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Post by phssthpok on Sept 16, 2013 11:40:46 GMT -5
Something I've noticed about my 'new' scoot is that while up on the stand and idling, the rear wheel is in constant motion. Not too terribly fast...maybe about 5MPH equivalent...but it's a smooth steady turn, not a slight, pulsing twitch like I see in many YouTube videos. When down on it's wheels and at a stop, there is a noticeable load on the engine (idle drops from a smooth 1400, down to a ragged and strained 11-1200rpm) which results in a 'pulsing' sensation in time with the idle. This pulse is so pronounced that it 'shakes' the bike making it hard to tell if it's the low rpm rotating mass of the engine internals shaking things up, or if it's a slight pull from the drive wheel (or both). Now to my mind (and limited understanding of the CVT mechanics), a moving wheel at idle means there is *some* belt engagement occurring, which translates into unnecessary belt wear at stop lights/signs. This means that, while I *could* turn up the idle to stay steady at 1400rpm while 'on the ground', this would not solve the problem of the belt being at least partially engaged. In fact it could exacerbate the issue, as the only reason I can think of for the belt to be moving the rear wheel is for the three clutch pads to be ever-so-slightly engaged, and a higher RPM would cause them to engage even more, resulting in 'automatic creep' (that phenomenon where an AT car will move forward unless you keep the brakes engaged). So either the belt or the clutch (or both) is slightly engaged and slipping at idle, which to me translates into unnecessary wear. If not for the noticeable 'load' on the engine at stop signs, I'd attribute the wheel spin on the stand to sympathetic drag. The glaringly obvious solution is to replace the three small clutch springs with slightly higher rate springs to ensure that they do not engage at too low of an RPM. This should (in theory) eliminate the spinning wheel while on the stand, as well as the added load on the engine while stopped on-the-road. What I haven't been able to determine through research is just exactly what effect swapping *only* those three springs would have on the rest of the CVT. I'm all about economy...I'm not terribly interested in neck-snapping acceleration, or tear-inducing top speeds so a complete weight/pulley/contra/clutch-spring revamp isn't in the cards (though I understand that a taller variator may result in better upper end efficiencies). I can't imagine that simply ensuring the clutch doesn't engage at idle speeds would have any effect on the ret of the CVT's normal function, but I figured I'd lay my situation out for more experienced folks to chime in on...so, chime away! ;D *Something else that just occurred to me (literally...just now, so I haven't researched it yet) is what exactly the RPM 'ratings' on aftermarket springs means. For example, the 1500rpm clutch springs...does that mean they begin to engage at 1500rpm, or that at 1500rpm they reach full engagement?  |
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Post by pgs on Sept 16, 2013 12:05:09 GMT -5
i had a similar problem on a scooter it turned out that one of the clutch arms was broken and always engaged, the 1500 rpm springs do not engage at 1500 rpms, Clutch springs commonly come in 3 denominations. 1,000RPM, 1,500RPM and 2,000RPM. The numbers don't indicate the engagement RPM, but rather the estimated RPM increase. For example, if your scooter's clutch engages at 2,000RPM stock and then you add 2000RPM clutch springs, it should engage around 4,000RPM. Unfortunately, it seems that the actual stiffness of both stock and aftermarket springs from one manufacturer to the next can vary, so these are just rough estimates of the increase in engagement RPM
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Post by JerryScript on Sept 16, 2013 13:04:35 GMT -5
Remember, it's not the RPMs of the engine that determines when the clutch pads engage, it's the RPMs of the clutch assembly.
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Post by phssthpok on Sept 16, 2013 14:51:30 GMT -5
Adjust your idle on your carb. ... SRSLY? I understand you're only trying to help, and I don't want to sound like a burro sphincter here, but did you even read my post?  My (no load) idle is currently set at 1400rpm which, from what I've been able to research, is just shy of the lowest settings recommended for the 150cc GY6 (1200rpm) . If I turn the idle down any lower, the drive train drag (which is the issue at hand) would place to much of a load on the engine while on the street and it would die every time I came to a stop. i had a similar problem on a scooter it turned out that one of the clutch arms was broken and always engaged... I certainly hope this is not the case, but it does fit the symptoms. It gives me something to check for. Thanks.  This is actually quite helpful. Again, thank you. Remember, it's not the RPMs of the engine that determines when the clutch pads engage, it's the RPMs of the clutch assembly. I am aware of this, but you make a good point.  Regardless of the RPM differential from the drive pulley (variator) to the driven pulley (clutch), there shouldn't be enough RPM to engage ANY of the clutch arms while at normal idle speeds. I have watched several YouTube videos where the belt is so loose when the throttle is closed that it actually attempts to spring into a more rounded (relaxed) shape...there is ZERO belt movement when this happens regardless of the fact that the engine is still running. The problem I'm describing indicates that there is a certain amount of belt engagement, even at idle speeds, such that there is some power being transferred to the clutch pulley, causing it to spin. Since the clutch arms rely on centrifugal force to move out and engage the clutch bell (and thus transmit power to the rear wheel), and until such time as that force level is reached there should be no engagement at all, then since my tire moves at idle I can only presume that SOMETHING is causing the clutch assembly to spin enough to cause at least partial engagement. Whether it's a broken clutch arm, or a broken/disconnected clutch spring, or something else I don't know, but everything I've been able to research indicates that there should be ZERO power transmitted to the drive wheel at (engine) idle speeds, and I obviously have SOME.  |
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Post by f4milytime on Sept 17, 2013 2:00:30 GMT -5
That happened to me, in my case it was my clutch springs were no good.
