Forum

[DonMc]

After many years of use I decided to overhaul the front forks on my 1959 350 Bullet and I found a couple of things which made me wonder. First off, a pair of small springs which look look heavy valve springs fell out when the main spring was removed. I am fairly sure this is not standard, but wondered why they might have been fitted. My first thought was that the springs had taken a set and this was a way of taking up the slack, so I measured then free length, which came out as 20.5" - well within limits. Then, looking at the springs, the coils were closer wound at the top for about 2 inches, and there was green paint on the ends of both springs. could they be sidecar springs?
Any thoughts on the matter appreciated
Don

[stinkwheel]

I usually need to do something to my bikes front suspension because I'm big and tall. As standard, the vast majority of them have WAY too much rider sag. Best thing is to swap out the springs for heavier ones but where this isn't possible for reasons of cost or availability, the next best thing is to increase the preload. I used to do this with spacers (or even washers), ones cut out of blue alkathene water pipe work very well and are infinately adjustable. However an East German friend said they used to use old valve springs on top of the fork springs to increase preload and I have to admit, it works better than spacers alone.



So, not saying that is necessarily the case but fitting valve springs on top of the fork springs is a known way of increasing preload/reducing rider sag on bikes with no adjustment.



Later model 500 bullets have a small spring that looks like a valve spring between the shim stacks on the damper rod to increase compression damping.

[stinkwheel]

By later model, I mean later Indian ones.

[Marko]

I've done this on my bike (1957), i.e fitted some valve springs from a 500 triumph (they just happened to fit) on top of the normal enfield fork springs. I'd fitted the softer springs from our hosts but they were a bit saggy (for me) - the addition of the valve springs made it just right and the whole plot works nicely now

[John M]

The later Indian Bullets have a short spring part number 143898 that fits near the valve port at the bottom of each leg.

The parts book does not make it clear how they fit, but from memory they prevent the forks "clunking" on full rebound extension. (I may be wrong.)

These springs are attached to the bottom of the fork legs and can be retro-fitted to older Bullets.

[DonMc]

Thanks for that tip John. The reason I dismantled the forks was because they were clashing on bump and rebound especially due to the increasing number of potholes. I thought perhaps a spring had broken, but the only thing which seemed amiss was that the brass valve port on the right hand fork leg had partly unscrewed itself. My thoughts now are to fit new, possibly softer, springs but to turn up a spacer to give a bit of pre-load and add the lower springs you mention, which presumabley fit on just below the valve port.

[ric]

Adding the shorter springs to the lower section of the leg near the valve port is should give you some preload, about an inch of it 😉

[John M]

The small spring is visible in the small pic on page 2 of the notes on replacing fork seals in the notes page.

http://www.hitchcocksmotorcycles.com/pi ... 988_on.pdf

Unsurprisingly my previous guess about rebound is incorrect and stinkwheel is correct in that they assist at full compression.

[ric]

Yes, seeing a picture is worth a thousand words! Most definitely not a top out spring as fitted on most modern right way up forks. Looks similar in purpose to the early MZ forks and as mentioned is there to enhancie fork damping.