Author Topic: Stay up float  (Read 625 times)

0 Members and 1 Guest are viewing this topic.

royblackburn1@btinternet.

  • Royal Star
  • ***
  • Posts: 148
    • View Profile
Stay up float
« on: 24 June, 2019, 11:40:55 »
Hi all, would fitting stay up floats and alloy float needle set to correct level to concentric carbs help with starting when hot and where to get the best deals from.thanks Roy

berniej

  • Royal Star
  • ***
  • Posts: 198
    • View Profile
Re: Stay up float
« Reply #1 on: 25 June, 2019, 08:52:08 »
Hi Roy,

I wouldn't have thought so. As far as I know the modern stay up is a plastic replacement for the brass and solder originals which could leak if the brass or solder cracked. I fitted one when I noticed continual flooding and found some pinholes in the float.

However I can't see how they would help hot starting which is often due to the fuel evaporating in the carb body before it can be drawn into the combustion chamber. Fitting a tufnol spacer - or a thicker one if present - might be a better bet?

Cheers,
Bernie
'49 M21/B31 hybrid
'56 M21 combination
Bantam D7
C15 project
B40 Super Star
A50CC project

chaz

  • Silver Star
  • ****
  • Posts: 364
    • View Profile
Re: Stay up float
« Reply #2 on: 25 June, 2019, 17:33:43 »
have to go along with the tufnol spacer. been working on a B33 motored WM20, brand new carb , valves checked, new fuel and plug.. starts second kick. BUT, I have noticed that the carb gets hot, supplied with a normal thin gasket.
the excess heat has a couple of effects, heats up fuel so thinner and not as good, thicker cooler fuel is better for combustion, the heat can distort the throttle valve or bore with the potential to keep the revs on even when throttle closed. heat could evaporate the fuel in the carb which would cause harder starting.

BEEZABRYAN

  • Blue Star
  • **
  • Posts: 88
    • View Profile
Re: Stay up float
« Reply #3 on: 25 June, 2019, 17:51:45 »
In agreement with Chaz

royblackburn1@btinternet.

  • Royal Star
  • ***
  • Posts: 148
    • View Profile
Re: Stay up float
« Reply #4 on: 25 June, 2019, 21:19:52 »
Thanks guys, where would the tufnol gasket best be situated between cylinder head and spacer, or spacer and carbs. thanks Roy

chaz

  • Silver Star
  • ****
  • Posts: 364
    • View Profile
Re: Stay up float
« Reply #5 on: 25 June, 2019, 23:57:01 »
Normally between carb and manifold or head whichever you have. Usually with one thin gasket either side to ensure sealing as a leak on inlet side will increase revs.

royblackburn1@btinternet.

  • Royal Star
  • ***
  • Posts: 148
    • View Profile
Re: Stay up float
« Reply #6 on: 26 June, 2019, 11:17:29 »
Thanks everyone for the replies. Roy

royblackburn1@btinternet.

  • Royal Star
  • ***
  • Posts: 148
    • View Profile
Re: Stay up float
« Reply #7 on: 04 July, 2019, 19:28:59 »
well fitted quarter inch tufnel spacer between metal spacers and carbs, went for a run and still the same reluctant to start when hot, yes Chaz the bowls where hot could only get quarter inch tufnels because only got that room on the studs for carbs, any other ideas please or does it mean bin the metal spacers and get the largest tufnel spacer Surrey cycles do, how do other A65 riders deal with it. thanks Roy

BEVANC

  • Royal Star
  • ***
  • Posts: 100
    • View Profile
Re: Stay up float
« Reply #8 on: 04 July, 2019, 23:31:14 »
Is it possible you have a failing ignition coil, rather than a carb problem ? i don't have an A65, so am not sure if the coil (s ?) are situated where they may get warm ?
Just a thought.
Cheers,
Bevan

JulianS

  • Empire Star
  • *****
  • Posts: 1565
  • A10
    • View Profile
Re: Stay up float
« Reply #9 on: 05 July, 2019, 09:02:41 »
Not sure about the metal spacers you mention?

Dont recall any metal spacers being fitted between the carb and head on the A65.

Could you post a photo or description?

royblackburn1@btinternet.

  • Royal Star
  • ***
  • Posts: 148
    • View Profile
Re: Stay up float
« Reply #10 on: 05 July, 2019, 17:46:01 »
Hi Bevan it has new duel coils fitted in same position as originals, Julian the spacer could be called a manifold its nearly 3/4inch long with a flange either end of a 32m diameter tube that slides over the carb studs from cylinder head, Roy

JulianS

  • Empire Star
  • *****
  • Posts: 1565
  • A10
    • View Profile
Re: Stay up float
« Reply #11 on: 05 July, 2019, 17:58:29 »
Have you tried removing the metal spacers and see if it improves the hot start. They sound like an "extra" fitting rather than a BSA factory part.

BEEZABRYAN

  • Blue Star
  • **
  • Posts: 88
    • View Profile
Re: Stay up float
« Reply #12 on: 06 July, 2019, 18:36:51 »
That "metal spacer" is not original BSA & may well be the root of your trouble, I suggest you follow Julian advice.

royblackburn1@btinternet.

  • Royal Star
  • ***
  • Posts: 148
    • View Profile
Re: Stay up float
« Reply #13 on: 11 July, 2019, 11:05:27 »
Hi all fitted the stay up floats and alloy needles because I had already bought them kept the spacers (I thought they would help disperse the heat) put the tufnol insulators on, I read that stay up floats may make the fuel rich, not good for hot starts so turned the air screw out a further half turn been on a couple of long runs and every thing seams ok plugs are biscuit brown and starts when hot,will see how it goe's  on may try with out spacers.thanks Roy