3c carbs

C

Chrisninja

Junior member
Location
Essex
Hope everybody had a great Christmas just new year to get through know .I managed to get in the garage today and after ultrasonically clean the carbs I now have a problem starting it .the accelerate pump works well on left carb right carb not so well middle carb nothing everything cleaned and blown out but will only start if a squirt petrol in the rear of carb other than the obvious blocked somewhere anyone tell me how accelerator works .has anyone else experienced this problem
 
Hi Chris
You need to prime the pumps. Remove the brass plug on top of the plunger, carefully fill the chamber, refit the plugs and off you go.
Enjoy Bob
 
Replace diaphragms along with both 2-way valves that are involved with the pump. If, and that's a very BIG if, if EVERYTHING is clean and un-clogged, the pumps will start working after 3-5 strokes. No need to prime, just get it all in working order. Actually quite simple.

Chucking them in the ultra-sonic tub guarantees nothing. Just 'cos "it looks OK" also won't guarantee that anything will work.

There's also threads a mile long on the subject.

piet
 
I think that's the problem I only have one carb that really pumps a jet into engine one that dribbles in and one that dosnt do anything
 
my triple has had disabled pumps for more than three decades, it starts just fine, hot, cold or warm. In fact it starts when warm or hot without "half choke" which seems to be needed by most triples and I fundamentally state that IMHO this is wrong. If it is jetted correctly the choke will only be needed to enrich the mixture for a cold start.

silly old Cam, you know better than that!

I suspect the carbs have been cleaned but not stripped, every removable part should have been out. The pumps work via a bell crank in the top of the bodies wich is activated by a ramp on the slides, this bell crank then presses on the diaphram which moves to suck the fuel up from the bottom of the float chamber (NRV) and eventually through the finest of jets, which can be accessed externally from the carb bodies via the biggest brass screw that you can detecet, this jet has a "flat" on it, when installed to ensure correct orientation of the jet, it would be no good if it sprayed anywhere other than into the carb throat. You would know that if you had stripped completely the carbs, and would not need to ask how the pumps work. "anyone tell me how accelerator works" presumably that meant the pumps not the throttle twist grip.
CLEM
 
CLEMTOG said:
silly old Cam, you know better than that!
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What's silly about it? I know plenty of people with pumper carbs who give the throttle a few twists to squirt a bit of raw fuel into a cold engine before hitting the start button. I do it myself on occasions. It's just another way of enrichening the starting mixture.

It does exactly what Chris is doing when he sprays fuel in with his little spray bottle.

There's more than one way to get a rich mixture for starting. Some bikes have actual chokes that blank off the air, some have enricher jets, some have ticklers, some have accelerator pumps that can be used for priming. Some (like Dellortos) have more than one of those options.
 
sfcpiet said:
He's complaining his pumps aren't working. And that the bike won't start. 2 completely independant issues.
Click to expand...
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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