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  Aug. 12, 2011 8:41 a.m. 914Driver SuperDork

  http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=51891&rnd=03252011

  I ordered a Corbin seat for my 1976 BMW R-90/6 and it's ~1.5" too long up front. I've researched BMW part numbers and they are different for the /6 and R-90s, all of the parts catalogs show a tank with indents on each side which have rubber pads on them. My tank has no indents but appears to be a BMW item.

  The attachment is a pretty good reference for parts and assembly ideas, from a local Dealer.

  I'd love to hear any ideas or suggestions.

  Dan

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  Aug. 12, 2011 1:40 p.m. alex SuperDork

  Can you snap a pic of your tank?

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  Aug. 12, 2011 3:25 p.m. 914Driver SuperDork

  
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  Aug. 12, 2011 5:36 p.m. alex SuperDork

  I'm certainly no font of BMW parts knowledge since I left the shop several years ago, but I think there was a mid-model-year change on tanks, or yours may be a later or R90S tank. Early /6s had either that slender, small tank or the kneepad tank you referred to earlier.

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  Aug. 12, 2011 5:41 p.m. alex SuperDork

  Oh, and the Max parts fiche used to let you look up parts by the last 10 digits of your VIN. Do that, if you can, since that will get you parts that are date-specific to your bike.

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  Aug. 13, 2011 2:23 p.m. motomoron HalfDork

  Regular /6 tanks were interchangeable with long wheelbase /5 tanks if I recall.

  R90S tanks - which were essentially unchanged among all subsequent /7 bikes, R100/R100S/R100CS/R100RS/R100RT will fit on an R90/6 frame - in other words the front rubber bumper fits either tank and the posts the thumbscrews go on are in the right place...

  But the length of the tank from the rear mounts aft differs.

  Your Corbin seat is for this, probably:

  
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  Aug. 13, 2011 2:31 p.m. BoxheadTim SuperDork

  Definitely looks like a later tank - in fact that looks like it's the same shape as the one on my '81 R100RS.

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  Aug. 13, 2011 5:51 p.m. motomoron HalfDork

  The bodywork is R90S. Note the position of the nose of the seat relative to the front corner of the side covers on the OP's bike relative to this:

  

  ...On the bigger R90S - /7 tank the seat is in fact about 1-1/2" shorter.

  BTW - the seat on the OP's bike is from a 1977 R100RS - they're pretty rare and in decent shape fetch some major coin.

  BTW - I have a full set of everything needed to convert a /7, S or RT into an RS. Fairing, bars, "impact pad" brackets, hardware, clock and volt. It's all leftover from when I converted my '83 RS to a CS which was a lot more pleasant in the steamy DC summer weather.

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  Aug. 13, 2011 8:25 p.m. 914Driver SuperDork

  Thanks Motomoron, if you look at the orange bike you posted vs mine, the rear of the orange tank is forward of the side cover where mine is flush with the side cover. I hope the folks at Corbin are following this thread .....

  I'm negotiating with a guy on the left coast for the S fairing volt meter and clock, he wants $25 each + $10 shipping, $60 total. Sounded more than fair to me.

  Dan

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  Aug. 13, 2011 8:36 p.m. BoxheadTim SuperDork

  motomoron wrote:

  BTW - the seat on the OP's bike is from a 1977 R100RS - they're pretty rare and in decent shape fetch some major coin.

  Yup, definitelty the notorious 1 1/2 passenger seat from a really early R100RS.

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  Aug. 13, 2011 8:49 p.m. 914Driver SuperDork

  Wait, if I bought an R-100 seat it would pop right on?

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  Aug. 13, 2011 9:20 p.m. BoxheadTim SuperDork

  With the caveat that the advice is worth what you paid for it, I would think so. The frame didn't change much between the R90 and R100 (IIRC the R100 has a bracing tube between the downtubes that the R90 doesn't and that's it) and everything else should be in the same place.

  Actually you already have an R100 seat on there .

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  Aug. 13, 2011 9:45 p.m. motomoron HalfDork

  Yes - R90S or R100/7-up (or R80/7-up) tank dictates the seat.

  Or buy a R90/6 (not S) appropriate seat.

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  Aug. 16, 2011 5:39 a.m. 914Driver SuperDork

  motomoron wrote:

  Or buy a R90/6 (not S) appropriate seat.

  The Corbin is allegedly made for a /6. I think it's going back and I'll cut up a perfectly good pan to have Sargent recover it.

