Good because I don't know how lol. I may go your route, get a little limbing saw. At least I think you made a thread about finding a nice little saw for limbing.
The 6421 seems pretty simple. I didn't do much to it yet, just pulled off the carb to clean out some paint residue. Some genius in Home Depot thought it was a good idea to spray orange paint on the filter.
Bought one last week I believe. I've been so concerned with finding the elusive four stroke sound I haven't really had a chance to use it.
I love lightweight limbing saws, that's why I've put so many hours on a 41 cc RedMax, and am waiting on delivery of a Tanaka 3351 from Bailey's. If they're still available for $150 on closeout special, it's a no-brainer. I've got huge amounts of work waiting on getting mine broken in (in wood, natch.)
Re 4-stroking, if plug insulator color looks good after sustained full-bore running
, I'd not be concerned. One approach to H adjustment is to richen the H until it 4-strokes in a cut, then lean it to where it just starts to 4-stroke when you lift the bar a bit.
Painting the carb? Que pendejo?