Author Topic: Cb550 wont start  (Read 585 times)

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Offline Lochlea21

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Cb550 wont start
« on: December 02, 2015, 12:50:24 PM »
Hi guys a wee problem thats doing my nut in,Ive a 550 four that was running fine ,but now wont start .it seems to spark ok and the plugs are wet .its got electronic ignition amd strted first start of the button ,had a few backfires but thats all

Offline Gene

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Re: Cb550 wont start
« Reply #1 on: December 02, 2015, 12:54:37 PM »
You've checked for spark?  Make sure the plugs aren't fouled, and - not being a jerk - you have fuel?
*1973 CB750K3 (Bow)

Offline Lochlea21

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Re: Cb550 wont start
« Reply #2 on: December 02, 2015, 01:02:31 PM »
Yea just put fresh fuel in ,battery started to go flat but still wouldnt start from the kick,

Offline Gene

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Re: Cb550 wont start
« Reply #3 on: December 02, 2015, 01:14:08 PM »
If it had points I'd say it's maybe the points.  I'm not familiar w/the electronic ignition - from what little I can tell sounds like a timing issue.

Smarter people than me will be along - what year is the bike?
*1973 CB750K3 (Bow)

Offline goldarrow

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Re: Cb550 wont start
« Reply #4 on: December 02, 2015, 01:21:39 PM »
You mentioned the plugs are wet, I would start off with that.  Get new plugs
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Offline Lochlea21

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Re: Cb550 wont start
« Reply #5 on: December 02, 2015, 01:25:41 PM »
Do i need a fully charged battery to give a decent spark

Offline flybox1

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Re: Cb550 wont start
« Reply #6 on: December 02, 2015, 01:33:20 PM »
no, but one certainly does help.
'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 mrbreeze

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Re: Cb550 wont start
« Reply #7 on: December 02, 2015, 01:41:06 PM »
Sounds like you flooded it and fouled the plugs. Did you initially try to start it without the choke on? Clean or replace plugs and try again with choke on.
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Offline Lochlea21

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Re: Cb550 wont start
« Reply #8 on: December 02, 2015, 01:42:29 PM »
when I take a plug out ,stick it in cap and turn it over against the head the spark is weak ,but when i hold it against the exhaust seems to be better?

Offline Lochlea21

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Re: Cb550 wont start
« Reply #9 on: December 02, 2015, 01:43:02 PM »
Do they foul plugs easily

Offline Gene

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Re: Cb550 wont start
« Reply #10 on: December 02, 2015, 01:45:00 PM »
Do they foul plugs easily

Depends on the set-up and situation.  Generally, no.
*1973 CB750K3 (Bow)

Offline mrbreeze

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Re: Cb550 wont start
« Reply #11 on: December 02, 2015, 01:50:26 PM »
You say the spark looks weak. Try it with a new plug. If it still looks weak you have other problems (state of charge, points, etc.). Also.....if it still looks weak....swap over to a plug wire from the other coil and do your spark test. 1-4 are on one coil......2-3 on the other.
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Offline Lochlea21

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Re: Cb550 wont start
« Reply #12 on: December 02, 2015, 02:04:33 PM »
You sure that 1&4 is on one coils and 3&4 on the other cause ive seen wiring diagram where 1&2 r on one coil and 3&4 on the other ?

Offline Gene

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Re: Cb550 wont start
« Reply #13 on: December 02, 2015, 02:20:08 PM »
You sure that 1&4 is on one coils and 3&4 on the other cause ive seen wiring diagram where 1&2 r on one coil and 3&4 on the other ?

Mr. Breeze is correct.
*1973 CB750K3 (Bow)

Offline Lochlea21

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Re: Cb550 wont start
« Reply #14 on: December 02, 2015, 02:24:21 PM »
Could be the problem as i seem to to have 1&2 of one coil and 3&4 of the other ,dont know how that happened .So if your sitting on the bike what plugs do the left hand coils feed and what ones for the right ?

Offline Lochlea21

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Re: Cb550 wont start
« Reply #15 on: December 02, 2015, 02:25:08 PM »
I presume this will stop it starting lol

Offline flybox1

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Re: Cb550 wont start
« Reply #16 on: December 02, 2015, 02:36:52 PM »
the coil with the short wires feeds 2/3
the coil with the longer wires feeds 1/4
'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)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

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Offline Gene

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Re: Cb550 wont start
« Reply #17 on: December 02, 2015, 03:14:29 PM »
On my hopelessly stock 550 - Left is 2-3, Right is 1-4
*1973 CB750K3 (Bow)

Offline mrbreeze

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Re: Cb550 wont start
« Reply #18 on: December 02, 2015, 03:21:52 PM »
I think we may have found the problem. I don't think the 2-3 wires are long enough to reach the outer cylinders (1-4) though.. But then again....the bike isn't in front of me.
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Offline jonda500

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Re: Cb550 wont start
« Reply #19 on: December 03, 2015, 05:26:46 AM »
On all three of my 500/550's left is 2&3, right is 1&4.
John
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