amal concentric questions

I have a bad miss when going down the road to the point that the bike wanted to quit completely. I could nurse it home at lower speeds and revs so was checking for dirt in my main jet. I have good filters on the carbs and the tank is clean. I first removed the banjos and their filters and they were clean. I'm not sure exactly how to remove and clean the main jet with the carbs on the bike. I removed the large brass screw directly at the bottom of the bowl. The bike was on the side stand and the carb on the uphill side was bone dry and dirty inside the brass screw. On the downhill side, inside the brass screw was wet (gas) and dirty. I see the main jet up inside the bowl but not sure how it comes out. Does it screw or is it a press fit? Thanks for any help on this. Jim

99% of carb problems are electrical, and vice versa.

Lets start with the basics ?
Fitted new plugs lately.
What ignition is this using.
How is your battery voltage.

Rohan said:

99% of carb problems are electrical, and vice versa.

Lets start with the basics ?
Fitted new plugs lately.
What ignition is this using.
How is your battery voltage.

Click to expand...

Plugs are good.
Ignition is early model Boyer.
Battery is gel cell reading 13.2 volts.

You have Amals ?

Mainjets screw out. Getting something under there to do that is going to be tricky ( is there a special tool ?).
Small socket drive should do it.

P.S. If carb genuinely was dry, then its not a mainjet problem, the problem is fuel is not getting into the floatbowl ?
Checked fuel flow out of the tank ?
Tried turning on both taps...

Rohan said:

You have Amals ?

Mainjets screw out. Getting something under there to do that is going to be tricky ( is there a special tool ?).
Small socket drive should do it.

P.S. If carb genuinely was dry, then its not a mainjet problem, the problem is fuel is not getting into the floatbowl ?
Checked fuel flow out of the tank ?
Tried turning on both taps...

Click to expand...

I always turn on both taps. I will check to see if that bowl is filling up.

I wonder how likely it is that there is some dirt in the main jet. I could just blow it out with compressed air with the throttle open.

There is an Amal "jet key" for this job, if you can't find one anywhere else try my webpage.

http://www.vinceandersononline.com/mm5/ ... ry_Code=FE

Vince

Blowing stuff INTO jets etc is usually not recommended.
You want to be sure its OUT, and out of the way.

Removing the floatbowls is not that difficult - remove fuel lines, and then a small screwdriver to take out 2 screws per bowl.
Lets you get a look at everything.

Dry floatbowl suggests the problem is further back up the fuel-feed chain though....

I believe the only reason I had the one dry fuel bowl is because it was the uphill carb on the side stand and sat for 2 or 3 weeks. I turned the petcock on with the access screw out of the bottom of that bowl and gas immediatelty flowed out.

Rohan when you say, "Removing the floatbowls is not that difficult - remove fuel lines, and then a small screwdriver to take out 2 screws per bowl.
Lets you get a look at everything."

I don't have a problem removing the bowls but not sure what else I would be seeing. If you are talking about getting to the jet easier and if I should remove the jet and be sure it's clear, then I'll do that next. I did blow that jet out with the throttle open

Carbs might be the problem but it also sounds suspiciously like what would happen with a Boyer ignition and intermittent current interruptions. While giving the carbs a good cleaning will never hurt you might try working through the Boyer trouble-shooting proceedure to make sure there is no problems with the ignition if that doesn't cure it. I've had two bikes that acted similarly due to faulty ignition switches not supplying the EI unit with needed voltage.
http://www.ntnoa.org/engine.htm

probably th th th thirteen . A wasp couldve climbed in the tank , down the fuel lines ( if you left the tap on ) and got stuck at the float needle . Unless it was a spider . :?

Or it might be a sticky float . Blowing down fuel line tests . The FLOAT NEEDLES should really be the rubber tipped ' Viton ' float needles , if available .

htown16 said:

Carbs might be the problem but it also sounds suspiciously like what would happen with a Boyer ignition and intermittent current interruptions. While giving the carbs a good cleaning will never hurt you might try working through the Boyer trouble-shooting proceedure to make sure there is no problems with the ignition if that doesn't cure it. I've had two bikes that acted similarly due to faulty ignition switches not supplying the EI unit with needed voltage.
http://www.ntnoa.org/engine.htm

Click to expand...

Ultimately it was a bad battery. My other bike has a newer Pazon and doesn't act like this (early Boyer) when the battery is weak. Thanks. I'll know what to expect now.

The older Boyers need close to 12 volts to function properly. New systems including the Pazon, Tri-spark and new Boyers can get by on less. I seem to recall seeing somewhere as low as 8 volts.