Author Topic: 039 power tips for build off  (Read 1791 times)

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Offline rms61moparman

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039 power tips for build off
« on: December 22, 2011, 06:26:42 pm »
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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Offline Cut4fun

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Re: 039 power tips for build off
« Reply #1 on: December 22, 2011, 06:33:33 pm »
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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Offline rms61moparman

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Re: 039 power tips for build off
« Reply #2 on: December 22, 2011, 06:44:42 pm »
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

Offline Cut4fun

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Re: 039 power tips for build off
« Reply #3 on: December 22, 2011, 06:49:37 pm »
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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Offline Al Smith

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Re: 039 power tips for build off
« Reply #4 on: December 23, 2011, 06:00:36 pm »
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 .

Offline rms61moparman

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Re: 039 power tips for build off
« Reply #5 on: December 24, 2011, 01:12:26 am »
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

Offline Al Smith

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Re: 039 power tips for build off
« Reply #6 on: December 24, 2011, 05:34:49 am »
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 .

Offline rms61moparman

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Re: 039 power tips for build off
« Reply #7 on: December 28, 2011, 12:03:41 am »
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

Offline Al Smith

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Re: 039 power tips for build off
« Reply #8 on: December 28, 2011, 03:42:59 am »
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 ?

Offline Cut4fun

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Re: 039 power tips for build off
« Reply #9 on: December 28, 2011, 12:34:52 pm »
Mike did your piston start with a welded center then cut pop up out of it?
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