Monoblocs creating super rich startup

I had some great advice when I was chasing down an electrical problem with my Atlas and now I'm hoping I get lucky a second time.

I have a 1961 Dominator 99, all stock, twin right hand mono blocs, clean as a whistle, the floats are seating properly by the looks of it and it has good fuel flow and good spark. There are no leaks or dribbles from the carbs when the tap is on so I assume the floats are shutting off the supply correctly. it ran a few years ago but not well. I put it back in the storage for another day and that was a few years back.

My issue is the bike has been off the road for a few years now and is a real cow to start. Fresh fuel and oil. Most times when I pull the plugs to look they are wet. I don't tickle the carbs or see anything dribbling in so I don't know why they would be so wet. The bike has caught and run a few times but not for long. It just peters out. It looks as though the choke is on and it is getting too much fuel but there isn't a choke installed. The choke/restrictors have been removed as they were binding in the barrels and causing the throttles to stick open. (Another problem for another day)

Thanks for any suggestions you might have.


On another note.........
Doesn't help that the kick lever is so short I'm losing a lot of leverage and having to work harder with the kicks. If anyone has a kick lever that is longer than 6" and wanting to part with it please let me know.

I had an over rich problem on the right carb. Just as you describe, the plug was always wet when I pulled it, and the bike was running on the left cylinder.

The problem was a bad gasket where the jet block seats in the carb body. After replacing the gasket, the bike fired right up and ran on both cylinders. You might try replacing those gaskets. Sorry, I do not have the Amal part number for reference but can have it tomorrow.

Slick

Edit: Look here ..... part number 376/067. Jet block washer

Thanks for the info - I'll have a look first thing in the morning.

Well - the good news is after dissembling the carbs, I found both the washers in place. The ports were clean and passed lots of air through each. The needles are straight and everything went back in according to Hoyle. It started after a number of kicks and grunts, ran a little white on the left cylinder then settled down, ran for another moment, revving OK then quit. A couple of belches for all my further efforts and nothing else. When it ran it would rev up nicely but I didn't get far enough along to set the idle or air screws.
Any thoughts on where to look next?

When I had my problem with the jet block washer, it WAS in place, but looked a bit ragged. A new one in each carb solved my problem.

I would check the float level next. This is best done by taking a spare pilot jet cover, drilling and soldering in a 1/8 " OD brass or copper tube, fitting a Tygon tube to the brass tube, forming a manometer to view fuel level. Proper level is the pimple on the float chamber cover, but my Atlas likes it higher.

It sounds like you have made some progress. Are the plugs still wet When you pull them?

Magneto or coil ignition?

Slick

Have you pulled the fuel tap from the tank to check the screens?

From your description it sounds like it had been stored for a couple of years with fuel in the carbs. Is that correct?

It was always stored dry and I made sure the liquids were evacuated before hand. It is a distributor/coil ignition. I had to put on a new fuel tap as the cork in the original had dried and leaked.

I don't see any place where I can adjust the float level on the Monobloc as there's no tab to bend. I guess a person could add or subtract a washer from the inlet side? Flooding through the floats doesn't appear to be an issue here though .

The plugs are a little drier now. but if I tickle or introduce any extra fuel into the system they immediately wet foul.

Got a huge bang out of the left side during one kickover!

I was surprised to see how thin the washers were but they were in really good shape.

Do you think the air screw would have that much effect on the amount of fuel at start-up? I've tried 1 1/2 turns to start then out by 1/2 a time.

I got tired of kicking it over after about 40 minutes so I left it for the night.

It sometimes happens that somebody has fitted a washer when screwing the float needle seat into the carb body. There should not be one as it raises fuel level.

54degrees said:

It was always stored dry and I made sure the liquids were evacuated before hand. It is a distributor/coil ignition. I had to put on a new fuel tap as the cork in the original had dried and

Click to expand...

Strange things can happen where a bike is stored, even where the fuel is drained.
Did you check that the float still floats and it actually cuts off the float needle ?
If it doesn't rev at all upon starting then it may not be fuel related. Are you using old petrol and spark plugs?

The float level is set by adding or subtracting shim washers under the needle seat. As Mike40M states, adding a washer raises fuel level. There is a multiplying effect .... that is, adding a 0.020" shim will raise the level much more than 0.020".

Re: air screws - start with 1 1/2 turns out. They are not that sensitive. If all else is well, the engine will run well. You stated that air passages were clear, but it is easy to miss a clog in the tiny passages supplying the air screw.

After I stored my Atlas for 15 years ( in an air conditioned environment), I found rust in the fuel tank which quickly clogged my fuel screens.

Slick

Shake float and listen for gas inside?

Or immerse float in hot water and check for air bubbles.

I'll suggest as its magneto, you need to clean out the oil that has got past the oil seal, new seal, and check with a timing disc it fires at zero and 180 degrees exactly.

It shouldn't start from cold without "tickling" the carbs. As it does start without tickling, it suggests the fuel level is too high. I'd remove the needle holder and if there is a washer under it, remove it.

Thanks everyone! I'm heading out of town for a few days but will get back to it on Sunday. Lots of good tips to try!