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Post by scooter7878 on Aug 9, 2021 21:41:45 GMT -5
Try making ur new rollers a gram to a gram and a half heavier. If u search the site or Google it there's videos on doing it I believe Brent from here was using tin foil inside each roller center but idk how he made out with that or if he found something else better or but 8 g or 7.5 g rollers or preferred sliders maby ur rollers aren't able to push the belt all way up or variator or rear pulley is jamming or some issue
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vacationer
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Post by vacationer on Aug 14, 2021 15:53:44 GMT -5
Alright I added some tin foil to the rollers. I don't have a scale but I used a crude sort of weighting method to estimate that I added about 1.5g to my 6g rollers. After doing that and stretching the belt some, I'm reaching ~3mm from the top of the pulley. Better than before. Speed has not changed noticeably.
I think next step will be buying a new variator and clutch after I get paid this week.
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Post by scooter7878 on Aug 14, 2021 23:54:50 GMT -5
That's about right for a stock variator u should be getting about 35 mph out of a stock 50cc u really need a accurate rpm reading but it seems like ur cvt is working correctly now. At this point u got something going on in the motor I don't remember what u have done or checked but things that need to be verified are compression, valve timing and clearance,a restricted air filter or fuel filter, something restricting exhaust, possibly a stretched timing chain,a intake leak or exhaust leak at the head or any emissions device if one is installed,check to be sure ur butterfly on the carb is opening all way when throttle is wot twist grip full throttle and manually try to move throttle actuator on carb where cable goes in if u full throttle and u can move butterfly more ur cable needs adjustment also look at throttle butterfly and twist grip be sure it's not binding up half way or something,. Most important ones are valve /cam timing marks and valve clearance both will give u this issue. Check for timing chain play rock crank back and fourth there shouldn't be much play at all,and a compression check is def in order could have a leaking valve or worn rings. Also carbon build up in top piston and valves will rob a lot of power the carbon soaks up fuel and create a slightly lean condition I took my head off one time after about 4000 miles and there was about a 1/4 inch of carbon on piston I cleaned it and my power increase was greatly improved
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Post by GrumpyUnk on Aug 15, 2021 11:10:07 GMT -5
Perhaps spring for a tach that detects by a wire wrapped around the spark plug wire. Yesterday I found I was turning 9,999 rpms going downhill and starting up another. The tach went nuts and reset itself to unknown mode. I watched it happen. Never knew I was turning those rpms, even with 12" wheels. If you are not getting the rpms, you will never get the speed of motion. You can get tachs from a lot of places, and I got several from aliexpress, for around $4-6 shipped. They are supposed to last several years before the battery is kaput. They also record hours of use, such as for oil change intervals. I have mine hanging off the handlebar and the wire strung back to the spark plug. It is almost a necessity for tuning the CVT. tom
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vacationer
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Post by vacationer on Aug 25, 2021 16:21:20 GMT -5
Alright, tach and compression gauge came today. Tach shows max 8000 rpms.
There are some sections of the instructions that I don't understand, I assume since they refer to vehicles other than scooters. For example:
- loosen spark plug about half a turn, remove dirt and debris from spark plug well, remove spark plug. [Not sure what that means or why it's an instruction] - remove air filter. [Is this necessary?] - set throttle plates to wide open. [So just turn the handle to WOT?]
I went ahead and tested at WOT with the air filter removed. At first, I was clocking about 90psi (it's possible that at this point, I'd forgotten to open the throttle - poor memory), then I realized the gauge wasn't screwed in all the way. I tightened it and tried again and couldn't get above 25psi (definitely WOT this time).
Obviously both those readings are bad, but the fact that it changed like it did makes me think something is amiss with the way I'm measuring. I'm hitting the kick start to press the gauge up until it stops increasing.
I also noticed that all my oil seemed to have leaked out at some point due to the cap being loose. I imagine this might affect compression but not sure by how much.
What a nightmare.
