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Essentials for the FT500

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After reading about the various improvements that can be made to the FT500 I ordered and received from Allens Performance a #58 low speed jet and a #145 main jet here in UK.

Regarding changing jets in the carb - I presume that this applies to American bikes only with the Keihin VB10 carb.
My UK spec bike is fitted with a VB11 carb and in the Honda workshop manual it lists for the carb as follows:

Carb Type VB11 CV type 35mm bore
Main jet    PRIMARY # 78
                 SECONDARY #128

When I strip the carb, if the existing jets are as the manual, the new main will be bigger but the primary will be smaller.
Is this because it is a different model of carb or because of less restrictive emissions regulations here in the UK at that time?
Any ideas about the jets would be most welcome!!
Cheers Rob

Hi Rob,

This is the first time that I've heard of this situation. I would be willing to bet that the USA bikes may have had to meet a more strict emissions requirement. If you can measure or somehow determine which jets have the larger orifice, I'd be inclined to use the larger jets. Better a bit rich than lean, especially for an air cooled engine.

Good luck & please let us know what you find out.

PS. Check out this old FT500 Ad:  There is mention of a larger carb than on the US models. Don't know if this was a typo or what.

You guys run a different grade fuel then we do, I'm sure the less strict emissions play a role aswell. But you also have to account for different locations as far as altitude, and climate. Weather plays a good role with fuel/air mixture

So I changed the jets to the recommended sizes main and low-speed jets to
#145 and #58 respectively.
With the original jets it was running poor so with a white spark plug but now it's running way to rich. Resulting in a black spark and at higher speed the engine holds in and is running bad. :( At lower speed it's running good
The original main jet is #128 so I think I need a smaller size then #145.
Slow jet is #45 original.

Have you updated the air-filter as described?

Have you removed the rubber air-filter intake snorkel?

Sounds like you may need more air flow.



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