lean-burn carbs?

[lazlokovacs]

can anyone confirm if these are lean-burn carbs?

and if so, how does one change that high brass insert for a normal one??

thanks as ever

[Triple Jim]

A taller primary choke height makes a richer midrange mixture.  Assuming you're referring to the shroud around the needle jet, going to a shorter one will make it run leaner.

[Vasco DG]

Why would you want to change them? Set up correctly the 'Lean Burn' type give crisper performance and use less fuel.

Pete

[sib]

Why would you want to change them? Set up correctly the 'Lean Burn' type give crisper performance and use less fuel.

Pete

If I've learned anything on this forum, it's that some folks want to change things just because they can.

[NCAmother]

If I've learned anything on this forum, it's that some folks want to change things just because they can.

You're right, but if you never change you never learn.

[Bisbonian]

I thought this was a diet thread.

[jacksonracingcomau]

can anyone confirm if these are lean-burn carbs?

and if so, how does one change that high brass insert for a normal one??

thanks as ever

Answer is it knocks out , I think Rod (Yak Fat, RIP) did a summary of changes, search on here
But as Pete says, nothing actually wrong with them , my experience with LM 3 (LB PHF 36) over 1 or 2 (old PHF36) is they are only a problem when people put big jets in.

Nice dress
MH

[lazlokovacs]

thanks everyone,

original question was 'are these lean-burn carbs'?

anyone got a Y/N answer?

[Vasco DG]

Yes, they area hat have been described as 'Lean Burn' type. The shroud creates a greater depression around the anulus of the atomiser meaning for any given aperture more fuel will be pushed through from the float bowl.

Pete

[lazlokovacs]

thanks mate...

[sib]

Ah, so THAT'S where the Mystery Pin goes.

[mtiberio]

forget the carbs, who is she?

[lazlokovacs]

vasco, (or anyone), do these lean-burn carbs require different jetting then? I was planning on using Ed Milich's jetting recipe as a starting point, engine is a lemans 1000 big valve...

^and our current assistant prefers to remain anonymous...

[Vasco DG]

Almost certainly yes. To the best of my knowledge all big valve 948's came with 'Conventional' carbs but that may not of been true for the U.S. market.

Pete