Author Topic: mikuni floatvalve removal  (Read 553 times)

Offline RDfella

  • Wise & Enlightened
  • *
  • Join Date: Aug 2017
  • Posts: 2193
  • Karma: 15
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, '62 Flash special, '00 Firestorm, Weslake sprint bike.

Online berger

  • Wise & Enlightened
  • *
  • Join Date: Nov 2017
  • Posts: 2909
  • Karma: 20
  • keith.uk 500sscafe.norbsa JDM honda 750fz
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*

Offline RDfella

  • Wise & Enlightened
  • *
  • Join Date: Aug 2017
  • Posts: 2193
  • Karma: 15
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, '62 Flash special, '00 Firestorm, Weslake sprint bike.

Offline metalflake11

  • Resident Legend
  • *****
  • Join Date: Aug 2012
  • Posts: 678
  • Karma: 9
England N.W
1960 A10
England

Offline Joolstacho

  • Wise & Enlightened
  • *
  • Join Date: Jan 2010
  • Posts: 1094
  • Karma: 7
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.

Offline metalflake11

  • Resident Legend
  • *****
  • Join Date: Aug 2012
  • Posts: 678
  • Karma: 9
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.
England N.W
1960 A10
England

Online Kickaha

  • Valued Contributor
  • ****
  • Join Date: Apr 2014
  • Posts: 277
  • Karma: 6
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
1956 BSA Gold Flash
New Zealand

Offline RDfella

  • Wise & Enlightened
  • *
  • Join Date: Aug 2017
  • Posts: 2193
  • Karma: 15
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, '62 Flash special, '00 Firestorm, Weslake sprint bike.