Sq4 MkI- new life

[simon.holyfield]

Have you added a fuel filter? How's the filter in the Solex? Float valve? Float level?

[Gui.dorey]

I have no fuel filter. Petrol hose from the petcock into the Solex. I removed the Solex when the engine bust, and it was in perfectly working order, and just layed on the counter for a year or so. But yes, I might have to take it out, inspect and clean..

[john.bebb]

Hi Gui - you describe the symptoms which caused me to scrap the Solex & fit an Amal!!!

[simon.holyfield]

I removed the Solex when the engine bust, and it was in perfectly working order, and just layed on the counter for a year or so...

Sorry, I should have remembered who I was talking to!

The lack of power might be valve timing, but that wouldn't get worse. It does sound like it's bogging down.

[Gui.dorey]

I removed the Solex when the engine bust, and it was in perfectly working order, and just layed on the counter for a year or so...

Sorry, I should have remembered who I was talking to!

The lack of power might be valve timing, but that wouldn't get worse. It does sound like it's bogging down.

Yes, when I open the throttle. It’s fine just above tickover and then it bogs down. It starts dying and spluttering. But only when in gear. On the stand it revs fine. To me it seemed like it was a lack a petrol and going lean.

John, I know your dislike of the Solex, but with mine I never had any complaints and always ran very well. And if it was running well before, there’s no reason it shouldn’t now.

I am probably missing something after assembling the engine back together. Could also be something with the ignition, although I didn’t notice anything there. All plugs looked fine after the run.

[paul.jameson]

Problems like this under load point me to the ignition system. Tracking inside the distributor cap is a possible cause, as is a cracked distributor baseplate.

[john.bebb]

further to Paul's msg - is the retard/advance working???
... & so as we know; - is the R/A mechanical as orig...
or electronic? - similarly points as orig. or please detail#
make & model of the ign pack, thanks.

[paul.jameson]

Another one I have had to cause this was the stud on the side of the distributor having become unsoldered from the strap which runs round the inside of the distributor to the points.

[Gui.dorey]

Thanks Paul,
I’ll check the distributor to see if I find anything.

I don’t have points anymore. I have a Thorspark electronic ignition which replaced the points inside the distributor.

But further to Paul’s idea - what happens under load that causes the ignition to fail? I’m trying to understand the mechanics behind it. In other words, what happens in the distributor under load that doesn’t happen when the bike is on the stand?

Thanks,
Gui

[nevhunter]

With higher pressure in the combustion chamber the voltage required to jump the plug gap increases. Have you got suppression leads?