Suspension dyno

[Gremlin]

( Note that Gremlins example is an extreme one as he has the full blown electronic suspension with wiring looms etc )

Simply pointing out what is possible, and that it's each bike to their own as to how long it could take.

For example... On the BMW, the first step to removing the front shock is taking the back seat off...

[Robert Taylor]

The outright lap record around Manfeild on a 600 is still held by Sketchy, running a stock Gixxer BPF front end.

Are they just poo on the road,

With an Ohlins rear and steering damper and with some pre mods that we had done inside those BPF forks, yes. And yes on the road they are quite horrible on bumpy surfaces. When you fit the Race Tech high flow piston kits they are markedly better, excepting the setting bank recommendations for rebound are way off the mark. ( which makes a mockery of the self instal philosophy ) Thats where ( again ) the suspension dyno has been worth its weight in gold

[Robert Taylor]

So on my old bike its common to swap GSXR 750, CBR, RC51 forks on to them. Would I be right in saying that has limited improvement as the damper is not that much better? Obviously being upside down and bigger diameter its much stiffer. As we have spoken of before i am looking at a brace for the stock forks.

Would you consider the stock VTR forks to have a harsh rebound damper? Ive never ridden the fork stock as I fitted the gold valves to the compression side when I got the bike. Mine is a little harsh in the fork but again I believe that could be the seals as they are the All Balls ones.

On a side note would the BPF forks need more regular fluid changes?

If the alternative forks add a compression clicker where there was none with the original then they have more potential from that perspective alone. There are some many other variables so there cannot be a standard /regimented answer. Some have good pistons, some dont. Etc etc.

Rebound is normally not so bad on the VTRs but there is still scope for improvement. As we almost always change spring rate and preload that then dictates that we have a rebound force curve commensurate with same.

If you have too high an oil viscosity that can help to make the forks lazy and harsh, but again variables. Certainly though the seals you mention cause MASSIVE friction and therefore harshness. We refuse point blank to fit them .

There is no reason I can see that fork oil interval changes need to be different for BPF. The reality being that suspension oil is in most cases changed too infrequently anyway.

[Robert Taylor]

Simply pointing out what is possible, and that it's each bike to their own as to how long it could take.

For example... On the BMW, the first step to removing the front shock is taking the back seat off...

Yes indeed, it was just that your example was quite extreme due to the complexity and most installations are very quick. Id hate everyone reading to think that your example was typical, which of course it very much isnt

Have you ridden with the firmer rate spring yet?

[nzspokes]

If the alternative forks add a compression clicker where there was none with the original then they have more potential from that perspective alone. There are some many other variables so there cannot be a standard /regimented answer. Some have good pistons, some dont. Etc etc.

Rebound is normally not so bad on the VTRs but there is still scope for improvement. As we almost always change spring rate and preload that then dictates that we have a rebound force curve commensurate with same.

If you have too high an oil viscosity that can help to make the forks lazy and harsh, but again variables. Certainly though the seals you mention cause MASSIVE friction and therefore harshness. We refuse point blank to fit them .

There is no reason I can see that fork oil interval changes need to be different for BPF. The reality being that suspension oil is in most cases changed too infrequently anyway.

I will pull the rebound rods and send them down to you next time they are out. It doesnt have a comp clicker but I have wondered if a F4i comp piston would fit.

Those seals will be coming out soon.

[Gremlin]

Have you ridden with the firmer rate spring yet?

No, got home around middle of Tuesday, pulled it apart again to remove the CB radio, got it back together end of Wednesday, and this weekend I'll put some km on...

[Robert Taylor]

I will pull the rebound rods and send them down to you next time they are out. It doesnt have a comp clicker but I have wondered if a F4i comp piston would fit.

Those seals will be coming out soon.

Try the seals first and foremost with no other changes.

The other factor ( but this is a minefield that I dont have the energy for at this time ) is the amount of bypass bleed that is added or taken away. It can be a very fine balance and often counter-intuitive

[nzspokes]

Try the seals first and foremost with no other changes.

The other factor ( but this is a minefield that I dont have the energy for at this time ) is the amount of bypass bleed that is added or taken away. It can be a very fine balance and often counter-intuitive

Interestingly ive just read a thread on this. An "expert" said they need a 1mm bleed drilled I think in the gold valve. This expert had some time racing these bikes and also did a change to the rebound stack.

I will try to do some reading on the bleed.

[Robert Taylor]

Interestingly ive just read a thread on this. An "expert" said they need a 1mm bleed drilled I think in the gold valve. This expert had some time racing these bikes and also did a change to the rebound stack.

I will try to do some reading on the bleed.

Yes bypass bleed can be a very critical thing. Too little and it can be harsh / non responsive . Too much bleed in the base pistons and you can reduce back pressure on the ''pumping'' piston. That shows as cavitation in the third quadrant of a ''full circle'' dyno graph as it reverses direction. The very earliest stages of cavitation can be picked up on a premium suspension dyno ( such as our Roehrig equipment ) that cant be picked up on a manual push test such as regular mechanic with no such equipment would do.

Most forks arent pressurised like a quality shock absorber so anyone engaged in modifying these has to be VERY attentive to what a fine line it is to achieve a credible level of ''pressure balance''. Frankly this is where I personally have serious reservations about the mentality of self instal. Its more of a marketing and sales exercise than doing what is technically correct, at all times.

Another major advantage that I think that we KSS effectively offer is the benefit of our accumulated experience. My 2IC Dennis Shaw is a guy that I have worked with / known most of my working life. His experience is decades and he comes up with clever solutions. Moreover when we are each working on various jobs we discuss constantly what we are doing and the old adage that ''two brains are better than one'' is ringing very true for us.