Too much timing advance?

[Old2stroke]

I'm in the process of modifying the timing on a saw so that I can use a coil not meant for it. This coil has way too much retard and in the process of modifying it , I could end up with too much advance. I've never ran a saw with more than 30 deg of advance so my question is, how much advance is too much and what operational issues and risk of damage can be a result? The low RPM timing is now set to 5 deg BTDC so just starting it is not a problem.

 

[huskihl]

Usually they will kick back on the starter (maybe not with the retard feature) or start to pop a little in the cut. Too much and the pop can’t be tuned out or possibly the crank won’t last. It’s model dependent as to how much is normal vs too much

 

[pioneerguy600]

Usually they will kick back on the starter (maybe not with the retard feature) or start to pop a little in the cut. Too much and the pop can’t be tuned out or possibly the crank won’t last. It’s model dependent as to how much is normal it too much

This^^^ and on the 1300 series Stihl modules too much advance and the engine will run away when the bar comes out of the cut, it takes many blips of the throttle to bring the revs back down and it cannot be tuned out through the carb settings. Around 30 degrees is ok but much past that and there is troubles.

 

[Lightning Performance]

This^^^ and on the 1300 series Stihl modules too much advance and the engine will run away when the bar comes out of the cut, it takes many blips of the throttle to bring the revs back down and it cannot be tuned out through the carb settings. Around 30 degrees is ok but much past that and there is troubles.

You generally have this nailed down. I think the issues arise when port work and compression is added to make it past 30 total advance at X rpms. Outboard boat engines tend to run along the same lines with crossflow popup pistons. The newer looper engines can be pushed to near 32° total if you smooth all the rough edges and wide quench pads if any are present. The biggest overlooked bit is the machining of pointy edges left behind from chamber cuts and no finishing was done. It will make it pop like crazy and you have to back down the total advance most times. Proper chamber areas need less lead most times and 30-32 is usually about it for full advance to go fast on short bars. I've had really nice chambers backed up for long bar saws running closer to 24 total but the usual 26 is built in most times on so many models out there.