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7 tooth vs. 8 tooth sprocket

Discussion in 'Chainsaw' started by mattellis2, Feb 1, 2011.

  1. mattellis2

    mattellis2 ArboristSite Member

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    Relatively new here, and have a question. I have an MS270 that is about 7 years old. It has been a great saw, and I've not really ever had to do anything to it, other than keep gas and oil in it, and the chain sharp.

    I've recently started to go over it...new air filter, new plug, carb tune up, new bar, new sprocket, new chain, etc.

    The first time I went to the local stihl guy, his retard mechanic gave me the wrong part number for my sprocket. I took it back, told him it was wrong, and he went to find the right one for me. He came back with an 8 tooth sprocket. OEM is 7 tooth, and the new MS270 he had on display was wearing a 7 tooth as well. He told me i would just pick up a little bit of chain speed with the 8 tooth. Is this accurate? If so, why is stihl still putting the 7 tooth on as original equipment?

    thanks,

    -matt
     
    bluesportster02 likes this.
  2. komatsuvarna

    komatsuvarna Arboristsite MVP

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    Yeah, itll pick up chain speed, but loose torque. If it were mine Id want a 7 pin on that saw.
     
  3. mweba

    mweba ArboristSite Sponsor

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    Out of the wood chain speed would be faster but a MS270 does not have the torque to pull an eight.

    I find that I hold faster chain speed with nearly all my saws with the seven.
     
  4. Nardoo

    Nardoo Addicted to ArboristSite

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    Not sure you would be welcome in my local Stihl shop with the kind of attitude where you need to label people so. (Or my home either)

    You just might find that Stihl mechanic could be of great help to you in your situation. Wonder what he thinks of you?

    Al.
     
  5. SawTroll

    SawTroll Information Collector

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    I generally agree regarding a MS270 - but 8-pin ones will work very well with some bar length/wood combinations on many saws.

    What that "tech" missed is that his statement was only true out of wood, and in very small wood, on that saw - not for general use. I would say it was really bad advice for the owner of such a saw.
     
  6. jimbojango

    jimbojango AboristSite Guru

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    I'm agreeing with everyone else about using a 7. And the stihl mechanic might be a moron, go to another stihl shop and give them your business if you're unsatisfied. otherwise give him the benifit of the doubt and know he made a mistake
     
  7. Andyshine77

    Andyshine77 Addicted to ArboristSite

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    Most of the saw mechanics are under paid, and for the most part know little about the equipment they work on. The 8 pin will give you about 15% more chain speed and 15% less torque. Unless you run a 12" bar run a 7 pin. I run 7 on all my firewood saws, even the big ones.
     
    Last edited: Feb 1, 2011
  8. Jtheo

    Jtheo Addicted to ArboristSite

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    I will second that. I have tried an 8 pin on a saw that size and it does not work out well.

    But... give the mechanic a break,, we all make mistakes from time to time.
     
  9. mattellis2

    mattellis2 ArboristSite Member

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    whatever. this particular stihl shop is the closest one to my home, but is still about 15 miles out of the way. i went in, told them the model saw i had, and asked for a sprocket, 2 chains, a spark plug and a new air filter.

    they didn't have an air filter in stock, and looking up a sprocket part number shouldn't be that hard. when i got around to cleaning the saw up last night, i removed the old sprocket only to discover the new one was at least 1/2" too large in diameter. because he was too lazy to actually cross reference the part numbers, i spent an additional hour trying to chase down the correct part (and it still sounds like i have the wrong thing) again, this is not an arcane part that should be a special order, it is a sprocket for crying out loud. i don't see how giving me the wrong part helps in anyone's "situation".

    beyond being a cheap son-of-a-gun, this is why i wrench on my own equipment. i certainly can't do worse than a bunch of the "techs" out there.

    i do appreciate the insight on the 7 vs 8 tooth count. i will call around tomorrow and see if i can find a 7 tooth version elsewhere.
     
  10. Andyshine77

    Andyshine77 Addicted to ArboristSite

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    We are talking about 3/8 chain and a rim sprocket correct? Any saw shop will have a 7 pin rim sprocket that will fit your saw, no need to look up a part number.

    Don't down all the techs now!! they're many good ones out there as well.
     
  11. Evan

    Evan Addicted to ArboristSite

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    i run 7s on everything muf modded 026 thqt runs very good, 440 thats fully ported, and a 06 fully ported. ivel played around with a 8 on the 440 and even a 9 on the 066 but i find when cutting wood to bar tip with each saw that they feel best with a 7. the 026 wears a 18 440 a 28 and 066 a 32. these all reguarly cut wood past theyre tip. the 66 is my work horse and screams through wood flooding chips like you wouldnt belive. with the 8 on i have to be alittle finessy on how much pressure i have on the saw. with the 7 it doesnt seem to matter. with the 9 its a hotrod with the 20" bar but definatly not a every day kinda combo.

    same story with the 440. runs the 8 pretty good but feels best with the 7 cutin wood past the 28" bar.

    ive never ran a 8 on the 026 and wont it runs very good cutin wood past the tip but isnt a grunty saw.

    if i just limbed or cut only small wood 18" and smaller my saws might were the bigger sprockets more often .
     
  12. mattellis2

    mattellis2 ArboristSite Member

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    not a rim type spocket. it looks like this: [​IMG]

    the saw chain is a 0.325 - 1/16th, and i have an 18" bar.
     
  13. Stihl-Pioneer

    Stihl-Pioneer Addicted to ArboristSite

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    I assume you have .325 pitch. Since you are replacing it anyway I myself would look at a rim and sprocket kit for only a couple $ more to fit your saw, the # for .325-7 is 1121 007 1037.
     
  14. czar800

    czar800 ArboristSite Operative

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    I have a 8 on my 046 muf modded 3/8" mostly a 24" bar sometimes a 28". I cut mosty wood 20" and under and alot of cherry. On any smaller saw stay with a 7. my stock 026 I run 3/8" 7 pin and a 18" bar. and that plenty and works well.
     
  15. Slamm

    Slamm Addicted to ArboristSite

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    7 pin on everything. 8 pin is rarely faster at the end of the day or a week of work (When you figure in all of the "stallouts"), and is a lot harder on your clutch and saw overall.

    My oPINion,

    Sam
     
  16. redoakneck

    redoakneck Addicted to ArboristSite

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    I have an 026 pro with .325 pitch, 16" bar. I am going to try an 8 pin. I usually don't cut much bigger than 12" with this saw. Sounds like a mistake.??

    The saw is muffler moddded and tuned right.
     
  17. SawTroll

    SawTroll Information Collector

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    Just try it, rims are cheap - but it isn't really much point with that saw, unless most wood is much smaller than those 12 inches.....
     
  18. Andyshine77

    Andyshine77 Addicted to ArboristSite

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    With .325 chain you could probably get away with 8 tooth spur. Here's the part number for the 7 tooth 1121 640 2004. I'd upgrade to the rim system honestly, that way all you really need to replace is the rim when it wears out, not the whole drum.
     
  19. SawTroll

    SawTroll Information Collector

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    To split hairs, about 13% is the accepted figure (actually it is 12-14% depending on which way you do the maths).

    Anyway, the only way to really know what works best is to try both options.

    At the moment, I have an 8-pin on my 346 and a 7-pin on my 2153, and use what I think will fit best, depending on what I do.

    It will probably not stay that way forever, but so far it does, and I have no complaints. :good:
     
  20. jimbojango

    jimbojango AboristSite Guru

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    Go to ebay... i'll bet you have a new sproket found in less than 5 minutes. :) shipped to your door
     

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