Engine dies when stopped - Clutch?

Hi all,

I’ve tried so many things to get this fixed, but no luck. Moped is a 1979 Puch Magnum MK II-ZA50. So I’ll start with the top where problems all started:

I swapped the transmission fluid, it came out thick and was grey in color (almost looked like liquid clay).

I put in 10W-40 and bike started-no problem, but at stop signs would stall out on me.

I then tried ATF (but could only find CVT fuild). Same issue as above.

I’ve tried upjetting the carb, actually swapped the rear axel to sealed bearings, played with various idle setting and have ensured consistent fuel flow.

I do have proper type F oil, and lucus oil additive if needed, but before I go trying more oil types I wanted the forums thoughts on this.

The bike shifts into 2nd without issue. This is very annoying for me so any thoughts here are appreciated.

Re: Engine dies when stopped - Clutch?

clean air filter m exhaust n put the og jet back in.

Re: Engine dies when stopped - Clutch?

Jordan Carter /

Well I took apart the carb (bing 14mm), the clip on the pin had gotten bent and the pin/needle was not properly engaged. Challenge is that it's still not running properly. I do think it's an issue with fuel/air mix though not the clutch.

Best performance at WOT and acceleration seems to be a 74 jet, but I cannot get the idle to function properly. I'm thinking it's possibly a bit rich at idle so I'll try lowering the pin a notch.

Honestly I have no idea how to get this thing tuned in. There's just so many variables at play on these old bing carbs. I can't even really tell when it's lean or rich - any suggestions for tuning in the idle?

Re: Engine dies when stopped - Clutch?

74 on a stock jug? huge

Re: Engine dies when stopped - Clutch?

Jordan Carter /

Setup is a 50cc stock za50 motor with a high flow (metal mesh) air filter, bing 14mm, and Boss exhaust.

What would folks suggest I jet at? (edited)

Re: Engine dies when stopped - Clutch?

Dan (high idle) Conway /

I jetted my e50 with same setup at 66... you’re probably gonna be around that. ive also got that needle set 3rd setting up.

Re: Engine dies when stopped - Clutch?

Drake Abrahamsson /

This helped me quite a bit. Hope you haven't seen it already so this isn't redundant!

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