How to discern *and* do a timing advance? And...what of plugging a decomp-valve with a LONGER bolt, to boost compression?

eye.heart.trees

eye.heart.trees

arborjunky
Joined
Jun 25, 2019
Messages
142
Location
Tampa-Area
Will start with the latter item (these are in-relation to my 590's "hot woods-port" project but also just to understand!) Decomp valves are often removed, am uncertain if the chief reason is their potential to fail, or their OEM characteristics (my understanding is they ALL cause some compression loss?)
I'd learned of filling-in the valve's hole with JB Weld, but then was shown a better, purpose-built plug for decomp's but it made me think "Why bother ordering&waiting for a bolt? I'll just go to Ace with my cylinder and get it there....but wait, if plugging that hole/recess boosts compression, and people have spoken of welding-in a dot of 4130 into the comb.chamber to reduce volume/increase compression, so what if I got a bolt that was longer-than-necessary, and let it stick-into the combustion chamber a couple millimeters?? Would use JB Weld 'as Loctite' when doing this, of course (would've done that when installing a purpose-made plug, anyways!)


Timing....I know the 590's(and many newer models?) are sensitive here, and that it may not even need it, and that before I'd even go do it I'd need to somehow measure to know IF, and HOW MUCH, to shave off the keyway on the flywheel.... ANY insight into how to measure/determine timing here would be incredibly appreciated, as would guides on doing a perfect job of the filing (I know how, but haven't found a guide that's taught me a way I'd feel confident "I'm doing this 100% properly"!)
/Saw a youtuber('mweba1') using this timing-gun, if that kinda tool is the only means then my question would be "Where are these guns, is it something I rent, is it something I go to an auto-repair-shop and offer them $$ to do the timing-test for me?" :)

Thanks a ton for any insight on these two, am doing a "2nd round" of work to my new 590 that I did a VERY mild woods-port on recently, goal is making it "as hot as possible for a work-saw", it won't be used all day for bucking in fact for a majority of my jobs I don't need the 590 my lil 355t is all I need to get through like 90% of my work...the 590 makes some of it easier but my 355t can do all I need to the smaller trees here in FL, heck 50-55' is the tallest tree I've done/been on this year!!
 
  • Like
Reactions: Den
eye.heart.trees

eye.heart.trees

arborjunky
Joined
Jun 25, 2019
Messages
142
Location
Tampa-Area
Hate to jam-in a Q like this but expect anyone who can answer ^ my OP could answer this and this doesn't deserve a thread..What is the norm for oil% for you guys? I'd gone to 40:1, then 45:1 which is where I am now...Donny Walker says to go by the label (50:1) and I put weight on his opinions (should I be doing this or his he considered more like iron horse/tinman?) so it has me 2nd-guessing the "add extra oil" thing (40:1 is a big jump in oil%!!!)
 
  • Like
Reactions: Den
Maintenance supervisor

Maintenance supervisor

Every 100yrs, All new people...
Joined
Feb 1, 2019
Messages
3,103
Location
South Carolina
More oil? When did that ever end up with a scored piston and cylinder?
Less oil absolutely has scored pistons.
If you've ever seen a professionally ported saw the porter usually puts a "40:1 only "sticker on the fuel tank, must be a good reason.
 

Latest posts

Top