55 plunger spitting fuel

[Drew Back]

I just got my plunger going with a brand new 276 carb with stock jets (1955 Plunger) It starts real easy but idles really rough and seems to be spitting a lot of fuel out of carb and turning pilot screw does not seem to help any..It idles real nice just before it runs out of gas??Could this be a float adjustment??

[beezermacc]

I'm guessing your spark plugs are black? Maybe the float needle isn't working as well as it should. Does it run OK at mid range and wider throttle openings? If you leave the petrol tap on does the carb flood?

[Rgs-Bill]

If they run really good just before running out of fuel, they are usually overly rich.. If they run worse just before running out of fuel, they are usually overly lean.  If turning the pilot screw has no affect, the idle circuit is not operating properly.
   Go to     porklips.org/~masonmotoamalspecshtml      Not sure if they list the 55 plungers in there, but you could get some Idea for a carb jetting starting point.
  Another place to go on the web is Motorcycle Carburetor Theory 101, some good general helps here also. A lot of spitting back through carbureter usually equates, but not always, to timing setting, or Ignition or magneto problems.

[Drew Back]

Its not really spitting out of carb just seems to be dripping a lot out. I am running strait pipes for now took it for a ride and it ran strong just a lot of gas coming out of carb then got a flat tire so I guess im done for today..

[terryg]

I'd definitely check the float setting and that it shuts off. Even new carbs can require adjustment. Best not to assume that 'new' means 'correctly adjusted' and I must remember that soon when replacing a Monobloc.

[muskrat]

Yep, sounds like float height to me as well. No change on pilot screw adjustments mean a blocked pilot OR the fuel level is too high and sucking up extra through the needle jet.
Cheers

[Gavin]

Hi Drew hope the bike is back and running again soon.

Joining the thread and taking it in a slightly different direction, as I am doing up a 55 plunger. Should it have a 276 carb or a monoblock, or is this an issue like many others where there was some variety in the year model anyway?

As well as that, which of the 2 is the better carby and why?

Thanks

Gavin.

[Drew Back]

I learned the hard way Monoblock wont fit because of frame clearance issues/no clearance at top some guys run concentrics with no problem I decided to go with the 276 for originality and forget about using a choke I think that is because I have the thick flange jug..I am completely new to these every step is a learning experience Im lucky to have access to all the knowledge on this forum

[Greybeard]

I am doing up a 55 plunger. Should it have a 276 carb or a monoblock...?

My '55 plunger has a 276 that I believe is original. The bike runs very well. I have a modified K&N air filter element in the original housing.

[Drew Back]

I went through cleaned out completely tried again samething i did discover a head gasket leaking pretty good and i suspect timming was off so now everything torn appart wont get back together till weekend could bad head gasket or timming be the culprit..

[Drew Back]

Got everything torn appart and redone reset timmining cleaned carb checked float all looked good new plugs and now it refuses to start even with swapping plug wires I do have a nice bright spark but it does not seem like plugs are getting wet..I do get gas dripping from the jet block overflow..I have the pushrods adjusted at 10 for intake and 16 for exhaust thats what my book said by this time im totally out of ideas ready to put a free poster on her just to get it out of my sight..I did not do compression test as the valves are opening and closing..

[beezermacc]

If the plugs are bone dry I suspect a carb issue. To check that the plug wires are connected correctly..... take both plugs out..... turn the engine over slowly with your thumb over one of the plug holes and feel for compression......... when you can feel compression bring that cylinder up to t.d.c. ....... take the points cover off the magneto .......... observe which pickup is nearest to the heel of the points  ... make sure that the pickup nearest the heel of the points is wired to the cylinder under compression.  Double check by removing the pickup and looking in the pickup window with a small mirror and you should see the brass strip on the slip ring.

[wilko]

The new monoblocs are knownj to have a washer under the the needle and seat holder which shouldn't be there. Is this the case with yours?

[muskrat]

Don't dispare Drew. It will be something silly like an air leak at the flange/drip tray.
276 wilko.
Cheers

[Drew Back]

Wilko are you talking under the float needle for this washer or by the jet block itself..I went ahead and checked timming last night and it seemed good got the plug wires the right way did check the slip ring to make sure then ran out of time might try to fire her up tonight if we dont get a snow storm can you send me a pic of where that washer is not supposed to be that would be greatly appreciated..