Solex 32dis 2nd stage adjustment screw

[Fordy]

Putting this here so i don't forget or loose the information, probably be useful for others.

5mm drill aluminium blanking ball.

Measured at spring seating area to screw seating area.
1 curved washer = 1mm
2 curved washers = 2.2mm due to curve i guess.

Half turn = roughly 0.25mm increase in preload
2 whole turns of screw inwards = 1mm increase in preload
4 whole turns of screw inwards = 2mm increase in preload

Spring length uncompressed 23.1mm

[Matt Cole]

Nice info Fordy. I used to shim it with 1 X washer (can't remember thickeness) which used to get rid of the horrible 1st to 2nd stage rich spot and bogging down.

[francob80]

@Matt - When you say bogging down do you mean bogging between gear changes?

Currently have an issue with bogging between high rpm gear changes, most noticeable between changing from 3rd to 4th. Any thoughts or ideas how to solve this?

Many have suggested gasket between carb top being perished but I have tried two different carbs both with new rebuild kits. I have also tried an additional washer on needle jet (currently 1.7mm)

Any other ideas that I can try ?

[Trevhib]

Good info gents

[Fordy]

More is coming as I get round to it

Replacement throttle shaft bushes are next on my list to make/obtain, not sure if bronze bushes are a good idea incase they wear and we can't remove them in the future, not enough room for roller bearings either. So nylon it might have to be

[Ian S]

There is already a plastic bush in one end. See my photo in the article:

https://www.rtoc.org/boards/showthread.php?t=4734

[Fordy]

yup and those plastic bushes are pretty much all worn now, got 3 bases here all with slop in them but noone changes them and rely on the seals to take it up

self oiling bronze bushes but they need modification to fit or maybe try find/make new plastic ones

Decided to make a new pump jet but praying the bends don't crush the very small tubing

[Ian S]

Yes, that's what I meant, make new plastic tubes, that sorts one end anyway.

[Fordy]

I can confirm that if your running higher fuel pressure than standard and experiencing rich off boost fueling, that this screw will also help.

2nd stage is opened via fuel pressure, raised pressure 2nd stage opens early.

For example in my case I'm running 5psi base pressure and had horrible off boost fueling cruising around 13.5-7,

Added 2 turns preload (1mm) and now the fueling is much better that I see 14's-15's

[Matt Cole]

Excellent info Fordy!It was a mod that wasn't as common back in the day. But those that new about it sorted the timing of 1st to 2nd stage fueling issues.

[Matt Cole]

You could make the bushes out of maybe nylon 6.6? Not sure on hoe resistive to fuel it is.

[Fordy]

Matt I've already got new bushes here.

made of out specific material made for automotive purposes, chemical data sheet aswell with excellent resistance to pretty much any chemical.

Interference fit into the base and need to be 8mm reamed or 8mm drill bit run through as the ID goes to 7.8mm roughly,

Perfect for matching to worn throttle shafts.

Also have bronze bushes for the other end where it's not bushes but involves drilling of te carb base to fit.

I'll be making a guide on the next base I refurb and then offer the repair service to members

[Trevhib]