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Author Topic: CB550 issues after warmup  (Read 1085 times)

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Offline 550Resto

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CB550 issues after warmup
« on: August 07, 2016, 08:55:30 AM »
Recently upped my mains to 100 from 90 due to an exhaust swap from stock. Before doing the jet swap I had an issue with the bike running like crappie after warming up. I would come to a stop and she didn't want to run and sounded like she was running on less then 4 cyl. So did the swap and she ran great for about 15 mins. Stopped for gas and then headed towards home and she sounded different. Quieter and at higher rpm in 5th she would stutter at maybe half throttle like a duh duh duh stutter then go away. My question is the only other thing that has not been changed are the wires and plug caps as well as coils. They're 40 plus years old. Would this be the issue?

Carbs have been rebuilt by harisuluv. Stock airbox. New petcock since old one was leaking. Delkevic 4 to 1 exhaust. Haven't done a clear tube test yet. IMS out 1.5 turns. TIA
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Offline calj737

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Re: CB550 issues after warmup
« Reply #1 on: August 07, 2016, 09:03:53 AM »
Not likely to be your coils, they seldom go bad. Plug caps, points and condensers are the most likely culprit. Especially condensers if the issue is after warming up.

The stock plug wires are hardwired to your coil. You can trim a 1/4" back, screw on new NGK resistor caps (measure yours for verification they're bad) and you're on your way. But, troubleshooting your ignition and points/condensers is the first place to start.
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"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline 550Resto

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Re: CB550 issues after warmup SOLVED
« Reply #2 on: August 11, 2016, 04:05:46 PM »
Well I bought coils, wires and new NGK caps. I just replaced the caps at the moment and took her for a nice long ride putting her through her paces. Stopped a couple times and shut the bike off and she started back up nicely and sounded good each time. I had to adjust the idle screw a little at a stop or 2,but she isn't idling high so that's good. Hopefully the caps were the issue!
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Offline calj737

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Re: CB550 issues after warmup
« Reply #3 on: August 11, 2016, 06:06:39 PM »
You can measure the resistance of the cap itself with a meter. They are very often a culprit of a poorly running bike. The coils, not so much. Most people replace them because they prefer the convenience of modern coils with detachable plug wires. But this is generally not necessitated due to a damage coil, just a "preference".
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"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline luvmy71

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Re: CB550 issues after warmup
« Reply #4 on: August 11, 2016, 07:44:24 PM »
We need to have member of the month in addition to bike of the month.  CAL I would nominate you straight away.  You are tremendously helpful and never get snarlyl  Thanks!

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Offline calj737

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Re: CB550 issues after warmup
« Reply #5 on: August 12, 2016, 05:16:34 AM »
Quote from: luvmy71 on August 11, 2016, 07:44:24 PM
You are tremendously helpful and never get snarlyl  Thanks!
Sure I do; you just haven't read those posts  :-[
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"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline flybox1

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Re: CB550 issues after warmup
« Reply #6 on: August 12, 2016, 06:40:59 AM »
Quote from: calj737 on August 12, 2016, 05:16:34 AM
Quote from: luvmy71 on August 11, 2016, 07:44:24 PM
You are tremendously helpful and never get snarlyl  Thanks!
Sure I do; you just haven't read those posts  :-[
;D
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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

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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