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Author Topic: cb550 coils???????  (Read 1310 times)

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Offline blakes1975

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cb550 coils???????
« on: July 30, 2013, 09:58:38 PM »
can i use cb750 coils on my cb550???? 
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Online bryanj

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Re: cb550 coils???????
« Reply #1 on: July 30, 2013, 10:35:52 PM »
They will fit and run but not perfect, you can however use 500 four ones as they are identical
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Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

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Offline blakes1975

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Re: cb550 coils???????
« Reply #2 on: July 30, 2013, 10:40:29 PM »
when you say not perfect care to explain????.
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Offline goldarrow

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Re: cb550 coils???????
« Reply #3 on: July 30, 2013, 11:16:10 PM »
Different resistance.  Long story.  Do search and you'll find lots of info on this.  Go with 500/550 coils to reduce headache.  I might have one I can let go.  If interested, Pm me and i'll double check.
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Life Is Full Of Challenges - And My Backyard Is Full Of SOHC4's

CB550 K0
CB750 K0, K2, K23 JDM, K45, K5
And the little ones z50r, xr50r, st90


750k5 http://forums.sohc4.net/index.php?topic=114817.0

Offline dave500

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Re: cb550 coils???????
« Reply #4 on: July 30, 2013, 11:16:45 PM »
if you think the coil is at fault from your other post its not!these fire a waste spark,,the coil for your dead cylinder #1 fires #4 at the same time,2 and 3 also fire together,,if the coil is dud a pair will not fire.
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Offline Bankerdanny

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Re: cb550 coils???????
« Reply #5 on: July 31, 2013, 08:08:30 AM »
Dave, not necessarily. The coils do fire in pairs, but it is possible for one of the two wires to have a faulty connection at the coil, so one plug fires while the other doesn't.

However in this case since he says he has spark at 1 and 4 you are correct, there doesn't seem to be a coil issue.
« Last Edit: July 31, 2013, 08:11:27 AM by Bankerdanny »
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline blakes1975

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Re: cb550 coils???????
« Reply #6 on: July 31, 2013, 09:09:37 AM »
do the spark plug boots go bad....?
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Offline TwoTired

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Re: cb550 coils???????
« Reply #7 on: July 31, 2013, 09:12:51 AM »
Quote from: Bankerdanny on July 31, 2013, 08:08:30 AM
Dave, not necessarily. The coils do fire in pairs, but it is possible for one of the two wires to have a faulty connection at the coil, so one plug fires while the other doesn't.

Technicality:
If a connection is broken, both plugs with not fire because current can no longer circulate in the coil's secondary loop.  If one plug is shorted, or one lead shorted to frame, then only one plug of the pair will spark.


Putting 750 coils on a 550 will not make it run or have the power of a 750.  But, you will be more likely to have battery recharging issues, which itself can be impacted by many other factors.

Quote from: blakes1975 on July 31, 2013, 09:09:37 AM
do the spark plug boots go bad....?

They can, as anything that man makes can fail.  The 550 plug caps should have 10K ohm resistance through them (+/- 10%).   However, 5K ohm will work, too.  The caps unscrew from the wires, if that helps.

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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

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Offline blakes1975

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Re: cb550 coils???????
« Reply #8 on: July 31, 2013, 09:16:40 AM »
ok i will test the ohms and get back to you...

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