Dr. Pulley & Contra spring testing

[Nobody]

Finally got around to installing the bits that have been lying around for the last couple of weeks. My PCX is stock except for a Givi Screen (normal size) and a termoscud.

So I did the following tonight:
1. replaced the stock 15g rollers with 11g Dr Pulley sliders
2. added a 0.5mm shim to the end of the variator boss (to prevent possible vibrations on takeoff)
3. replaced the stock clutch contra spring with a SP Takegawa 11% uprated spring.

A lot of things in one go but I will get to that - wanted to see how it all went together. Install is dead simple. It is raining and late so only did a quick spin to see how it went around town. Brilliant! Takeoff with acceleration happening at around 7800-8000+ rpm, mid speed roll-on acceleration is really excellent for about 40km/h upto 80. It was a great setup for around the city. Actually this is what I was looking for, need to try out the hills and switchbacks on the way to work.

But did a quick speed test on a short bit of road and think I've lost some top end. Will try to get out and test this properly tomorrow. Not sure what yet but I could get to 97 km/h with a gps (107 on the dial) with the original config but just felt like I was running out of legs under that tonight. Wasn't really paying attention to the actual speed but it was slower.

Is easy to identify the possible causes here and to even randomly speculate:
a. Shim is not allowing the belt to get to the top of the variator face. (highly possible)
b. Contra spring is too strong for the lighter sliders. (highly possible)
c. 11g sliders are just too light for a stock configured bike. (maybe)
d. Everything needs to settle in a bit before I just to conclusions. (maybe)
e. stock variator (CH / EU version) is different to other countries??? (ah, conspiracy theories - love these)

To try and end some speculation I will just try with the sliders only (will remove the shim and replace the original spring). Want to be a bit more scientific about this. Dirk from Dr Pulley did say that most PCX guys put in 12g sliders and the German mag review used 13g and had a 7km/h speed increase.

Will try to do some testing this weekend and will get back with more results. So try not to slag the sliders off just yet.

Nobody...

[Nobody]

Just did a quick test this morning when picking up the post. On a section of motorway it hit the redline at about 104-5 on the dial. So not much of a loss (the belt has 2000+ km on it since I hit 107). Forgot to turn the phone gps on.

Will take out the shim first and see what happens. But not expecting big speed increases.

[sendler2112]

Good information. I would be interested to know what the stiffer contra spring does different from just changing the weights. If it makes the belt tend to gear back down more readily for acceleration when you have already been cruising at 80 kph and then grab full throttle.

[sendler2112]

Can you measure the i.d. of the contra spring? I want to try adding a shim to stiffen it up rather than going through the trouble of an overseas mail order.

[you you]

Why don't take it back to standard and fit and test one thing at a time?

[jasontheparamedic]

One thing at a time will help so as to develop a control variable for your testing purposes.

[Nobody]

To try and end some speculation I will just try with the sliders only (will remove the shim and replace the original spring). Want to be a bit more scientific about this.

Got the apprentice to work today and removed the washer and uprated contra spring taking the bike back to stock with just 11g sliders installed.

Without the shim I did not notice any vibration on takeoff. There have been a couple of post on this so that is why I installed it. Looks like it is not needed. Without the contra spring I think the bike did not rev quite as high. A bit hard to tell as I only did a quick ride the other night in the rain. Think the higher tension spring helps keeping the ratio lower on acceleration allowing the bike to rev up a bit more.

Did a speed run and hit ------ 110km/h on the speedo or 99 gps with my phone. So an increase of just a couple of km/h. The belt has been run for at least 2000km (actually could be 3000) since I tested and had 97 gps.

Will keep it running like this for the week and see if the sliders settle down a bit. Then next weekend will put the contra spring back in with the sliders.

@sendler2112: The contra spring has an inner diameter of 49.8mm and outer 57.8mm. But there is a cap that sits on the top and in fits into a grove on the bottom. I think adding any sort of shim here is going to be a hard job.

Nobody....

[sendler2112]

The contra spring has an inner diameter of 49.8mm and outer 57.8mm. But there is a cap that sits on the top and in fits into a grove on the bottom. I think adding any sort of shim here is going to be a hard job.

Thanks for the report and it's good to see your helper getting some early experience with mechanics. I work at a Mercedes dealer and am always surprised at the general lack of knowledge of my clients who sometimes don't even know how to open the hood.
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The 11% stiffer contra spring should raise the pulling rpm the same amount as using 11% lighter sliders. It also would tend to increase the tension of the belt so it does make changes other than just rpm. What I wonder about is if a stiffer spring makes the trans more responsive and more likely to rev up to a higher rpm when accelerating up a hill after you have already been lightly cruising in top gear with the weights all the way out at 80kph. There is some speculation to the presence of machining on the rear pulleys and spindle that will tend to pull the belt back up against the weights when load on the belt increases.
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I had the idea to shim the spring rather than replacing it since there is still poor availability of performance parts for the PCX in the USA but after thinking it through, can see it is infeasible due to the fit and the thickness required. You would have to change the length 11% which might be 10mm so I will just have to pay the additional shipping if I want to try it.

[sendler2112]

Here are some screen shots of what the DR Pulley sliders do differently from rollers. This is actually a very nifty invention and has been patented. Good for them.
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The only draw back seems to be the possibility of the low ratio going below the design threshold and allowing the belt to go slack on some bikes which causes a shudder on take off until the weights swing out to take up the slack. Some people have had to add a shim to stop the travel of the variator.
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[EddieC]

this is very cool... i'm new to CVT's... so this is all news to me! I have just over 12,000 miles now... WIll have to think about clutch weights and all sometime soon-ish. Any special tools needed for the job?

