Cleaning a Crusty Dell'Orto Carburetor

[blaat!]

Anybody found a sure-fire risk free way to clean a carburetor that has been all "crudded up" and out of service for years and years? I have it partially disassembled, but the slide is stuck, the slide cap will not thread off, and the float bowl cap will not thread off. I have repeatedly soaked it in Berryman and sprayed it off with carburetor cleaner. I have sprayed it with penetrating oil and left it for days. I'm now trying Kano Kroil. I'm in no rush and I prefer to avoid ham-fisted force methods. I have read up on people boiling the carburetor for an hour or so in a vinegar/water solution or water with a little bit of laundry detergent. Anybody ever try that? I have someone local (Massachusetts) that does ultrasonic cleaning. Anybody ever had that done? Does it do an amazing job, or just so-so? Is there any risk of damaging parts with ultrasonic cleaning?

Thanks!
-Jim

[MotoMike]

Hi Blaat

I used to use a cleaner that came in the gallon bucket with a parts basket inside that you put all the parts in and left it sit overnight. The stuff I used 25 some years ago cleaned all metal to bright and shiny. There are several that follow this theme, but I think government regulations have taken the bite out of this stuff as it has many other chemicals we used to use. maybe someone else knows.

http://www.autozone.com/autozone/access ... ier=139313

[wcorey]

An ultrasonic can certainly help, particularly in conjunction with a good heated cleaning solution, though it's still far from a sure thing. I've never seen anything damaged by one even with extended use.
Be careful of leaving the carb in acidic stuff like vinegar for too long (like overnight), it can really etch/pit the surface, especially if there's a lot of oxidization present.

Bill

[machten]

I've used sonic cleaning on dellorto's for twins many times. It works really well but you need to be concious of the contents of the bath. My experience has been around the the carb being totally dismantled and the primary aim was to dislodge fuel junk from passages rather than "break" contact surfaces.

It is a very good process and totally gentle unless you use solvents in the bath that are agressive to ali alloy. So, for example, you can use dishwashing liquid as a wetting agent to get liquid between surfaces. (good way to start). There are production liquids that are progessively more acidic and agressive. For these, you need to monitor in real time and take them out of solution as early as possible.

Have a look on youtube, there are some good vids of the process.

Kev

[double diamond]

On the float bowl, there's an 8mm bolt on the cap that locks the cap to the bowl. Loosen this bolt a little (don't remove it). If you remove the fuel banjo, there's a hex on the threaded inlet that allows using a socket instead of just gripping the knurling on the perimiter of the cap. Try heating the bowl a little with a propane torch (don't get carried away). Try heating the mixing chamber cap a little as well. Make sure you don't have a broken off retaining clip in the cap. If the slide is stuck, heating the carb body a little might help. MW

[blaat!]

Thanks all. I got the slide cap off with a strap wrench, but the slide is still stuck. I'll have a look at the banjo hex to see if I can use that to get the float bowl open. For now, I'm just cycling back and forth between cleaning it and soaking it with penetrating oil. Don't really need patience with a basket case as there are always hundreds of other parts to work on in the meantime

[blaat!]

You're a genius Double Diamond. The hex on top of the float bowl cap worked perfectly. I ran the battery down on my impact gun so that it wouldn't be too powerful, put the 12mm socket on and viola! it came off in just a few seconds.

These are the items left to remove:

1. Stuck slide - time, patience, solvent, and last resort will be ultrasonic cleaning.

2. Velocity stack - This is aluminum on aluminum threads... may require some judicious heat on the carb body.

3. Jet - It looks slotted with no center. My experience is that this type of thing can strip easy. Any suggestions on getting this out?

4. Choke slide - I still have a piece of the cable hanging out. I'm hoping to get it freed up with solvent and pull it out.

Thanks!
-Jim

[double diamond]

The slotted jet you're referring to is called the "atomizer holder" in the dellorto exploded drawing. You'll round the slot very easily if you don't have the right tool. The trick is to make a tool that's exactly the width and length of the slot so it won't move at all when you apply torque to the jet. I used a large impact driver bit that fit into a 1/2" drive holder and ground it to the correct dimensions. You can then use a T-handle or ratchet to turn the tool. A really nice tool would be a piece of rod the diamete of the I.D. of the jet threads with the end machined to fit the slot. Someting like this wouldn't move around at all. Clamp the carb body solidly in a vise by the spigots (you'll have to get the stack off first) in such a way that it won't move and and position a wood block underneath (against the cap threads) so you can push down hard on the tool as you turn it. If you keep the tool engaged all the way into the slot and press down hard as you apply torque, these jets will come out without damage. Heat and penetrating oil as required. Once you get this jet out you might be able to fashion a metal tube to slide over the needle and tap the slide out from beneath. The slide has a tapered projection on the underside that the needle fits into so this tube would have to be of a larger I.D. than the O.D. of the projection. I'll have a look at a disasembled carb and see if this approach would work. By the way, I believe you've identified your model as a Mach 1. Is the engine number on your cases a DM250M1 number? MW

[blaat!]

Awesome, great info. The carburetor wasn't cheap, so I'm trying to disassemble and rebuild without causing any damage. This is my first rebuild on a Dell'orto.

The engine has DM250M1 on one case half and the other half has a number that looks like an east coast zip code (five digits...0-1-8-something-something, I don't remember off hand).

Thanks for all the help!

-Jim