So. That fllywheel is rotation counter-clockwise as seen from "outside". IF, therefore, you "relative-rotate" that flywheel COUNTER CLOCKWISE, you are advancing the timing. (There is a SMALLER pre-TDC rotational "distance" to get to the trigger (and bigger rotational distance from spark to TDC) so the "spark" happens sooner.)
Husk 440 starting problem
- Thread starter PT81man
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PS you will find that the keyway cut in the crankshaft is close to the middlle of the bar side / opposite the ignition coil at TDC. You can get a pretty good TDC w/ that saw with just a long square pin (piece of small keystock, for instance) in the spark plug hole. If you have a dial indicator... well, bless you, but just about anything will do.
Post in thread 'Dolmar PS 7900 timing' https://www.arboristsite.com/threads/dolmar-ps-7900-timing.366487/post-7960602
PT81man
ArboristSite Member
Two questions I have. The name tag mentioned below is not on this saw. Unless it is located on the tank and is now covered by the power head, I can not find it. Second, is the mark on the outside of the flywheel, the location of the key since the key is completely gone. The flywheel casting has a small raised portion shown in the picture that looks like a key. Is that the location?
PT81man
ArboristSite Member
I am still waiting for a replacement flywheel from SEPW. Husky had them backordered so it may be a while. For $10 I'll wait. Just in case they do not ship, how do you determine the correct location on the flywheel if the cast key is completely gone? There is a small mark on the face of the flywheel that looks like an indication as to where the key should be. It is shown in the picture posted. The location on the face of the flywheel at the 9:00 position is where I think the key location is situated.. On either side of this, are two circular impressions in the casting.
Read the thread I linked to in post #43... set piston at TDC & line up trailing edge of the flywheel magnets with most advanced side of the coil. That should get you in the ballpark & you'll be able to see if that casting lines up close to anything
There are several ways to "approach" the flywheel-without key orienting problem.
one: Location replication style. Get some sewing thread and clear tape, and, using measuring tools and your "line-up" eye, tape the thread across the exact middle of the underside of the flywheel in the exact middle of the "remains" of where the key used to be (running the thread just up the "edge" of the flywheel). Now make a mark at each lower edge, from which (say, using marker and then some kind of needle or scratch awl) make two lines up the two opposite edges of the flywheel oriented at the exact ex-key place rotational position. Now do something similar from the crankshaft "keyway" so that you have two marked "spots" on the orange plastic, etc. in the middle of which the flywheel rotates. When the lines are at the spots the flywheel is where the key, if present would have put it. Tighten it down there, being careful, etc.
two: Play the "timing game." Print out a "degree wheel" from one of the several sites on the net, tape it to something right size(CD, etc.) and round. Find TopDeadCenter, tape the degree wheel to the flywheel, with the 0 at TDC. Move flywheel rotational position to about a 28 degree advance (your mileage may vary - or play with a protractor to see what amount of advance was "built into" your flywheel). Then fasten down your flywheel to the shaft so that the thinner metal space between the two magnetic steel bits on the flywheel lines up with the not-grounded metal "shoe" from the coil (i.e. is at spark-firing position) Tighten, etc.
three: Fake the key. Super-glue a piece of relatively harmless something (thin wedge of wood, width of the former key, alcohol to clean - no oil) to the place on the inside hole of the flywheel where the key is now so nicely out of the way, leaving a little clean strip. Use magnifiers, etc. Have fun, maybe w/ tweezers to place the thing. When glue set, then gently lower flywheel in place, not putting so much push on the flywheel that you would mess up your glued object placement. Etc. Tighten very carefully, making sure...
four: Sorta fake the timing and sorta check where you are. Find top dead center, and figure out (pretty exactly) where "key slot for key on shaft "points" at that moment, marking that spot. (It is legal to make a pointer, the exact helpful length, with a nice clean straight line in it if you want to.) Then rotate the shaft (timing amount - 28? - degrees), marking, then put the flywheel onto the shaft with a marked location for the ex key location and while checking the spark-making features (flywheel / ignition module) for being where they should be. And tighten, being careful....
Or.... similarly invent in a way that makes you happy.
