About the Author
Eric has owned and ridden a GasGas motorcycle since Jan 2001. He currently owns a 2001 XC300 and 2006 EC300, both with Rekluse z-start auto clutches.
Prior to installation
Before you install your z-start, your clutch must properly manually disengage. Proper clutch disengagement is essential for proper Rekluse operation. The engine needs to idle smoothly, without clutch drag when in gear with the clutch pulled in. If you have clutch drag the areas to check are: 1) hydraulic clutch system free of air – it may need to be bled. 2) clutch plate warpage and 3) type of oil – I have had best results with AmsOil Formula 4-storke 0W-40 oil.
The Rekluse clutch needs a low speed idle to function correctly. Too high of an idle will prevent complete disengagement at idle. If you are unable to get a smooth, low idle, then jetting work is necessary. I suggest using LTR jetting. If you are still unable to get a smooth low idle, then you may have a worn needle jet and/or worn jet needle, which need to be addressed to get a smooth, low idle.
Once you have good cutch disengagement and a smooth, low idle, then install your z-start per Rekluse instructions. If you have questions, call Rekluse. They are very knowledgeable and helpful.
The measured gap is critical to proper function and longevity. Installation requires measuring clearances and stacking the appropriate combination of stock and z-start drive plates to get the correct operating clearances. Set per Rekluse specs. Run it for a while under load to get it broken in and recheck the clearance. If needed, adjust it within spec. I like to run the gap on the low end of spec for a strong engagement. If you run too large a gap you will not get full engagement and will quickly burn out your clutch.
There are lots of small pieces to assemble. Make sure and stuff rags around the clutch to avoid dropping parts in the case.
The clutch cover has to be shimmed out with gaskets that should be provided by Rekluse. I suggest that you measure the clearance between the clutch and clutch cover to ensure the added gaskets provide adequate operating clearance.
In the newer kits, Rekluse provides brake pedal mounting hardware to reposition the brake lever farther out to compensate for that added gaskets moving the clutch cover out. Depending on the position of the stock brake pedal, you may be able to install the Rekluse auto clutch without having to use the brake pedal mounting hardware. My brake stock brake pedal just cleared the clutch cover, even with the added gaskets, so I didn’t have to install the brake pedal repositioning hardware Rekluse provided.
The stock clutch cover bolts had very little thread engagement with the added gaskets. Rekluse did not provide longer bolts. I purchased and used (2) 80 mm long bolts and (3) 30 mm long bolts.
Another tip on installation and adjustment – instead of removing the brake lever for clutch cover installation and adjustment, just pry the rear brakes shoes apart and move the brake lever down out of the way and secure it with a piece of wire. Make sure to pump the brake pedal to get the pads fully seated before you ride.
Manual clutch override
I leave the GasGas hydraulic clutch system on and use it for a manual override. For me, the manual override is a mandatory safety feature in the event of a stuck throttle. I will not run an auto clutch without a manual override for that one reason alone. A stuck throttle can result in serious or even fatal injury. If you have ever had a stuck throttle, you will know the importance of disengaging the clutch, since the kill switch doesn’t always work at high RPM.
Further, when specifically set up, the manual override feature allows you to pull the clutch lever in to quickly build up RPM and then release it to get a quick burst of power like a manual clutch. The set up I use to get effective manual override at high RPM is to replace the Rekluse Bellville spring with a flat washer. This is to compensate for the short travel of the GasGas hydraulic clutch slave cylinder.
What I will cover here is on how to tune your auto clutch to get optimum performance on a GasGas. Please note that it takes time and patience to dial the Rekluse z-start in.
Before you start tuning make sure the installed gap is in spec.
The 2 key factors in tuning are 1) engagement force primarily set by the number and type of clutch balls and 2) clutch engagement speed primarily set by spring force.
Engagement force is primarily set by the type of clutch balls. I have run a set up with 30 steel balls and run a set up with 25 steel balls and 5 tungsten carbide balls. The setup with 25 steel balls and 5 tungsten carbide balls works far better. The tungsten balls are twice the density of steel increasing overall engagement force by about 17%. It provides strong, effective engagement that works very well for trail riding and works especially well for high torque situations like technical hill climbing when the clutch is under a lot of load. The newer Rekluse clutches come with 5 carbide balls. If you have an earlier clutch that did not come with carbide balls, I strongly suggest that you order a set of carbide balls from Rekluse. Please note – the tungsten carbide balls need to be evenly spaced around the clutch.
Clutch engagement/disengagement speed (RPM) is primarily set by spring force. Spring force is varied with spring rate and shims. Setting the engagement point just above idle works well for trail riding and is essential for clutch longevity. Too low of an engagement speed will result in partial engagement and drag at idle. Too high of an engagement speed will result in too much clutch slip at low RPM, resulting in excessive clutch slip and wear. Expect some adjusting to get it tuned. When set correctly, there should be complete clutch disengagement at idle and a smooth, solid clutch engagement just above idle. Having a high engagement RPM does not enable better power high RPM power delivery as the clutch is fully engaged at high RPM regardless of minor RPM variation in the engagement point. A high engage point really has no benefit for trail riding and will result in rapid clutch wear if you do any low RPM riding. A good starting point is to use (1) L2 spring without shims.
A Rekluse will not make your transmission a continuously variable transmission. You still need proper gear selection. With that in mind, the Rekluse works very well when set up correctly. It essentially precludes stalling and the need to finesse clutch engagement. I can ride more difficult places successfully with far fewer mistakes and have more fun doing it. Enjoy your GasGas with the Rekluse z-start.
Periodically check the installed gap. I have run the Rekluse on my ’01 XC for over 150 hours and the installed gap has not measurably increased since break-in.