Bst40 carbs

[clivegto]

What's the best main jet size, needle hight & mixture screw turns out to set some bst 40 mm carbs with pod filters on a 1100m motor. No room for a air box as it is fitted to a 1100 slabside.

Edited August 16, 2018 by clivegto

[Gixer1460]

Good luck - they are a PITA to set up! 

[clivegto]

1 hour ago, Gixer1460 said:

Good luck - they are a PITA to set up! 

Yes I have read that they are hard to set up. Was just after some basic settings really.

[Oilyspanner]

I tried a set-up a bit like that Clive - I think I used 155 mj, needles on bottom notch and 42.5 pilots  - should be close enough to work with anyway.

Those don't look like 1100 m/n 40mm carbs -  are yours from a 750 rk ?

40 mm cv carbs can be/are mo fos to set-up...… I always see it as a personal challenge to make them work ! - they work better on my big bore and flowed motor, I kept the a.box as the power was much smoother with it in place.

[Gixer1460]

3 hours ago, Oilyspanner said:

they work better on big bore and flowed motor, I kept the a.box as the power was much smoother with it in place.

That's the secret - they don't respond well to disrupted air flow - open, ram pipes, small filters etc.

[manden]

8 hours ago, Oilyspanner said:

I tried a set-up a bit like that Clive - I think I used 155 mj, needles on bottom notch and 42.5 pilots  - should be close enough to work with anyway.

Those don't look like 1100 m/n 40mm carbs -  are yours from a 750 rk ?

40 mm cv carbs can be/are mo fos to set-up...… I always see it as a personal challenge to make them work ! - they work better on my big bore and flowed motor, I kept the a.box as the power was much smoother with it in place.

I think my rack had 42,5 pilots and 160 mains. Tapered needles 1 from bottom

[clivegto]

@Oilyspannerthe carbs were on the bike when I got them so don't know if they are RK ones. Bst40mm on right side the others are some bst38mm ones I have, they doo fit the same carb rubbers.

[Oilyspanner]

The 1100 m/n ones have a cable choke, remote idle speed like your 38's and the top carb spacer bracket is flat - just checked 750RK carbs on csmnl site, the rk carbs have odd diaphragm covers/ carb tops ……. dunno, just something I noticed about your 40's.