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Dellorto DRLA accelorator pump issue
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demon1018
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PostPosted: Mon Oct 10, 2016 11:33 am    Post subject: Dellorto DRLA accelorator pump issue Reply with quote

Ok found out that one of the accelerator pumps isn't working so I took it apart, cleaned everything then put carb cleaner in the bowl and hit the throttle and it squirts up into the bowl instead of out the nozzles. I believe the pump non return valve is bad but it doesnt look like much. Just a ball inside a little jet like piece. Is there suppose to be a spring pushing the ball down inside there or something? The other carb seems to be working so I will get that one off shortly just wondering what I'm suppose to be looking for
Thanks!
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esde
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PostPosted: Mon Oct 10, 2016 3:05 pm    Post subject: Re: Dollorto DRLA accelorator pump issue Reply with quote

yes it's just gravity, no spring. I'd pull it out and look it over really well to see if theres some deposits or grit holding it open. The only time I've needed to replace them is if they get destroyed during removal, so it's likely that its just dirty.
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Vw1600dellortoGR
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PostPosted: Mon Oct 10, 2016 3:13 pm    Post subject: Re: Dollorto DRLA accelorator pump issue Reply with quote

I had the same issue , there was some dirt under the ball not allowing it to seat properly .
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Dougy Dee
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PostPosted: Tue Oct 11, 2016 5:58 am    Post subject: Re: Dellorto DRLA accelorator pump issue Reply with quote

There should be a piece of brass rod, about 5/8" long, holding the ball down.
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esde
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PostPosted: Tue Oct 11, 2016 2:42 pm    Post subject: Re: Dellorto DRLA accelorator pump issue Reply with quote

That's the second check valve, there's one up by each nozzle under the brass screw. I'm pretty sure he's talking about the first check valve, which is threaded into the bottom center of the float bowl
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Hustlers67
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PostPosted: Thu Feb 23, 2017 2:15 pm    Post subject: Re: Dellorto DRLA accelorator pump issue Reply with quote

I have a separate issue with the accelerator pump mechanism on my DRLA 40s.

Thought it best to put it under the same thread heading.

I have disassembled these, put a kit through them changed jets to better suit my engine size, checked the float etc. I'm now running a bit of fuel through them before bolting them up to the heads.

When twisting the throttle, everything is smooth and appears fine, but at full throttle it pushes the accelerator pump rod, but at no point does it actuate the acc pump lever - which means I get no squirt! I have manually pushed on the accelerator pump lever, and I get a good squirt of fuel down to the main barrels.

I haven't played with the rod adjusting nuts or the spring. Is my spring too soft? Or could it be something else?
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mcdragracer
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PostPosted: Thu Feb 23, 2017 11:14 pm    Post subject: Re: Dellorto DRLA accelorator pump issue Reply with quote

Can we get a pic of your spring?
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Hustlers67
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PostPosted: Fri Feb 24, 2017 6:33 pm    Post subject: Re: Dellorto DRLA accelorator pump issue Reply with quote

Yeah, here are a few shots of each carb. I'm still new to this whole playing with cars stuff in that I have never handled a pair of carbs until these two.

The throttle twists, pushes the rod, but the way I see the pump lever working is that where it meets the rod, it needs to be pulled in, under the carb, not pushed out, so the top part of the lever (in the middle of the acc pump) pulls away from the center of the carb?? I cant seem to push the pump into the carb - is it supposed to? I think I'm missing something really obvious. ?

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mcdragracer
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PostPosted: Fri Feb 24, 2017 11:14 pm    Post subject: Re: Dellorto DRLA accelorator pump issue Reply with quote

Turn the pump rod nut clock wise until the steel part of the diaphragm with the slot in it is level with
the pump cover exit hole, looks like it needs about a 1/16 of an inch in movement.
Also do you have the proper pump spring?
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Hustlers67
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PostPosted: Sat Feb 25, 2017 12:06 am    Post subject: Re: Dellorto DRLA accelorator pump issue Reply with quote

I have the wrong spring?
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mcdragracer
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PostPosted: Sat Feb 25, 2017 2:27 am    Post subject: Re: Dellorto DRLA accelorator pump issue Reply with quote

The stock spring is a soft pressure spring, If for some reason you have a super strong spring under the diaphram it might not compress, from what im understanding if you manually move the lever if functions and squirts normal, so my thoughts are you dont have enough
throw at the lever to operate it, thus turning the adjust screw clock wise will give you more
throw and travel on the pump lever.
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mcdragracer
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PostPosted: Sat Feb 25, 2017 2:35 am    Post subject: Re: Dellorto DRLA accelorator pump issue Reply with quote

As far as Demon 1018 question, what your refering to is the intake jet valve at the bottom of the float bowl, there is a ball inside, no spring, the ball should be free inside, remove it and shake it, it should just rattle inside, if it doesn't, spray some carb cleaner in it until you free up the ball, there also needs to be an oring on the intake jet valve, make sure its not missing, that could be your problem also.
If that is all good, you couild have a problem in your passages where the delivery weight and check ball are located, the ball and rods could be stuck or gummed up.
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Hustlers67
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PostPosted: Mon Feb 27, 2017 11:30 pm    Post subject: Re: Dellorto DRLA accelorator pump issue Reply with quote

mcdragracer wrote:
, so my thoughts are you dont have enough
throw at the lever to operate it, thus turning the adjust screw clock wise will give you more
throw and travel on the pump lever.


Thank you. This has helped. I've turned the nut in about 3-4 turns. I'm getting a squirt now. I'll keep playing with it, but am back on track. Cheers.
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mcdragracer
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PostPosted: Tue Feb 28, 2017 11:49 am    Post subject: Re: Dellorto DRLA accelorator pump issue Reply with quote

Applause
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