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A Short Primer on Carburetor Jetting

1/7/2018

4 Comments

 
Things you may not know.
 
1 - An engine will run richer in taller gears. This is due to the acceleration rate being slower & allowing more time for the carburetor to deliver fuel. Fuel flow always lags behind air flow as fuel is heavier.
 
2 - The longer you hold the throttle open the richer the jetting. Same reason as above.
 
3 - If you snap the throttle open & the engine doesn't respond - 90% time  it's lean. Same reason as above.

4 - CV Carbs deliver fuel in response primarily to rpm, a piston slide carburetor responds to throttle percentage opening.

5 - When your jetting is correct a carburetor will work good in a surprising large range of air temperatures and humidity. If it doesn't then your jetting is on the fringe of the optimum setting.

6 - Slightly lean and your engine response and performance will be poor, slightly rich and you will likely not notice a problem. This is why most jet kits are setup on the rich side of optimum to avoid customer complaints.

7 - Airbox modifications or removal will have the biggest impact on jetting.

8 - On a CV Carb, you do not control the rate of acceleration....that is set by the size, number of vacuum slide lift holes and stiffness (rate) of the slide lift spring.
Picture
4 Comments
https://ifreedownloadings.com/winzip-17-download-latest-version/ link
9/15/2018 01:04:59 am


Nice post. I learn something more challenging on different blogs everyday. It will always be stimulating to read content from other writers and practice a little something from their store. I?d prefer to use some with the content on my blog whether you don?t mind. Natually I?ll give you a link on your web blog. Thanks for sharing.

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Kentucky Live Cams link
3/1/2021 08:32:56 pm

Thanks for sharingg

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Jeff Carbine link
1/29/2022 04:50:24 am

My favorite part of this article is a CV carburetor responds to throttle percentage opening, whereas a piston slide carburetor responds to rpm. Someone recently told me about this and it is different from what I understand. Thanks for helping me understand carburetor.

Reply
Renton Water Features link
10/8/2022 07:59:57 pm

Nice posst thanks for sharing

Reply



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    I have been involved in mechanics and motorcycling from a young age. I formed Cycle Improvements in 1981 and still have the same passion to learn today as when I started. Hope you find this blog interesting and educational.

    James Hunt

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