Author Topic: mikuni floatvalve removal  (Read 141 times)

Online RDfella

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mikuni floatvalve removal
« on: 01.10. 2020 20:37 »
Just for anyone with the misfortune of owning a mikuni carb (OK, allright, I know Amal designed them and then sold them on when they found they weren't too hot for four strokes). Anyway, they don't have that helpful little filter incorporated into the incoming fuel passage as Amals do, so this is now the third time I've had to take one apart to stop it flooding. Seems even the smallest particle under the float valve has a desire to stay put.
Trouble is, to remove said valve, you need to remove the brass lever between it and the floats - and that's retained by a pin. A pin that's a press fit in the carb body pillars, meaning if you try to drive the pin out with a pin punch, there's a fair chance you'll break a pillar. And that means a new carb body, so it's essential to support those pillars before getting out the toffee hammer. I made a jig out of a piece of hardwood, as shown in accompanying pics. The first pic shows the pin already drifted out of the retaining pillar and ready to pull out completely. Why didn't they screw the damned thing in?
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Online berger

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Re: mikuni floatvalve removal
« Reply #1 on: 01.10. 2020 21:18 »
well RD you get all the back luck *problem* the mikuni I HAD on my beeza is the same float etc and the pin nearly fell out when I tipped the carb over *grins*

Online RDfella

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Re: mikuni floatvalve removal
« Reply #2 on: 01.10. 2020 21:21 »
You're probably right about luck, Bergs, but the pin being a press fit is apparently a known issue and there's nothing else to keep it in place.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Online metalflake11

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Online Joolstacho

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Re: mikuni floatvalve removal
« Reply #4 on: 02.10. 2020 01:18 »
I've played with a few of these and have never encountered more than an easy press-fit. Maybe I've been lucky.

Online metalflake11

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Re: mikuni floatvalve removal
« Reply #5 on: 02.10. 2020 01:44 »
I've played with a few of these and have never encountered more than an easy press-fit. Maybe I've been lucky.


Same here, but it is a known problem on some of them. Maybe quality control?

Suzuki, Yamaha and Honda seem to rate them though, and they've sold one or two bikes between them over the years.
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Online Kickaha

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Re: mikuni floatvalve removal
« Reply #6 on: 02.10. 2020 19:58 »
Just for anyone with the misfortune of owning a mikuni carb

I've had dozens of them, haven't once had the problem you describe, always found them very easy to work with
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Online RDfella

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Re: mikuni floatvalve removal
« Reply #7 on: 02.10. 2020 20:11 »
Maybe Bergs is right - both mine are a tight press fit, needing several smacks on a pin punch. I'd break one of those pillars driving them out without support. When I first came across the problem, I searched the internet for a solution and that's where I found others had encountered the same issue and so I copied the support block design. Mine cetainly don't push out as the youtube video shows!
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.