Chainsaw Repair
Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Stihl => Topic started by: rms61moparman on December 22, 2011, 06:26:42 pm
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Who has any "go fast" tips for the 039?
This one I'm building runs good but loses power in the cut.
Mike
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Mike as you know the 290 310 390 will gain about 20% after a simple 30min muffler mod and carb retune.
oops I just noticed it said for build off. Better go with welded up pop up then and have Nik machine it up for you. My bad I didnt read that before. I was just think a mild work saw.
http://chainsawrepair.createaforum.com/stihl/stihl-ms390/
You could always do basic woods port or do a weld up pop up. No sense in all of that though. JMO.
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I've opened up the exhaust a bit and modded the muff.
Don't know if the muff mod went far enough.
I've got a pop-up piston coming from a good friend, hopefully it will be here tomorrow.
What can you tell me about the transfers on these saws?
I guess that is the next step. They are the flat top type, will they benefit from angling them up a few degrees?
Mike
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To be honest I never paid attention inside one on transfers when inside. I despise the whole series of these saws 170-390 to be truthful.
That stumpbroke guy has been deep into them. But I think he is the one having the build off. So he might not share much right now.
Here is a new site started up CompetitionSaws and run like this site without all the BS ;). More of a porters site too. http://competitionsaws.createaforum.com/index.php
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I've got part of a box full of parts from a couple 029 and 039 that couldn't cut the mustard for a tree service crew . The boys killed em dead as a door nail never to run again .I could look at the porting but quite honestly I don't think you can do a lot to them being a clam shell design .
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I guess, the weather permitting, we will find out tomorrow.
I put a custom piston in it today and I think it'll run pretty good.
I'm certainly no saw builder but I just hope to not finish in last place in this buildoff.
Al,
I might be interested in some of those parts.
Mike
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It's a story but technically the parts aren't mine .
I kind of adopted this tree service guy who is kind of my wifes adopted son .Not legally but she changed his diaper when he was a baby .
I service a lot of his equipment and store some of his saws because where he lives he has experiaced a lot of theft .
So much for that now the 029's and 039's .For what they were built for they do just fine which is a consumer fire wood saw .In service for a tree company ran by people who don't own the saws they just can't take the abuse .Those guys beat the tar out of them .
Eventually all those dead and wounded saws make it to my shed .I either get them running if I feel like it or just toss the parts in a box .So much for that .
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Well the 039 runs real good with a HUGE popup piston but is still only making around 150# of compression.
I took some measurements and the saw doesn't have any squish!
Instead has more of a gentle squeeze...LOL
The best measurement around the squish band is .050 and they go up from there to about .053.
I am looking at the piston from a TS400 concrete saw, does anyone know if it is any taller from the pin to the crown???
Any other suggestions?
I don't think I will gain anything with a bigger pop-up. This one is .160 tall and a work of art.
Mike
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Did you cut a raised dome in the piston or weld one up and then turn it down?
If you cut one in it will actually lower the compression unless it's on an engine design where the base can be cut down .Not so on an 039 because it's a clam shell design .
I'm confused .With 160 thou raised dome it's obviously cut in which in effect would raise the exhaust by that much which would be huge . In my way of thinking that high of an exhaust port opening would be upwards of 80-82 degrees opening and would kill the torque on that thing .It would or should wind up but won't have any grunt .--Am I missing something in the description ?
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Mike did your piston start with a welded center then cut pop up out of it?
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Yeah it was welded up and turned back down.
Nothing was removed from the original piston crown.
Mike
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Take a look at the Poulan pistons. I know the 60cc 365 3750 uses the same rings as 390.
Least I hope I got that right 49mm x 1.5mm My memory isnt what it used to be so check. Also I never measure wrist pin sizes on the 290 - 390 or poulans.
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The 029-390 wristpins are 10mm.
Thanks Kevin..I'll take a look at some of those.
Thanks.
Mike
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So then evidently with this welded pop up it's skinny one else you couldn't stick 160 thou raised dome inside of a 50 thou head deck clearance without sticking it in the combustion chamber .
I know it's done I could just never figure why .
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Well Al,
I'll just tell you why.
It's no big secret.
The sole reason I'm doing this is............................................................................................desperation!!!
Mike
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If it runs better than a stock piston I guess it worked out .
Now I've seen little domes about as wide as a nickle .In my mind I can't see how that could help out any .You're not redirecting the flow around the back and upwards over the piston to aid in blow down and it's not raising the compression noticabley . It's a problem with a clam shell unlesss you put a head on it .
Then it's not longer stock appearing .Besides it probabley is not a good cantidate for an all out cookie cutter . The pile of parts in my shed is a good indication they aren't up to the task of supporting tree trimming work so it wouldn't take much soup to just make them die on the vine never to run again .
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Add more nitro.
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No THANKS Blood,
They aren't a bad saw for what they are but I don't want to be wearing one, or any part of one, for the rest of my life!!!
