Dr. Pulley & Contra spring testing

[maddiedog]

This thread got derailed. I've moved the crapposting to the Drama and bullcrap section. Of all the forums and threads here, I'd like to see actual performance testing threads stay on track since there are so few good threads about performance for the PCX. For those of you who want to read the posts, they're in this thread.


Please continue where you left off, Sendler and Nobody, and next time, just ignore the flame bait please.

[Nobody]

Cheers for the cleanup Maddiedog, this thread had gone a bit silly (almost given up on it).

Only had the spring in for a few days so still letting everything settle in before I come to a final conclusion - but can feel the difference. Much better mid range roll-on acceleration, coming out of corners or going uphill you can feel it. Cruising rpm's are much the same as with just the sliders (up just a bit on stock) so figure it is letting the variator fully expand. Spend far less time WOT as it get me upto speed faster.

Issues? Sort of I notice in very slow traffic or 30km/h zones the bike is revving a bit more (4.5k to 5k) as the variator hasn't fully expanded. But it is sitting right in the torque band so acceleration is great from here. Thinking that 11g sliders are a touch too light with the stock variator if always in town/traffic but for my commute they are fine. Probably 11.5g or 12g sliders would be it (or 10.5g or 11g rollers).

Main thing is.....it has made the PCX a lot more fun to ride...

[sendler2112]

The guys at Scooterworks.com had an NCY drivetrain upgrade kit for the PCX which allowed them to determine that the contra spring has the same dimensions as all of the standard GY6 125cc springs. They stock the "1000 rpm", 1500, and 2000 rpm springs. I tried the 1500 for $18 shipped and installed it with the stock weights which will take about 20 minutes next time. It is really stiff! I'm glad I made a rough measurement of the comparative spring rates before putting it in. You can measure it with a digital scale. Choose a socket with an extension in it that is about 70% of the free length of the spring and place it inside the spring on a scale. Tare the scale to zero and then press down with your hand until it is just skimming the top of the extension which is being used as a travel gauge. I found 6.5kg for the stock spring vs 10 kg for the new one. The aftermarket spring is a whopping 35% stiffer. Takegawa lists their spring at 11%. I wonder what it really measures. I put the NCY in anyway to see what it would do. My PCX is now much more responsive. It now immediately down shifts, or revs up, whichever way you want to look at it, when increasing the throttle. All of the rpm ranges were shifted upwards. Even mild coast down. Light cruise at 30 mph is running 5,000 rpm now and it immediately jumps to 6,400 on accel. Maybe this is the 1,500 rpm the rating is referring to. Once past 30, the pulling rpm continues to rise up to 7,400 whereas it used to be 6,600. I may get a chance to do some timed runs later today but it feels much quicker. There is still some action at 50 mph. The stock drive train has the weights locked all the way out by 50 mph with almost no kick down available. The new spring still allows some down shift from 7,000 to 7,400 at that speed. Pulling speeds of 8,000 are said to be at the power peak so I can still go with slightly lower mass in the weights but the 12gm sliders I have are probably too low now with this spring. There is a big loss of top speed though so I am going to try the next lighter spring and then play with the weights and may even spend some more money to see if there is any difference with a kevlar belt. I'm not sure if the loss comes from the rear torque pulley being still too active over 60 and pulling the weights off of the stops, or if the added spring force is squashing and stretching the belt slightly causing it to ride lower in the front pulley even though the weights are all the way out. Top speed now varies from 62-65 mph at the rev limiter depending on the wind. I used to get 67 every day easily. The good news is that there is quite a bit of untouched metal on the face of both pulleys. Once I settle on how much spring and mass to use, it occurs to me that there may be another big advantage to the sliders. It might be possible to tune a set for any given combination of parts on a bike by looking at the remaining virgin metal. We might be able to remove some of the material on the part of the slider that is in contact with the variator at the outer stop little by little until full belt travel is achieved.
.
.

.
.

.
.

.
.
The last image shows the famous torque grooves. Honda is using a progressive profile. Kick down should become less active at high speeds.
.
.
.

