Guys,
Ok i was asked by our moderator (Husky T)
to post a how to on 40mm fork conversion for the 1978-1980 250, 390 Huskys. I've done this on my 1980 390CR and it's a bolt on conversion & one of the easiest suspension improvements you can make.
So in my opinion, this mod only really helps the 1978-1980 model bikes, as the older bike had fairly short suspension to begin with. And to be truthful the older model bikes would probably benefit more with just rebuilt stock suspension than by putting longer/larger late model diameter on.
1st thing If you go the 40mm route be careful to get forks that are close to the same travel as you currently have. Later model Husky had much longer travel shocks and are closer to 17-19" c-c so they made the forks longer too, besides larger in diameter.
Because of this you could easily mess up the very good steering geometry Husqvarna designed into the bike to begin with, by putting too long of forks or shocks & not adjusting the opposite end ,close to equaling it out. Of course you can go with longer length shocks and
adjust the forks to match, but i wouldn't go over an inch longer than
stock, as you'll be putting the swingarm at angle it was not designed for.
Now of course Huskys didn't always turn as fast as alot of other bikes, but usually nothing could equal it on whooped out straight away or rough sand section.
So for example if you used forks of a 81 250CR they have close to 14" of fork travel & have 17" c-c rear shocks. So you'd need to pull the forks up 2" in the triple clamps to have the same balanced handling when using 15" c-c shocks.
Ok , so what do you need, it's really simple
1) Set of 40mm forks 81-85, a complete set works best, with front
wheel,as the front wheel spacer & axle is more than likely different
from the stock one you have.
note:
Husqvarna gave their MX or CR/XC models longer length suspension then there enduro or WR models of the same year, usually there about a 1" difference on both ends. So take some measurement before you head off to Ebay or Mid-Ohio or the like to buy parts.
Take a measurement off the distance from the bottom of the triple clamp to the fork seal, so you have a base dimension,write it down.
Once you pull the old front end off, the 40mm set just bolts right on.
Hopefully you've changed the fork seals 1st, i perfer 12w oil (10 & 15w
mixed 50/50) , no springs in & 6" of oil from top, no air in forks. Put a
cable tie loosely above one of fork boots, so you can check fork travel.
Put the new forks on using the same dims you measured from the 35mm set to start out. Ride the bike & adjust the fork height if needed.
Ok, i'm not a 40mm fork expert, but i found the 81 or 82 CR worked
best on my 80 390CR, as there more than long enough. Also someone
on another forum told me you can make the 80 front wheel work
by modifing the wheel spacer, but i have no info of what's entailed.
Also i believe the 84 & up 40mm steering stem offset is different then the 81-83 ones, and the 85 & 86 have disc brakes so the fork legs
maybe different. The 84 models have double link brakes,but they
should work on the older 81-84 , but the again the wheel spacer
maybe different so try & get a complete set will help.
Ok a few other tricks
1) safety wire the front brake cable, down to the fork mount. Tie it
where the metal adjusting is and tighten it downward toward the
axle, as the cable can pull out of the adjuster.
2) make sure you replace the numberplate with the extended cable
saver type (vertical tab the attaches to the crossbar) as the cable
can easily get caught on the top portion of the fork that sticks
above the top triple clamp & cause the front brake to drag or even
lock
I can post picture if someone needs any
Later
John
Ok i was asked by our moderator (Husky T)
to post a how to on 40mm fork conversion for the 1978-1980 250, 390 Huskys. I've done this on my 1980 390CR and it's a bolt on conversion & one of the easiest suspension improvements you can make. So in my opinion, this mod only really helps the 1978-1980 model bikes, as the older bike had fairly short suspension to begin with. And to be truthful the older model bikes would probably benefit more with just rebuilt stock suspension than by putting longer/larger late model diameter on.
1st thing If you go the 40mm route be careful to get forks that are close to the same travel as you currently have. Later model Husky had much longer travel shocks and are closer to 17-19" c-c so they made the forks longer too, besides larger in diameter.
Because of this you could easily mess up the very good steering geometry Husqvarna designed into the bike to begin with, by putting too long of forks or shocks & not adjusting the opposite end ,close to equaling it out. Of course you can go with longer length shocks and
adjust the forks to match, but i wouldn't go over an inch longer than
stock, as you'll be putting the swingarm at angle it was not designed for.
Now of course Huskys didn't always turn as fast as alot of other bikes, but usually nothing could equal it on whooped out straight away or rough sand section.
So for example if you used forks of a 81 250CR they have close to 14" of fork travel & have 17" c-c rear shocks. So you'd need to pull the forks up 2" in the triple clamps to have the same balanced handling when using 15" c-c shocks.
Ok , so what do you need, it's really simple
1) Set of 40mm forks 81-85, a complete set works best, with front
wheel,as the front wheel spacer & axle is more than likely different
from the stock one you have.
note:
Husqvarna gave their MX or CR/XC models longer length suspension then there enduro or WR models of the same year, usually there about a 1" difference on both ends. So take some measurement before you head off to Ebay or Mid-Ohio or the like to buy parts.
Take a measurement off the distance from the bottom of the triple clamp to the fork seal, so you have a base dimension,write it down.
Once you pull the old front end off, the 40mm set just bolts right on.
Hopefully you've changed the fork seals 1st, i perfer 12w oil (10 & 15w
mixed 50/50) , no springs in & 6" of oil from top, no air in forks. Put a
cable tie loosely above one of fork boots, so you can check fork travel.
Put the new forks on using the same dims you measured from the 35mm set to start out. Ride the bike & adjust the fork height if needed.
Ok, i'm not a 40mm fork expert, but i found the 81 or 82 CR worked
best on my 80 390CR, as there more than long enough. Also someone
on another forum told me you can make the 80 front wheel work
by modifing the wheel spacer, but i have no info of what's entailed.
Also i believe the 84 & up 40mm steering stem offset is different then the 81-83 ones, and the 85 & 86 have disc brakes so the fork legs
maybe different. The 84 models have double link brakes,but they
should work on the older 81-84 , but the again the wheel spacer
maybe different so try & get a complete set will help.
Ok a few other tricks
1) safety wire the front brake cable, down to the fork mount. Tie it
where the metal adjusting is and tighten it downward toward the
axle, as the cable can pull out of the adjuster.
2) make sure you replace the numberplate with the extended cable
saver type (vertical tab the attaches to the crossbar) as the cable
can easily get caught on the top portion of the fork that sticks
above the top triple clamp & cause the front brake to drag or even
lock
I can post picture if someone needs any
Later
John
