3c carbs

Dellortoman said:
Having said that, I'm still not sure why Chris isn't using the enricher jet for cold starting.
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Exactly what I mean.. ;)

All his queries tell me he's running around in circles, not knowing where to start or what to do, hence my very basic advice.

Many think throwing their carbs into the ultra-sonic tub will magically make all the issues disappear. These instruments are now the best part of a half-century old and usually require quite a lot of TLC before they'll even work half-decently. Not knowing the working principles of carbs does not help either. There's a legitimate reason why so many junk the Dellortos in favour of a set of Mikunis.

Even if the engine starts on the enrichener, it will shut down immediately if the idle/starting circuit is blocked and/or the float heights incorrect, unless revs are already sky-high and running on the main circuit. It doesn't NEED the pumps to start. In fact, it doesn't need the pumps at all, but if they're there, they may as well be made to work properly.

piet
 
For what it`s worth there seem to be two issues both relating to the middle carb , starting circuit and pump,not neccessarily related. I wouldn`t have thought the lack of squirt from that carbs` pump would prevent starting,so the problem there lies within that carbs` starting circuit , although I would still expect it to catch and attempt to run on the two outers.
My starting procedure is throttle shut,starter motor on and a slow introduction of the "choke" lever to bring the starting circuits into play , the pumps wouldn`t really come into it.
I didn`t disable the pumps completely like Clem , but I did adjust them right down to a dribble rather than a squirt so to speak,actually in a not very successful attempt to improve mpg !!! ,but as he says no difference in general running as far as I could detect.
 
Dellortoman said:
Not completely independent, as explained above.

If he has to prime the middle carb with a spray bottle to get it to start, he could do the same thing with the accelerator pump if he can get it working. Chris, as Bob Sol said in the second post. Sometimes you need to prime the accelerator pump chambers to get them working after a carb strip down. You only do it once and they should be OK until next time you take them apart.

Having said that, I'm still not sure why Chris isn't using the enricher jet for cold starting.
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If he has to squirt neat petrol in it to get it to cough, it's because the idle circuit isn't delivering, so, check jets and idle passages and float level.

Paul
 
Paul Marx said:
If he has to squirt neat petrol in it to get it to cough, it's because the idle circuit isn't delivering, so, check jets and idle passages and float level.

Paul
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I would have thought if neat petrol is needed to get it to start it`s the starter circuit and jet that isn`t delivering,not the idle circuit and jet which is a different thing altogether.
It`s the starter jet that provides the enrichment to help it start , not the idle jet , although you would inspect everything once you were inside there obviously.
 
Yes. But even with the choke on, the idle circuit is delivering fuel for start up. Both would need to be functional. The choke is only an enricher of what's already there.

Paul
 
Paul Marx said:
Yes. But even with the choke on, the idle circuit is delivering fuel for start up. Both would need to be functional. The choke is only an enricher of what's already there.

Paul
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Yes I guess thats right,you would need all systems operating properly,not just one or the other.
The only answer is for Chris to get in there and have a look , which I suppose he will do eventually.
 
If it starts coughing on the enrichener circuit but doesn't catch, the idle circuit is at fault. Not enough vacuum at cranking speed to recieve fuel from the idle jets, either because fuel level is far too low in the bowl or jets/passages are blocked.

A friend had recently "overhauled" his triples' carbs, went through the ultra-sonic 3 times, cleaned them inside out, clean enough to eat from... didn't want to start, not even on the enrichener, not so much as a hiccup. A squirt of brake cleaner got the thing coughing with a short stumble. Removed the carbs to find clean but knackered float valves, needle jets, jet needles, pump diaphragms and pump valves. Float height was around 22-23mm. Rectified float heights, fished out the last crumbs of debris from 2 of the idle circuits and the bastard started immediately. All it now needs is a proper going through with a handfull of new bits.

Reckon Chris will require much the same, just like about 98.7% of all Dellortos that find their way on my workbench. Could state "100%", but there has been an occasional exception.

piet
 
Have to love the "character" factor of the Dells, asking a lot for them to be working for some 40 to 50 years, right on the money Piet. FWIW, on all my Laverda and customer Laverda ( think the spell checker needs a dose of ultrasonic cleaner, running a red line under my Laverda...wince ), turn off the pumpers ie backing out the stroke/metering screw on the diaphragm. Unatomized fuel into the intake had a lot more to do with the bosch ignition than best practice for metering fuel, cold crank starting moreover. The experienced here know the background, as to the original operation of carby/ignition interactions and original factory setups. BTW it took me 12 hours to "clean" a triple carby bank, including the cost effective sealed rebuild kits, money well spent whatever the cost. j. *** may have been turn the stroke set screw all the way in to limit the "pump" action, correct me please as to correct method.
 
Chris looking at your original post , just wondering when the engine does eventually
start will it then tick over reliably and pick up ok from there?
You could also just try using the pump adjusters to even out their action.
 
I'd agree it sounds like there is probably more than one issue going on here. But regarding the pumps themselves, my experience is that even if the rest of the carb is perfect and the they are visually ok, no amount of priming will get stiff old pump diaphragms to work properly. New diaphragms fixed it for me when all else was good.
Good to hear from you John!!
 
Tah, Mr SB, do you always look that alarmed in your crash lid??, maybe a stock SF1 just overtook you on a bend.... a grin here.
 
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