[gn2]

It now immediately down shifts, or revs up, whichever way you want to look at it, when increasing the throttle. All of the rpm ranges were shifted upwards. Even mild coast down. Light cruise at 30 mph is running 5,000 rpm now and it immediately jumps to 6,400 on accel.

Without proper timed testing the only thing you will ever know about this increased rpm is that it means increased fuel usage.

Maybe this is the 1,500 rpm the rating is referring to.

So lets get this straight, you don't even know the properties of the product you have purchased so how can you possibly asses what it's supposed to do?

may even spend some more money to see if there is any difference with a kevlar belt.

The material in the belt does not affect the gearing.
What makes a difference is the belt length and width.
You need to get the length and width right or no matter what you do with the rest of the fiddly bits you will not be able to get to the longest available gear.

Kick down

No such thing, it's a CVT.

[maddiedog]

Kick down

No such thing, it's a CVT.

I think he's referring to the pin and slot that varies the ratio progressively. Since the power band isn't linear, it makes sense for it to have the "kick down" to vary the gear ratio nonlinearly as well... It's just like where Sendler says "immediately downshifts" -- he's not suggesting it's actually shifting down a gear, he's implying the gear ratio is dropping. You can't be so literal, this isn't a technical document... It's documentation of experimentation.

Sendler - rather than modify the variator, would using a smaller set of spacers between the pulleys accomplish the same effect? It seems less costly if you accidentally screw up.

[Nobody]

Maybe this is the 1,500 rpm the rating is referring to.

So lets get this straight, you don't even know the properties of the product you have purchased so how can you possibly asses what it's supposed to do?

The "rpm" ratings on contra springs are basically misleading. The only reason I can see for the 1000/1500/2000rpm etc ratings is to differentiate the increases in tension from a particular manufacturer. Either a xx% difference from stock or an actual rating (there is a company that does this-forget who) is really relevant. In my case the SP Takegawa is 11% uprate. RPM? no relation in my book.

Kick down

No such thing, it's a CVT.

I think I understand the context but think the logic may be off a bit. Now with a higher contra spring rating the clutch can close much faster when you roll off the gas and rpm's drop, causing the cvt ratio to decrease. Now when you get out of that sharp corner going up Alp d'Huez and hit it, I could see why the term 'kick down' could be used. Engine revs pick up much straight away and the acceleration is there due to the lower ratio, like an auto transmission has kicked down a gear. With the stock settings you just feel bogged down.

If looking at clutch torque cam, the angle of the slot/gating seen above has an effect of determining the amount torque required to expand the clutch and allowing the cvt to move to a higher ratio. Now as the Honda part has a slight kink resulting in a dual angle (larger angle to lesser angle). What does this mean (this is my understanding anyway).
- at a low cvt ratio (ie. starting from stopped), the larger angle provides greater resistance to opening the pulley. This is good, keeps you in a lower cvt ratio for acceleration from the line and also lets the engine rev up.
- once underway and the clutch is opening, we hit the 'kink' and are now in the lesser angle. Now less torque is required to fully open the clutch. Crusin' mode - the engine can relax a bit.

The transition from one angle to another on heavy acceleration can sometimes be felt on some bike as a noticeable drop in rpm. This is really of utmost importance if running a bikes with a narrow power band (ie. a 50cc 2 stroke screamer). They have to maintain constant rpm's throughout the whole acceleration cycle if possible to keep in their power band. A drop off rpm's can really lead to a fall off in power. This is why cvt tuning gets to be more fun the less power you have.

There are a few 3rd party clutch cams out there for the PCX from the usual suspects (KN, Chameleon & Kitaco) without any change in angle - just a straight slot. The KN and Chameleon even have 2 different angles so you can try to fine tune even more. pcxdeamon has the Chameleon (think he likes it from what I read).

I did do a bit of reading on this a while ago. Think that for the PCX unless you really want to look at really doing major mods, the stock is fine. My aim is to get better acceleration/performance on my daily commute. I'm no speed freak. Keep at it Sendler, interested to see where this end.

