Carb Jetting Suggestions

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Carb Jetting Suggestions

Ronnio
 Guys, I want to start of by saying sorry, because I know this topic has been beat to death, but I could really use some help on jetting my carbs. It is 75 CB750F. The bike has pod filters on it and I'm NOT going back to airbox on this bike. Just wanted to get that outta the way. It also has a custom 4-1 exhaust. Used the stock header all the way back to the pipe though. The carbs are currently at stock setting, but I am just looking for a direction to go. I rode the bike as is for about 2 weeks before winter. I just put some tape around the filters because I wanted ro ride it instead of tinker for what was left of summer. It ran pretty darn good , but not perfect. Either way, I knew it would need jetted properly.   A couple days ago, I went out to start it just to remind her that I knew she was there. FAIL. Put new plugs in and got it going. Weird part to me is that the plugs were black. I figured the bike would be lean if anything due to the pod filters. Anyways, I then got it running how it was during the summer, or so I thought. It ran good for the day. I tried to start her again today, FAIL 2. It actually started but would not stay running. After choke, unchoke,throttle, blah blah blah for 5 minutes, I just let it die. I then came in to do some reading and saw a guy with a formula he swears by. ( I know each bike is different, but it is supposed to get you started)  Anyways, by his formula, I would be going up 6 sizes on mains and 2 on pilots. A)  Does this seem extreme?   B)  wouldn't black plugs mean I need less gas, not more? Needle position need changed too? Any help leading me in the right direction would be awesome. Also, should I move to a hotter plug? I realize it is the middle of winter, but I'm actually looking at selling the bike. Whoever buys it will possibly need to jet it again, but I just want to know it's leaving here running well.  I'll let you gurus have the floor now. Thanks.
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Re: Carb Jetting Suggestions

shinyribs
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I have a 76F with pods and a very open 4-1. With roundtop carbs I'm running 125 mains and 42 pilots and needles in the very middle position. Runs flawless except for very cold ,windy days. Then I get the famous pod-cross-wind issue.
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Re: Carb Jetting Suggestions

Lucky 1
That is a good combo for that set up on that bike in my opinion Shinyribs.
On a Roadstar Adventure.
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Re: Carb Jetting Suggestions

Larry spillman
In reply to this post by Ronnio
Jet up 2 sizes from stock on low end and leave top end along ride bike do a plug check after 50 miles or so and after a high speed shut off if plugs are light brown or tan and bike runs well your done
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Re: Carb Jetting Suggestions

Lucky 1
Not very clear.

When you say "low end" do you mean the idle jet?

The main jets have to be larger with after market exhaust and pods.

I would use 120 mains and #42 idle jets. The clip on the needle is going to depend if you have the 7A or 657 carbs and you did not tell us which ones you have.

The 657;s used the 4th groove down from the top for the needle clip so I would move that to the 5th position down from the top for the midrange.

If the carbs are the 7a's the stock position was the 3 rd groove down from the top and I would move the clip to the 4th position down from the top.

The mixture screws will have to all be adjusted also.

The mixture screws on the 657's and 7A's were 1 turn open so I would richen those up.

The "F" models were the leanest of all the 750's They are all running lean from the factory.
On a Roadstar Adventure.