My 89/90 CBR seems to have black plastic caps fitted to the fork tops. I have a set of 41mm FZS600 Fazer fork caps with the preload adjuster in them, can I fit them and dispense with the preload spacer?

Anyone done anything similar?

 

Well, I woke up this morning wondering the same thing. Fit adjusting preload caps . I see no one replied which is odd as I would of thought someone must of tried it . Exuptoy, did you try it ? If so how did it go?

 

I had my forks in bits when I overhauled them and there is no chance fella. The fork spring sits under a large flat washer and then there is a spacer collar and another washer, then a 'C' shaped spring seat through which the damper rod bolts, then the end cap threads on to the end of the damper rod. The only thing you could do is increase the length of the spacer to increase the preload on the spring but you'd have to know how much to increase it before you rebuild the fork.
To fit the Fazer preload end cap I had I would have had to cut down the damper rod then make a threaded spacer to accept the both male threads. It is do-able but would take some fecking about.

Honda Cbr1000f 1990 (l) England Front Fork - schematic partsfiche

Best you can do is either increase the oil level by decreasing the air gap (or increasing it for a light weight) or increase the viscosity from 10wt to 15 or even 20 (or decrease it if you're a lightweight).

 

^ That about sums it up.

 

Oh I see. :-(
On my 1987 the forks are slightly different . Refering to :-


https://www.motorcyclespareparts.eu/...rk-711109.aspx

I’ve just done the fork seals and If I recall correctly , the antidive rod / mech ( 34) comes nowhere near the top . Correct me if I’m wrong, perhaps it does on full compression, but at the time of reassembly I couldn’t see it. This means that there is a big hollow space in this case, at the top of the stanchion.
So, I could fit an adjustment cap but I think I would need to shorten the collar spring tube (4) , that sits on the spring , by an amount equal to ½ the adjustment on the new cap. Meaning that when the cap adjustment is at ½ way then the fork spring has normal factory preload on it, if you see what I mean.
Then I can dial up more or less preload. It sounds easy, but I must be forgetting something. Am I?

 

Clearer drawings here.
Honda Cbr1000f Hurricane1000 1987 (h) England Front Fork (cbr1000fh/fj/fm) - schematic partsfiche

It looks like you may be correct, also I think you'll need to plate the upper spacer with a solid disc maybe 4mm thick as the fork top cap usually presses down on the end of the spacer to compress the fork spring, this will allow the adjustable top cap to be able to press down on the spacer as the internal of the preload cap has a threaded stem around 12mm diameter which threads in and out as you dial in more or less preload. I think the Fazer preload cap will be suitable as the thread pitch and diameter was the same as the CBR one.
If I get chance tomorrow I'll grab a pic for you.

 

I have not seen a fazer cap and haven't seen what it pushes down on. You would have to know what the reach of the cap is. After that I would think that replacing part #44 (at the top) with a solid, or stack of solid washers, may do the trick. The Fazer cap would have to seal the tube the way the OEM one does.

 

Been up the garage earlier and layed out the caps to see.

The pics is self explanatory.



Unfortunately the measurements across the thread were 36.75 on the CBR and 37.75 on the Fazer one so its not suitable. Sorry to raise your hopes. Maybe the 87 stancheons are different.
I knew they worked with Bandit forks and thought it'd be the same with the CBR.



I forgot how fowl old fork oil smelt!

 

Exuptoy, Thanks for taking the time taking the photos and investigating if this mod was possible . I'll just have to let it ponder in my head for a while . Still useful info though. Perhaps theres another version out there which could have compatible threads. Hmmmmm, off for a think .
Thanks again

 

Having a little look about and it seems that the VTR1000 has a 41mm OD fork and has a preload adjuster fitted.

Honda VTR1000 Firestorm Fork Top Cap | eBay

As does the CBR600 from around 96 (although the advertised top caps are shown on eBay as 31mm???).

95 96 Honda CBR 600 F3 Fork Top Upper Caps Lids Covers | eBay

http://www.ebay.co.uk/itm/FOR-HONDA-...EAAOSwSzdXBfY5