Jet size (air to fuel ratio)

[jhami970]

I live at 6000ft elevation and bought a .60mm jet to install to allow more airflow. When i check the spark plug, the bottom is still super oily and black, not the golden brown you want after running it. She tops out at about 25mph on flat. I was wondering if any one knows where i can find a smaller jet than .60mm because that seems to be the smallest I can find or if anyone has tricks to have a higher air to gas ratio. thanks

 

[Frogslayer]

You can solder it shut and re drill it with a smaller drill.

 

[GreasyChris]

I live at 6000ft elevation and bought a .60mm jet to install to allow more airflow. When i check the spark plug, the bottom is still super oily and black, not the golden brown you want after running it. She tops out at about 25mph on flat. I was wondering if any one knows where i can find a smaller jet than .60mm because that seems to be the smallest I can find or if anyone has tricks to have a higher air to gas ratio. thanks

This guy has jets smaller than 60. This listing is for a #38 but he has all the sizes. You can also check your local bike shop to get jets.

Dellorto main/idle #38 jet 5mm thread fits PH VH SH carburetor series 1486-38 | eBay

Dellorto main/idle jet with 5mm thread fits all PH VH SH carburetor series for all Ducati, Guzzi, and every Italian bike using Dellorto carburetors from the 1970's onwards. Every carburetor with a screw-in style pilot/idle jet uses this 5mm size (moped carbs may have only a drilled passageway...

www.ebay.com

 

[Dserna]

You can solder it shut and re drill it with a smaller drill.

When you solder it shut do you have to use flux?

 

[Frogslayer]

Maybe you wouldn't have to, i just always do.

 

[Wrench]

You can solder it shut and re drill it with a smaller drill.

Frog do ya know what size bit to use for a #85

 

[Frogslayer]

For a metric #85 jet at .85mm it looks like between a #65 and #66 drill bit. My cheap harbor freight micro drill set was marked wrong so i measured my bits with a caliper to find the one i needed. I ended up going between two sizes by reaming a little with a small bit but not so much where the next size up went through to get where i wanted.

Drilling Main Jets

Deciding which main jets to buy to tune your carburetor can be a difficult task. You may not know what jet size would be a good starting point for your combination. Why buy a bunch of main jets based on a guess when you may not ever use them again? By drilling out your stock main jet to larger...

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