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Old 5 Jun 2008
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Two kinds of float valve

Oh dear, tinkering has got me in the shit again.

Wandering through a catalogue, I came across a carb refurb kit (o-rings, gaskets, float valve etc), which looked like a good idea. So, I ordered it and fiddled around today fitting everything, which was a good thing as several of the o-rings were on their last legs.

Trouble was that the float valve needle and seat were not the same as my '83 bike - the old valve needle has a T-shaped pillar which fits into a slotted tang on the float itself, whereas the new valve needle is retained by a C-shaped wire, evidently hooked around the tang of a slightly different float.

Here's a photo of old and new parts, so it makes a bit more sense.

So, I phoned Kedo, who I got the kit from, and the chap there said, "yes, there are 2 types of float needle - just cut the little wire off and you can use this new needle no problem". So, I cut the wire off.

Trouble is, my "double tang" on the float - the slotted lower and upper - tended to foul the new needle, jamming when the floats were at the bottom limit. So I thought, no problem, I'll cut the slotted tang off, don't need it.

Except that now I don't really have any reference float height - since I don't know where the tang sits on the new-type-float, I've got nothing to measure from the gasket face to the top of the float (nominally 26mm +/- 1mm).

I thought this would be OK, since all that really matters is the fuel level, which should be 5-7mm below the float bowl mating surface. So, I tinkered around, bending the tang and piping in fuel (carbs off the bike) until I achieved something close. This was a bitch, since there didn't seem to be much difference in tang bending between an empty float bowl and a freely overflowing carb. Got there in the end, put the carbs on the bike and ran the engine ... all looks good, around 5-7mm. Phew.

So, go for a little ride to warm the engine up before resetting the pilot jet, bike is popping and banging a bit, running pretty lean by the sound of things, back to the garage ... arrghhh, its overflowing again!!?!? Fuel height is now about 10mm *above* the mating surface. Farrrrkkk.

That was today. All of it.

So, I'm wondering if my best bet is to replace the float with the correct part for my new valve and seat, at which point I will again have a reference I can work to with the carb off the bike.

Did that make any sense?

Comments and suggestions very welcome indeed. I'm slowly beginning to hate these carbs ...
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Old 5 Jun 2008
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Is your old needle and seat still working as it should? If it is,i would put them back in and carry on as before especially as in the photo it appears that the tapered end of the needle has the black sealing coating (Teflon?) still in good nick as they just never seem to wear like the old uncoated ones did(as on older BM's).Like you say it's a farqun annoying job having to mess about with the float height especially if you've got to take the carb off to do it....at least it's only a single!
Just going for a short ride on my bike....
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Old 5 Jun 2008
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Thanks for the input, Jon. The old valve is a bit worn - there's a definite step in the tapered part now - it is 24 yrs old, after all, so I'd like to replace it if possible.

I suppose it doesn't really matter that I've cut the slotted tang off - that only pulls the needle out, which fuel flow and gravity should accomplish well enough. Much the same as Kedo recommended cutting the little wire. Hmmm.
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Old 7 Jun 2008
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OK, I put the old bits back in and it all works fine. Phew. Obviously that slotted tang isn't doing much!

I guess that little experience comes under the heading of "if it ain't broke, don't fix it"

Last edited by xtfrog; 7 Jun 2008 at 13:41.
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