Rekluse Auto-clutch on KTM990S

By:Cyborg

Rekluse z-Start Pro 101

Installing a Rekluse www.rekluse.com zStart Pro auto-clutch in my 2007 KTM990S!

Here are a few pictures of my recent installation of a very new Rekluse z-Start Pro for the big twin KTM (will work on any KTM 950/990 v-twin, SE, SM, SD). I did the work myself and this report is by no means a complete technical document, and is being supplied just for your curiosity. Accurate technical docs are supplied with the Rekluse kit and the KTM engine shop manual was my other reference.

First, remove skid plate then place the bike on it's left side. I didn't drain any fluids and nothing leaked out of the bike even after a few hours sitting that way. I've done the canisterectomy and proper tank venting so no problems with fuel dripping. I put a few shop towels on the floor and put the bike on it’s crash guards and rear luggage rack, nothing else touched.






Remove clutch cover






Remove pressure plate screws and springs






Remove friction plates and steel plates, paying particular attention to the last special metal friction plate and 2-part Belleville clutch boss spring – those will be going back in later per Rekluse instructions. Then remove the clutch nut remove the center hub






Here is the clutch basket empty but still in place




Note this spacer ring, do not remove it.




Install the Rekluse center hub




Rekluse says to use the stock washer and clutch nut to attach the hub




but I didn't’t think the nut threaded down far enough




so I removed the washer and put the nut straight down on the steel hub with Blue Loctite. I didn't’t see any problem with doing that. This was a very early kit and I’I'm sure Rekluse will address the issue with production kits.




Next place the first Rekluse steel plate and then the re-used special thin steel plate (blue arrow) and inner 2-piece Belleville clutch boss spring (red arrow), detailed in Rekluse instructions.




Then load the clutch pack per Rekluse instructions, steel, friction, steel friction, etc. Stock friction plates are re-used in this kit.




After all the frictions and steel plates are inserted, install the Rekluse middle hub assembly. This supports the top pressure plate assembly.



It’s important to make sure to install the thrust bearing correctly per Rekluse instructions




Here it is installed.




Next install the engagement RPM wave spring. Engagement RPM can be set using various strength springs here. Rekluse can supply various tension springs and provide a proper spring in the kit based on the average idle speed of the KTM 990/950 engine.


The ball plate




All loaded up with steel balls. A few tungsten balls can be substituted for firmer engagement action but I’I've been happy with just steel balls in a variety of riding conditions.




And finally the top of the pressure plate is fastened down with 10 screws and Blue Loctite.




All done with auto clutch assembly! There are a few steps to measure the pressure plate/friction gap for proper setting, and can be adjusted with several thickness steel plates Rekluse provides. The Rekluse instructions explain this procedure and I found it very easy to check and adjust.




Remove middle rubber damper from the clutch cover plate since it will not fit with the new auto-clutch installed.






Then put the cover back on and have fun! Oh, you will need to follow a very simple Rekluse break-in procedure that takes all of 30 minutes, cycling up and down through various RPM ranges. This is detailed in the Rekluse instructions.




Rekluse inside!







How does it work? Well, I just came back from a 3600 mile 9-day 5-state (WA, OR, ID, NV, CA) ride with it that ranged from cold mountain passes to blazing hot 6-bar days, Bonneville Salt Flats speed runs, Blackrock Desert playa running, long IronButt days at spirited highway speeds, part of the trip 2 up with full luggage on super-tight twisty mountain roads. Off-road on rough 2-track trails, whooped out roads with deep sand washes, silt beds, sharp rocks, steep rocky hill climbs and slide-downs. Did a little bit of everything except deep water crossings, mostly because I didn't’t see any. The Western states are pretty dry right now. Ride report soon...

The Rekluse auto-clutch performed flawlessly! In heavy stop and go traffic having an “automatic” is awesome. On rocky hillclimbs I just popped into 2nd and chugged my way up whatever was in the path. Never touched the clutch, this unit ‘feathers’ the clutch on gnarly terrain far better than I ever could.



This is my second Rekluse zStart-Pro, the other is in my Aprilia RXV550. So far I haven’t had to do any auto-clutch adjustments after thousands of miles on either bike, with especially brutal abuse on the Aprilia RXV. All I can say is the Rekluse folks are great to work with and these auto-clutches ROCK!!

Additional: The auto-clutch slightly engages when the bike is ice-cold (can be held in place with feet on ground). When up to 2-4 bars temp, it works perfectly. That's why it's nice to keep the clutch lever, for the cold-running first few minutes, if you just HAVE to ride away on a cold engine...

More stuff: If you are having a hard time shifting into first or neutral, or regular up and down shifting:

First make sure you break in the clutch per the instructions, takes all of 10 to 20 minutes. Also make sure you have the proper gap set after break-in. If it's too narrow, you'll be partially engaged all the time, or very close to it. Again see the instructions. (Note: I haven't seen the 'official' kit instructions, so I'm assuming all that info is in there). Setting the gap is a bit tougher on this bike because the KTM regular clutch design uses a pre-loaded clutch boss spring and you have to overcome it to measure the gap properly.

Assuming all the above is done proper:

Normally, if your idle is below "engage" RPM and the bike is up to operating temp, the clutch should be free/released and shifting into first (or neutral) no harder than if you had pulled the clutch handle in or a regular clutch bike. Sometimes first doesn't always engage with with a regular clutch either, without a little clutch handle "jiggle". If the bike is cold, under 3-4 bars, the auto-clutch will drag a bit (i.e. partially engaged) and will make shifting harder and require the clutch lever a bit. This is due to the "slow hydraulic effect" the KTM's clutches have and other hydraulic clutches Rekluse has worked with in the past. Cable clutches, like on my Aprilia RXV550 w/auto-clutch, are much faster and positive in this regard. The KTM990 tranny prefers a quick, positive shift style, no slow soft-shifting. It will take a bit to get used to, but it does work well. Remember, get the bike up to temp first, and if you must ride away cold, be prepared to use the clutch handle a little.

The slow hydraulic effect is likely why you may not be able to get into Neutral easily immediately even when warm because the auto-clutch is still partially engaged for a little bit. This is especially obvious if you have your engage speed too close to the normal idle speed. I have mine about 400-500rpm apart. Stiffer spring = higher RPM engage speed.

Clutchless gear changes aka "speed shifting" are like they would be on any other regular clutch bike, i.e the Rekluse does not do any magic there. You have to use throttle blips appropriately, up or down, depending on up or down shift. If you've ever done a lot of offroad riding on dirtbikes, speedshifting is the norm. It's an acquired skill.

I use the clutch handle when needed, without thinking about it, but when the bike is warm, I rarely ever touch it.

From guru Youngwerth: When riding on the street lower your idle a couple hundred rpm below your engagement point. This makes it easy to click all the way down to first when you come to a stop without pulling in the clutch lever at idle (and all 2 pounds of force that takes at idle).

Off-road, turn up your idle so your bike wants to creep forward, just barely, in first gear at idle. Works better off-road like this.