XR650R Auto clutch GROUP PURCHASE anyone?

I’ve been talking to a company that will soon be offering auto clutches for various bikes and the product sounds really interesting to me. If anyone else is interested in getting one of these products for their XR650R at a great price of under $400 (hopefully), please send me an email and I’ll keep you updated as things progress. I don’t yet have final pricing, but it ‘might’ be significantly under $400! :)

I’ve put together a FAQ on this product based on reading various information, which will hopefully answer questions you might have. If you have other questions, please let me know and I’ll try to get them answered. I will be out of town this week for the Thanksgiving holidays, so give me until the following week to answer your questions.

1) Why are you doing this group deal?

First off, I have no affiliation whatsoever with this company and I started this purely because I wanted one for myself, but several people have emailed me with interest and I thought we could put our collective buying power together to get a special one time group deal price for anyone interested.

2) How much will it cost?

The cost should be under $400 and I’m working to bring it down significantly, but I can’t make any promises. It just depends on how many we order as a group. In order to get this special one time limited pricing, we need to order at least 10 of these products as a minimum.

3) Where do I send my money?

Once this limited time special offer is made available, money will need to be sent directly to the company that’s making this product.

4) How long is this offer good for?

Right now I’m just trying to find out if there’s enough interest in this product to get us a group deal. If I get enough email responses from people who really seem interested, then I’ll talk to the manufacturer and work out final pricing and other details. Once I get the final details worked out with the manufacturer, then I’ll make a final offer to anyone interested and from there you can place your order directly with the manufacturer using a special promo code to get the special one time limited pricing.

5) How long will it take to get my product?

First we need someone to volunteer an XR650R for a few days in the Boise ID area so the designer can take various measurements and make a prototype for our bike. Since they’ve already made a product for the CRF450, it shouldn’t take too long to get a prototype done for our bikes. They’d need the bike for a few days and the person who volunteers their bike for this will get to keep the prototype for $200. Once they make a prototype for our bike, we’re looking at about a month before production units are available.

6) Which auto clutch is this? Revloc, EFM, etc?

This product is called the z-Start and was developed by Al Youngwerth of RMS Inc. The z-Start is a low cost alternative to other auto clutches, but that doesn’t mean it’s an inferior product, as you’ll soon see. In fact, it offers several advantages over the products, two of which are price and ease of installation.

7) How hard is it to install this product?

The z-Start is easier to install than the other auto clutches on the market since you’re not replacing the entire clutch or basket. It should take less than an hour to install this product from start to finish. If you’ve installed a few of these before, then you’ll be able to do it in less than 10 minutes from start to finish.

8) What kind of advantages does the z-Start offer over other products?

As with any good product, you’ll find reasons why you’ll like the z-Start over the other products and you’ll also find reasons to like the Revloc or EFM products over the z-Start, but the choice is yours. First off you’ll notice the price of the z-Start is significantly less than the other products. Secondly, the z-Start can be swapped back to normal operation (stock manual clutch) in less than 15 minutes. The z-Start simply replaces the pressure plate and there are no changes to the inner hub or outer basket, etc. To install this the z-Start, you simply lean your bike on its side (or drain the oil), pop the clutch cover off, remove the 6 bolts for the pressure plate and bolt in the z-Start pressure plate assembly (6 bolts). If you choose to return your bike to normal operation with the manual clutch, you simply reverse this process and your done.

One of the advantages of the Revloc product is that you get a nice billet outer basket in the deal. Also, once you get the Revloc installed, it’s pretty easy to adjust the stall speed and it shouldn’t require much adjustment over the life of the clutch plates. The z-Start is similar in that it too should not require much in the way of adjustments over the life of the clutch plates. In addition, the z-Start may also offer a bit less flywheel effect and you’ll only lose one friction surface with the z-Start as opposed to two friction surfaces with the Revloc. It should be noted that neither design actually eliminates any plates, but that some of the friction surfaces no longer turn against a drive surface.

The z-Start will support about .035" of clutch plate wear. After that you can buy new clutch plates or you can optionally buy an extra thick drive plate for $25 that will allow you to get more life out of your existing plates. Clutch plates these days last a long time if the clutch cable is properly adjusted. The vast majority of premature clutch failures are due to improperly adjusted clutch cables (too tight).

Clutch feel is yet another advantage the z-Start offers. With the Revloc, the manual clutch override pushes the balls back down the ramp. At low engine RPM you have a light clutch pull, but the clutch becomes significantly harder to pull as the engine RPM increases and in fact becomes much harder than stock. The z-Start "top plate" acts as a spring and once its "pressure plate" engages (travels down to and touches the plate), the force required to disengage the clutch remains fairly constant because its not forcing the balls back down the ramp, but rather bending the top plate instead, per design. The top plate acts as a straight rate spring and requires about the same pull force as the stock clutch lever.

