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Author Topic: 1976 cb550k 4-into-4 jetting with pod filters  (Read 598 times)

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Offline loveliverpool

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1976 cb550k 4-into-4 jetting with pod filters
« on: July 22, 2013, 07:03:47 PM »
Hey all. This is my first post and I was hoping to get help with my jetting issues I'm having.

My 1976 cb550k has had pod filters since I bought it a year ago and haven't had the time to re-jet. It must be running lean right now and there is a distinct bogging down when I am near full throttle, especially on a hill. The same thing happens when I pull it to full throttle quickly any time.

The bike has stock 4-4 pipes and 4 Emgo pod filters on. What's the recommended jump in main jet size that I should go to? Is #105 sufficient, should I go bigger? (The stock mains are 100 aren't they?)

Thanks for the help!
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Offline goldarrow

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Re: 1976 cb550k 4-into-4 jetting with pod filters
« Reply #1 on: July 22, 2013, 07:07:10 PM »
jettings is trial and error process, if you're lean to begin with, then you just have to go up to rich, one step at a time. 
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Offline Dave Voss

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Re: 1976 cb550k 4-into-4 jetting with pod filters
« Reply #2 on: July 23, 2013, 07:27:27 AM »
Yes, it does sound like it is probabaly running lean, size 100 main jet is stock, I would try replacing those with size 105 as you suggest, and note the difference.  A lot of folks recommend a plug chop to verify full throttle jetting, have you performed this to see how they look?  It might be a good way to verify the present lean condition, that the size 105 main jets help, or that you might be better to use size 102 or 108 or another size main jets to adjust the mixture as close to optimum as you can get.
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Offline lucky

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Re: 1976 cb550k 4-into-4 jetting with pod filters
« Reply #3 on: July 23, 2013, 09:09:00 AM »
The main jet size is important so you do not seize the engine at full speed and throw yourself over the handle bars but the idle jet and slide needle are extremely important  or you will have very poor throttle response and a lean condition 80-90% of the time.

When we ride most of the time it is mot at full speed.


Since you have the STOCK mufflers A slight increase in main jet size is good insurance against seizing and all it probably needs is 1/4 turn richer on the mixture screw.
If it is not popping or backfiring the mixture is close.
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Offline loveliverpool

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Re: 1976 cb550k 4-into-4 jetting with pod filters
« Reply #4 on: July 23, 2013, 09:26:23 AM »
Thanks a bunch for the help! It does backfire every once in a while but not a common thing.

I think I'll try the 105 and see how that goes. I definitely think I need to make the mixture richer than it currently is.
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