Non monster question HD issue

[jerryz]

In am trying to sort out the front forks on a friend s custom  bike its part HD part Buell hard tail with brembo brakes and with lots of nice home produced parts it looks gorgeous
its a lovely performer but the front forks are  off a HD Big twin  and the bike only weighs in now at 467llbs  with 102hp at back wheel 

the front end is too stiff its 41mm forks   springs must be very heavy more likely for a 650lb bike

problem is no HD dealers or mechanics know anything about spring rates  , i was thinking that maybe sporster springs  39mm would do the job as the sportsters are usually about only 485lbs

can anyone help

[koko64]

Sounds like a cool bike.
I would take the springs to a suspension guy who can measure and test them. Even sporty springs might not be correct. You would want them tested to be sure. Then it would be a matter of selecting springs for the bike/rider weight. What does the rider weigh?
Any suspension shops you trust nearby?
If not, measure up the spring dimensions and order something for the weight from a good suspension shop to be shipped out to you if you are doing the work. Talk to the shop and remember to tell them its a hardtail.

[scaudill]

Look at the Progressive and RaceTech websites, they both have upgrades for H-D bikes.  I have a set of OEM '97 Sportster springs you could try.  If you want I'll measure length and diameter.  I can't really measure the spring value.  Let me know.
Sterling

[Kev M]

Even us Sportster guys are pretty constantly complaining or messing with springs, emulators, fluid, etc.

Personally my XL is near 600# wet and has the stock front forks/springs from a 1200R (taller of the 04-current bikes) and I'm ok with the springs... they're maybe a little soft. So yeah, I bet they might be close to what you want, but still it would probably make more sense to measure and decide rather than shotgun it.

Of course me being a lazy bastid, I'd probably shotgun it and give em a try, especially if I could find some take offs...

[jerryz]

I used to race sporsters back in the late 80s and 90s but i put trick front ends on or heavily modified standard ,,,
i have a really good spring shop nearby in Sussex England so will  take the springs down to them  get them tested  and go from there ,,,personally I also think that big twin forks are probabl;y crap butt in this case thats what my pal likes ,,,

thanks for your input I will try and post a photo of the bike

[Bill in OKC]

I put Race Tech gold valves in my 41mm HD/Showa forks (+ correct springs) and it made a big improvement.