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Post by scooter7878 on Aug 25, 2021 22:01:09 GMT -5
When u check compression u want the most air that ur engine can intake that is why they want u to remove air filter and hold wot. When u screw adapter in be sure it bottoms out and there should be a rubber seal on adapter be sure that is sealing and adapter is threaded all way in till seal is compressed. That seal will fall off adapter sometimes be sure y don't loose it. Y can lightly coat threads and seal with oil to help. Hold wot and be sure ur battery is fully charged so u get good cranking speed. Time the crank u want to always do the same amount of seconds every time something like 5 or 6 seconds just be sure when u recheck u cranked same length of time
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Post by scooter7878 on Aug 25, 2021 22:04:24 GMT -5
8000 rpm is about right and u should have between 150 to 180 normal maby a little more check compression cold and try it hot. It should be consistent if u check it 2 times when hot it should be within a few psi and same cold cold and hot checks may differ a bit but warmed up wot crank for same amount of time should be very close to each other
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Post by scooter7878 on Aug 25, 2021 22:06:37 GMT -5
Alright, tach and compression gauge came today. Tach shows max 8000 rpms. There are some sections of the instructions that I don't understand, I assume since they refer to vehicles other than scooters. For example: - loosen spark plug about half a turn, remove dirt and debris from spark plug well, remove spark plug. [Not sure what that means or why it's an instruction] - remove air filter. [Is this necessary?] - set throttle plates to wide open. [So just turn the handle to WOT?] I went ahead and tested at WOT with the air filter removed. At first, I was clocking about 90psi (it's possible that at this point, I'd forgotten to open the throttle - poor memory), then I realized the gauge wasn't screwed in all the way. I tightened it and tried again and couldn't get above 25psi (definitely WOT this time). Obviously both those readings are bad, but the fact that it changed like it did makes me think something is amiss with the way I'm measuring. I'm hitting the kick start to press the gauge up until it stops increasing. I also noticed that all my oil seemed to have leaked out at some point due to the cap being loose. I imagine this might affect compression but not sure by how much. What a nightmare. . The electric start is better for compression u can use kick start but kick it a few times noting pressure on wack kick by 4 or 5 kicks u should be above 140
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Post by GrumpyUnk on Aug 26, 2021 7:53:00 GMT -5
The instruction about loosening and un-screwing a bit are to allow you to loosen and then blow off any dirt around the spark plug before removing it altogether. Once off, screw in the adapter snugly. Open the throttle fully. While watching the gauge, use the electric starter to rotate the crankshaft UNTIL you do not see an increase in pressure. That is a repeatable test, while kick starting X number of times is not nearly so because of human muscle different actions. The kicks will not be the same, and may affect results. The battery, if charged, should have no problem running the starter motor the same each time. If you are turning 8000 rpms, you should be traveling over 30mph. If your speedometer indicates lower, it could be the meter. There are speedo apps for smart phones available at no cost that should(may) give a more accurate reading of velocity. As you accelerate from a stop, the engine revs should climb, and the bike will seem to 'catch up' to the engine rpms as the CVT changes ratio. Seems like there is a 'rubber band'between the engine and scooter, and it stretches at first, and then seems to contract as you speed up. If the rpms go up and you don't feel the acceleration the CVT may be slipping. This string of posts is too long to know what's up, and I won't go read the whole thing. May need a 'summary' of what is going on, and how things are working. tom
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Post by vacationer on Aug 26, 2021 17:41:35 GMT -5
Summary is a good idea. Here goes:
Had scooter in storage for a few months. When I took it back out, I couldn't get it to go above 20mph.
I put some seafoam in it - no change. Remedied some leaks found with starter fluid (RPMs went down instead of up - never got an answer as to whether this is normal). Put more air in tires. Gained ~3mph. Tried different jet sizes - no change. Spark plug was a dry black with some orange on the tip (pic on first page) Found out the belt wasn't traveling its full distance. I took the variator and clutch apart and cleaned them a bit. Found that the rollers were somewhat flat. Replaced them with my best guess at stock weight - change. Discovered the black ring caused by the belt melting onto the variator. Sanded it off and tried again - no change. Replaced the belt - no change. Ran it without the belt to see if something obstructing the movement of the variator - nope. Hypothesized that since the ring was forming, the variator must be squeezing the belt pretty hard, so the problem is likely the rear pulley. Ran the bike for a while to stretch the belt - no change. Weighted down the rollers with tin foil - no change. Confirmed good RPMs with tach. Still need to test compression with electric start.
