Chainsaw Repair

Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Stihl => Topic started by: dpjones on September 19, 2017, 02:03:17 pm

Title: Black Piston
Post by: dpjones on September 19, 2017, 02:03:17 pm
This is the piston from an 029s with the 039 A/M cylinder. This is the second time I've tore it down after milling about 500 or so board feet of yellow pine. At the time it was what I had, got a 660 now. The rings are stuck and the exaust side of the pistone is solid black. I'm was 93 octane with Klotz synthetic oil the first time, second time was Motul 710, same gas at 50:1. Just don't seem normal to me, any ideas? I thought the oil would be ok, maybe not?
Thanks
DPJ
Title: Re: Black Piston
Post by: dpjones on September 19, 2017, 02:07:04 pm
Forgot the piston
Title: Re: Black Piston
Post by: Cut4fun . on September 19, 2017, 02:14:33 pm
Which klotz oil?  That looks like super techniplate.   I had it start doing that to my saws about 10 years ago and quit using it.

I dont know anything about the Motul 710 oil. Mike does I think. 

Title: Re: Black Piston
Post by: Cut4fun . on September 19, 2017, 02:16:58 pm
@mdavlee
Title: Re: Black Piston
Post by: mdavlee . on September 19, 2017, 08:09:14 pm
Motul 710 was a clean burning oil. What kind of tune are you running?
Title: Re: Black Piston
Post by: dpjones on September 19, 2017, 09:10:24 pm
Your rite, it is the super techniplate, and I didn't run the saw too much after I started using the Motul cause I got my 660 and the 029 was running awfull.  I thought I may have been a little lean on the tune, the spark plug tip was  a lite color, sure looks rich on the piston though and the black is sticky/gummy also. My 038s done the same thing only not as bad, rings didn't stick. I thought the rings might be leaking the exaust by them? When I rebuild it I'll go back with Caber.

You seemed to have spotted the techniplate oil right off so maybe it's not good in saws.
I just thought it might lube better milling.
 I've went through allmost a quart of the Motul 710 in my 660 at 50:1 I'll pull the cylinder and check it. If it's like this I guess I'll just run stihl oil. Any advise is appreciated, milling seems all together different on the saws than firewooding
Thanks
DJ
Title: Re: Black Piston
Post by: mdavlee . on September 20, 2017, 08:07:16 am
I've run down to 16:1 with some of the bike oils milling. I never run less than 32:1 since that's about 60% more oil. Heat is the killer and 50:1 doesn't leave much oil for bearibgs. Pistons are cheap compared to a crank.
Title: Re: Black Piston
Post by: dpjones on September 20, 2017, 10:35:56 am
You think at 50:1 it ran hot and heat caused the piston to look like that? I don't see any wear, the first time I tore it down it was just as bad, when I got it cleaned up it looked fine, ring gap was same as when new, machine lines still on piston, maybe the cylinder an piston was a dudd, when I got it the impulse line connector was missing from the cylinder, had to rob one from another cylinder. I'll run the 32:1 don't mind at all, I don't want this to happen to my 660 or even the 029 for that matter.
Thanks
Dj
Title: Re: Black Piston
Post by: Cut4fun . on September 20, 2017, 12:38:28 pm
JMO if going to use Klotz go to the  Klotz KL-200 Original Techniplate 100% Synthetic. Thats what I switched to 10 years ago and never a problem. https://cometkartsales.com/Klotz-KL-200-Original-Techniplate-Quart.html

(https://cometkartsales.com/images/D/klotz-techno.jpg)
Title: Re: Black Piston
Post by: dpjones on September 20, 2017, 01:01:44 pm
I had the other Klotz. Allmost afraid to do any more milling till I find out what the problem is or was? Maybe my tuning, When I set the high side, I set it so it would 4-stroke untill I put it in the cut and cleared up, when I set for milling same thing and then turned out maybe 1/8 more. I'm not doing something right though
Title: Re: Black Piston
Post by: mdavlee . on September 20, 2017, 01:22:31 pm
660 I set to 13k with a tach milling. It woukd be 4 stroking hard at that rpm
Title: Re: Black Piston
Post by: dpjones on September 21, 2017, 01:05:16 pm
 I don't think I'm anywhere near that much, I would guess 8 to 10,000 maybe less. I'll hold up on the milling until I get a tach, it's just something I like to do anyway. I do think cut4fun was right about the oil though and me running too rich really added to the problem and me not knowing what I was doing. I aprieciat the help.
Thanks
DJ
Title: Re: Black Piston
Post by: Cut4fun on September 21, 2017, 01:32:10 pm
660 I set to 13k with a tach milling. It woukd be 4 stroking hard at that rpm

stock or ported 660?   I was thinking stock max 13.5K.  I know my woods ported one bucking was in 15 range and would 4 stroke like that at lowers.


