Brief spluttering when revving up

[2011dandd]

Hi all

Turns out when I rebuilt my te 20 z120 I had the ignition pretty badly retarded. Have now static timed it set to 7degree BTDC as per the book I think.
It certainly pulls better and runs cooler, still have a bit of a dead spot (splutters a wee bit) as I did before when I initially increase revs. I’m guessing this is a carb dial in related issue.
Am I on the right track?
Cheers
Dan

 

[Jim L WA]

Wow, it could be carburetor related or ignition related. Did you put in new points, rotor etc. when you did the rebuild? How about checking the centrifugal advance mechanism under the plate it the distributor? If all that is good, then I guess you tried adjusting the main jet? If so, then it may just be that the carburetor just needs a good cleaning.
If you disconnect the rod from the throttle shaft to the governor linkage and rev up the engine from the carburetor itself, does it still sputter?

 

[2011dandd]

Thanks Jim I Went through absolutely everything when it was all sorted. Distributer was thoroughly cleaned and checked with new parts as was the rest of the ignition system and the carb. I can live with it. It still does everything I need it to do

 

[rustred]

open the main carb jet 1 turn and see what happens. go from there.

 

[Charles in Aus.]

I'm not too familiar with the Z engines , more so the Standard motors UK built ones.
These have a rocker cover breather pipe and valve . If the pipe is blocked or the valve is missing very similar symptoms happen . A popping , fluffing sound from the exhaust also occurs

 

[miner09]

The fuel (large knob-screw) needs adjusting. Turn one and 1/4 turns to start. Then open or close as needed. Most the times you will need to open to give more gas. Turn little at time. Pull throttle wide open at a time between adjustment until it runs correctly. If this doesn’t work you may need to clean and put a kit in carburetor.

 

[DanielW]

Not sure about the Z120, but other Continentals of the era would occasionally have their governors get a little loose and 'hyper active' after many years of wear & use. When they get like this, they open up a little too fast & aggressively when you rev up or first put it under a load, and it can sputter or stall out for a second.

I don't think that problem would be as common on the Z120 because they use a different governor than the really problematic ones (like the F162 & H260). But still worth taking a look. Watch the linkage to the carb as you go to throttle up. Does it move smoothly and cleanly, or does it whip itself open too far & aggressively for a brief second before going back to where it should be?

But it could equally be a timing/ignition issue. Often very hard to distinguish between a carb, governor, and ignition issue.