Common Stihl 090G Misbeliefs

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I would like to address a couple of common misbeliefs about the Stihl 090G. For a long time I’ve heard folks talk about chain drive 090Gs and an 090GS or 090G Super. I do not believe either of those to be true. I am not an expert on the matter, but I’ve done a good deal of research and inspection in order to come to my conclusions. If anyone has documentation or proof that what I post here is inaccurate, please let me know. My focus is not to be right – it’s to learn and share.

First, every 090G that left the factory was fitted with a 58mm top end. Never a 66mm. There was no such thing as an 090GS or 090G Super. Yes, there were Contra G saws with 58mm top ends and Contra GS saws with 66mm top ends, but never an 090GS. It is very common to find a 66mm top end on an 090G, but that was swapped out after leaving the factory. Many users did that, and even today many collectors and enthusiasts do the same. I've been told the distributor in the Pacific Northwest would install 66mm top ends back in the day. Dealers would even swap top ends on new and used saws upon customer request. There is zero documentation I've seen to support the theory that there were factory 66mm 090G saws. I’ve personally had a couple of these chainsaws with 66mm top ends and an “S” stamped at the end of the serial number – that was just added after the top end swap, and I theorize some dealers did that when they upgraded the saw. In both cases of mine, the “S” was a very slightly larger font than the serial digits which only confirms for me that the ‘S’ was not original. I also have had an 090G with the 66mm top end and a little “SUPER” sticker on it. That sticker was not factory – I’m sure it was just another dealer (or owner) addition.

Second, I’ve heard many people claim that the very earliest Stihl 090G chainsaws were factory fitted with the same chain drive transmission as the Contra G/GS. I do not believe this to be true either. I have not seen any documentation of factory chain drive 090G chainsaws. Yes, you will occasionally find an 090G with a chain drive setup, but they have either had the transmission changed out or they are actually a Contra G/GS case with an 090 top end and cover set; they were not setup that way from the factory. Between myself and another collector I know, we own the three earliest 090G serial numbers I’m aware of. None of those have chain drive setups. Absolutely every chain drive 090G I’ve seen had both a later serial number (if a number present) and later features than those three saws.

Furthermore, a chain drive setup will not fit into an 090G gearbox without modifying the case. In the following photos I have examples of an 090G gearbox that I removed a chain drive setup from, a chain drive Contra GS gearbox, and a stock unmolested 090G gearbox. This first photo is all three side-by-side.

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These next three photos show two bosses that are important in this comparison. First is the 090G stock, unmolested case. The second is the 090G case that I removed a chain drive setup from. The third is the Contra GS case.
 

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These next five photos are of the lower boss. The first is the 090G stock, unmolested case. The second is the 090G case that I removed the chain drive setup from where you can see the boss has been machined down to accommodate the chain.. The third is the Contra GS case. The fourth shows that the 090G boss is about 1-1/8” from the bottom edge of the case. The fifth shows that the chain from the GS is also about 1-1/8” from the bottom edge of the case
 

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These next three show the upper boss. The first photo is the 090G stock, unmolested case. The second is the 090G case that I removed the chain drive setup from where you can see the chain had been contacting and wearing into the boss during operation. The third is the Contra GS case.
 

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Dunno why but some of your pics aren't showing. Sad cuz this is a really interesting thread.
I almost had my hands on an 090, but ended up buying my 660 instead. Stihl kinda regret it.
 
I can see them too on Tapatalk. I didn’t even know there was a chain drive contra much less a 090 chain drive. I heard that the 090g started out with the 66mm end but it had cooling issues. That’s why they put the 58mm top end on from the 070. All rumor I guess. I have an original 090g with the 58mm top end. I would like to put the 66mm top on, but I don’t want to take away from the all oem all original machine.


Sent from my iPhone using Tapatalk
 
I'm on Sh!t tapatalk. Half of the pics don't show. Don't care if you see them. Whatever. Uns
 
These next five photos are of the lower boss. The first is the 090G stock, unmolested case. The second is the 090G case that I removed the chain drive setup from where you can see the boss has been machined down to accommodate the chain.. The third is the Contra GS case. The fourth shows that the 090G boss is about 1-1/8” from the bottom edge of the case. The fifth shows that the chain from the GS is also about 1-1/8” from the bottom edge of the case

5.jpg6.jpg7.jpg8.JPG9.JPG
 
A lot of rumors float around regarding the chain drive. I guess the manufacturing transition was gradual and the very first 090G were using existing the Contra G cases discussed in the Swedish forum a number of years back.
http://chainsawcollectors.se/phpbb3/viewtopic.php?t=21321

I'm very familiar with that thread Seam. What I have posted above, I believe, dispels what was discussed (assumed) in that thread. I have also posted this new info on CSCF. I do not believe there was a transition period, it was an abrupt change from the chain drive Contra to the gear drive 090G.
 
This is cool info Beau - Thank you for posting. I know nothing about these saws so this is all new to me. I have seen a lot of discussion though on the differences between the chain-drive and geared saws, as well as the regular vs. super
top ends and whether that was a factory decision or not.
 
You might be correct there, Beau!
There is a list of Stihl series with production start/stop dates in the German Forum's Wiki:
http://wiki.motorsaegen-portal.de/wiki/STIHL_-_MOTORSÄGEN_VON_1929_-_2020
It seems that the 090G was introduced at the same time as the 090 (April 15, 1969 - might have been a reason for them to unify the "090" designation despite the displacement difference) while the Contra G/GS series was discontinued about 9 months earlier (July 1, 1968). The 070 was introduced quite a while earlier (Sept. 9, 1967). According to this list, there was a time gap between the discontinuation of the Contra G/GS and the introduction of the 090G which would indicate a "from scratch" production start for the 090G. Interesting... :surprised3:
 
I would love to see an old video of one of these saws being used to fall some really big old growth. I've seen pictures and one of the companies I cut for when I was young supposedly had one with an 84" or 96" bar but I never saw it. I have seen at least one other and I remember the chain turning really slow (go figure, huh?) but it wasn't cutting, just running in somebodies garage if I remember correctly.
 

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