SFC1000 delorto carbs

A

andre

Senior member
Guys

Carbs fully rebuilt early this year as a 100,000 birthday gift. Parts replaced included slides, float needle and seat, needle jet, gaskets, o-rings, other things..

The bike ran better than when I bought it new on Sept 30, 1988.

Minor problem - bike can be left to sit for  month or two. I've had two recent instances of the carbs 'overflowing' when the gas is first turned on. Seems like the float needles arent closing off. What on earth can cause that? Old needles? Wrong flow rate needle and seats?

Your wisdom appreciated. Thanks.
Andre
 
I'm gobsmacked that your bike is 100,000 years old. Those Neanderthals were smarter than I thought.

My guess would be that fuel evaporates from your float bowls while the bike is parked for the month or two that you mention. That might leave a gummy residue that causes the float valve to stick.

Try turning your fuel off a couple of hundred metres before you get home, so your float bowls are pretty much empty when you park up. Either that or crack the flat bowl nuts briefly to drain them (with a suitable collector underneath) if you're going to be leaving the bike unused for a while.
 
Hi Andre, instead of the float valves you might take a closer look on the check valves of the accelerator pumps, sitting in the float chamber. They are feeded directly from the tank by a bypass channel in front of the float valve. In case they are not sealing properly this could cause the overflow of your float bowls. I'd guess those check valves, sitting low in the chamber, are way more sensitive for being gummed up by fuel residue than the float valves itself. If the check valves are old or show the slightest signs of corrosion just replace them right away.

Regards,
Stefan
 
When I park my Breganzie for awhile I always drain the tank remove the float Bowls from them Delorto's clean them and spray Red Rust Check into the Tank, Carbs, Float Bowls and any Orifice I see ...etc.  Plus the Cylinder Bores. Ensure your Enricher's are lubed and free to seat properly.

Actually I will spray the whole bike with Red Rust Check put her under a cotton veil when in storage.

One thing you must learn is how to dissemble a Delorto, even on a road side, look at it and be able to clean and adjust it. - As a matter of fact you need to be capable of doing this with the whole of a Breganzie Motorcycle ;o)

It's a leaning experience living with a Breganzie until you become the Doctor but most of all they like to be Clean and Lubed.
 
I've had exactly the same problem with my SFC 1000, occurring just after a carb rebuilt. The cause was the brand new float valves themselves, red rubber tips, refitting the old (black tips) valves solved the problem.
 
It's just sticky float needles, they don't do it when they're old and worn out.
It's not the tips, its the sliding surface between float needle 'flanks' and the bore, the old ones have polished in.
Happens more now than years ago, it's different fuels; as has been said, run the fuel out.
You actually don't need to run it dry, just get it parked, and run it at idle for a minute or so with the taps off (I can't help a little 'revving'  8) ) you can tell when you've got it low enough, starts running funny (funnier).

This stops any bike from suffering with sticky float needles, my Commando especially!

Some bikes are more prone than others, two strokes on pre mix for example!
 
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