fork emulators

[bazza]

Thinking of putting emulators in my 76 CR250 elsinore. Any one done this in a 74-76 ? was it worth it?

[bigk]

Emulators are fantastic things but only if you are prepared to take the time to tune them, which means a morning or afternoon of actually riding the bike over the same terrain & making small adjustments as you go. This means, handlebars & fork caps off, springs out, reach in grab the emulators, make the adjustment & go again. They are highly tuneable & come with a selection of springs & valve plates (at least Racetech units do). I've spoken to many who have been disappointed with fitting emulators & all say the same, they've never bothered to  tune them & they "should just work".
Yes, they will work well for your application if you take the time to tune them, if you're not that way inclined, probably best to not spend the money on them.
K

[bazza]

did you need stiffer springs as well?

[ralph311]

I have them in a couple of my pre '75 bikes (not CRs). I found the recommended settings to be a good starting point and just tweaked them at home between rides. The right spring rate/preload/oil level are basic requirements for a good result too so you do end up with a lot of variables you can (must?) juggle to get a result. Make sure to measure the actual fork travel available when you have the springs out and put a zip tie on the fork tube so you can see how much you use on track.

One of these grabber tools from super cheap is a good idea. As well as making it easy to get the valve out its good for assembly. If the valve goes in crooked they can be damaged. Thread the tool thru the spring, grab the valve and insert the whole lot into the fork as an assembly. They make one with an led in the claw end too.

https://www.supercheapauto.com.au/p/sca-sca-pick-up-tool-claw-spring/293796.html#q=claw&lang=en_AU&start=1

[TT5 Matt]

at seven and a half bucks thats cheep enough!

[Wasp]

did you need stiffer springs as well?

YES.  Normally I don’t enter those sorts of posts anymore and I will be careful not to offend members with vested interests. I designed the PD valves late last century. Hmm, that sounds funny. Seems a long time ago. I don’t have the claim to fame of inventing them. That was done by KAYABA in the late seventies for a road race team and then later in the eighties other people made some under different names and top pricing. I named my valves PD valves, short for “progressive damping” valves. What do they do? When installed correctly they give you compression damping control. Because there is not much from standard. Check the piston ring set up on the OEM damper rod and make sure it seals on the walls, otherwise you have no oil getting forced up through the middle of the rod. Pre 75 forks sometimes need an adapter and machining for the valves sit on and seal. As the oil is forced up and approaches the valve body. It will look for the easiest way to pass. (low speed) that is done with free bleed holes. Standard, I made two. That is normally enough, but you can either enlarge them or drill another one. There is provision for another two holes. Once those holes have reached full flow capacity, the oil is gradually building up pressure and will start pushing the lift plate. The stroke and resistance of the lift plate is governed by the design of the lift spring. The pre tension of that spring should be 2 full turns normally. Rebound damping is NOT affected by the PD valves, that needs to be tuned with oil viscosity. PD valves do NOT substitute fork springs that are not strong enough for the rider weight!!!
Pre 75 bikes have tiny forks and the results are not as good as with 41- and 43-mm forks, but forks with PD valves and the correct springs will work better than standard.
https://store.suspensionshop.org/media/wysiwyg/Manuals/PROMAX-PD_FORK_VALVE_INSTALLATION_ENG.pdf

[PeterC]

Thank you Walter for taking the time in explaining the history of the emulators and explaining how they work and why they do or don't give the results expected