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Old 04-17-2011, 02:50 PM   #457
Airhead Wrangler OP
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Joined: Mar 2008
Location: Back in Seattle, FINALLY
Oddometer: 6,319
What can't (easily) be lightened

I decided to look at the weight saving issue from the other side - what is my minimum possible weight? There are plenty of things on the bike that cannot be lightened without compromising safety/reliability or involve more effort than they're worth. This is what they weigh:

Frame 28.4 lbs
subframe 5.1 lbs
centerstand 3.2
driveshaft /swingarm w/ bearings and pivot pins 11.2 lbs
final drive 16.2 lbs
engine 127.9 lbs
carbs 4.5 lbs
tranny 25.1 lbs
rear wheel 13.0 lbs
solo seat 5.6 lbs
battery 13.7

250.9 Total without ANY front end parts or taking any small fasteners, body panels or lighting into account.


Rear End Comparison:

I also got curious about the conversion to the R1100GS rear end and wondered what it would weigh compared to a monolever rear end:

R1100GS
final drive 16.7
paralever rod 1.3
swingarm 7.8
drive shaft 5.2
rear wheel 14.7
disc 2.0
caliper 1.8
shock 10.0

59.5 lbs total


R100GS or GSPD
rear wheel 14.2
swingarm w/ all bearings, pins, lower boot 6.2
tie rod 1.0
driveshaft 4.4
final drive 17.8
brake shoes, cam, lever 1.9
shock 8.4

53.9 total



R80ST
swingarm w/ bearings and pivot pins 7.3 lbs
driveshaft 3.9
final drive 16.2
rear wheel 13.0
brake pads, cam, lever 1.4
shock 6.3

48.1 total




HP2 just for curiosity's sake
final drive 17.4
swingarm 9.6
paralever tie rod .9
rear wheel 11.3
driveshaft 4.8
rear disc 2.1
rear caliper 2.1
shock 4.9 (I find that very hard to believe)

53.1 lbs total


It looks like the monolever, despite being heavy as hell, may still be the lightest shaft-driven rear end BMW has made to date.

I also realized I could save 1.6 pounds by going with 1000cc jugs/slugs rather than 800cc ones
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R80ST Gets The HPN Treatment
Seattle to TDF on an airhead

Current rides: HPN #834, '93 R100GSPD "red rocket", '73 R75/5 Toaster mongrel, '80 Ducati Pantah 500SL, '92 DR350, '67 Honda SS50, '80 Honda Chaly.

Airhead Wrangler screwed with this post 04-17-2011 at 03:20 PM
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