I don't think they would hold up well at all to a shot of nitro.
Mike
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No THANKS
Mike
Mike excuse my derail for a moment. But I was talking with JJ a year or so about putting real rollernose tips on hard nose bars and GB type roller nose bars on CCSite.
Now what I am wondering. Who is the guy in KY that is able to cut bars etc? I can cut etc on the tail mounts, but I dont know if I can do one for a roller tip mount.
Just a idea I am playing with to make a large husky mount 050 60dl 16" bar.
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I don't have a clue.
I will ask around though and see what I can come up with.
Mike
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Brad uses him to cut his bars down. I can email him too.
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Mike, Brad said it is That is Wigglesworth Jeremy. I need to get in contact with him. Help somehow?
I know he lives down close to Murray KY where I was born on the other side of KY Lake. I go fishing there every year still.
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Oh yes!
Shoot me a PM with your phone number and I'll have himgive you a holler or you can shoot him a PM yourself at ........the other site.
his username there is wigglesworth.
Mike
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Hey Mike, I'll send you a link @ the other site to my MS 290 thread. Everything I know about those saws is in there.
I know that 290 is a stout saw. It was cuttin right close to a 440 last time I ran it. The vids are in that thread.
I think you asked me about this saw a while back. I can't remember if I ever got back to you. If I didn't I appologize. Please let me know if you need any help with it. I don't have to many secrets.
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Well Stumpy I'll definitely need all the help I can get.
This saw runs out great but it really needs about 30 lbs. more compression.
I have got a MONSTER pop-up in it and it brought it up about 15 lbs.
What I REALLY need is a .030 taller piston.
Mike
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The idea was right you just didn't go far enough with it .
There have been people who welded pop up to increase the comp on clam shell saws but they were wide pop ups ,not like the head on a rivit .A little skinny pop up won't do you a lot of good for several reason .
First up inside the combustion chamber it does nothing for the flame front except blow it out sideways .It doesn't do a thing to redirect the transfer around the intake side of the cylinder for a better scavanging to purge the residue exhaust gasses .
To raise the comp you have to fill the void that would normally be air space with metal ,you just don't have enough of it .
This is a standard pop up on a removable cylinder Stihl saw which is somewhere around 25-30 thou .It was not done to raise the comp but to improve flow over the top of the piston .I could have made it a tad wider but it works as intended
Now I hate to bust your bubble on this and I'm not trying to be a smart azz but that design of pop up is just not going to work the way you want it to .
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Thats a good idea you have with the block holding the piston in place when installing the cylinder. ;)
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My bubble isn't really burst Al.
It's like Edison said when inventing the light bulb. "Now I know of a thousand things that won't work.
This is just a toy for me anyway.
Hopefully I'll get the right combination before I die!LOL
Mike
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Mike looks like mweba figured out something to get that psi up with a mac piston and shortening the rod. :o I think he said something in the 170psi range .
McCulloch Titan 57 piston in this saw due to the thin rings and domed crown.
This 310 saw is running a McCulloch Titan 57 thin ring domed piston. In order to fit this piston having a lower pin placement, the connecting rod was shortened by 3.5mm. In this wood with a 20" full ch it pulls a consistent 10200
http://www.youtube.com/watch?v=khmvGjPRjMk
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This saw has my mind spinning. Ended up with four tanks through it today. BTW the grinder has not touched a port or tranfer on this thing yet. Kinda scared to honest LOL I wore my grinding face shield for the first tank................
(http://farm8.staticflickr.com/7070/6900026305_e7bc27e641_z.jpg) (http://www.flickr.com/photos/mweba1/6900026305/)
Mod ms310 (http://www.flickr.com/photos/mweba1/6900026305/) by mweba1 (http://www.flickr.com/people/mweba1/), on Flickr
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A windowed piston goes against everything I had in my mind about controlling open transfer flow. Any thoughts on this subject? I can't be getting good direction out of this but yet it works??? Walked out and took this pic for the after four and change tanks. squish is .018
(http://farm8.staticflickr.com/7058/6900089411_96ac0858b1_z.jpg) (http://www.flickr.com/photos/mweba1/6900089411/)
Ms310 (http://www.flickr.com/photos/mweba1/6900089411/) by mweba1 (http://www.flickr.com/people/mweba1/), on Flickr
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Well Mitch,
It looks like we know who to chase in this buildoff.
I thought about con-rod work but I guess I'm just askeert.
According to the squish calculator an 039 should have 27 thou. but I just don't think that will give enough compression to these saws.
Mine with 150 runs great but falls on it's face when you put the pressure to it.
Oh well it's good that we still have some time left to work on them.
Mike
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Mike,
Yes its tough to get the comp up on these and even more tricky to find that torque sweet spot.
Think I'm done with mine as interest is fading.
http://www.youtube.com/watch?v=bVaK1uCt7IY (http://www.youtube.com/watch?v=bVaK1uCt7IY)