Hi, I have just completed a rebuild on my stihl 038 super and having a few issues getting it to start. It was running before I did the tear down. I replaced seals and bearings as well as cylinder and piston. Using fresh gas, it just does not want to start and run for duration. I was able to start it but couldn't run it for 10 seconds but carb was out of adjustment and couldn't rev high. Ended up stalling out. Now when I trying to start I hear popping from exhaust like a backfire, which makes me believe that it's a timing issue. To add to the fire the flywheel key is sheered off. I have made marks on the flywheel in relation to where the key lies. Anyways did that and installed the flywheel nut and locked cylinder position. Started up first pull but sputtered and died out. I rechecked the marks and basically marks were 180 degrees apart. What can I do to make this work? It's a really nice saw and trashing it is not an option. I've heard people being successful with this because the flywheel is pressed on but I can't seem to get it to stay.
Timing issue?
- Thread starter Tyl206
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The taper bore is damaged on your flywheel, it now needs to be carefully lapped back into true, smooth and clean so that it will be a tight fit when the nut is tightened to spec, 22- 25 ft lbs should hold it.
I'll have to look into that. I just verified it's getting fuel and spark, the only thing left is timing. I checked my timing marks and they seem like they are still correct. How much would the timing be off, if I am basically getting a no start?
You need to be more accurate than that, the key lines up the two parts fairly accurately, crank and flywheel will only mate up properly with the use of a key in the slots.
The magnet on the flywheel should lead the coil at tdc about 3/4" , but no more than 26 degrees. Find tdc with a screwdriver on top of the piston through the sparkplug hole.
I use laquer thinner to get the oil and grease off the crank hub and the flywheel. Then do what you did before with indexing the flywheel and the crank so its visible after the nut is on.
Block the piston and get it really tight. Chive on
I use laquer thinner to get the oil and grease off the crank hub and the flywheel. Then do what you did before with indexing the flywheel and the crank so its visible after the nut is on.
Block the piston and get it really tight. Chive on
The bore in the flywheel is easily damaged , the flywheel being softer aluminum so on a few occasions I have had to use valve lapping compound applied to the crank taper. Put the flywheel on and twist it to and fro with slight down pressure , may take several applications of compound and flywheel turning to get the taper cleaned up but it will dress up nicely, then clean inside the flywheel bore and the crank stub very diligently with a cleaner that leaves no residue. These two parts must be absolutely clean bare metal, no oil !
@pioneerguy600 ,
If it was an old low rpm tractor and no parts were available, I'd say go for it.
But this is a common saw they made jillions of.
Putting a good donor on is a better solution in my opinion. I have a couple lying around, he can PM me for a near free one.
No offense, but advising someone to lap a mating surface of an aluminum flywheel that spins 9,000 plus rpm, by hand, is probably not a good idea as far as safety is concerned. Especially in our litigious society.
If it was an old low rpm tractor and no parts were available, I'd say go for it.
But this is a common saw they made jillions of.
Putting a good donor on is a better solution in my opinion. I have a couple lying around, he can PM me for a near free one.
No offense, but advising someone to lap a mating surface of an aluminum flywheel that spins 9,000 plus rpm, by hand, is probably not a good idea as far as safety is concerned. Especially in our litigious society.
I'd recommend picking up another flywheel and removing that variable.
Alright good to know. Also what is the best technique for block/locking the piston? I have been just using nylon rope but squishes a bit. I saw they have a tool that screws into the cylinder, but using metal to block the piston makes me weary.
Boleclimber
ArboristSite Guru
I'd put tooth paste on the crank side, line up flywheel key, and tighten the nut. Let paste dry over night and run it in the morning.
I have used this method on a number of saw's with 100% success.
I have used this method on a number of saw's with 100% success.
Boleclimber
ArboristSite Guru
Rope is best. Metal stops have been known to poke holes through piston tops.
Use more rope. You're not going to hurt it. Just don't feed the rope into a port and hurt your piston.
gorman
Addicted to ArboristSite
I personally have done this with a perfectly good 260.
If the spark plug is at an angle and not straight up and down with the piston and cylinder bore, I wouldn't recommend using the metal piston stop. The edge is likely to dent or put a hole in the piston crown from less surface area getting the same force.
Toothpaste?
Toothbrush?These plastic stops work great... but I've been know to use a toothbrush as well
We saw guys are resourceful. Toothpaste and Toothbrush in the same post. Lol
Off topic, but;
Do you know how historians know that the toothbrush was invented in Arkansas?
Anywhere else would've called it the Teethbrush....
Do you know how historians know that the toothbrush was invented in Arkansas?
Anywhere else would've called it the Teethbrush....
Boleclimber
ArboristSite Guru
The tooth paste drys and becomes glue like while diatoms (grit) give extra holding ability. I didn't come up with the method on my own; I first read about it here on AS many years ago and later read about the method in a two stroke tuners book.
Used when the keyway is sheared, missing, or removed to advance the timing - to promote a better grip (and not slip) as it's being tightened, right?
