[harleykenn]

   My Woodsman starts and ticks over as it should,  as soon as i rev it it starts backfiring and flames from the silencer,
   carb has been off and jets cleaned, diaphragm checked, new coil lead and plug, there is no power to the ammeter, although i believe this was working when i got it eighteen months ago,  while it's ticking over i have adjusted the air screw all the way in and all the way out, makes no difference, when you rev it it still backfires with flames, plug is always sooty.

[axman88]

I'm no expert, but it sounds like it's running rich enough to be misfiring and putting enough unburnt fuel into the exhaust to result in the afterfiring, and flames.

Or, it could be misfiring due to an intermittent ignition fault, or maybe a leaky valve, but perhaps these faults wouldn't result in a sooty plug.  Again, no expert, I'm mainly here to make suggestions that can be corrected by the wiser sages, and get the ball rolling.

I think I'd go looking for restrictions in the air intake, like a clogged air filter.  If I didn't find that, I'd explore my fuel mixture.  Could it be that the float is set too high, or stuck open?

What carburetor is installed, and how is it jetted?

[Adrian II]

When you say backfiring do you mean spitting back through the carburettor or the explosions in the exhaust? If the latter, is that WHILE revving on on over-run?

From the previous posts it seems to be the stock 29mm CV carb. These were jetted to run lean from the factory, but the Woodsman exhaust as fitted by the importers is quite free breathing, it could be that the pilot jet is too lean for the exhaust, causing popping and banging on overrun. I had this with an aftermarket Mikuni carb on my Electra-X, this issue went away with a larger pilot jet (and re-sealing the exhaust pipe in the head with some bathroom silicone RTV goo just to eliminate the possibility of any air leaks).

If it's spitting back through the carburettor try raising the carb needle one notch.

All of the above assumes no Electrical faults. I think you have already been through the spark plug issue, but a Champion RN3C with a Champion non-resistor plug cap is a good combination, RN4C if you want of hotter plug. OEM plug caps aren't that good.

The stock carb isn't the best, it can be tuned up to a point, but an Amal conversion kit from Hitchcocks' is preferred by many. There are various Mikuni and Dell'Orto options available.

[Paul W]

Is the float needle sealing properly? If not if will run very rich.

[tooseevee]

   My Woodsman starts and ticks over as it should,  as soon as i rev it it starts backfiring and flames from the silencer,
   carb has been off and jets cleaned, diaphragm checked, new coil lead and plug, there is no power to the ammeter, although i believe this was working when i got it eighteen months ago,  while it's ticking over i have adjusted the air screw all the way in and all the way out, makes no difference, when you rev it it still backfires with flames, plug is always sooty.

       I'm curious what you've done & found out as of today. I hesitate to make any guesses 'til I know if you've fixed it. 

         But it seems like it's something about the pilot circuit that's hat's causing the damn thing to have explosive farts.

          You say it backfires out the exhaust with mixture screw all out OR all in? And you're saying it makes no difference in RPM with mixture screw all out OR all in?

      Will it start & idle with the mixture screw 1 and a 1/2 turns OUT? Does it then STILL backfire out the exhaust at 1/4 throttle. At 1/2?

      Is it then backfiring out the exhaust WHILE revving up? OR when you release the throttle?

[harleykenn]

Thanks for your replies, I don't think i have done anything since i wrote, the float needle was replaced, made no difference, it spits back through the carb and backfires while revving it on the stand, it can't be ridden, i'll move the needle tomorrow and keep a better check of what is happening.  Thanks guys.

[tooseevee]

Thanks for your replies, I don't think i have done anything since i wrote, the float needle was replaced, made no difference, it spits back through the carb and backfires while revving it on the stand, it can't be ridden, i'll move the needle tomorrow and keep a better check of what is happening.  Thanks guys.

     You might also check the pushrod settings on the way to getting it dialed back in.

      And jot down jet numbers & needle clip position. If the jet numbers are stock (my Snidal is downstairs, but I believe they were 25 & 110) then it should start & idle with the mixture screw out 1 and a 1/2 turns from a gentle bottoming.