Dellorto help

[mach1mustang351]

So here is the deal. For the past 3 days I have been trying to take my 1000SP on its maiden voyage. The problem is it wont run on the right cylinder. The basics have been checked. It has 150lbs cranking compression, and a good solid spark. The cylinder runs when the choke is on and doesn't contribute when it is off.

The carb had been overhauled earlier this winter.  when this problem was encountered I tore it down again, soaked it in carb clean and blew it out with air again. No change. Convinced I still had a plugged idle circuit I tore it down again and ran it in an ultrasonic cleaner.  I reassembled and still same issue. The cylinder fires with the choke on, but wont run without it.

I would appreciate any help on this. I am still convinced it is a carb issue, but I may be over looking something. Please help!!

[guzzisteve]

Swap the carbs around L to R to be sure.

[Antietam Classic Cycle]

You may still have a plugged idle circuit. If either of the holes in the carb throat are not flowing, then it will have the effect you describe. Hold the carburetor so that you can see down the throat. Squirt aerosol carburetor cleaner in through the mixture screw hole while covering the the idle jet hole with a finger. You should see the cleaner squirt out of two holes on the bottom of the carb throat, forward of the slide area. Do the same again except cover the mixture screw hole and squirt the cleaner in through the idle jet hole. You should see cleaner squirt from the same two holes.

(photo courtesy of Greg Bender)


BTW, my favorite aerosol cleaner is Berkebile 2+2 Gum Cutter, nothing else even comes close. I also use undiluted Super Clean in a spray bottle to clean carb parts - spray it on and down into every orifice, scrub with a toothbrush, flush with hot water and blow dry. Super Clean removes gasoline gum and varnish better than almost anything.

If you've not already seen this carb rebuild tutorial, it might be helpful:
http://www.thisoldtractor.com/moto_guzzi_loopframe_carburetor_rebuild_-__vhb.html

[nunzio]

air leak around manifold or the screws for the carb balancing ports?

[Chuck in Indiana]

air leak around manifold or the screws for the carb balancing ports?

Could be, but I'm with Charlie.

[JoeW]

Check the choke plunger seal,  it may not be sealing anymore allowing too much fuel. I've had these get hard and leak so often that I'm replacing them on almost all rebuilds.

[mach1mustang351]

Thanks for all the help everyone. I went the super clean route since I had some of that in the garage. I then threw it back in the sonic cleaner. I then rinsed it with warm water. I was sitting on the couch blowing into the idle jet passage wondering how much blowing resistance I should have, when all of a sudden, it was way easier to blow through it. I went out to the garage and did Charlie's test and i got some light sprays out of the hole nearest to the carb throat, then both started spraying clear!! I am confident that there was an issue there and we have at least made it better. I was about to assemble and run it but my choke lever o ring tore and i need to hunt one down tomorrow. Does anyone know of a non Guzzi dealer o ring that will work?? Anyway, thanks and I'll post when it runs on both cylinders.

[Vasco DG]

The accelerator pump assembled wrong? Just a suggestion.

[mach1mustang351]

I reassembled the carb last night and ran it this morning.  It works!!! It pops through the carb a bit and runs a little rough but at least I can work on straightening that out now.  The right cylinder is alive!!!