I don't think I'm anywhere near that much, I would guess 8 to 10,000 maybe less. I'll hold up on the milling until I get a tach, it's just something I like to do anyway. I do think cut4fun was right about the oil though and me running too rich really added to the problem and me not knowing what I was doing. I aprieciat the help.
Thanks
DJ

I dont mill but that sounds fat fat fat to fat

Title: Re: Black Piston
Post by: dpjones on September 21, 2017, 03:59:43 pm
I'm only guessing about the rpm's. On all three saws, 038, 029 and 660, if I pushed a little too hard they would start 4-stroking or kinda flooding, I'd let up a little and let them clear out and go again. Just a good light steady push. Now at least I thought that was what was happening.

I took all the guts, cages, out of the mufflers, opened the outlet up on the 29 an 38. Had to heat the crimp with a torch on the 29 to get it apart, then heated it to crimp back.I put a new Walbro WJ-76-1 and a 98cc kit on the 660. The 98cc kit was probably a mistake and may change it back when I check for carbon. I also got a new Cross cylinder kit on the shelf I could put on, one of them MMWS cylinders. Even if it's better it wont cure what I'm doing wrong. I think a tach may at the least tell me where I'm at with the rpm's, my ear don't seem to be doing it.
Thanks
Title: Re: Black Piston
Post by: Cut4fun . on September 21, 2017, 04:07:55 pm
Before you buy the wrong tach. Info from 2011 to 2017 so far. https://chainsawrepair.createaforum.com/stickys-of-how-to-basics/chainsaw-tachometer-choices/
Title: Re: Black Piston
Post by: mdavlee . on September 21, 2017, 09:35:32 pm
Yeah if they're that rich it will really make a mess with the heat from milling. I tuned ported 660s to 13k milling.
Title: Re: Black Piston
Post by: deezlfan on September 22, 2017, 09:41:25 am
Using my hillbilly, back forty edjuamacation, I'm gonna say you are overheating the oil beyond it's capabilities. The black is obviously carbon. The only sensible place carbon can come from is the oil. I find it hard to believe that the carb settings could be so rich that you could build up that much residue. [If it was, that saw would smoke like a diesel rollin' coal!!] Opening up the muffler should reduce the cylinder temps.  Also are you keeping the powerhead as far away from the work as is possible? I've seen many guys mod the muffler on the front face and then let the saw pull up tight in the cut blocking exhaust flow. 
Title: Re: Black Piston
Post by: Cut4fun . on September 22, 2017, 10:53:47 am
Just my WAG on the reason. Heat = using the Super Tech oil with 20% Benol  castor oil caramelize on piston.   
Title: Re: Black Piston
Post by: Cut4fun . on September 22, 2017, 10:56:45 am
This was a husky 562 stumpy did running 32:1 with super tech  no no ;)

Title: Re: Black Piston
Post by: dpjones on September 22, 2017, 11:55:48 am
That looks the same as mine, wouldn't it do the same in a dirt bike? When my son had a Suzuki 125 RM I think, very powerful, that's what we were told was best to run and we did. I rebuilt it and don't remember that or stuck rings so I thought it be good for saws or any 2-stroke. Guess not
Title: Re: Black Piston
Post by: dpjones on September 22, 2017, 12:29:52 pm
deezlfan, The exaust is blowing the same as stock, out the chain side on the 3 saws.
I thank everybody for the input, can't get this kind of info around here. I don't know of anyone milling and what very few friends I got think I'm crazy for using saws when I don't have to.
DJ
Title: Re: Black Piston
Post by: Cut4fun . on September 22, 2017, 01:09:29 pm
That looks the same as mine, wouldn't it do the same in a dirt bike? When my son had a Suzuki 125 RM I think, very powerful, that's what we were told was best to run and we did. I rebuilt it and don't remember that or stuck rings so I thought it be good for saws or any 2-stroke. Guess not

I only seen it in very hard worked saws like stumping and ripping etc. Lot of heat.  Not just normal easy cutting type stuff.
Went to KL200 Original 100% synthetic and never seen it again. Thats why I blame the 20% castor in the super.
Title: Re: Black Piston
Post by: dpjones on September 22, 2017, 01:57:15 pm
That's the caster cooked on there then, I'll see if I can find the KL200. I figured someone would have said just buy stihl oil.

Title: Re: Black Piston
Post by: Nathaniel Vansickle on September 22, 2017, 05:06:15 pm
That's the caster cooked on there then, I'll see if I can find the KL200. I figured someone would have said just buy stihl oil.

Never hear me say buy Stihl oil but I will say....stick to quality synthetic FD rated OPE formulated oil, no guessing if its gonna leave carbon or caramelize on the piston from heat. Run 40:1 for everyday cutting and listen to some experts on ratio to run when milling.



