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Author Topic: Backfire and odd point sparking.  (Read 2450 times)

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Offline mpgholston

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Backfire and odd point sparking.
« on: July 05, 2016, 12:04:43 PM »
'74 550, all stock

I've been dealing with a running issue for quite some time. I've checked almost everything I can think with the ignition from battery to plugs and down to points. also cleaned the carbs four times now including a soaking in lemon juice. 

Running condition- starts easily with choke on.  engine will idle fine once warm, but once I start revving (in Neutral) backfiring begins right after rev peak. Definitely out the pipes. If I increase rpm to 2000rpm and hold, engine runs under powered with short surges as if one or more cylinders is working partially. I have determined by pulling plug wires that cyl 1 is backfiring and also most likely 3 or 4.

Last night I noticed the 1&4 point was badly pitted. I filed both sides but one has a pretty significant indent right in the center.  No changes to the running condition after I put it back on and set the gap.  I was looking at it real close and noticed that on occasion, the point would spark but not really arc.  It looked more like a little explosion with tiny sparks going in many directions.   

Any Ideas? Thanks in advance if you do!
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All Stock and All Spec 1974 CB550.
In my book, you either screw a guy out of tires OR upload pictures of yourself playing with your crank on the web.  Performing both will render absolutely horrible results. #brimmer.

Offline b52bombardier1

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Re: Backfire and odd point sparking.
« Reply #1 on: July 05, 2016, 12:13:44 PM »
Arcing and sparking at the points is often a sign of a dying condenser.  How old are yours?

Rick
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Offline mpgholston

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Re: Backfire and odd point sparking.
« Reply #2 on: July 05, 2016, 12:16:56 PM »
Age not known but my guess is o.g.  I though the points would function fine with bad condensers.  Am I wrong?
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All Stock and All Spec 1974 CB550.
In my book, you either screw a guy out of tires OR upload pictures of yourself playing with your crank on the web.  Performing both will render absolutely horrible results. #brimmer.

Offline flybox1

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Re: Backfire and odd point sparking.
« Reply #3 on: July 05, 2016, 12:42:32 PM »
what brand points/condensers do you have?
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'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

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Offline mpgholston

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Re: Backfire and odd point sparking.
« Reply #4 on: July 05, 2016, 12:56:52 PM »
Original
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All Stock and All Spec 1974 CB550.
In my book, you either screw a guy out of tires OR upload pictures of yourself playing with your crank on the web.  Performing both will render absolutely horrible results. #brimmer.

Offline Deltarider

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Re: Backfire and odd point sparking.
« Reply #5 on: July 05, 2016, 12:59:44 PM »
I'd say typical for a bad condensor. Anyway two easy checks anyone can do.
Condensors. When idling look for possible arcing. Some tiny sparks are OK.
For clarification see this video. In this video left condensor (1+4) is bad and causes arcing which means little or no spark at plugs 1+4. Right condensor (2+3) shows only very little sparks and is good. When in doubt, replace. Condensors are cheap. When you fit one, pay attention to the following.
Whilst you're there have a close look at the breakerpoints. Check carefully none of the connectors at the breakerpoints is too close to the plate and so can make ground intermittently when engine vibrates. Failure of a breakerpoint or condensor would affect two cilinders, 1+4 or 2+3.
« Last Edit: July 05, 2016, 01:18:30 PM by Deltarider »
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Offline flybox1

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Re: Backfire and odd point sparking.
« Reply #6 on: July 05, 2016, 01:01:29 PM »
Quote from: mpgholston on July 05, 2016, 12:56:52 PM
Original
Original is not a brand.  TEC or ND?
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'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

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1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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"Knowledge without mileage equals bullsh!t" - Henry Rollins

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Offline mpgholston

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Re: Backfire and odd point sparking.
« Reply #7 on: July 05, 2016, 01:14:49 PM »
TEC
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All Stock and All Spec 1974 CB550.
In my book, you either screw a guy out of tires OR upload pictures of yourself playing with your crank on the web.  Performing both will render absolutely horrible results. #brimmer.