Reassurance... I and my friends have a few Husqy saws without flywheel keys that run well and we use often, including in situations in which the saws get "tossed about" a bit....
one: Location replication style. Get some sewing thread and clear tape, and, using measuring tools and your "line-up" eye, tape the thread across the exact middle of the underside of the flywheel in the exact middle of the "remains" of where the key used to be (running the thread just up the "edge" of the flywheel). Now make a mark at each lower edge, from which (say, using marker and then some kind of needle or scratch awl) make two lines up the two opposite edges of the flywheel oriented at the exact ex-key place rotational position. Now do something similar from the crankshaft "keyway" so that you have two marked "spots" on the orange plastic, etc. in the middle of which the flywheel rotates. When the lines are at the spots the flywheel is where the key, if present would have put it. Tighten it down there, being careful, etc.
two: Play the "timing game." Print out a "degree wheel" from one of the several sites on the net, tape it to something right size(CD, etc.) and round. Find TopDeadCenter, tape the degree wheel to the flywheel, with the 0 at TDC. Move flywheel rotational position to about a 28 degree advance (your mileage may vary - or play with a protractor to see what amount of advance was "built into" your flywheel). Then fasten down your flywheel to the shaft so that the thinner metal space between the two magnetic steel bits on the flywheel lines up with the not-grounded metal "shoe" from the coil (i.e. is at spark-firing position) Tighten, etc.
three: Fake the key. Super-glue a piece of relatively harmless something (thin wedge of wood, width of the former key, alcohol to clean - no oil) to the place on the inside hole of the flywheel where the key is now so nicely out of the way, leaving a little clean strip. Use magnifiers, etc. Have fun, maybe w/ tweezers to place the thing. When glue set, then gently lower flywheel in place, not putting so much push on the flywheel that you would mess up your glued object placement. Etc. Tighten very carefully, making sure...
four: Sorta fake the timing and sorta check where you are. Find top dead center, and figure out (pretty exactly) where "key slot for key on shaft "points" at that moment, marking that spot. (It is legal to make a pointer, the exact helpful length, with a nice clean straight line in it if you want to.) Then rotate the shaft (timing amount - 28? - degrees), marking, then put the flywheel onto the shaft with a marked location for the ex key location and while checking the spark-making features (flywheel / ignition module) for being where they should be. And tighten, being careful....
Or.... similarly invent in a way that makes you happy.
Reassurance... I and my friends have a few Husqy saws without flywheel keys that run well and we use often, including in situations in which the saws get "tossed about" a bit....
Post Script... Another probably too "advicey" post (for which I usually get in a little "trouble") but... you are going to want the recoil starter with the vertical coil spring inside it for a 440 with advance at 28 deg. (You probably want the spring style starter in any event - big difference from the low plastic thing with just the two turning "landings" for the pawls. "Chunky" on the human wrist when pulling it.
This group of saws, 440s, 435s turned into 440s, etc has plenty of compression in its original, un-fried state, and they start quite well (even with slightly less than wonderful Zama carburetors). If yours doesn't start well, it needs some kind of love you have not given it
This group of saws, 440s, 435s turned into 440s, etc has plenty of compression in its original, un-fried state, and they start quite well (even with slightly less than wonderful Zama carburetors). If yours doesn't start well, it needs some kind of love you have not given it
PT81man
ArboristSite Member
"Magneto" is kind of a funny word for the black item in the picture. It is closer to just being a "coil" although it almost certainly has some semiconductors in it. The "leg" that is grounded (see socket head screw) is NOT the magnetically centrally active / "hot" leg. The other one is.
PT81man
ArboristSite Member
I used a loupe to locate the missing key on the flywheel and it is in the location as shown on the face. So now I have a location to install the flywheel. Husqvarna customer service emailed the maintenance manual so I know the torque to tighten the nut.
Now advice on starting and break-in this new piston/cylinder. Should I add a little extra 2-cycle oil to the tank? How about running for 2-3 minutes and letting it cool down and then restarting and running for more time?
On older car engines, the use of brake-in oil and limiting the top speed is good practice. Is this true on these engines?
Thanks to all for the suggestions to allow me to progress through the rebuild.
Now advice on starting and break-in this new piston/cylinder. Should I add a little extra 2-cycle oil to the tank? How about running for 2-3 minutes and letting it cool down and then restarting and running for more time?
On older car engines, the use of brake-in oil and limiting the top speed is good practice. Is this true on these engines?
Thanks to all for the suggestions to allow me to progress through the rebuild.
Tomos770
ArboristSite Guru
32:1 or 40:1....