Stihl oil, orange bottle and the silver bottled Ultra are both crappy oils and only meet JASO FB specs which means they leave behind allot more carbon and deposits than most other oils out there today. 
Title: Re: Black Piston
Post by: dpjones on September 22, 2017, 08:44:46 pm
This last oil I bought says  JASO FC/FD-ISO-L-EGD
Title: Re: Black Piston
Post by: mdavlee . on September 22, 2017, 09:28:30 pm
I milled with the Super template and maxima 927 castor. The tune has to be more spot on or you get the results like the gunked piston. Amsoil saber seems to work good as does the new VP oil. Echo red armor also works very well.
Title: Re: Black Piston
Post by: dpjones on September 22, 2017, 09:34:54 pm
I finished up a red oak log today and it sounds rich, here's the plug
Title: Re: Black Piston
Post by: Al Smith on September 26, 2017, 05:53:33 am
To me it looks like it's burning chain oil but I have no idea how it could get in the crankcase .
Title: Re: Black Piston
Post by: dpjones on September 28, 2017, 12:57:26 pm
I hope it's just  Motul 710 and not chain oil
Thanks
DJ
Title: Re: Black Piston
Post by: dpjones on September 29, 2017, 04:43:39 pm
660 tached out at 10,200 rpm
Title: Re: Black Piston
Post by: mdavlee . on September 30, 2017, 03:14:09 am
Way way too rich
Title: Re: Black Piston
Post by: dpjones on September 30, 2017, 11:11:42 am
OK Thanks, I'll put it on 13,000.
Title: Re: Black Piston
Post by: Cut4fun . on September 30, 2017, 07:35:33 pm
Way way too rich
OK Thanks, I'll put it on 13,000.

Mike isnt 13K max for stock  660 or is it 13.5K?

http://www.madsens1.com/saw_carb_tune.htm

Found this tidbit pm 650 660. * max RPM for carburetors without limiter caps is 13,000.  max RPM for carburetors WITH limiter caps is 13,500, according to workshop manual from 2007. 

stock stihl 066 shows 13K max

Title: Re: Black Piston
Post by: mdavlee . on October 01, 2017, 01:23:31 am
13.5k is safe. I've had them a touch over 14k stock with open muffler. 12.8-13k for milling or blocking big trees
Title: Re: Black Piston
Post by: dpjones on October 01, 2017, 12:04:54 pm
With this tach of my friends this saw will only turn up to around 12,000 and that's without 4-stroking.

Could this be the a/m big bore kit or the tach? My 026 shows over 11,000 before it 4 strokes.

If it's port timing I'll leave it be for now. When I put it on all I did was a little beveling to the ports.

If it matters, I put on a new wj-76 and the muffler is hollowed out, no cage.
Title: Re: Black Piston
Post by: jmester on October 01, 2017, 03:48:34 pm
I would have to say that it is your tach. Where is your high speed screw at. Is it close to 1 turn out from a lightly seated position. Also do you have an aftermarket ignition module. Port timing has more to do with where the saw makes peak power under load then max rpm out of the wood.
Title: Re: Black Piston
Post by: dpjones on October 01, 2017, 06:57:13 pm
The high side screw is 7/8 or real close, low is 1, the ignition module is farmertech, only thing that is name brand is carburetor. It was a kit saw, I just don't want it to end up like the one in the picture at the first of the post

I'm sorry if I lead anyone to think it was a true stihl. it's just a copy

Didn't know that about the timing, just figured cheap parts, get what you pay for.

I'm going to get a good tach, just not sure which one.

I really appreciate everyones help.
Title: Re: Black Piston
Post by: jmester on October 01, 2017, 08:37:39 pm
If you get a new tach and it still will not come up to at least 13,000 with the high speed screw around one turn out. I would look into another Ignition Module. I had some problems with the aftermarket ignition module on a husky saw it would not let it make full rpm.
Title: Re: Black Piston
Post by: dpjones on October 01, 2017, 10:10:12 pm
I've got a 026 and a 029 Stihl brand module, not sure if they are the same. When it gets around 11,000 it don't miss it seems like my 78 chevy truck with the time pulled back too far
Title: Re: Black Piston
Post by: trappermike on December 29, 2018, 05:39:35 pm
Synthetic 2-stroke oils started in the 70's when I was fixing motorcycles,some were very expensive and highly regarded but I noticed many times on looking at a piston run on it for a long while the piston would be totally black,even the underside. I would suggest going to a good quality mineral oil.
Another more common cause for a black piston,often in very short running time is caused by a far too restrictive muffler,causing the burned oil smoke to be held back and it re-condenses as burnt oil on the piston.