First Generation Ascots > Tech Section

Essentials for the FT500

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thewiddaman:
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
 

J6G1Z:
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.
J.

PS. Check out this old FT500 Ad: http://ascot500.com/index.php?topic=82.0  There is mention of a larger carb than on the US models. Don't know if this was a typo or what.

WTF304:
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

Kornfed:
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.

J6G1Z:
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.

J.

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