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Old 04-11-2014, 01:54 AM   #1
dalla OP
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R2V engine in R51/3 frame

Hi Guys

I have found a R51/3 frame for sale. Now i am toying with the idea of building a low cost bobber. Does any of you guys know if it would be posssible to install a later Airhead engine in this frame. Maybe something like a R65 engine? Maybe cut down to clear the upper frame tube?

Also could you point me i direction to where i can buy shocks and other parts for a R51/3.

Any help/ideas are appreciated.

Kind regards
Dennis
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Old 04-11-2014, 04:48 AM   #2
spo123
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Cool2

Maybe you should post this on the Vintage BMW Motorcycle forum......Someone just MIGHT be looking for that particular frame.
Or don't.
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Old 04-11-2014, 05:00 AM   #3
danedg
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Some sources

http://www.meyer-bikes.de/index.php?...atic&path=home
http://www.benchmarkworks.com/
https://bmwbike.com/index.php?l=english&n=1&c=13

What's the VIN on the frame? There really is an "orphan list". Somebody might just be holding on to the motor for that frame.
http://bmwvmca.org/joomla/index.php?...=317&Itemid=42

51/3's don't really have "shocks" or "suspension". They have "dampeners" , leather seals and a big spring under the seat...
A lot of folks have stuffed modern motors in /2 frames. Dealing with that /3 frame isn't going to be quick, easy or cheap...
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danedg screwed with this post 04-11-2014 at 11:11 AM
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Old 04-11-2014, 11:11 AM   #4
Beemerguru
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See if someone will trade you for a later model /2 frame. The /3 is worth more complete and the /2 gives you more options and includes a real 2 shock suspension.

Post to the Vintage BMW forum with the VIN..Collectors are always looking
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Old 04-11-2014, 01:58 PM   #5
Biebs
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Pissed Sawzall

Sawzall will make a nice Honda 750 fit in that frame - convert to chain drive and you will have one sweet bike!!!

Do it then my R51/3 will be worth more $$$$ - another one bits the dust

Oh wait I don't have a R51/3 - Put down the sawzall.

really the /2 frames will take a newer engine flip the /3 frame for some $$$


is there a R51/3??? what year??? Look up years 1951 telescoping front forks?? Does the frame have sidecar lugs??


Looks like any airhead engine would fit this frame with some mods of course - Wikipedia is your friend.

Biebs screwed with this post 04-11-2014 at 03:44 PM
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Old 04-11-2014, 06:14 PM   #6
bmweuro
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You can stuff a post 70 motor and trans in that frame. You will need a /3 driveshaft and rear drive as well you will need to modify the transmission output flange for a /3 driveshaft which is something that Kevin Brooks should be able to do.

Start cutting
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Old 04-11-2014, 08:49 PM   #7
supershaft
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Quote:
Originally Posted by bmweuro View Post
You can stuff a post 70 motor and trans in that frame. You will need a /3 driveshaft and rear drive as well you will need to modify the transmission output flange for a /3 driveshaft which is something that Kevin Brooks should be able to do.

Start cutting
That frame came with both the twin cam /2's and single cam /3's. Both engines used a two shaft transmission. All BMW's used a two shaft transmission until '55. Very important since the engine has always turned the same direction thusly the drive shaft turns one way out of a two shaft transmission and the other way out of a three shaft transmission. If you use a late model three shaft transmission with the plunger frame's final drive, you are going to go backwards when you let the clutch out since the plunger frame's final drive has the pinion gear on the opposite side of the ring gear compared to '55 on final drives. That's how pre and post '55 bikes both have engines that rotate the same direction and both move forward when you let the clutch out although one of them has a two shaft transmission and one of them has a three shaft transmission. The key is the final drives that have their pinion gears on opposite sides of the ring gear. Easily discernible just looking at them assembled. Be careful! A late engine and tranny in a plunger frame will have four or five speeds of backwards!!!! Not good in my book!
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