Mukuni Hard Start

gnolan said:

Here is the starter jet in the float bowl.

View attachment 14538

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Here's a clearer picture.

swooshdave said:

Who wants to be the first to tell George that his wife Amal will one day look like her mom?

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Or she might look like a carburetor with a bell end!

Ok, so I took the carb off to take a better look. Pilot jet was fine, as I suspected due to the good idle. I looked into the main jet and the hole looked tiny, about the size of the pilot jet (35). So I blew on it and out came a chunk of something. Now it looks like the main jet that it is (260).

I put it together and gas came out of the seam at the bowl. The gasket is, ahem, vintage, and I need to replace it.

I also need to check the needle valve and starter jet.

Although I suspect you can buy these parts anywhere, where do you like to get Mikuni parts from?

Is it just as easy as getting them from Amazon?

https://www.amazon.com/VM30-Carbure...+vm+gasket&qid=1582487055&s=automotive&sr=1-3

Interesting Swoosh. (I recommend getting Mikuni parts from "MAP" in Florida ... support our British Bike suppliers who have stood by us all the years. Amazon doesn't need our money IMO, but those who sell us parts for our old British Bikes do.)

https://www.ebay.com/str/mapcycleinc

or

http://rockypointcycle.com/

Several months ago I could ride my Norton w/single Mikuni, idle just fine as long as you want, but after two miles it what shut off. Then you could start it right up, go two more miles, and it would shut off again. (like fuel starved) So ... I removed and stripped the single Mikuni. Low and behold ... a little, tiny piece of black fuel line rubber; was wedged inside the float needle and seat So my guess ... is that at higher RPM it didn't allow enough fuel into the float bowl, it got low, so the bike shut off; only to easily start and run again because the bowl had time to fill up enough with gas when not running. I removed the tiny speck of rubber, replaced my fuel lines with that "see thru greenish tubing" ... for Marine use ... and the bikes running great again. I have since removed all the black rubber fuel line on all my bikes; and replaced them with this "Marine" fuel line. Nice to be able to see fuel in the line too.

Not sure if those are factory, Mikuni parts.
Myself, I only buy genuine Carb parts.
jetrus.com is my go to Mikuni/Keihin parts.

Get the Viton float needle btw.

rockypointcycle.com probably does too.

swooshdave said:

I'll stick the bowl in the ultrasonic cleaner and see if that helps.

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Ideally, use a 50/50 mixture of Pine Sol and water in there. Works a treat.

BrianK said:

Ideally, use a 50/50 mixture of Pine Sol and water in there. Works a treat.

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I prefer the purple simple green.

swooshdave said:

I prefer the purple simple green.

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Does the purple simple green darken the carbs? I used dish detergent once and it did. Ugh.

Scout63 said:

Does the purple simple green darken the carbs? I used dish detergent once and it did. Ugh.

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Does this answer your question? The green Simple Green will damage the alloy, DO NOT USE THAT. But you can see that a couple cycles through the ultrasonic cleaner has it looking really nice. This was probably 1:1 Simple Green and water. And the ultrasonic cleaner has a heater too.

Did you get much crud out of it ?

I hope you removed the cold start mechanism and air screw etc when cleaning them? Otherwise dirt could be loosened, but still trapped inside... making things worse!

Fast Eddie said:

Did you get much crud out of it ?

I hope you removed the cold start mechanism and air screw etc when cleaning them? Otherwise dirt could be loosened, but still trapped inside... making things worse!

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Stripped it bare of anything that could unscrew. Blew out the orifices. Partially reassembled for the photo.