sq4 solex-bi-starter

[simon.holyfield]

Just discovered that my pilot jet is too high, so the float chamber cover "rides" on the pilot jet .

Picture? Sounds like that would lead to an air leak in the pilot circuit.

[Henning G]

Absolutely right, that’s really bad. I guess that the fuel camber and fuel camber cover should be a tight fit to create the necessary vacuum for the idle system.

[Henning G]

the drill is slightly over 2,5mm

[chris.shearwood]

I can put a .113 inch (2.87 mm) drill bit into the hole in that jet on my Solex bi-starter.
Another place you might try to find jets is:
https://classiccarbs.com.au/index.php?r ... y&path=261
Here is a scan of a page of Ariel The Post War Models by Roy Bacon on which I have written the Solex part numbers:

[Henning G]

WOW, that’s great, Thanks. I wonder how big influence my faulty Air Correction jet will have on my Idle, should be a 150 jet, mine is 120..

[Henning G]

My pilotAir Bleed jet is 150, correction jet 120, is that way out..

[simon.holyfield]

I thought the air correction jet was supposed to emulsify the fuel coming into the main choke, not the idle supply. I think it would make the bike run rich overall wouldn't it?

[Pete.Silson]

Both the Air Correction Jet and the Pilot Air Bleed should be 150 (1.5mm).

The tickover mixture is governed by the ratio of the Pilot Jet 070 (0.7mm) and Pilot Air Bleed 150 (1.5mm). The tickover mixture is further adjustable using the Volume Control Screw - clockwise for weaker, anti-clockwise for richer. The tickover speed is adjusted by the throttle stop on the main butterfly.

The ratio of the Air Correction Jet and the Main Jet and the Emulsion Tube controls the mixture over the whole rev range. The Air Correction Jet has more influence at higher revs.

[Chris Sealy]

I use Mikuni for the main jet, 120 with a 5mm thread; and the air correction jet 150 with a 6mm thread. There may be other jets that will fit or could be adapted to fit, but my experiments have not gone that far yet.I have found genuine Mikuni jets to be very accurately made, unlike some of the genuine Solex jets that I have come across. Mikuni were agents for Solex back in the day and some of their jets are still identical today.

[simon.holyfield]

I use Mikuni for the main jet, 120 with a 5mm thread; and the air correction jet 150 with a 6mm thread. There may be other jets that will fit or could be adapted to fit, but my experiments have not gone that far yet.I have found genuine Mikuni jets to be very accurately made, unlike some of the genuine Solex jets that I have come across. Mikuni were agents for Solex back in the day and some of their jets are still identical today.

That’s really useful,thanks Chris.