9) What happens to my existing clutch?

The z-Start is designed so that you can also use your existing clutch lever to override the z-Start engagement (for MX starts or if you prefer to shift gears with your clutch disengaged). In order for your existing clutch lever to work in addition to the auto clutch you’ll need to remove 12 M3 allen head screws on the z-Start and place your bike's existing clutch throw-out mechanism into the z-Start.

10) Will I loose my engine braking?

No, you will not loose your engine braking even when going down a hill. The only time you’ll loose your engine braking is when the engine speed is low enough to where the auto clutch disengages, which is typically just above idle.

11) Can you tell me anything about the inside of the z-Start?

As with most auto clutches, there’s a centrifugal pressure plate bolted to the outer hub. Inside, the z-Start design uses tungsten carbide balls riding in billet ramps to generate centrifugal force. Ball ramps are easy to machine, but tungsten carbide balls are expensive (tungsten carbide has more than twice the mass of your average steels, generating more force in a small space).

12) How do I adjust the z-Start for different stall speeds, engagement, etc?

The z-Start can be adjusted for both stall speed and engagement through the use of springs, shim washers and the amount of tungsten carbide balls used. Stall speed (when it begins to engage) is a function primarily of spring preload (# of springs (can be 3, 4 or 6) and shim washers under the springs) and to a lesser extent the number of balls in the clutch. The engagement spread is strictly a function of the number of balls. By changing the number of balls, you change the stall speed slightly, but the spring pre-load is where you get your big changes in stall speed. More balls give a quicker final engagement, fewer balls spread that engagement out over more RPMs. Quicker engagement works better for lazy trail riding, slower engagement works better for MX (and there is a happy medium, for everybody).

A higher stall speed comes in handy when you aren't already in the power band (at the gate or a slow turn a gear high) because the slower clutch engagement takes you higher into the power band where you need to be. With the higher stall speed, the auto clutch provides an excellent start if you pin it from idle just as if you started out from idle while perfectly fanning the clutch manually up into the powerband. Configuring the z-Start simply comes down to personal preference and that’s why it’s been designed so that you can adjust the engagement and stall speeds to best meet your needs. Rather than starting from scratch on these adjustments to figure out your needs, there will be guidelines to help quickly get you to where you want to be.

13) Is there’s anything special I need to be aware of when it comes time to replace my internal clutch parts?

For the most part, it's just the clutch plates that wear. The clutch plates are all standard except for one. The z-Start includes one "special" clutch plate that’s screwed into the z-Start’s pressure plate and if you should need another one, it will only cost you $20. The pressure plate in the z-Start is a Barnett carbon fiber plate, so it should last longer to begin with and when it is worn, you can flip it over and wear out the other side before it needs replacing.

14) Will the z-Start wear out?

All products wear out and the z-Start is no exception. The clutch itself has a couple of wear parts. There is a needle thrust bearing that can wear out (similar to the CRF throw-out bearing), but unless you spend LOTS of time at idle or with the clutch in a slipping state, this inexpensive bearing should last far longer than the rest of the bike. The tungsten carbide balls actually "skid" down their ramps. The pressure plate ball ramps are expected to wear somewhat, especially if your transmission oil is in bad shape. With this in mind, you will eventually need to buy a new pressure plate. The goal of this product is to provide a minimum life expectancy of 300 hours use on all parts except the clutch plates. The life of the clutch plates is primarily up to the user.

15) Will the z-Start damage my bike since an auto clutch can generate much more engagement force than the springs in a stock clutch?

This is a good question about auto clutches and the z-Start offers a unique feature to minimize excessive forces. The balls in a centrifugal clutch can generate more than a 1000 pounds of force at redline. A typical clutch has a spring preload of about 250 pounds. When you're spinning through mud near redline and catch a nice solid rock for traction, a tremendous amount of shear stress can be generated. At 250 pounds of clamping pressure, some of that energy might get dissipated through slipping of the clutch plates. A 1,000 pounds of energy at redline will have to be dissipated somewhere and you don’t want it shearing the tooth off a gear or something like that. One of the several patent pending features of the z-Start is the top plate that captures the balls, which is designed to act as a spring and absorb some of this energy. It allows the force of the balls to be driven down into the plates up to a limit. Eventually the balls travel to the end of their ramp and the remaining force goes into a stout vertical wall at the end of the ramp. The deflection of the z-Start’s top plate ends up acting as a spring much like the springs in a regular pressure plate. As an added bonus when using the clutch lever for manual override, the balls get pushed back down the ramp and the top plate deflects. This provides for a slightly lighter than stock clutch pull that remains nearly consistent in feel from engagement to redline.

16) What kind of warranty is there on the z-Start?

