Motor pops and bangs and stalls when throttling up

[topconker]

Hi Guys,
I have a Honda RM55 powered mower that starts easily even on tick over but when I go to throttle it up it pops, bangs and stalls. After a minute or two it will suddenly start to run perfectly and I can then throttle up and down with no probles?
I have fitted a brand new carb, (yes I know OTT), new spark plug and filter, checked the valves gaps, checked the compression, (it's a little low but still ok), checked the air gap for the mag so am a complete loss. The only thing I can think of is the mag is giving a poor spark, what do you think?
Cheers,
TC

 

[ILENGINE]

Could be the coil acting up but that can be checked easy enough with one of those blinking type spark checkers. Install it per instructions and then have somebody watch the light to see if it become erratic or not when throttling up. The issue could be as simple as fuel quality also. Just on the verge of not being flammable enough.

 

[topconker]

Forgot to add also checked the timing ensuring the flywheel key was not damaged/broken .

 

[topconker]

Hi ILENGINE, should I disconnect the kill wire if I test for spark whilst running?

 

[ILENGINE]

Hi ILENGINE, should I disconnect the kill wire if I test for spark whilst running?

Don't think that is necessary. If you think it could be suspect inspecting the wire would be in order, If the kill wire was suspect I think the problem would be continuous with no regard for engine speed.