Anyone know the stock fork spring weight? Need to change the oil in my forks and with me being not much bigger than a japanese featherweight im not sure its worth spending out on heavier springs. Maybe a grade heavier oil, 15W instead of 10W will do the job.

The racetech site has it listed as 0.68 kg/mm:

http://racetech.com/ProductSearch/2/Honda/RVF400R/1993

That's pretty soft for a sportsbike, 0.85 is a good compromise for road and track in my opinion (I weigh 70 kg's kitted up).

Drunkn Munky wrote:Anyone know the stock fork spring weight? Need to change the oil in my forks and with me being not much bigger than a japanese featherweight im not sure its worth spending out on heavier springs. Maybe a grade heavier oil, 15W instead of 10W will do the job.

Not a fan of putting in heavier oil, some do as it will make the forks feel stiffer, but.

Changing the oil will affect the damping and rebound instead of the spring rate, thicker oil will take longer to compress the forks, but also longer to allow the forks to retract which will have a negative effect overall, if you hit a bump for example it will take longer for the forks to come back down.

Unless you played about with the internal oil ways id stick with stock oil grade and just do the springs. that way your damping and rebound rates will stay the same, just the fork will be harder to compress.

If NC35 fork springs are the same style as an NC30, they will be progressive starting at a quite low rate. Calculations for my OEM NC30 fork springs give a rate of 0.65kg/mm rising to 1.2kg/mm at 90mm of compression. HRC TT F3 fork springs options include three spring rates that are all progressive but have a higher initial rate. RO springs calculate as 0.9kg/mm.

The common rules for spring rate are derived from suspension sag figures. IMHO, I would suggest that you do some sag measurements and then decide what spring rate you need and then select the oil weight to match the final spring rate.