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Old 02-14-2012, 12:30 AM   #31
Padmei
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OK - those that have done the conversion- what are the bikes like to ride? Much discernabale difference? Would you do it again? Would you do it differently?
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Old 02-14-2012, 12:46 AM   #32
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Originally Posted by Padmei View Post
OK - those that have done the conversion- what are the bikes like to ride? Much discernabale difference? Would you do it again? Would you do it differently?



(I'm still undecided about this. Was going to go 50mm extension, but am currently tempted to keep the shorter wheelbase and raise the suspension a little ala Rucksta style by moving the swing-arm shock mount forward a little, plus the other alterations required)
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Old 02-14-2012, 12:48 AM   #33
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Originally Posted by lewisjohn View Post
I should have mentioned i am converting the bike from an RT donor bike,and using a standard RT bevel box,so have moved the lower shock mount onto a bracket welded on to the monolever arm


Sweet looking ride
Nice choice of parts .



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Old 02-14-2012, 02:17 AM   #34
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Nice thread

I have an 85 G/SPD and have fitted R100GS front forks and 4 pot brembo caliper.

I recently purchased the Paul Rooney 50mm extension kit for the swing arm, but am unsure if i will fit it due to the 6mm offset spacer for the back wheel to allow tyre clearance to the swing arm. My main objection is having a 6mm gap between the hub and diff, as this will let all maner of nasties into the already poor brakes.

Has anyone fitted the 50mm extension and modified the swing arm, or has anyone got experience with living with the 6mm gap?

thanks
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Old 02-14-2012, 02:58 AM   #35
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Quote:
Originally Posted by Padmei View Post
OK - those that have done the conversion- what are the bikes like to ride? Much discernabale difference? Would you do it again? Would you do it differently?
Nah, Go the 100mm


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Old 02-14-2012, 05:39 AM   #36
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Quote:
Originally Posted by Padmei View Post
OK - those that have done the conversion- what are the bikes like to ride? Much discernabale difference? Would you do it again? Would you do it differently?
I've tried a few different lenghts including shorter.
I'm back to stock length swingarm and wheelbase after puting the steering head rake back to stock.

This is where I'm at now. It's a setup I've been playing with for 5 years and will get it right one day.



The weight bias is slightly to the rear and the trail is long due to only 20mm offset on the triples.
I think I'd like 25mm offset but the straight line stability is everything a longer swing arm produced without as much reduction in turning ability.
I'd just like a lttle bit better turn and am prepared to sacrifice an equal or slightly greater amount of straight line stability to get it.
Maybe this year if I get a milling machine lathe combo for Christmas I'll have a crack at a new set of clamps.

When I think about doing another swing arm mod 60-75mm looks attractive but it's already hard to get my ageing legs over the seat even without a swag on so I probably won't bother given how happy I am with the current setup.

Here's what I found mucking around with longer swingarms.

Longer swingarms reduce shaft jacking improving traction under power over rough ground especialy rutted uphills.
Under power the longer swing arms steer better and more predictably once you cross it up but you have to push that bit harder on corner entrty to get the front to break loose.
If you're not a cross up style rider the long swing arm will take more power input on corner exit before it starts to break loose. (slower turn rate higher exit speed - complete more of your turn on entry usually at a lower entry speed can be a positive or a negative depending how you ride.)

There was a noticable gap between the two styles that I did not find away to get the transition smooth with extended swing arms.
I've come closer to the smooth transition since going back to stock but not as good as the seamless transition between tracking and sliding that the stock bike delivers. (maybe the 25mm triple clamp offset would improve that)

Long improves straight line stability especially on loose surfaces e.g. sand but the forward bias of the mass centre means the front buries more easily and a more agressive riding style is required to keep the front floating.

Long also improves comfort as the suspension just seems more progressive and the load carrying capability is improved as you don't have heaps of gear behind the rear axel even when fully loaded.

In tight going I noticed a reduced willingness to turn.
The increased ground clearance was partially or totally discounted by the longer wheelbase resulting in getting hung up on the same rocks and trees the improved stock setup.
Long also makes it harder to loft the front end.

On the sealed twisties long gave a tendancy to understeer or push in corners.
Without as much shaft jack effect I found it hard to hold the bike down under power to stop it running wide but power down on exit was great just like in the dirt.

Long also helps get you over the saggy arse look that all G/Ss have especially those with a stock rear end and an enhanced front end.