[sendler2112]

The changes made by the super stiff contra spring are a wash and choosing to change it will depend on your intended use of the scooter. The big advantage is increased 5-40 acceleration. I haven't done any timed runs in this range but the spring makes the trans instantly down shift over 1,500 rpm when cruising at 20 mph and gunning it. With the initial increase in speed that is also occurring, the rpms jump right from 5,000 to 6,800 and continue to wind up to 7,400 by 40 mph. The 0-50 times are down some to between 12.5 and 11.8. call it 12.2 which is .5 seconds lower than before the spring but this maybe too broad a test to really show what is happening between any rolling speed and 40 mph. The problem with 0-50 as a test is that the launch is very slow. There is a programmed delay in the engines output on take off. I haven't timed it but it is at least half a second. Maybe more. No changes will ever effect this unless you get into a replacement fuel ECU or something. So this is always dead data right in the front of the timed run. The next issue with using 0-50 as a yard stick for playing with the trans is that by 50 you are close to max gearing and will be near the power peak so changes in 40-50 times will be very much less affected by the small amount of gearing change that is left at the top of the gearing. 50 mph used to run about 7,000 under load and now with the spring it runs at 7,400 as it is still getting 400 rpm of kick down under high load. It used to be much less active with only about 150 rpm of change between light cruise and gunning it. The change in gearing (as indicated by the change in rpm for any given speed) is much less between 40-50 than it is between 5-40 mph. But by far the longest portion of the run is from 40-50 which isn't going to change much regardless of what you do to the trans operating points. What I am trying to say is that most of the .5 second improvement from the stiff spring is between 5-40 mph at which it becomes pretty significant. This is more beneficial to shooting through city traffic than climbing a hill on the highway. For blasting around in the city, having a stiff spring to spool up quickly and launch you out of corners is really fun.
.
But in just a day of riding I can see several down sides to a super stiff contra spring. There is an obvious increase in the running losses in the belt. I think the increased compression on the sides of the belt, and the increased tension, are creating added friction and heat losses. The loaded hill climb speeds are down a percent to 49 mph. Top speed is often way down to the 63 mph range. Some of this my be due to the tighter belt riding down lower in the front pulley but I am also sometimes not making it to redline, indicating some loss somewhere. Fuel economy is also down 6% to 90 mpgUS. Partly due to higher rpms everywhere but I think also due to increased friction losses in the belt. Maybe a stiffer Kevlar belt could give some of this back but for highway commuters it looks like the light factory spring with lighter sliders might be the better option. An after market torque pulley with more aggressive slots could give a similar amount of kickdown using the stock spring as what the stiff spring gives now, without increasing the losses in the belt, but I haven't seen one for less than $160 and I am not ready to go there.

[sendler2112]

rather than modify the variator, would using a smaller set of spacers between the pulleys accomplish the same effect? It seems less costly if you accidentally screw up.

We don't have to touch the variator ramps. Because the DR Pulley sliders don't ever roll, they have 4 specialized surfaces. Each one with a different job that is normally done by four lines across the surface of the round rollers. The bottom of the slider is roughly round to approximate the shape of the roller as it follows the ramp. The top of the slider is flat and angled to ride against the plate. The other two sides are the high and low stops and could be shaved to any thickness just shy of having the belt ride off of the pulley at the top or go slack at the bottom. The sliders are a brilliant design and become obvious when you consider that many "rollers" are always sliding on a flat spot anyway.

[Nobody]

.
But in just a day of riding I can see several down sides to a super stiff contra spring. There is an obvious increase in the running losses in the belt. I think the increased compression on the sides of the belt, and the increased tension, are creating added friction and heat losses. The loaded hill climb speeds are down a percent to 49 mph. Top speed is often way down to the 63 mph range. Some of this my be due to the tighter belt riding down lower in the front pulley but I am also sometimes not making it to redline, indicating some loss somewhere.

If you are not hitting redline with the standard rollers installed, it is obvious that the spring is much too strong. The good old GY6 must be using a higher tension (could imagine this as the PCX is current tech design to minimize losses). Before playing with belts I would try to get a spring fit for purpose. Dropping effective roller weight with sliders would only make this worse.