Or you can use 32:1 for first 2-3 tanks.....and 40:1 later in the process....
I am using 32:1.....550xp mk2......450 mk2
Or you can use 32:1 for first 2-3 tanks.....and 40:1 later in the process....
I am using 32:1.....550xp mk2......450 mk2
PT81man
ArboristSite Member
Any restrictions on top speed?
Tomos770
ArboristSite Guru
Its a chainsaw....not a mofa....so idk about its top speed 
(joke)
I am not aware of any restrictions regarding rpms....
550xp is an AutoTune.....so it is, always set @optimum...
450 is an auxiliary saw.....so idk if it is 5% +/- from optimum
Husqvarna spline tool is always with me btw
(joke)I am not aware of any restrictions regarding rpms....
550xp is an AutoTune.....so it is, always set @optimum...
450 is an auxiliary saw.....so idk if it is 5% +/- from optimum
Husqvarna spline tool is always with me btw
Tomos770 -
I also just ordered another spline tool (due to easy misplacement when carried in pocket and taken out of pocket -- whether or not actually to use the thing -- somewhere out in the trees). But I think my 440/ 435(turned into a 440) etc. saws are settling down with use. (And, frankly, I'm running them a little rich-ish. Low needle about 3/8 to maybe even 1/2 turn open from middle-middle. High needle so 4-stroking goes away nicely with load). The saws are not that good; the carburetors are not that good. But FWIW, I continue to find the saws very cheap (time and money both) and very practical to own and use -- especially if you are willing not to "fight" with them. I'm "fussy" with some Husqy "arborist" top-handles (and I think I get repaid for being fussy with them). But I think the "zen" way to have the 440s, and a 325, etc. is exactly just to "organize" them, but not to try to reach a level of "fine" that may not exist to be attained. (just a thought)
I also just ordered another spline tool (due to easy misplacement when carried in pocket and taken out of pocket -- whether or not actually to use the thing -- somewhere out in the trees). But I think my 440/ 435(turned into a 440) etc. saws are settling down with use. (And, frankly, I'm running them a little rich-ish. Low needle about 3/8 to maybe even 1/2 turn open from middle-middle. High needle so 4-stroking goes away nicely with load). The saws are not that good; the carburetors are not that good. But FWIW, I continue to find the saws very cheap (time and money both) and very practical to own and use -- especially if you are willing not to "fight" with them. I'm "fussy" with some Husqy "arborist" top-handles (and I think I get repaid for being fussy with them). But I think the "zen" way to have the 440s, and a 325, etc. is exactly just to "organize" them, but not to try to reach a level of "fine" that may not exist to be attained. (just a thought)
PT81man
ArboristSite Member
After using my loupe to determine the key location on the FW, I was about to install the FW when I determined the nut was all buggered up. Another problem. Off to my local HW store and they did not have an 8mmX1.0 pitch nut. Luckily my neighborhood AGWAY did have what I needed. I put a dot of white paint on the crankshaft where the keyway is and installed the FW. I also purchased some 40:1 fuel since all my tanks have 50:1. I set the magneto to a 0.012" gap and filled the fuel and oil, engaged the choke and two pulls and it burped. Disengaged the choke and one pull and it ran perfectly.
I am going to instruct the owner to run 2-3 tanks of 40:1 and then return it to me to do a final carb mixture adjustment. I have it running a little rich right now until the break-in is completed.
Thank you all for the instructions and encouragement during this endeavor. I did spend about $112 on parts so I do not know what to charge for the labor. A lot was my learning curve and time spent online reading so I do not think that should be translated into labor charges.
Any thoughts?
Regards,
PT81man ( My 39 Plymouth Truck)
I am going to instruct the owner to run 2-3 tanks of 40:1 and then return it to me to do a final carb mixture adjustment. I have it running a little rich right now until the break-in is completed.
Thank you all for the instructions and encouragement during this endeavor. I did spend about $112 on parts so I do not know what to charge for the labor. A lot was my learning curve and time spent online reading so I do not think that should be translated into labor charges.
Any thoughts?
Regards,
PT81man ( My 39 Plymouth Truck)
PT81man
ArboristSite Member
Just looked, and it was only $87 in parts.
81
81
Husky77
ArboristSite Operative
not always the case, its a rough guide at best. my husky 550 drops doing this test with a 15" bar on, yet runs like new.
I would be looking at why its starved of fuel
