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914World.com _ 914World Garage _ ATTN: Carb Experts!

Posted by: jr91472 Apr 1 2006, 07:30 PM

Ok, this winter I bought a pair of used Dellorto DRLA's, rebuilt them with all new gaskets, o-rings, etc. I put them on the motor and today started it up for the first time.

I will get to the point: On one of the carbs, fuel from reservor drains into one (only one) of the barrels and collects on the butterfly (i.e. makes a puddle and produces a rather rich mixture ).

I spent most of the afternoon troubleshooting this and call tell you that even with the motor off, once there is fuel in the bowl...it drains out and into one on the barrels. With the carb still on the motor, I cannot tell exactly where the fuels is entering the barrel, but it seem to be near the bottom (like one of the holes near the butterfly). While cleaning them, I didn't notice any cracks or wear,

I will be pouring over my Dellorto manual tonite and probably take the carb off the motor in the next day or so and go through it completely. But I thought I would see if anyone had any thoughts.

This is my first dual carb experience, so be gentle and thanks in advance.

Posted by: tat2dphreak Apr 1 2006, 08:06 PM

did you check the float adjustment? I had a similar issue on my webers... turned out the float was adjusted wrong and would overfill...

Posted by: jr91472 Apr 1 2006, 08:17 PM

That was my first thought too. But if I simply pour some gas into the bowl till about half full, its starts flowing into the barrel.

It is coming out right above the butterfly, so Its not the idle port (which is below the butterfly), has to be the progression port right??

I got a bad feeling

Posted by: So.Cal.914 Apr 1 2006, 08:46 PM

That bad feeling is the money you are going to have to pull out of your butt, for a set of webers. Crack detector is a dye you can mix with some fuel, it will tell you exactly where your leak is.

Posted by: rhodyguy Apr 1 2006, 10:19 PM

the fuel is running out of the little tube directly above the butterfly? the accelerator pump jet? i always ask. what kind of fuel pump and/or regulator are you using?

if they were webers i would suspect the accellerator jet rubber diaphragm and the related pump jet fuel circuit.

k

Posted by: olav Apr 1 2006, 10:34 PM

I had that kind of issue with my Webers. One of my needle valves was stuck open. Cleaned it out and problem solved for me.

I don't know if Dellorto's have needle valves.

Posted by: mikelsr Apr 1 2006, 10:36 PM

I don't have my books in front of me but IIRC there is a check valve at the bottom of each float bowl. Check them to make sure they are loose. I'll look at my book in the AM.

Mike

Posted by: jr91472 Apr 1 2006, 11:56 PM

QUOTE (rhodyguy @ Apr 1 2006, 08:19 PM)
\what kind of fuel pump and/or regulator are you using?

I am using one of those rotory fuel pumps from CB. Got rid of the Fucet (too loud).

Thanks everyone for the ideas.

Posted by: jr91472 Apr 2 2006, 12:07 AM

QUOTE (mikelsr @ Apr 1 2006, 08:36 PM)
I don't have my books in front of me but IIRC there is a check valve at the bottom of each float bowl. Check them to make sure they are loose. I'll look at my book in the AM.

Mike

hmm, check valve?

I have a accel pump valve at the bottom of the bowl, but it is one per carb.

Also I have a Progression Port Inspection screw (2 per carb / 1 per barrel). But there isn't much instruction in my book about these.

thanks for looking into it

Posted by: mikelsr Apr 2 2006, 10:25 AM

I attached a jpeg. If you look at the circled (in red) part 30, intake valve. IIRC inside the intake valve is a metal ball that acts as a check valve. I took mine competely apart last year soaked everything and make sure that check ball was loose.

Mike

Attached image(s)

Posted by: Jake Raby Apr 2 2006, 10:36 AM

You have "Dellorto Drip", undoubtedly. Its an internal leak of the fuel passages arond the internal lead plugs.

It is repairable and Art Thraen at Aircooled Engineering in SLC Utah is the man.
Tell him I sent you.

This is common and can be fixed for a couple hundred bucks. Dellortos spank the pants off of Webers- I love them.

OK, back behind the curtain I go- see ya

Posted by: jr91472 Apr 2 2006, 03:21 PM

QUOTE (Jake Raby @ Apr 2 2006, 08:36 AM)
You have "Dellorto Drip",

Can't they just give me shot or something

Seriously, thanks for the tip Jake. I will monkey around with it some more but probably call him on Monday. Beats starting over.....

Posted by: mikelsr Apr 2 2006, 04:51 PM

I hadn't heard that about the carbs. Thanks to the man who won't be on the non-club this month...

Mike

Posted by: jr91472 Apr 2 2006, 05:41 PM

Mike, I checked the input valve per your advice, unfortunately the little ball moves freely.

Looks like I got the drip. At least its repairable.

Posted by: jr91472 Apr 4 2006, 01:24 PM

Just an update for future "Dellorto Drip" victims.

I shipped my Dell 40 off to Aircooled Engineering for repair. Quoted repair price of $65.

wish me luck