and not just AM junk metal. If you can bend it fairly easily with your fingers, it's no good.
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Re: Backfiring: rich, lean, or timing

Postby King » Thu Aug 12, 2004 5:19 pm

Cotten

Thanks I'll give it a try.

Plumber

I should be OK as the clip is original.

Thanks

King
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Re: Backfiring: rich, lean, or timing: circuitbreaker spring

Postby 58flh » Wed Jul 31, 2013 2:36 pm

I know this post is very old!---However I was just reading thru the K-Base & it said that turning the ADJ.-mainjet on a Bendix Clockwise is Richening the MIXTURE!.--Clockwise is Leaning it out!, Counterclockwise is Richening it!. To dial one in correctly ,get it to operating temp. & start turning it clockwise-(lean)-until the RPMs go up!. Continue to lean it until it runs erratically--NOW turn it counterclockwise-(richening)-until it runs real Smooth!--Set your Idle speed & give the Mainjet another half-turn counterclockwise-(rich)--This is where your happy spot is!--Ride the bike for 5-10,miles & shut-down ,pull the plugs & they will be a tanish--brown color!--(this is considered a PERFECT-BURN-or balanced burn)--I like to go more on the Rich-side!---Maybe another half-turn counterclockwise, I get a slightly black color that easily wipes clean with your finger!.& that's good for a cooler motor temperature,& wont make much difference in fuel-mileage!----RICHIE
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