[sendler2112]

Using way too light a roller for any given spring would make the bike redline more often and at a lower speed if they were too light to max out the variator. My variator is definitely maxed out above 8,000 rpm but it seems that increased belt losses from the tighter spring can actually amount to a sizable amount of hp. In the range of .1 hp? This is like running an 80 watt heating element in your belt. No wonder the front outer pulley has cooling fins.

[sendler2112]

Changing the torque driver to one with a more aggressive torque slot would give the benefits of more active kick down without the draw back of increased belt losses. The tight spring does eliminate a lot of the harmonic belt flapping that is sometimes felt at speeds above 50 mph with the stock set up.

[sendler2112]

I may also get a Malossi X Kevlar belt to play with now that I see how much loss is involved from over working the stock belt. The X belt may be good for a few percent in top speed all by itself if it is less compressible and less lossy. Honda is using a similar design as OEM in the newer Silverwings.

[DDirk]

Hello PCX fans,
by chance I found this discussion about our Dr.Pulley sliding rolls. We have many customers with a PCX scooter and the most are very happy with 12 or 12,5g rolls. In my opinion 11g is too light. You get a very good acceleration, but you have problems to reach the top speed. With 12,5g you can expect to get a much better acceleration as with 15g stock rolls, and a better top speed up to 8-10 km/h. AGerman magazin tested the PCX with 13g rolls and they got 9km/h more than with the stock rolls.

Have fun!
Best regards

[Nobody]

Think that with a stock CVT system you can get away with 11g sliders but they are already on the light side. No problem getting to top speed but rpm's up fairly high so an impact on economy. 12g sliders are probably the best bet with such a setup. But once you add an up-rated contra spring into the mix then they are too light for most people (unless you want to run at higher rpms).

For fun on the weekend I wacked the 15g rollers back in with the up-rated contra spring. Surprisingly good combination. Seems to sit at about 6800 rpm or so on acceleration and gets me up hills a lot better than stock. Not as rapid as with the 11g sliders but still ok.

The main feedback here is that the contra springs effect is much greater than I expected. Without testing can only guess on the best combination here.

[maddiedog]

Thread cleaned up again, unproductive posts moved here. Please keep any opposition to performance modding here: http://hondapcx.org/viewtopic.php?f=9&t=626

[sendler2112]

I have been methodically testing all of the changes I have made to my PCX150 with 0-50 times, weighted hill climb speeds, and fuel economy data. Much of which is not posted on this site due to my thread getting bombed. If Maddie will clean up my " bought the 150" thread I will be glad to post all of my results. I will also begin to include 5-40 mph or 10-40 times which will more readily show changes in transmission tuning than 0-50. 0-50 mph times have an end speed that is too close to the top speed of a small engine like this so the times are very long from 40 to 50. And there is a programmed .5 or so second lag in the power output when launching from a stop which is also swamping the data with a dead spot that we cannot change. Saying that changing the trans tuning resulted in dropping the 0-50 time from 12.7 to 12.2 seconds doesn't sound like much. Saying that you can drop the 5-40mph time from 6.0 to 5.5 seconds is a much better description of what the gains are from tuning to a higher pulling rpm and how much quicker the bike will be around town. I am open to suggestions for any other tests I can add to my regimen. I wish I had a dyno that didn't charge $400 (Harley) in my area as this is the one most important pieces of info on the PCX which is still lacking.

[sendler2112]

I have been methodically testing all of the changes I have made to my PCX150 with 0-50 times, weighted hill climb speeds, and fuel economy data.

And of course, top speed.

[maddiedog]

Again, I take a hands-off approach to moderating. The other thread did escalate quickly, but was all in good fun. It hasn't been replied to in two months either, so it might as well be a dead thread.

I encourage you to post the results in this subforum, and I'll moderate them however you'd like me to if you create your own thread. I don't want to extend my moderation to other threads if I don't have to, because a lot of why this forum was to promote free speech about the PCX... That approach has some side effects (we get distracted easily), but I think it's better than me ruling the forum with an iron fist.

Now then, let's please keep this on topic (because even though this isn't a crap post, it is irrelevant to this thread).

[sendler2112]

Let it die then I guess.

[gn2]

I look forward to seeing some well presented long-term test results.