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Post by jjoshua20213 on Sept 17, 2013 7:26:21 GMT -5
I'm not even gunna waste my time explaining my reasoning. Your welcome for trying to help.
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Post by robrun on Sept 17, 2013 8:35:10 GMT -5
Check your clutch for a broken shoe or spring - more than likely the problem. IF theyre in good shape it could be you have the wrong belt size. Could be the person who sold it to you (or fixed it for him) just slapped on a belt from another 150 to make a quick buck. I see that in my shop from time to time.
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Post by JerryScript on Sept 17, 2013 10:49:52 GMT -5
I'm not even gunna waste my time explaining my reasoning. Your welcome for trying to help. Perhaps he will learn and understand in the future, at least you tried to help! |
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Post by phssthpok on Dec 17, 2013 15:06:16 GMT -5
Necro-thread resurrection for an update. I got the clutch swapped out today (just finished in fact). What a colossal pain. Even with an air impact wrench, I still had to heat the nut with a propane torch to break it loose. I don't feel so bad now about breaking down and buying an impact. All other attempts to 'lock' the bell and use a box end failed. It turns out that all three arms of the clutch were in various stages of disintegration, though the pads themselves were just fine, if just slightly glazed (it's as if the pad material was holding the last bits of each arm together). The inner bell surface was smooth as glass, but showed no signs of overheating or glazing. I gave it a light scuffing with some sandpaper as I would do a brake rotor when servicing. The pads on the new clutch had a nice rough surface already, so no pre-scuffing there. After a test fire and some carb tweaking, the rear wheel is now behaving normally. Smooth idle at ~1300rpm, and just the slightest hint of 'residual drag' wheel movement instead of the previous 5-10MPH (guestimated) spin. Unlike before, applying the brakes does not affect the idle at all. Now for the test ride. |
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Post by tvnacman on Dec 17, 2013 15:46:37 GMT -5
good luck !!!!!!!
John
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Post by alleyoop on Dec 18, 2013 15:47:30 GMT -5
Good Job,
If there is still some wheel spinning get 1000 rated clutch springs and that will let the motor idle nice at low rpms without the clutch engaging the bell. The OEM clutch springs are rated at around 700-800.
Alleyoop
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Post by phssthpok on Dec 18, 2013 20:28:41 GMT -5
Good Job, If there is still some wheel spinning get 1000 rated clutch springs and that will let the motor idle nice at low rpms without the clutch engaging the bell. The OEM clutch springs are rated at around 700-800. Alleyoop After the test ride (and everything got good and warmed/limbered up) I put it up on the stand to see how it was holding. Idle had increased to just under 2000, but there was ZERO movement in the rear wheel. ZERO...not even the 'residual drag' stuff. . I still need to futz with the idle settings though...I didn't have time (to do it right) after the test ride. I don't know what the springs in the new clutch are supposed to be rated at, but I didn't opt for any kind of 'performance' unit or springs. Regardless... the clutch arms seem to engage at around 3000rpm (it's kind of hard to get more exact than that as I can't watch both the wheel and the tach at the same time ). As it stands now I'm happy with it's engagement point though, so I'm not gunna futz with it. Unfortunately, I tried to ride my wave of good-wrenching-luck and figure out where the slow leak in my front tire was. I traced to the valve stem (still the factory unit), and the center brass tube blew out as I was examining it. So now I get to fiddle-fart around with replacing the valve stems (yes...I'm doing both), but apparently we don't actually have the C-clamp I seem to recall stumbling over constantly ('cause I sure as can't find it now that I need it!  ). *Le Sigh* such is life...  |
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Post by alleyoop on Dec 18, 2013 20:42:27 GMT -5
Which clutch did you get(LINK) and if you noticed what color are the Clutch springs.
Alleyoop
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Post by phssthpok on Dec 18, 2013 22:23:30 GMT -5
This one. Apparently I did get a 'performance' unit...to be honest I was just looking for the least expensive clutch I could find. $35 and free shipping fit the bill. In the photo you can see blue springs. I didn't examine the springs closely, but they looked black on mine...though it's possible they were a very dark blue. All in all, I'd have to say I'm 'satisfied' (so far) with the item. The pads themselves seem to be a touch shorter from end to end than the stock unit, as well as about 1/3 less thick, but fit and function seems to be just fine.
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Post by alleyoop on Dec 18, 2013 22:39:21 GMT -5
That is why I asked what color are the springs, I figured the clutch you got came with stronger springs if it grabs at around 3000K. Standard Clutch Springs will throw out the pads when the rpms climb from little over 2000-2500 rpms. As you put miles on it the springs get a little weaker and they will require less centrifugal force(less rpms) to swing out and grab the bell. My NCY clutch with standard Springs grab right around 2300 rpms.
Alleyoop
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..BAD TO THE BONE..
