850 style centerstand failure

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Rick,

Even considering 140# pull on the spring, it is at about a 45 degree angle from the vertical, so the most it offsets is about 70#. I believe ths addition was more to dampen some harmonic vibration than attempt to support the drive unit. I played with the one on my cafe racer increasing and decreasining the 1.5 inch coil length the manual specifies and saw no real affect on handling, but a small difference in transmitted vibration.
 
Sorry, that was at least 15 years ago, I can hardly remember yesterday! :roll:
 
As I am left-handed or better "left-footed", it is most convenient for me to start the bike while it rests on the center-stand.
Could this be the reason for its breaking ?
 
A decent quality stand in good condition should be able to cope with a lot more abuse than you've been able to give yours in the time that you've had it. I'd suspect that it has fallen on to it at some time in the past and either fractured slightly at the time or when straightening.

BMW K100s are known for this. If they've ever fallen over (usually due to the silly retracting side stands) then the mainstand foot tang will load up the stand tube and it will break at some point.

...Mine did it to me when putting the bike on the stand in the garage. It all happened so quickly. I briefly fought a losing battle to hold the overweight brute upright before the invisible man gave me an Irish Whip and I headbutted the opposite wall. :oops:
 
Thanks for your reaction, 79 x 100. The stand has been welded today, I've painted it and it's already mounted. The topic:

changing-center-stand-spring-t4388.html?hilit=center stand spring

helped me a lot: I mounted one side of the spring in a piece of iron screwed in my vice, used an iron wire to strech the spring by foot and put wooden wedges to "fix" the streched state.
Moreover, I realised it makes no sense to omit the center stand for my race track participation next Friday as I saw that not only the center stand has touched the road but also the left exhaust pipe. :cry:
The ground clearance is a bit disappointing though.
 
Most of the pipes available these days don't tuck in tightly enough. Proper PR pipes don't flare out as wide. It might well be worth talking to someone such as Norman White about a pair that tuck in properly. If you look at 1970s photos, you'll see that many of the privateers ran high level pipes.

Ground clearance was always a problem on the PRs. The 'works' bikes had the front engine mounts raised and shifted 1/2" to the right and it is not uncommon to see a chamfered area let into the chaincase on bikes which retain the standard item.

Sidestand mounts drag as well.

What size rims and tyres are you running ?

Are you off to Gedinne ? Begonia Rally for me. :)
 
Interesting information ! I have 19" rims. Tires: Avon AM 26. I think some harder front fork springs would help as well and if I lost some weight, even better ...
Anyway, I don't think to race often with this precious bike. The track in Croix-en-Ternois is very short: only 1,9 Km (1.2 miles) so no high topspeed and that's what I prefer for bikes suchs as Nortons or Buells. So I consider it more as a kind of demo race.
If I'm still alive and kicking tomorrow evening, I'll maybe go to Gedinne as well - but by car anyway: don't want to let the Norton a long time out of sight.
 
So, it was a nice opportunity to make the maiden trip on a race track with a restaured Norton Production Racer.



850 style centerstand failure



As you can see on the picture, it wouldn't have made sense to omit the center stand as the ground clearance is restricted by the exhaust pipe. (and so was my speed in the bends)
 
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