Carb Jetting Guidence

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bobcat
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Re: Carb Jetting Guidence

Post by bobcat »

daves79x wrote:
Wed Aug 17, 2022 2:15 pm
I know, I've done a bunch of them. Also have a bunch of spare hold-down screws.

Dave

Spares are nice if you have them. :-)

Tedious when "a little dab 'ill do ya" ! :P
Bob
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bobcat
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Re: Carb Jetting Guidence

Post by bobcat »

daves79x wrote:
Wed Aug 17, 2022 2:15 pm
I know, I've done a bunch of them. Also have a bunch of spare hold-down screws.

Dave
Off topic ; speaking of spares, would you happen to have a set of 79 slide needles
(VB60A) you could spare ? I just need one but a set would be nice.
Bob
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Re: Carb Jetting Guidence

Post by daves79x »

Sorry, none to spare. I have to keep every one I get my hands on for rebuilds. We'll soon be stuck using aftermarket ones, as it's insane to buy a parts set of carbs for hundreds of dollars just to get the needles and a few other consumables. Many, many good stock needles and other parts got thrown out over the years and replaced with aftermarket junk.

Dave

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Re: Carb Jetting Guidence

Post by jt »

Bobcat and all,
Worked on the X some, used stock slow speed jets drilled out with #79 bit and stock main 105's and I put two shims under needle, the shims measured .018 thou each . and I have pilot screw out one full turn. Here is a pic of plugs after about two miles or a little less. There is some poping on decell, maybe need to open the pilot screws some ? Other wise it is alot cleaner going up the rpm range off the slow speed jet and onto the mains. Have a vid but cannot seem to load. The ground strap on #1 & 6 seem a little whiter than the others ??.

Thanks for the help !
thumbnail 2.jpg
http://youtu.be/fMm6lxSJnlU
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Last edited by jt on Fri Oct 07, 2022 8:52 pm, edited 1 time in total.
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bobcat
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Re: Carb Jetting Guidence

Post by bobcat »

Excellent ! Open the pilot screws out to 1.5 turns and that should take care
of the popping. 1 and 6 are coloring the same as Bill Kemp's plugs did and might
need to be set slightly richer (pilot screws) than the rest. I hope to see your video.

My guess on 1and 6 is they run cooler than the other cyls. and want more fuel.
You need to put more miles on it and check the plugs again.
Bob
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Re: Carb Jetting Guidence

Post by bobcat »

After you put more miles on it, if the plugs continue coloring lean on 1 and 6
it might be a worthwhile experiment to try no. 38 pilot (slow) jets in those
two carbs with all mix. screws set at 1.5 turns. That is if you can access them
without having to pull the carbs again and/or have the time and patience.
If 1 and 6 want more fuel they likely need it at more than just idle.

Note; drilling with a #79 bit = 36.75 slow jet.
1 and 6 plugs don't look unacceptably lean but the ideal would be to have all
the plugs color the same. (fine tuning).
Bob
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Re: Carb Jetting Guidence

Post by jt »

Ok will try a few things suggested !
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Re: Carb Jetting Guidence

Post by bobcat »

See if you can get that video to post.
Bob
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Re: Carb Jetting Guidence

Post by jt »

bobcat wrote:
Fri Oct 07, 2022 9:54 pm
See if you can get that video to post.
Bob, I put the link in my post above under the plug pic.

Thanks
JT
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Re: Carb Jetting Guidence

Post by bobcat »

jt wrote:
Sun Oct 09, 2022 9:49 pm
bobcat wrote:
Fri Oct 07, 2022 9:54 pm
See if you can get that video to post.
Bob, I put the link in my post above under the plug pic.

Thanks
JT
I can't get it to open, answered your pm.
Bob
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Re: Carb Jetting Guidence

Post by Larry Zimmer »

Not being a youtube guru, I'm not sure what you do, here. When I tried it, the message said it was a private video. Dunno.
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Re: Carb Jetting Guidence

Post by NobleHops »

Nils Menten
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Re: Carb Jetting Guidence

Post by jt »

Thanks Nils !

JT
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Re: Carb Jetting Guidence

Post by bobcat »

Well, that sounds a lot better ! It's not popping on deceleration that bad.
If you can do another video with more than one burst through the rpm range
in different gears (without getting in trouble), it would be easier to tell more
about it.
Maybe just go one and a half turns out on 1and 6 screws and one and a quarter
on the rest.

And yes, thanks Nils !
Bob
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Re: Carb Jetting Guidence

Post by NobleHops »

My pleasure fellas. Just delete the “s” in “https” and your videos should link.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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