One year against any manufacturing defects AND normal wear. Failure due to not following the installation instructions is not covered.

17) What can you tell me about installing a rear brake lever in place of the clutch lever?

If you wish to replace your clutch lever with a rear brake lever, you MUST use a left-hand master cylinder that uses brake fluid such as the one made by Magura. The Magura left-hand master cylinder can be adapted to various bikes with the proper brake line.

The following are some pictures of the z-Start so you can get a better idea of what it looks like.





I'm in! Let me know when and where to send the check Gary. This little gadget will turn the BRP into a nimble woods fighter! :)

The idea of an auto clutch for my XR650R first struck me as something I would not want or perhaps something for my wife or kids, etc, but after reading so many positive opinions from hard core riders about auto clutches, I began to rethink this topic and now I want to buy one to try out for my bike :)

For anyone interested in opinions on auto clutches, all you have to do is search various boards including ThumperTalk for topics such as "auto clutch", "Revloc", "EFM", "z-Start", etc, and you'll find all kinds of information and people to talk to about these products. I've read some favorable opinions on a KTM board regarding auto clutches and also have read plenty of favorable information here on ThumperTalk in the CRF forum among other places and these opinions along with curiosity have steered me toward wanting one. Here's a list of reasons off the top of my head as to why someone might want an auto clutch.

Both stall speeds and engagement can be customized to meet specific needs. If you’re racing MX, then you know how important a perfect start is. You can configure an auto clutch so that the stall speed is such that you’re more into the power band by the time it engages. You can think of an auto clutch as giving you that perfect start just as if you were perfectly fanning the clutch without all the wheel spin when taking off, but an auto clutch does this for you automatically and its always consistent.

An auto clutch also eliminates the problem of stalling in tight corners. If you’ve ever come flying into a tight corner while jamming on the rear brake, then perhaps you’ve stalled your bike a time or two while doing this, all the while losing precious time during a race. Since the auto clutch will automatically declutch if your engine speed drops to idle, your engine will no longer stall in these situations. You’ll also be better positioned coming out of the corner, as the bike will be into the power band by the time the clutch engages and you may be able to use a higher gear while coming out of a corner as a result of this. If for any reason you need more clutch slip at one particular point, then you can use your stock lever to over ride the auto clutch.

An auto clutch may also reduce arm pump, especially if you’re the kind of rider who uses the clutch a good bit.

Trail riders like the auto clutch when the going gets tough because they can keep both hands firmly gripped to the bars at all times while only concentrating on throttle control. Others have chosen to install a rear brake lever in place of the clutch lever so that both feet can be firmly planted on the pegs at all times while others who do this like to be able to use their legs to help them maneuver through difficult terrain and still have access to the rear brake function via lever control on the handlebar.

I'm wishing that this clutch might work on my L. Everything else aside, your post has an enormous amount of information. Thanks for all the info and the work on the research.

Qadsan, most important to me is really tight single track. The pig is geared too tall. I'd really hate to drop to a 13 tooth front sprocket as it kills my top end and DS ability. Even with a 13 countershaft the BRP is a handful on singletrack. Having to constantly clutch to keep the speed slow enought will cramp your hands too quickly. I ain't no Mike Lafferty for sure. Being able to just burp the throttle in first or second gear with both hands on the bars makes it worth the money.


Once again you have impressed me with you plethora of knowledge. An auto-clutch for under $400? I'm in.

What's next, the e-start group-purchase?

An auto-clutch for under $400? I'm in....What's next, the e-start group-purchase?

It could be significantly under $400 if there's more than 10 people who want in on this deal :) Yes, I did look into the 'e-start' group purchase as well :D but I just didn't think we'd get enough of a discount to where enough people would buy it. Heck, I don't know if we'll even get enough people here who'd want an auto clutch for their XR650R as I haven't had too many people respond yet even though this one time limited special price will be fantastic. It's not an idea that struck me at first as a product I wanted, but the more I've read about auto clutches, the more I now want one :D

If anyone is interested, please send me a PM or post on here that you might want one so I can provide the manufacturer with a running count of people who 'might' want one.

Happy Thanksgiving to everyone!

Sounds great. Any specific time frame as to when/if we can get them? :)

Sounds great. Any specific time frame as to when/if we can get them?

First we need someone to loan the company making this product a XR650R for a few days (in Boise ID) so they can take various measurements and perform some tests. They've already done this for the CRF and some other bikes, so it shouldn't be too hard to get this going for the XR650R. After they get a XR650R for a few days and if things go well, then we're looking at about a month before production units will be ready for us. I don't want to put words in the company's mouth, but I think we could have product ready by the last week in January 'IF' they soon get a bike to work with and 'IF' we get enough orders together in the next two weeks.

Great info! You truly do your homework. Sounds like a great idea, Im interested! Keep me informed!

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