[Nobody]

this is very cool... i'm new to CVT's... so this is all news to me! I have just over 12,000 miles now... WIll have to think about clutch weights and all sometime soon-ish. Any special tools needed for the job?

It is a fairly easy job to do. What you need are:
- 8 & 10 mm sockets (1/4" drive best as it is quite tight to get a couple bolts out).
- 22 mm socket for the variator.
- torque wrench to tension the nut up correctly when re-installing. Sort of optional but something I feel needs to be done right.
To get the variator off there are 2 methods.
a. electric/air impact wrench. Most people seem to use this method.
b. variator tool & a breaker bar (that is what the apprentice is doing in my pic).

A variator tools is really simple to make and I also use it to get the clutch off with and to open it up. There is a how-to on total ruckus on how to make one. Just note that the pcx variator requires 6mm bolts to fit into the variator holes.
http://battlescooter.proboards.com/inde ... hread=2663

There are lots of youtube vids on this: some are good and others not so. Just don't do anything like overtighten the nuts or use loctite. Is too easy to go thump, thump, thump with an impact wrench.

For the clutch, if you are thinking of changing the contra spring you need a 19mm socket to get it off and a 39mm socket to open it up. If no 39mm, there are other methods (vice, oil filter strap etc) but I just got one as I like buying tools.

If you have 12,000 miles, have the variator rollers and belt been changed already? Could be due soon at a service.

I'm still not convinced yet on sliders vs rollers on the stock variator. It does not look like there are any speed increases to justify the price of the sliders. Could be that this variator is already running at max - it does look like the wear marks are close to the edge. Just getting 10.5g or 11g rollers may be the best payback but you will not see a speed increase, just better acceleration. Other option would be something like a SP Takegawa variator / longer belt but that is another discussion.

Will keep mine running this week with the sliders to see if anything changes and report back.

[maddiedog]

Thanks for sharing your research.

I've heard such good things elsewhere about the sliders, so I'm a bit disappointed that you didn't see more results. Definitely keep reporting back, I'll be watching this thread.

Would it be possible to shorten the spacer on either the drive face or driven face to pull the pulleys closer together to get a steeper gear ratio? That might add back top-end, especially if you're getting shuddering from the belt being loose.

[EddieC]

If you have 12,000 miles, have the variator rollers and belt been changed already? Could be due soon at a service.

Nope havent changed them yet. I do all my own servicing... I'll probably have them ordered so I have them on hand when the time to replace comes. Soon I'll start putting 50 miles on 5 days a week. Right now I do about 30. Thanks for the tips! It'll be nice to figure this one out. I've done a couple wet clutches before... so this doesnn't seem very bad at all! Also.. great links. thanks!

[Nobody]

After having just the sliders in for a week they make a big difference in how the bike rides. Around 8000rpm or a bit over on acceleration and suit the terrain I have to ride on (lots of hills). Notice much better acceleration up hills now and a lot more fun tbh. Have to keep an eye on my speed as before constant revs resulted in a fairly constant speed. Now as I go down hill I notice a bigger drop in rpm even at speed etc.

Top speed has not been effected. Did a quick blast on the way home last night and still about 108 on the speedo. So if looking for higher speeds 11g Dr Pulley sliders are not going to do it with a stock variator. At least on my 125 (type WW125EX2A ED).

Just put in the contra spring this afternoon with the pulleys so will see how that goes.

[sendler2112]

I am going to try the 1500 rpm spring first to see what that does and then add the 12gn DR Pulley sliders. Do you have a tach on your bike? The Koso tach is very easy to install since it is self powered with a button battery and the pick up is inductive. Just wire up a ground and wrap the other wire round and round the plug wire.

[Nobody]

I am going to try the 1500 rpm spring first to see what that does and then add the 12gn DR Pulley sliders. Do you have a tach on your bike? The Koso tach is very easy to install since it is self powered with a button battery and the pick up is inductive. Just wire up a ground and wrap the other wire round and round the plug wire.

Yeah, I have an analog style Koso tacho (needs 12V). Really helps to see what is going on when you start playing around with the CVT. Interested to see what the pulling rpm is with the 12g sliders installed are. Only made a really quick sanity test ride to make sure everything was running smooth today and saw about 8200rpm. Need to let everything settle in again.

[sendler2112]

On your top speed runs is the bike hitting the rev limiter or just running out of power? What rpm? My 150 does 68 mph actual and is redlining at 9600 while doing it.
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I would have had my spring on today but couldn't come up with a large enough socket in any of the stores near me. 38mm and 1 1/2 inch are the largest I could find. I want to do the spring first to try to discern what changes other than raising the pulling rpm it accomplishes.

[Nobody]

On your top speed runs is the bike hitting the rev limiter or just running out of power? What rpm? My 150 does 68 mph actual and is redlining at 9600 while doing it.
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I would have had my spring on today but couldn't come up with a large enough socket in any of the stores near me. 38mm and 1 1/2 inch are the largest I could find. I want to do the spring first to try to discern what changes other than raising the pulling rpm it accomplishes.

Hitting the limiter at 9200 on all the runs. Will see how it goes with the spring & sliders now, may take a bit longer just to get the last couple km/h out of it. Maybe will loose a touch of top end. Dunno yet so will let it run in. Not a big issue as I rarely run at top speed anyway.

Any dealers or shops around you where you could take the clutch into? Only a couple minute job to swap the springs over once you have the clutch out.

[sendler2112]

I will just order a socket as I have a feeling this won't be the last time I need one.

[sendler2112]

Hear is a video showing the torque drive slots. This is a very obvious design parameter of the CVT trans that most explanations and videos totally ignore.
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http://www.youtube.com/watch?feature=pl ... jVhtKaOH04
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