rtn9105

My Feedback: (35)

I have a Sachs 33cc gas engine with a C&H electronic ignition and a Walbro carb. The engine runs great at idle and it runs great at full throttle. It even runs very good if I throttle up from idle to full throttle very slowly but if I go from idle to full throttle quickly the engine dies.
Does anyone have any idea what might be causing this to happen and what can be done to correct the problem?

F1race79

My Feedback: (6)

Open up the low end.

rtn9105

My Feedback: (35)

I had thought that also but the low end needle is already 2 1/4 turns out, do you recommend opening it farther than that?

Tired Old Man

My Feedback: (1)

Just for the heck of it, try closing it down to about 1-1/2 turns open, run the motor, and possibly take it down a tad more. See what happens.

Geistware

My Feedback: (16)

If you have mechanical advance, check to make sure it is right.
Usually a poor midrange just needs to have the low in set richer.
I am not a gas engine guy, but have learned a little over last couple of years.
Also check the plug gap. If I remember correctly, too close will make the midrange run rough. May have to open it up a couple of thousands

excaliber

RCJ7Y plugs, NGK and Bosch work very well at .022
try 1-1/4 to 1-1/2 turns open from closed on lo end.
then 1-1/4 turns on the HI end.
If ignition engine, check timing set to 28 degrees BTDC( could be retarded, won't take much)
If magneto set air gap the thichness of a business card (simplest way)

rtn9105

My Feedback: (35)

I'm using the NGK spark plug gapped at .020 (per the Brison web site) so maybe I'll open it up a little and give that a try.

The timing is set at 27 deg BTDC at full throttle and 5 deg BTDC at idle, I've tried to adjust the full throttle timing to 28-29 deg BTDC but haven't had much luck with it. Every time I adjust the linkage to increase the full throttle timing, the idle timing gets moved as well so I just gave up on it.

excaliber

RTN9105,
Not to worry, there is light at the end of the tunnel.
Call C/H ignition tell them what you have and they will sell you asyncro-spark that will solve your problem and even tell you how to install it.

rtn9105

My Feedback: (35)

I have a new C&H electronic ignition on this motor. My motor has the mechanical timing advance, is the system your talking about the one with the electronic timing advance?