Offline BomberMann650

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Re: Backfire and odd point sparking.
« Reply #8 on: July 05, 2016, 01:29:14 PM »
Quote from: mpgholston on July 05, 2016, 12:16:56 PM
Age not known but my guess is o.g.  I though the points would function fine with bad condensers.  Am I wrong?

Yeah, that would be a wrong assumption.

A functioning and oem quality condenser is critical to points making the coils do their thing.

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Offline mpgholston

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Re: Backfire and odd point sparking.
« Reply #9 on: July 05, 2016, 03:11:00 PM »
What would be the symptoms?  would a bad condenser lead to back firing and other running issues I've outlined.  Please expand.
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All Stock and All Spec 1974 CB550.
In my book, you either screw a guy out of tires OR upload pictures of yourself playing with your crank on the web.  Performing both will render absolutely horrible results. #brimmer.

Offline BomberMann650

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Re: Backfire and odd point sparking.
« Reply #10 on: July 05, 2016, 03:18:29 PM »
Quote from: mpgholston on July 05, 2016, 03:11:00 PM
What would be the symptoms?  would a bad condenser lead to back firing and other running issues I've outlined.  Please expand.

Absol-fcuking-utley

When I had a daiichi condenser go out it took a couple miles before it was officially kaput. 
Started as an intermettent issue of random sputters, ran good for a moment, then at the absolute end of its usable life, I had to hi tail it home at 7k rpm to achieve a record speed of 45mph.
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Offline mpgholston

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Re: Backfire and odd point sparking.
« Reply #11 on: July 05, 2016, 05:12:38 PM »
Much-a-fcuking-obliged!

I read in a couple of places that condensers merely keep the points from pitting and/or shorting.  Glad to hear i was wrong.I might have to clear my mind (get blacked out drunk tonight) and start reading up on ignition tomorrow.
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All Stock and All Spec 1974 CB550.
In my book, you either screw a guy out of tires OR upload pictures of yourself playing with your crank on the web.  Performing both will render absolutely horrible results. #brimmer.

Offline mpgholston

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Re: Backfire and odd point sparking.
« Reply #12 on: July 05, 2016, 05:26:38 PM »
So are daiichi condensors a good or bad idea?  whats the best low cost route?
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All Stock and All Spec 1974 CB550.
In my book, you either screw a guy out of tires OR upload pictures of yourself playing with your crank on the web.  Performing both will render absolutely horrible results. #brimmer.

Offline BomberMann650

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Re: Backfire and odd point sparking.
« Reply #13 on: July 05, 2016, 05:35:20 PM »
Quote from: mpgholston on July 05, 2016, 05:26:38 PM
So are daiichi condensors a good or bad idea?  whats the best low cost route?

They are failure prone, like 50-500miles failure prone.  Oem condensers will outlive them sevenfold.

Fyi, sudco tune up kits contain daichi parts.  The extra $3 got me a cool sticker tho
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Offline Deltarider

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Re: Backfire and odd point sparking.
« Reply #14 on: July 05, 2016, 11:44:26 PM »
Quote
So are daiichi condensors a good or bad idea?
Some have problems with them, some don't. Overhere most dealers trade them. Wouldn't be a bit surprised if there was Daiichi made in Japan and imitation Daiichi made elsewhere. TEC is top quality. I could easily do 20.000 kms+ without having to adjust and they live much longer than that.
« Last Edit: July 05, 2016, 11:47:11 PM by Deltarider »
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Offline RAFster122s

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Re: Backfire and odd point sparking.
« Reply #15 on: July 06, 2016, 01:10:12 AM »
Gotta watch even a few unscrupulous dealer (HONDA) were passing along Daichi parts when paying for good points expecting TEC or ND.  A good set of points will cost you around $50 or so.  Some sellers can even score one of the original full plates with points and condensors made by TEC or ND.  Don't know the going rate these days.  Just buy a good quality condensor and TEC points, they are out there and you can find them.  South Sound Honda in Seattle area is a good discount Honda MC dealer, inexpensive shipping and great prices...

David
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Offline BomberMann650

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Re: Backfire and odd point sparking.
« Reply #16 on: July 06, 2016, 03:11:59 PM »
+1 to the crew at south sound honda.

www.hondabikes.com

Discounted pricing on self serve oem parts.  The $9 shipping charge pays for local labor too!
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