  Dan

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  Aug. 16, 2011 10:24 a.m. BoxheadTim SuperDork

  Why not get them to swap it out for an R100/R90S style seat?

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  Aug. 16, 2011 11:20 a.m. alex SuperDork

  914Driver wrote:

  I'm negotiating with a guy on the left coast for the S fairing volt meter and clock, he wants $25 each + $10 shipping, $60 total. Sounded more than fair to me.

  That's a killer price, even if they need internal repair.

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  Aug. 16, 2011 11:34 a.m. 914Driver SuperDork

  BoxheadTim wrote:

  Why not get them to swap it out for an R100/R90S style seat?

  They claim to have nothing that fits my bike. It's been two weeks, I'm through.

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  Aug. 18, 2011 6:23 a.m. 914Driver SuperDork

  The guy I'm buying gages from is a BMW bike salvager, he tells me I have a 90s or R-100 tank, not a stock R-90 tank.
  

  Spoke with Corbin, they will refund my money minus 20% restocking fee. Wait, none of this is my fault, why should I eat $80? After a brief but intense discussion it was determined that because I placed the order via telephone and not on line there is no tracability or evidence of wrong doing on either part, so they waived the 20% fee.
  

  Whew. Now I have to mail it back ($40) and they will "custom make" one for my unusual application but not charge me the custom price.

  Never, never, never doing this again. I've used Sargent Cycles many times with no hassle whatsoever.

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  Aug. 18, 2011 9:31 a.m. minimac SuperDork

  What exactly did THEY do wrong? Some how it's their fault your bike is a morphedite? Seems to me that Corbin is going above and beyond. They sent the seat you ordered, for the bike you told them. I agree, they shouldn't have charged a restocking fee, but now you're getting a custom for the $40 to ship the seat you ordered back. That is good customer service, in my book.

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  Aug. 18, 2011 9:54 a.m. 914Driver SuperDork

  I understand at the end of the R-90 run they put R-100 tanks on it, morphing into the 100 model, mine is not that rare. Their custom is going to be an R-100 seat. Even after viewing multiple photos the tank couldn't be identified.

  My customer service issue is every conversation I had with corbin started right at the beginning of information gathering and "we'll call you back", this went on for ten days. The rep that took my order was in Sturgis for a week and I was not allowed to address my ill fitted seat with anyone but him.
  

  That's just silly.

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  Aug. 18, 2011 10:41 a.m. motomoron HalfDork

  It doesn't matter what "bike" you have so long as it's a BMW twin made between 1974 and 1983. All the tanks (small and big /6, R90S=/7=S=CS=RS=RT=CS) are interchangeable.

  Other than the R90S, that tank wasn't used on other /6 bikes that I'm aware of.

  What I mean to say is: The only tanks that required a longer nose on the saddle were the R90/6 small and large tanks.

  The R90S and every subsequent R80+R100 aside from the ST and GS made between 1977 and 1984 are interchangeable

  Go to realoem.com motorcycle catalog, archive, R90/6, final production date 1976, mid year. Look in fuel system. There's the small and large tanks and the cool tool-tray Euro cop tanks we didn't get here. R90S has the big (/7) tank.

  If your bike is still in factory paint (it looks like spheric silver. The 2-tone fade version was called polaris graphite) the bodywork came from a 1983-up bike.

  Order a seat for a 1977-up BMW R100/7 if you want a "bench" seat - they had those. Otherwise anything you get for a 77-84 R80 or R100 will fit your frame and tank, I promise.

  BTW - Corbin just sucks. I've had a few, don't like 'em, and dealt with them for scores of customer seats. They were involved in the "Corbin Sparrow" fiasco also. Google it.

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  Aug. 18, 2011 11:09 a.m. 914Driver SuperDork

  Thanks Moto, but corbin says they're on it and I'm tired.

  Dan

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  Aug. 18, 2011 5:02 p.m. minimac SuperDork

  Making you wait because the guy you were talking to went away is just just plain unacceptable. I stand semi-corrected. BUT, I sure liked the Corbin that was on my old Cavalcade.

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  Aug. 19, 2011 5:42 a.m. 914Driver SuperDork

  I'm sure I will like the Corbin once it's here, I'm underwhelmed by their service.

  YMMV.

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  Aug. 19, 2011 7:29 a.m. 44Dwarf Dork

  AHUGG... Some times in life your Chairlle Brown....sometimes your Lucy with the foot ball.

  Sadleman showed all sorts of combos for the bike long tank short seat short tank long seat etc. But if Crbins work abit slow at least there doing something. Hang in there.

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