Mikuni carb

[richard norris]

Anyone got experience of a mikuni carb i.e. best choke size etc? I have fitted a spare motor to my 2-speeder and my Amal is a bit tired, it runs but spits on idle and I have a feeling that air leaks are to blame at least partly. A 100% carb would be useful if only to check it all out. Of course I may need to fit the dreaded gauzes in the end.

[Oldguy]

No experience with Mikuni other than a long time ago on an Iron Head HD 🙂
I look forward to the responses though!

Mike.

[Barrie]

Richard, go and talk to Steve Doran at https://www.motocarb.com/, I think he will be able to help you

[BRIAN MARSHALL]

Why not keep it as original as possible, and let someone like Martyn Bratby bore out your Amal and fit an oversize slide to suit ?
Brian

[Tman]

@richard norris wrote:

Anyone got experience of a mikuni carb i.e. best choke size etc? I have fitted a spare motor to my 2-speeder and my Amal is a bit tired, it runs but spits on idle and I have a feeling that air leaks are to blame at least partly. A 100% carb would be useful if only to check it all out. Of course I may need to fit the dreaded gauzes in the end.

But wouldn’t a 100% carb require a rolling road set up to get there?
That, or the alternative of buying various jet combinations, would be more than a pro-carb overhaul.

[richard norris]

Yes I intend to sort out the Amal Brian, and thanks for the recommendation. While that is happening I thought it might be fun (?) to try a carb with a range of pilot jets just to see how near I can get to perfection…

[BRIAN MARSHALL]

No such thing as ‘perfection’ with a Scott… Everything has to be a compromise !
Brian 😉

[richard norris]

You’re telling me! But when they are running well it’s a pretty good compromise which gives me the strength to keep trying.

[richard norris]

Borowed a VM type Mikuni, 26mm (thanks Richard) with suitable adapter. Fitted straight on to my 2-speed Super, you can even use the same throttle cable with a suitable ferrule. No choke cable as it has a plunger choke on the carb. Jet sizes same as Amal so far as I could see. From warm it was fine but you can’t flood the carb like an Amal and my bike wouldn’t start from cold so I gave up.

Richard Tann’s German friend was asking about carbs (via Richard) and mentioned that his bike ran better after covering the small holes on the outside of the carb opposite the idle mixture screw and under the pilot jet. I did this with duct tape and it made my idling mixture richer which was what I wanted so I guess I owe him a beer. Anyone else noticed that?

Finally I have adopted the Ian Parsons cold starting method, i.e. flood generously, full choke, 2/3 throttle (seems such a lot!) and starts 7th or 8th kick.

[Author]

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