Kerker on my 79 CBX


Kerker on my 79 CBX

Postby sixinoz » Wed Apr 18, 2018 8:49 pm

I have a Kerker system on my bike from 10 years ago?? (See photo) Not sure of vintage but very loud and pops and burbles on overrun. Mixture good so not sure if this is a characteristic of the exhaust.
Question is would the carbs have been rejetted for this exhaust as I want to go to stock exhaust?

Thanks in advance
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Re: Kerker on my 79 CBX

Postby steve murdoch icoa #5322 » Wed Apr 18, 2018 9:12 pm

The burble might be from an air leak.
Check the boots.
If the stock airbox and filter are still there most aftermarket systems do not need rejetting.
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Re: Kerker on my 79 CBX

Postby sixinoz » Thu Apr 19, 2018 4:26 am

Ok - thanks for the reply.
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Re: Kerker on my 79 CBX

Postby daves79x » Thu Apr 19, 2018 6:26 am

The Kerker is one of the best aftermarket systems requiring no rejetting. If yours is loud, then someone has messed with the baffles - these are very quiet pipes. You could have carb issues if it is not running smoothly.

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Re: Kerker on my 79 CBX

Postby Jeff Bennetts » Thu Apr 19, 2018 10:04 am

There were two sets of baffles available for both series of that Kerker exhaust system, you either have the race baffle, someone has modified the street baffle or your existing baffles need to be repacked.

Like Dave said, it's not necessarily to reject with the Kerker system, with that said a lot of people did go up on the main and may have raised/shimmed the needle. Both those mods can be checked with the carbs still on the bike.
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Re: Kerker on my 79 CBX

Postby Rick Pope » Thu Apr 19, 2018 5:18 pm

Jeff said: There were two sets of baffles available for both series of that Kerker exhaust system

There was also the "Q" baffle. Almost as quiet as stock.
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Re: Kerker on my 79 CBX

Postby cbx1260cc » Fri Apr 20, 2018 9:44 am

May I make a comment?

While I realize the Kerker pipes are single walled the color of the head pipes and even the section of the pipe stretching back to passenger pegs seems quite "blue" in color to my eyes.

Is that what would be considered optimum? My limited knowledge says a bit of a "lean" mixture.

To me a reinforcement of the thought that there might be an air leak going on.

Will be watching this closely as I am doing a 1980 restoration and will be installing a set of Kerkers(so going the opposite direction).

best to all,

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Re: Kerker on my 79 CBX

Postby daves79x » Fri Apr 20, 2018 1:00 pm

Or, the bike could have been left sitting with the choke on. I wouldn't read too much into the color of the pipes.

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Re: Kerker on my 79 CBX

Postby sixinoz » Sun Apr 22, 2018 2:45 am

Thanks for all the replies. The bike was running rich ( black sooty plugs) set screws at 1 1/2 turns and much better with brown colour no soot. Carbs coming off this week for a clean etc.
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Re: Kerker on my 79 CBX

Postby sixinoz » Mon May 28, 2018 6:49 am

So after the carb clean the bike is running real good throughout the rev range. As mentioned before the Kerkers are real loud - as to be annoying. There are screws at the end of the muffler which I presume are to secure the baffles? Took the screws out but those baffles are in tight. Anyone know best way to get these baffles out so I can see what up with them?
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Re: Kerker on my 79 CBX

Postby tevan » Mon May 28, 2018 9:22 am

I think you can use a slide hammer tool. Be easy with it but I think it will pull them without damage. The baffles get kind of tight when they aren’t taken out often. Your packing might be gone from the baffles. You can get some on the web.
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Re: Kerker on my 79 CBX

Postby Rick Pope » Mon May 28, 2018 4:47 pm

Use a rubber or plastic mallet to tap around on the megaphones, and loosen the baffle. Even a piece of 2x4 works. No need to hit hard, all you're after is to break the bond.
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Re: Kerker on my 79 CBX

Postby sixinoz » Mon May 28, 2018 9:05 pm

20180529_104118.jpg

Ok - so I eventually took the muffler off, put some penetrating oil around the cone and with the muffler upright tapped the protruding baffle tube onto a block of wood and after a few good taps out it came.
From the photo you can see the condition of the packing - not too good. When stuffed into the muffler the gap isn't as wide as shown but the bottom section of the baffle isn't covered at all. Should this be covered all the way and if so is this contributing to the noise?
And on the subject of packing are there different grades i.e. dense not so dense (fine) as to restrict flow too much and do you wrap as much as you can around the baffle? As you can tell I'm no exhaust guru and know nothing of back pressure and other exhaust technology.

Thanks for the replies.
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Re: Kerker on my 79 CBX

Postby Jeff Bennetts » Tue May 29, 2018 11:04 am

Go to your local motorcycle shop that carries accessories or buy it online but make sure you buy the correct packing matierial (for repacking mufflers) not steel wool! wrap it around the baffle 1 1/2 times and use some safety wire to secure the packing the full length of perforated portioned the baffle, don't tie the packing too tight, just enough to keep it from sliding around.
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Re: Kerker on my 79 CBX

Postby Artie » Thu May 31, 2018 8:05 pm

I have same exact setup,wrap baffles with packing and secure with wire,
Put never seize compound around baffle can ends so they won't stick next time
My 79 purrs with stock jetting it is a little on loud side
Same level as pipemasters
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