Race tech emulator issues

[Agemax]

Fitted some Race tech emulators to my GS1000 (GSX1100SD Katana forks) along with some 1.0kg springs, 20w oil. The emulators were fitted exactly as the instructions stated.

Problem i got now is a slight knocking from forks when i brake. It did not do this before.
Has anyone had this issue with the emulators?

The forks were rebuilt fully with new slider bushes top and bottom, new seals. Everything is tight, no play in steering head bearings or wheel bearings so it has to be related to the emulators.

I will remove the new springs and emulators and put the old original springs back in tomorrow and see if the issue dissapears (hopefully)

[Buffalo Bill]

Can you describe the knock in more detail?
Also, why 20 wt oil?
Overall, with 1.0 springs, 20 wt oil and the emulators, it sounds like a very hard ride for the track!
I got 1.0 springs in my track bike, with 10 wt oil, I weigh 200 lb with gear.
Plus my GSX Katana has 3 dampening settings. I use the highest for the track, and the lowest for the street (country roads with lumpy pavements).
20 wt oil in my bike on our local country roads would be self torture.

[RichDesmond]

Highly unlikely to be the emulators or springs.
How much static preload (the amount the springs are compressed with fork cap installed and the forks fully extended) is there?
Try sitting on the bike, holding the front brake, and pull the bike back hard and then push forward. If you get the noise, get someone to listen closely and try to determine where it’s coming from. Might be brake pads shifting in calipers.

Did you drill out new compression holes and/or enlarge the existing ones?
And BB is right, 20w oil is too thick.

[Agemax]

Thanks for the replies. I initially had 10w oil in the forks but i thought that could be the issue, too soft, as Race Tech did actually recommend 20w oil. So i changed it to 20w oil to see if it helped and it remains the same.
It is quite a definitive knock/clunk, not to loud but loud enough to be a bit concerned.
As they are Katana forks which have the preload adjusters i cut the spacer 72mm long. This gives 16mm preload on the springs with the adjuster on its softest setting. i have tried it on its hardest setting which would equate to around 30mm preload and it makes no difference.
The holes, and extra holes were drilled in the damping rods as per instructions.
I have brand new Brembo P4 calipers, with brand new discs. There is no slop in the pads, calipers or discs.

[GregT]

Do the forks have anti-dive fitted ? Have you blanked it off ?

I have a racebike here which has the antidive blanked off and it's always had a slight knock on dive.
I've thought for years it's a hydraulic knock caused by air and oil getting trapped in the antidive takeoff holes in the sliders.
Never caused a problem so never done anything about it.

[RichDesmond]

Thanks for the replies. I initially had 10w oil in the forks but i thought that could be the issue, too soft, as Race Tech did actually recommend 20w oil. So i changed it to 20w oil to see if it helped and it remains the same.
It is quite a definitive knock/clunk, not to loud but loud enough to be a bit concerned.
As they are Katana forks which have the preload adjusters i cut the spacer 72mm long. This gives 16mm preload on the springs with the adjuster on its softest setting. i have tried it on its hardest setting which would equate to around 30mm preload and it makes no difference.
The holes, and extra holes were drilled in the damping rods as per instructions.
I have brand new Brembo P4 calipers, with brand new discs. There is no slop in the pads, calipers or discs.

Which Katana? Are the disks semi-floating?

[Agemax]

ok, so here is the situation. Yes the forks do have antidive and they have been blocked off, properly so the oil can still flow through the holes.
They are 310mm floating discs with Brembo P4 calipers.

So i took out the Sonic springs and the Race tech emulators and dropped the original springs back in with 10w oil. Result..... no change. Forks would clunk when bouncing on them with the brakes on.
Checked over everything again for play/movement/sloppiness, none found (slight play in floating discs, to be expected but not causing the offending noise)

Then i pulled the forks off, drained oil and removed springs. While dissassembling the forks i found the r/h leg was jamming half way down the slider. Bear in mind they are brand new fork legs, bushes and seals.
They were a bit stiff to slide when i assembled them but i just figured it was because everything was new but it never got so stiff as to actually stick. The l/h fork is absolutely fine.

Now comes the weird part. i measured the new leg compared to the old leg which (luckily) i kept. and it measures exactly the same on all measurable places on the length of the leg, down to 2 decimal places.
I fitted the new bottom leg bush to the old leg and fitted it in the slider........ perfect!

Bolted everything back together, with the emulators and sonic springs, fresh 10w oil and the forks work perfect now, no knocking and nice action. I havent actually ridden it yet but will go out for a ride tomorrow and test it all out.

So, whether one of the new legs was slightly oversize or bent or what i dont know but it seems there is something not right with it. The other new fork leg is perfect. Either way i am happy the bike is back together and ready to ride

[RichDesmond]

Glad you found it, and thanks for letting us know!

[Buffalo Bill]

Maybe you'll experience some hand numbing after an hour of riding, depending on your pavement. I do here.

[Agemax]

Maybe you'll experience some hand numbing after an hour of riding, depending on your pavement. I do here.

What makes you say that?

[salty_monk]

Adjust the rebound with the oil weight and then adjust the emulator to suite on the compression circuit....

[Carter Turk]

I like 20 wt in my spindly 37mm forks, been using it for years.

[Agemax]

I like 20 wt in my spindly 37mm forks, been using it for years.

That is what racetech recommend. I have put 10w in mine and they do feel a bit soft. I will play around with the emulator to see if i can improve things but i may try 15w if things dont get better

[Carter Turk]

I went for a for a ride on Saturday, with a couple of guys riding modern (to me) Triumphs, (1050-800) noticed one (2013 800) had a fork seal weep.

So the comment came up that I haven't changed a fork seal in 20 years, maybe I've removed the forks once to drain upside down, but usually just lazily drained oil from the bottom of fork legs not very often.

I didn't do the seals all those years back, a friend did, have no emulators, just some progressive springs & a big pvc spacer for preload w/1980 forks (no anti-dive) with more adjustment than in 1983.

Figure 20 wt. firms up/slows the action of an antiquated system, both up n down.

Never set sag all these years, but do have some Works Street Trackers out back 1/2" taller than stock.

Has worked well on the street/track for a porky 240 pound rider.

Might be thick for a lighter rider in cold weather, whose not pushing it a bit.