In the end you have to decide what you want from the bike as well as where and how you're going to ride.
If I was hauling luggage down red dirt roads more often than doing day rides and weekends along the East Coast Ranges I'd go the 100mm extension for sure.
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Old 02-14-2012, 07:37 AM   #37
rediRrakaD
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Great write up!
Thanks for sharing.
Cheers,
S.
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Old 02-14-2012, 09:42 AM   #38
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Quote:
Originally Posted by cenji View Post
and you bought the 75mm extension from the Australian guy?
Where exactly did you extend/weld the center-stand, midsection, did you use a larger sleeve or smaller sleeve to bridge the existing tubing? Do you have a pic, any hints what to do what to avoid? Thanks a bunch.
What is the length of your shock from eyelid to eyelid?
I manufactured the swingarm extension myself,i extended the centre stand by cutting off the curved sections below the cross brace, and machining two steel tubes which were then pressed into the stand,the joints were welded and feet welded on.My rear shock is a standard length 350mm eye to eye
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Old 02-14-2012, 11:51 AM   #39
cenji OP
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thanks for

answering all the questions, it helps. Ontic and I will have to do the extension on center-stands as well. A pic showing the conversion would come in handy down the line, whenever it fits into your schedule. Especially the feet option is interesting to me, as I wonder if they have built in curvature to make the moving of bike easier.
Good job with the homemade 75mm extension.


Quote:
Originally Posted by lewisjohn View Post
I manufactured the swingarm extension myself,i extended the centre stand by cutting off the curved sections below the cross brace, and machining two steel tubes which were then pressed into the stand,the joints were welded and feet welded on.My rear shock is a standard length 350mm eye to eye
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Old 02-14-2012, 11:56 AM   #40
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thanks for...

bringing it all to my attention. I hope down the line I will have accumulated all the facts that went into the rear and front suspension changes and can better understand how things are affected. If anyone would have that number of the shock-length and maybe how much the lower shock mount was moved, that would be groovy and another good info. Maybe there is website where all this info is posted or someone built an identical replica and has the numbers handy.
What also would interest me what is the exact offset of triples of the KTM 950se? Anyone?



Quote:
Originally Posted by Airhead Wrangler View Post
That info won't help much without knowing the geometry of the mounts on the main frame and swingarm both of which were modified from stock. It used a double sided swingarm
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Old 02-14-2012, 12:18 PM   #41
Airhead Wrangler
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Quote:
Originally Posted by cenji View Post
Maybe someone built an identical replica and has the numbers handy.
HPN made the originals and continues to make replicas to this day:

hpn.de

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Old 02-14-2012, 02:01 PM   #42
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Quote:
Originally Posted by cenji View Post
bringing it all to my attention. I hope down the line I will have accumulated all the facts that went into the rear and front suspension changes and can better understand how things are affected. If anyone would have that number of the shock-length and maybe how much the lower shock mount was moved, that would be groovy and another good info. Maybe there is website where all this info is posted or someone built an identical replica and has the numbers handy.
What also would interest me what is the exact offset of triples of the KTM 950se? Anyone?
A good friend is in the process of installing a 950SE complete front end onto his R100GS.
I will try to persuade him to send some pics/measurements over.
Total score on his part!! We'll see how it functions... already looks neato.

Cheers,
S.
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Old 02-14-2012, 03:17 PM   #43
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Quote:
Originally Posted by rediRrakaD View Post
A good friend is in the process of installing a 950SE complete front end onto his R100GS.
I will try to persuade him to send some pics/measurements over.
Total score on his part!! We'll see how it functions... already looks neato.

Cheers,
S.
Has he been following the threads here about the same conversion? There are at least 15 of us grafting KTM front ends onto BMW's...

Here is one thread:

http://www.advrider.com/forums/showt...ghlight=unholy
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your bike is suitably dirty. Well done.
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Old 02-14-2012, 04:58 PM   #44
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Quote:
Originally Posted by rediRrakaD View Post
A good friend is in the process of installing a 950SE complete front end onto his R100GS.
I will try to persuade him to send some pics/measurements over.
Total score on his part!! We'll see how it functions... already looks neato.

Cheers,
S.
and another
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Old 02-14-2012, 06:25 PM   #45
rediRrakaD
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Quote:
Originally Posted by SOLO LOBO View Post
Has he been following the threads here about the same conversion? There are at least 15 of us grafting KTM front ends onto BMW's...

Here is one thread:

http://www.advrider.com/forums/showt...ghlight=unholy
No, he is not a follower of ADVR.
Sorry, I hadn't researched the subject since I acquired my cheapo HUS front end, back in July of '10. I have never seen a complete 950SE front end fitted onto an Airhead...

Thanks for the link (you too hardwaregrrl!!).

I'll head back up to the workshop and stuff my 100mm extended driveshaft back into the swingarm. (Now that I have a functioning press).

Cheers,
S.
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