Stihl 029 Super PSI compression

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Dave2500

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Hello everyone,
Not sure if this is the right area to post, but question
I have a stihl 029 from i think 1998
It cut about 200 cords of wood (and ripped cut many more maybe 300 cords total if i had to guesstamate)

it seems to be getting tired (i think)

So besides pulling the muffler to check the piston i want to check the compression

Does anyone know what the compression should be for a 029 new?
and used
and at what psi does it need a rebuild or warn out

Thank you everyone
Dave
 
Thank you all,
all i can get is about 112 PSI compression cold (with like 8 pulls)

i wold assume that this would be pretty :"tired"

do you think i should buy a new ms 261 (can get it for about 450)
or i should fix this one,

also any idea what might be wrong the cyl looks good , but im no expert
 
>all i can get is about 112 PSI compression cold (with like 8 pulls)

to me, 300 cords is a lot of cutting. I have some 1997 stihl saws bot new, one is 026, both still running great! but they have not cut that much wood, despite cutting a lot of wood. compression is for all intents and purposes what takes place above the piston once the cycle goes into the compression stroke, prior to the ignition event. only one thing holds the compression in there... the rings. I am working currently on an 044 project, acquired saw not running. scored piston, no compression. the reason I mention it is because while the exhaust side of the piston is scored and rings stuck... the intake side rings are not and they exceed the ring lands OD. in working with it, and new parts, ie new rings... I note the old rings can be squeezed into lands to allow the OE cyl to drop down (just did it once, for heck of it) [cyl good] with almost no effort. this is a saw that saw daily Arbortist use... was running swell at end of day on a Friday, died 15 mins into Saturday... I picked it up Sunday... :) it was full of fresh bar lube and gasoline mix. so no doubt since your vid shows ur piston and cyl's bore to look good... your rings have just run the limits of their service life's utility. or are very close to it, ie - 300 cords. more than likely, assuming the nikasil is still intact a new set of rings and some light hone to the bore would bring your saw back into good running compression. piston kit even better! key is to ensure adequate cross hatch, hard to do with nikasil, but some scratching 100, 220 grit hand honed and spotlessly clean inside all parts... [I would not power hone it with a ball grit on wires hone!] and properly oiled for the top end reassembly would let the rings seat nicely. many like the Meteor ring. I only needed a piston/rings for my OE rework to cyl... and I chose Meteor despite numerous others out there due to the company's history and product quality. for me, the solution was in the rings! so rings had to be top-notch for best repair job and results. I was looking at a $20 piston/ring combo but opted for the $40 Meteor piston/ring combo because it came with Meteor rings... few years back when Meteor (Italian) got sold, also acquired by new buyer was their ring division. their rings are excellent rings!

if this was my project, I would pop the top, clean things up and replace the wrist pin bearing OE, and put in a Meteor piston, wrist pin and rings. ensure the combustion chamber is decarbonized. by all means, I would keep the OE cylinder... unless nikasil gone, but yours looks great per the vid. also know, however, that the Meteor piston is a bit heavier than the OE one... about 10 grams... Meteor wrist pin about 1 g. heavier. the new piston will tighten up some if any wear on old piston that could allow it to rock at TDC rollover, particulary down on lower skirt areas. u will want to ensure the ring's outter surface as parallel to bore as possible. if you repair, ensure the rings are install properly! ez to bend them, or worse, break them! things happen fast at 200+ times per second! and i would break it in easy. at least 3-4 tanks fuel mix at 40:1... maybe first tank 32:1. important not to abuse the seating process, so care is req'd. then just light work, couple more 40:1 tanks, but no all day cutting. after some easy cutting, etc, then should be ok to go to work. I would always run 40:1 in it, use stihl low ash oil and a good octane, or no ethanol gasoline mix. u will have to add oil if u use that as its 50:1....

hope this helps you some...

044.png

044a.png
 
I just reviewed your vid again. as a follow up thought, I would definitely NOT use your old piston! imo, it is plumb wore out!!! too polished from a zillion trips up n down! the machining on skirts is polished down. its minute to begin with on these small pistons, but it is there new. holds oil, etc. help rings do their job. stabilize piston n bore... the Meteor piston is well built, and if inclined... imo, one can 'whittle' it down to OE weight w/o much compromise risk to strength and durability. in any event, I would not worry about running it as received...
 
I have had nothing but bad experiences with hls pro, I have had orders misplaced or show up with broken or missing parts.... Just mah 2 sense
 
Backyard Lumberjack,
Thank you so much for all the info

i found what i think i need here,
Piston:
http://www.hlsproparts.com/ProductDetails.asp?ProductCode=PC2032&CartID=1
and bearing:
http://www.hlsproparts.com/ProductDetails.asp?ProductCode=H101413&CartID=3

(do these seem like fair prices or is their a better place to buy them?)

Thank you again,
is their anything else i am forgetting?
Dave

hello - you are welcome. glad to hear the info was helpful. I purchased my piston/rings etc from Northwood Saw in NY I think it was. http://northwoodsaw.com/store/index.php
I spoke to Dave, and he was helpful. their prices are competitive. I would also get a cylinder base gasket, too. get the $10.00 ring compressor kit, too. you will need sealant. most suggest Dirko or Yamabond. the links you are listing seem to have the right parts also. I have never dealt with HLS. take a look at the vids on utube for this kind of work. many there. ck out donnyboys stuff. I like his best. I would pull down the cyl, clean it up, clean the piston even you wont be using it. cleanliness of parts and proper oiling for reassembly are important in a job like this. don't let anything down into the crankcase. double check your case (crank area) is perfectly clean, get some 2-stroke oil on crank bearnings and outer seals once cyl off and just before reassembly. this thread could help others, maybe consider posting your progess to it here or start another. if u start another let me know so I can watch it... also, see if u go to northwoods see if they have the bent back circlips. install circlips gap down! or as your stock piston has them... according to one 2-stroke tech reference book... well respected author... to do a compression test: 3 pulls, throttle wide open. 90 is about minimin to run. I assume yours is running. Good Luck
 
you will also need a Torx wrench. it should be a T-27 most likely. no way to get to them cyl fasteners other than thru the cyl holes. long and slender. I looked at many, and chose one avail thru Amazon. it is the one that is a T-handle and the T slides to L or R with center detent. real nice tool! chances are you will have a composition base gasket if OE. mine did. it compressed to .019. I ordered a new one for my 044 project. it came as a metal one. I used it as a template as I wanted a thinner gasket to up the squish in the cylinder. the metal one was .019 also. it wont compress. lol. I chose .012 material for my new base gasket. cut it out of a folder. a pepsi carton is also .019. mite compress a few thou... and imo, this would be good as it won't alter any port timing yet will tweak the squish. a bit more squish, all other things considered, is probably worth thinking about on an older saw... as u will lose some compression #'s due to bore wear and the squish will help with the compression, pre-igniton event's phase.

http://www.amazon.com/BikeMaster-Sl...UTF8&qid=1453226283&sr=8-29&keywords=t27+torx

metal gaket - 044

044b.png

pepsi carton composition material (dense)


044c.png
 
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