Split Topic: Triple Trees

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L.A.B. I think we have the same dilemma with 06-1915 06-1916 and 06-1917. I cant find 06-1917 in the parts books but I have two top yokes with those numbers on. One is off my 72 and one is off my brothers 71.Phil
 
Norton-Villier said:
L.A.B. I think we have the same dilemma with 06-1915 06-1916 and 06-1917. I cant find 06-1917 in the parts books but I have two top yokes with those numbers on.
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The number on the casting isn't generally used for the finished component.

And once it becomes part of an "assembly" (yoke with stem) the casting number becomes even more irrelevant, as the assembly will have its own number. That's why it's not in the parts book.
 
some additional info :
trail with std 19" wheels :
750 with 3.50 front tire : 81 mm
750 with 4.10 tire : 82 mm
850 : 106 mm
 
ludwig said:
some additional info :
trail with std 19" wheels :
750 with 3.50 front tire : 81 mm
750 with 4.10 tire : 82 mm
850 : 106 mm
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So the question now (I think) is what is the trail if you put 750 trees on and 850 frame and visa versa? I was just searching for enough data to run the numbers but haven't quite figured out where to look for it.

FWIW - from the CNW web site..."Aligns the fork tube with the steering stem for greater high speed stability compared to the stock design. This alignment also betters the torsional rigidity in the steering neck"
 
Then what CNW does increases the trail a bit more then the factory trees. That would sacrifice some handling, but I doubt many of us are looking to drag knees:)
 
Just tossing this out, but I think many of CNWs bikes are more low-slung than average.
 
rvich said:
FWIW - from the CNW web site..."Aligns the fork tube with the steering stem for greater high speed stability compared to the stock design. This alignment also betters the torsional rigidity in the steering neck"
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I am surprised to read this ..
I suppose they mean compared with the stock 850 design ?
They do not explicitly say that their kit increases trail , but generally ' greater high speed stability ' is associated with increased trail ( everything else equal ) .
If this is what they mean , then their claim is false .
 
MichaelB said:
Just the opposite. Increase the rake, lessens the trail.
Refer back to Ludwig's post, page 3.
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Rake is the angle of the headstock ( frame ) .
Increase rake = increase trail .
The angle of the fork itself is a different thing .
( I didn't realise it was so confusing ! )
 
Just when I thought I had it figured out.
Thanks for setting me straight.
 
http://www.yamaha-motor-europe.com/

Split Topic: Triple Trees


"Trail. What is it and what does it do?

Trail is defined as the distance between the centre of the front tyre’s contact patch and the point where the steering axis meets the ground. (See figure 3. 1)

Virtually every motorcycle and bicycle ever designed has a trail value, and this is what gives the front wheel a caster or self-centring effect when in motion. In other words, a machine being ridden in a straight line is designed to continue travelling in a straight line unless other forces are brought to bear upon it. These forces may be rider inputs such as steering or leaning, or external forces like crosswinds or road cambers.
Trail creates a certain level of steering stability, and so by altering trail, a chassis designer can ‘tune’ the handling characteristics of any motorcycle to suit the purpose for which the motorcycle has been designed.

Caster, and its role in agility and stability.
Caster (sometimes referred to as rake) is the angle between the steering axis and an imaginary perpendicular line running through the front wheel axle. (See figure 3:1) As we have already seen, a motorcycle’s trail measurement plays a crucial role in achieving chassis stability, and it is the caster angle (among others) that helps to determine trail."
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On some hevyweight touring Harleys, the fork legs are actually offset BEHIND the centerline of the steering neck to increase trail.
 
Hi all, its well known not to fit earlier yokes to an 850.
is it possible to use very early or Featherbed yokes 2-1/4" offset on an 850 frame?
 
madass140 said:
is it possible to use very early or Featherbed yokes 2-1/4" offset on an 850 frame?
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I don't know, but the pre-'64 yokes are 3/8" narrower between stanchion centres (7" instead of 7-3/8").
 
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