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Author Topic: Running on one cylinder intermittently (CB450)  (Read 741 times)

Offline advCo

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Re: Running on one cylinder intermittently (CB450)
« Reply #10 on: Jun 07, 2018, 13:52:36 »
This sounds like it could be a carb sync issue to me. I didn't see you mention that you synced the carbs. My 360 will run like absolute crap if its even the tiniest bit out of sync.
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Offline redrover

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Re: Running on one cylinder intermittently (CB450)
« Reply #11 on: Jun 08, 2018, 01:40:34 »
Ok Iíll check the Ohm levels of the coils to eliminate that possibility.

Regarding the Pamco, installed it just a week ago in order to try to resolve this issue since it was doing it long before the Pamco came near the bike and thought maybe bad points were acting up intermittently.

And yes, although I thought I did sync the carbs, it is an art that I havenít perfected yet on the cb450... Need to do more research on how to master this. Does anyone have any tips on syncing 450 carbs?

Offline focusinprogress

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Re: Running on one cylinder intermittently (CB450)
« Reply #12 on: Jun 08, 2018, 10:35:21 »
what I've been doing on carb sync's lately is a neat trick I learned from a brit down in georgia. I sync with gauges the old-fashioned way, and then do a double check with an infrared laser thermometer. if the cyl's are within 10* of each other....you aren't getting any better than that....just have to make sure you're shooting temp the same distance away from the head on both pipes up by the clamps/mounts.

another thing to double check is make sure you're floats are set identical and you're getting equal fuel in both carb bowls....if one is slightly low, it could be intermittently running short of enough fuel to fire that side.
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Offline redrover

  • Posts: 193
Re: Running on one cylinder intermittently (CB450)
« Reply #13 on: Jun 10, 2018, 00:39:09 »
Ok so after checking the ohms on the coils... The coil on the side thatís been acting up was bouncing all over the place, and when it did stabilize it was 23ohms (other side was solid 17ohms).

I was going to swap the coils just to see how it would run, and noticed that the black power cable to the suspeft coil was barely hanging on and literally fell off. It didnít look salvageable... I replaced both coils.

Fired up on both cylinders! Idled perfectly. I shut it down to button everything else up and take for a test ride. When I started back up, the opposite cylinder wasnít running!

I shut it down, wheeled it to the street, fired up on both, but when I hit throttle, it would bog down and almost die, otherwise idled fine. I revved more and more and seemingly got better and better.

Finally running on both sides... bike is a screamer, but starts sputtering intermittently when I punch it in third gear. Even under level throttle, in third, sputtering with power coming in and out.

Any ideas?

Offline redrover

  • Posts: 193
Re: Running on one cylinder intermittently (CB450)
« Reply #14 on: Jun 10, 2018, 00:44:59 »
I checked the fuel lines, they seem ok.

I didnít have time to really get in and re-sync the carbs, not check the float bowl levels, but those are my next step.

Regarding the Pamco, does it work immediately upon setting the timing? Or does it take a few moments to learn the timing and stabilize?


Offline redrover

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Re: Running on one cylinder intermittently (CB450)
« Reply #15 on: Jun 24, 2018, 22:51:13 »
Adjusted the floats to the correct height and wow does she fly now!

Still sounds a little off... especially when I give it just a little throttle, but I think I just need to keep refining the syncing of the carbs.

Are the 500T carbs a direct bolt-on?

(they came with the vacuum ports, which should make syncing way easier).

Offline TheCoffeeGuy

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Re: Running on one cylinder intermittently (CB450)
« Reply #16 on: Jun 25, 2018, 20:50:53 »
they have been called high tension wires since Christ was a cowboy.    Ssounded electric to me form the start.
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Offline focusinprogress

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Re: Running on one cylinder intermittently (CB450)
« Reply #17 on: Jun 26, 2018, 13:42:51 »
Adjusted the floats to the correct height and wow does she fly now!

Still sounds a little off... especially when I give it just a little throttle, but I think I just need to keep refining the syncing of the carbs.

Are the 500T carbs a direct bolt-on?

(they came with the vacuum ports, which should make syncing way easier).

Yes they are...just may have to tweak jetting and such.

the trouble with these carbs is the individual idle set screws, individual throttle cables, and the sync of course.

What I do first is run the idle screws all the way out so they're both bottomed out. Then adjust the throttle cables so that both are pulling the plate open at exactly the same time. Then get the bike fired up (probably holding some throttle) and set the idle screws where the bike idles happiest and where a blip of the throttle below 1/4 turn doesn't cause a stumble. From here, on the 450 grab a $15 infrared laser thermometer and read your temps at the head pipes about an inch from the mount. if they aren't within 10* of each other, play with the sync until they are.

If after all of that you're still having trouble...it's bad float height(s) or not a carb issue.
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Offline davidricci

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Re: Running on one cylinder intermittently (CB450)
« Reply #18 on: Jul 21, 2018, 14:03:27 »
Double check timing or triple check it, buggered me once like this!