My roommate's girlfriend brought her scooter over since she was having the same problem (also gy6). Also said that she had to pull the break to keep the bike from running away at idle. Also died at red lights. Said she replaced the CVT and the problem went away. Goes a little faster now too, but not as much as before. She said a piece might be broken on her old CVT, but I told her to bring it over anyways to see if it could be changed out with mine for testing purposes.
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Post by vacationer on Aug 27, 2021 17:53:38 GMT -5
Okay, tried the compression test a few more times with the electric starter. Got up to ~105 every time. Have I found my issue at last?
Roommate's girlfriend's scooter had what was supposedly a new CVT in (belt was inside out - god only knows why) so I swapped her CVT for mine. The back disc of the variator had a few dents on it, which was suspect, but it didn't seem to affect performance. The sharpie mark left after running MY scooter with HER CVT was a little longer than on MY CVT, but I measured and found that my CVT is also a bit wider in diameter (talking about the back disc here).
I also noticed that there was a color difference on the front disc where the belt stopped, but when I swapped it onto my scooter, it started forming a ring like mine had. My hypothesis was that the rear pulley was causing the ring, but it's happening even with an entirely different CVT. Go figure.
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Post by scooter7878 on Aug 27, 2021 20:37:00 GMT -5
105 is not enough compression. If u have a way to pressurize the cylinder using the compression adapter and a air compressor that makes at least 90psi u can find where ur loosing compression if u have that capability lmk I'll explain how. If not do a wet test which put a little oil in cylinder through spark plug hole like enough to coat the top of piston maby a ounce or two of motor oil and redo compression test. If compression goes up a bit u got bad rings if no change u have valve issues or possibly a timing chain off or stretched
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Post by GrumpyUnk on Aug 28, 2021 7:42:51 GMT -5
I *think* the ring is formed by the rubber of the belt MELTING. Melt is caused by heat, heat by friction. Friction can be normal(it is), or abnormal. I think it abnormal when it leaves a mark... I think your belt is slipping where the black ring is getting deposited. Why? Shape, loose, stiff, weak springs, strong springs, worn out pieces, worn out belt, torque spring too strong/weak, variator weights too light/heavy, variator sticking, variator plastic guides worn/sloppy, variator arms(the guides use) worn/cupped/etc. My goodness, we have a plethora of conditions that could cause problems, but a paucity of answers. A good cleaning and a close inspection and comparison to new items may be in order. One other possibility is to replace both variator and clutch assembly(and belt, just because). {I had one Taotao, now sold, that had the best operating CVT I had ever ridden. It just worked. Engine would rev to a good rpm, and then the scoot would just accelerate to catch up with the engine sound. Was kind of nice to drive.} If the face of the variator or clutch is damaged or worn, I think it is time for a replacement.
tom
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Post by vacationer on Aug 28, 2021 13:59:19 GMT -5
scooter7878 I don't have that kind of compression available, but I'm wiling to bet the oil has something to do with it. Stay tuned. @grumpyunk The ring formed both on the old CVT and this supposedly brand new CVT, as well as with the old belt and the new. I may change out parts of the old CVT with the new, such as that dented variator face. I've tried 5, 6 and 7g rollers with no change. The belt is measuring 17.6mm instead of 18mm, naturally from melting/friction, but I'm wary of buying yet another new one until it gets worse or I'll just be wearing down a new belt every other day while I'm trying to fix this thing. Also, how do you define "slipping"?
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Post by scooter7878 on Aug 28, 2021 19:34:40 GMT -5
Vacationer put oil down the cylinder and retest compression that will tell u if it's ring or valve train related. But be sure the oil in ur motor is not fuel contaimated if compression goes up a decent amount with oil down the spark plug hole u got bad rings or ur cylinder was washed down with fuel when u did original compression test
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