DDK - Die Deutschen Klassiker

Hi! When using light throttle openings it pulls fine but put your foot down more than half and it 'bogs' (too rich) and stinks of fuel. Also idles badly too and backfires occasionally! I think it might be the float level or accelerator pump settings?

Can someone tell me roughtly where all these settings should be? Thanks!

Hi.
Old Solex are a bit of a nightmare as the brass bushes on the shaft wear out and they draw air from places the shouldn't and are a bugger to set up.

Take the phone off the hook before you start.

Check the condition of your mixture screws before you start but counting the number of turns it takes to remove them each so you can put them back in the same place. There is a lump in the plastic end to help you count.
If you loose count then 2 to 2.5 turns out from fully is a basic start.
If the point on the end is still a point and not covered with carbon then you are in with a chance.

You now need a means to check you revs on tick over. A strobe is best.
Disconnet the linkage from both carbs and with the engine running balance both carbs at about 2000RPM tick over.
Now by adjusting the mixture screws one at a time you can see the revs pick up or slow as you adjust in different directions. You need the most tick over you can get as this is where the mixture is correct and the engine is happy.
On a 912 you can also adjust the butterflys separetly so bare this in mind ie:- are they opening and closing at the same time on each throttle?

Now drop the revs to a normal tick over and balance carbs again.
This is the point when you can see how worn your carbs are as it draws air and won't tick over,then revs up ETC.
Now re adjust your throttle linkage.
If your carbs are knacked you just have to settle for whats best.

There is special measuring equipment to set float levels and acc pump.
If you don't have these then the float level needle valve only has one fibre washer as standard so to check that is trial and error as this has to be done on the bench under normal fuel pressure with the glass gauge to be proffesional.

The golden rule on acc pumps is you need a tooth paste lid full on each enrichment tube after two full pumps. When we set up race cars the more the better.
Again you need the real glass measuring tube to be spot on.

All this will work if you started with the ignition timing correct and all other parts are in good condition ie:- spark plugs,leads,cap,rotor arm,dizzy is advancing correctly,all carb gaskets are sealing ETC ETC.

I hope all this helps and may the force be with you.