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ES2 carb problem

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ES2 carb problem

Posted by ben_tomlin at April 16. 2017

I bought my 1952 plunger ES2 with an Indian Enfield carb fitted because the previous owner couldn't get it run properly with its rather worn original pre mono Amal 276. It runs perfectly with the Enfield carb but I had the Amal fully re-built (bored out with new slide etc etc) to get it back to original.  However, with Amal fitted it spits back through the carb (and backfires a bit) and only wants to run reasonably well on full choke and close to full retard.  I reckon it's running too lean and I've fiddled with mixture screw but it seems to make no difference screwed right out and raised the needle one notch from the middle one but still the same. I've double checked the ignition with a static timing light and that seems spot on (3/8" before TDC on full advance).  Don't want to go back to the Enfield carb so any ideas please?   Cheers, Ben Tomlin

Re: ES2 carb problem

Posted by robert_tuck at April 16. 2017

Fuel level too low.Wrong parts fitted . Cut a new slot on the float needle (use a hacksaw blade) set level about i/8" below point at which the carb floods.

Re: ES2 carb problem

Posted by ben_tomlin at April 16. 2017

Previously robert_tuck wrote:

Fuel level too low.Wrong parts fitted . Cut a new slot on the float needle (use a hacksaw blade) set level about i/8" below point at which the carb floods.


Thanks Robert, I'll try that!

Re: ES2 carb problem

Posted by Paul Knapp at April 16. 2017

 

Check for blockages in the carburettor, refurbished does not mean it doesn't have bits of swarf caught somewhere, missed by the assembler. If it is perfectly clean, then check the settings. First thing you need to do is establish if the fuel level is the problem. Remove the small blanking plug screw on the side of the bowl banjo and press the end of a length of clear plastic tubing over it. Run the tube up wards against the carburettor body and turn on the petrol. Observe how high the fuel rises in the tube, the level should be just below the idle mixture screw with the machine upright on level ground. Adjustment is made by changing the large union nut to either a longer or shorter one. From memory, there are 4 different lengths.

Re: ES2 carb problem

Posted by robert_tuck at April 16. 2017

If you raise the fuel level you may have to shorten the tickler ,try it with the tickler removed. You may have pilot drilling blockage and you can knock out the jet block to check the tiny pilot drillings,renew the paper gasket on the block, also check the by pass drilling in the carb body.

Re: ES2 carb problem

Posted by ben_tomlin at April 17. 2017

Previously Paul Knapp wrote:

 

Check for blockages in the carburettor, refurbished does not mean it doesn't have bits of swarf caught somewhere, missed by the assembler. If it is perfectly clean, then check the settings. First thing you need to do is establish if the fuel level is the problem. Remove the small blanking plug screw on the side of the bowl banjo and press the end of a length of clear plastic tubing over it. Run the tube up wards against the carburettor body and turn on the petrol. Observe how high the fuel rises in the tube, the level should be just below the idle mixture screw with the machine upright on level ground. Adjustment is made by changing the large union nut to either a longer or shorter one. From memory, there are 4 different lengths.


Thanks Paul , I'm bit flummoxed, maybe getting a bit thick in my old age but I can't figure out which union nut is the one you refer to........and gazing at my carb I can't see how changing a union nut can affect the fuel level in the float chamber?  Can you clarify please?  (a previous suggestion was to cut another slot in the float needle which I do understand!).....cheers, Ben

Re: ES2 carb problem

Posted by Paul Knapp at April 17. 2017

Hi Ben, the nut I refer to is the big one that screws onto the bottom of the carburettor body, to which the fuel bowl banjo is bolted to underneath. There are different lengths (heights), so by getting a shorter or longer one, it will lift the bowl higher or lower in relation to the main jet block, which is also raising or lowering the fuel level. 

One easy check to see if the fuel level is too low in relation to the needle jet is, while engine is running, lean the bike over to the right. This will raise the level in the mixing chamber and the engine will idle smoother with no spitting back through the carb. Lean to the left, as on the side stand, and the engine will falter, spit back and have an irregular idle, because the level has now been lowered in the mixing chamber.

OR, while riding, reach down and depress the tickler, this will raise the fuel level and once again, if the level was too low, this will smooth out the engine.

Just read your original post again, and the ignition timing is 5/8"B.T.D.C. fully advanced, not 3/8"as you state.

Re: ES2 carb problem

Posted by ben_tomlin at April 18. 2017

Thanks Paul, now I understand and I've just looked at the Amal website and there are 2 different lengths of union nut.  I'll check which I've got but I think it's the shorter one so the bowl is possibly as high as I can get. I've rigged up a way of determining fuel level and just waiting for some clear plastic tubing I've ordered but will try your 'tilting bike' thoughts in the meantime.  Just checked and I set the timing is at 5/8" BTDC not 3/8", old grey matter not working very well!  Cheers, Ben

Re: ES2 carb problem

Posted by robert_tuck at April 18. 2017

If when you have got it to run it needs the mixture screw nearly all the way in its likely that the pilot fuel supply is a bit too  small. Those tiny drillings in the jet block may need re-sizing ,its possible to do it with some very small drill bits that can be found on E-Bay,just go very slowly as new jet blocks are not that easy to come by. A micrometer is usefull.

Re: ES2 carb problem

Posted by ben_tomlin at April 19. 2017

Previously robert_tuck wrote:

If when you have got it to run it needs the mixture screw nearly all the way in its likely that the pilot fuel supply is a bit too  small. Those tiny drillings in the jet block may need re-sizing ,its possible to do it with some very small drill bits that can be found on E-Bay,just go very slowly as new jet blocks are not that easy to come by. A micrometer is usefull.


Thanks Robert, will bear that in mind........I restore antique clocks as well and have drill bits going down to 0.3 mm so should be able to do that if need be.....cheers, Ben

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