R/E, WD/CO Running weak

[gary0003]

The only original parts of my Type 276 carb are the carb body, the Jet Block and carb top and yet no matter what I do it still runs very weak and dies if I open the choke more than half way. I have fitted a larger main jet, but this has had little effect. There doesn't appear to be any air leaks at the head so I suppose I will have to replace the the parts mentioned above?

[GeePig]

I am not familiar with that carb, but is the float height set correctly? How are you checking for it running lean, by checking the spark plugs?

 

Carb problems can be quite tricky, but I reckon we can solve this

 

trevor

[Richard Farrant]

The only original parts of my Type 276 carb are the carb body, the Jet Block and carb top and yet no matter what I do it still runs very weak and dies if I open the choke more than half way. I have fitted a larger main jet, but this has had little effect. There doesn't appear to be any air leaks at the head so I suppose I will have to replace the the parts mentioned above?

 

Gary,

Check the carb flange, you often find these have been over tightened and with a soft gasket, they end up bowed. Put a straight edge (steel rule on edge from hole to hole) or place on a surface plate and check with feeler gauges.

[matchlesswdg3]

Another thing to check, which is allied to checking that the carb float is set up correctly......ie correct level......is the fuel supply to the fuel bowl in which the float sits. If you have any blockage or partial blockage in the fuel lines or taps, then of course you will get the fuel starvation problem. Fuel filters need checking if you have one fitted in the supply tube or as "top hat" mesh filters fitted on the inlet side of your fuel taps.....unscrew these from the tank and inspect. This is a common problem with rust flakes or old tank liner material which is attacked by ethanol in the petrol. If the latter is the culprit, you need to take off the tank and get the old liner out......and if needed, reline with the new generation ethanol-proof liner gloop. This happened to me, with the old liner deciding to slough off when I was riding to a show! The engine gradually died but restarted after five minutes, only to die again after another 200 yards......as the part blockage allowed the float chamber to fill when the engine was not running, but could not sustain enough flow when the engine got going. Needs sorting, though as lean fuel mixture is bad for pistons! Good luck!

[matchlesswdg3]

Finally.....forgot to say....under the jet block on the 276, there is a tiny drilling that must be clear......and that can block. So have a careful look and check against a 276 carb diagram.

[Chris Hall]

There's so many possibilities with the 276. Have you got a 1A float bowl? Is the needle in the correct groove? Is it the correct Union (This effects float height)? Is the bore of the body worn (Air can be sucked in past the throttle slide even a new slide). This is only the start!