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 Post subject: '79 CR250 fork springs
PostPosted: Fri Sep 05, 2008 9:43 am 
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Joined: Sat Dec 23, 2006 10:00 pm
Posts: 313
Location: CA
I have yet another question from my '79 resto. I dismantled the front forks and it is obvious they were recently
rebuilt (good seals, clean fluid, no stuck bolts), I measured the springs and checked that number against the
specs in all of my reference books (Honda, Clymer, etc). The problem(s) is, my forks only had one spring
while the factory installed two (spring A and B). That isn't a problem if the new spring is a one piece
replacement but the overall length is 21" which is roughly the length of the original spring B. Also, the
reference sources call for a 17"+ spring A and a 20"+ spring B for a total of more than three feet of spring
in each fork! That has to be a typo, but what are the real numbers? Looking at the diagrams it looks like
spring A might be 1.7" and spring B 20" but that's just a guess. Anybody know the real numbers? And, does
anybody running a one piece replacement spring know the free length?

Thanks in advance for any help/input.

dogger

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1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R


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PostPosted: Fri Sep 05, 2008 12:02 pm 
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Joined: Fri Jul 14, 2006 8:12 am
Posts: 323
Location: Wuppertal/Germany
dogger315 wrote:
I have yet another question from my '79 resto. I dismantled the front forks and it is obvious they were recently
rebuilt (good seals, clean fluid, no stuck bolts), I measured the springs and checked that number against the
specs in all of my reference books (Honda, Clymer, etc). The problem(s) is, my forks only had one spring
while the factory installed two (spring A and B). That isn't a problem if the new spring is a one piece
replacement but the overall length is 21" which is roughly the length of the original spring B. Also, the
reference sources call for a 17"+ spring A and a 20"+ spring B for a total of more than three feet of spring
in each fork! That has to be a typo, but what are the real numbers? Looking at the diagrams it looks like
spring A might be 1.7" and spring B 20" but that's just a guess. Anybody know the real numbers? And, does
anybody running a one piece replacement spring know the free length?

Thanks in advance for any help/input.

dogger

at my 79 owners manual it is
spring a: 41mm/1.6in.
spring b: 517,5mm/20.37in.
but this is the wear limit.

_________________
80 CR250Ra
80 CR250Ra
78 CR250R
80 CR80
82 Bultaco Sherpa 340
78 Bultaco Pursang 250 MK12
76 Bultaco Frontera 370 MK10
76 Bultaco Alpina 250
73 Bultaco Lobito 125 MK6
76 Suzuki RM125A
90 Kawasaki KX250


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PostPosted: Fri Sep 05, 2008 2:35 pm 
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Joined: Sat Dec 23, 2006 10:00 pm
Posts: 313
Location: CA
Thanks again b-joe. Your wear limits match mine once the decimal is moved to the correct location.
My Honda manual service limit states: Spring A 410 (16.142) Spring B 517.5 (20.3140) move the
decimal on the Spring A number and you get 41.0 (1.6142).

Transferring that correction to the standard length: Spring A 45.3 (1.7835) Spring B 529.5 (20.8465).
Add the upper spring seat and the total stock spring length is 577 (22.7165). So the spring I have now
is either 1.8" too short as a replacement one piece, or right on the money for Spring B.

dogger

_________________
1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R


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