Chainsaw Repair
Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Stihl => Topic started by: jmester on December 15, 2014, 07:41:56 pm
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Going to build a 390 over the next couple of weeks. I would imagine that a muffler mod helps. Would a timing advance also be in order. Have not messed with these saw much so I am all ears. Looks like it is going to be a fun build.
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File about half the flywheel key away to advance the flywheel that much.
Will not be enough to cause more kicking on start but will increase performance a little.
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20% just from a 30min muffler mod. Never messed with timing on stock saws.
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With the muffler mod, you not only open up the outlet, you need to open up the cage at the muffler inlet too.
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Yep I do that. Might have a pic somewhere.
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I did a 361 muffler not long ago I cut the muffler in half and cut the cage all the way out and increased the outlet hole and brass brazed it back together. That saw really picked up a lot in my mind any way. Glad you mentioned how you guys have done it. Was just thinking to open up the outlet only. Usually do a 1/3 the key is that not enough on these. Just wanted to make sure 1/2 is what you mean. Thanks guys
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I never opend the 290 310 390 muffler. I drilled right through center of cage. Only thing in front then is deflector. I also opened above and below cage, that way all would stay under deflector.
Then only remove a little on the exit of deflector itself.
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I open deflector at a angle just a tad. Dont want my muffler mod going straight out the front like some do.
(http://i59.photobucket.com/albums/g289/doemaster789/MS660066/310mufflermod002.jpg) (http://s59.photobucket.com/user/doemaster789/media/MS660066/310mufflermod002.jpg.html)
(http://i59.photobucket.com/albums/g289/doemaster789/MS660066/310mufflermod001.jpg) (http://s59.photobucket.com/user/doemaster789/media/MS660066/310mufflermod001.jpg.html)
(http://i59.photobucket.com/albums/g289/doemaster789/PP325/3450390025002.jpg)
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Looks good thanks for posting. Will give it a go like that.
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg1-8.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg1-8.jpg.html)
Before cleaning
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Take it to the car wash and pressure wash the parts?
One guy did that and caught his hand with the sprayer!
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Take it to the car wash and pressure wash the parts?
One guy did that and caught his hand with the sprayer!
Hey you talking about me ;) ;) :D? I did that once and never again. :P
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I guess you have to take a pair of Channel Locs with you to hold the smaller stuff?
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Speaking of chainsaws and the pressure washer . . .
Got to tell this story:
A guy bought a nice looking clean chainsaw off the Internet.
The bottom line,
The crankcase had water around the bearings . . .
The seller had pressure washed it without plugging up the inlets & outlets.
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg1-9.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg1-9.jpg.html)
Hot water, super clean degreaser, tooth brush and some time.
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg1-10.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg1-10.jpg.html)
Getting ready to flatten the engine pan.
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg1-11.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg1-11.jpg.html)
After a couple of passes. You can see the shiny corners.
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg4-1.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg4-1.jpg.html)
In action. You can see the filings in the bottom left corner.
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg5-1.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg5-1.jpg.html)
The finished engine pan nice and flat.
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Looking good
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Tomorrow I will shot a couple of pics removing the crank bearings. Have almost all the parts. Waiting on mako piston and cylinder kit, crank bearings. Piston pin bearing, crank seals. Fuel line and some other small parts. I will also take some pics when I get to the muffler mod. Going to go with cut4funs outlet design. Thinking I am going to cut the muffler in half and take the cage out and braze back together.
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Thanks 660.
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg1-12.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg1-12.jpg.html)
Began my muffler mod work. I put the muffler in the vice and used a flat file and went around the top of the seam. Once you go all the way around the two halves fall apart.
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg3-2.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg3-2.jpg.html)
This is with the cage removed all you need is the 2 dowels off the sides of the cage.
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What I have left to do is drill some holes for the outlet. Mod the deflector and braze back together. This one went better then the 361 muffler I did. Used a 4" grinder with cut off wheel to split that one. A little hard to control. With filing the seam off make a nice tight joint to braze back together.
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I liked the brazing better but brass will not stick to black oxide or cadmium. You have to remove the coating where you want the brass to stick.
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Nice work on the muffler and clam base. Top notch. 8) 8)
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Thanks guys. Do you all think that the cylinder where it meets the engine pan should be flatten as well?
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I did do mine and I found just a little distortion that was not as bad as the pan portion.
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Ok thanks. I will go over it just to make sure. Seems the 390 kit is back ordered. Thinking of going with the 290 kit instead.
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Where did you order your 390 kit?
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Trying out weedeaterman. Going for the mako kit
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Can save 10% by being memeber of this site. code chainsaw http://www.hlsproparts.com/Stihl-039-MS390-cylinder-assembly-49mm-overhaul-p/h30390-dns.htm
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Weedeaterman's major source is HLSparts and HLS is usually cheaper even before the discount but I could not find the Mako at HLS?
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg1-13.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg1-13.jpg.html)
Use the Husqvarna puller to remove the main crank bearings. Part number 504909001. It does **** a little side ways, but works well.
Cut thanks for the info on HLS. Going with 660 recommendation of going with the mako kit, seems that weedeaterman is the only one that stocks them. More to come on the muffler mod and installing new crank bearings.
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg1-14.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg1-14.jpg.html)
New bearings installed. I used skf 6203 bearings got them for about 12 a piece. Once old bearings were removed, wipe the crank down. Put the crank in the freezer and the bearings in the oven. STIHL recommend 50*C or 122*F. I show the press tool because I did not heat the bearings enough and got them on about half way then no more. So I pressed them down rest of the way.
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg1-15.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg1-15.jpg.html)
Went with a single hole additional outlet. I drilled it with a unibit the hole size is 7/16". On the deflector I cut down the long sides with a hack saw. And used needle nose to remove the piece. Then took a triangle file and clean it up.(no sharp edges)
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(http://i1250.photobucket.com/albums/hh535/jmester/imagejpg3-3.jpg) (http://s1250.photobucket.com/user/jmester/media/imagejpg3-3.jpg.html)
Muffler reassembled for brazing. I used the oe bolts washers and nuts to hold it all together. Only 1 of the dowels has any kind of locating taps to help hold it in position. Need to clean the paint off and get brazing. Will post some pics after it is brazed together hope you all won't laugh to hard. Not a welder by any means.