Did a little moped science. I was worried that the belt jumped a bit when I was coasting down hill and gave it a bit of throttle which caused the clutch to engage and the bike to stutter a bit. The belt is riding up into the teeth. I'm pretty sure that is something I don't want happening.
Trying to keep the bike running as it is I'm mulling over my options:
Higher gearing Stronger contra spring Possibly replace the stock contra (bought this used with 4500 on the speedo not sure if it's ever been replaced)
Belt stretched and or worn to thin and is riding too high,,, you may want to look at the spring also,, it may have fatigued and is weak,,, how does the belt look? On the side ,, both sides,,, did it get chewed by the teeth?
Please do check the part for run out,,find a shaft that will just slip into the hole of the part and spin it kind of medium slow ,,,i dont know if its an opitical illusion but it looks out of round to me,,,but it just may be the pic,,,i would check it tho
It is NOT the drive face that is causing the problem it is the BENDIX. The belt is hitting the BENDIX GEAR and tearing it apart. Very common on the 50s when folks put in a bigger Variator. So the best is to lower you rpms so put in 1 gram lighter weights to drop your rpms by around 500 rpms that may be enough for the belt not to reach the bendix. Remember the belt will only go as high as the SMALLEST CIRCLE and if you measure your drive face you will find that the DRIVE FACE is much bigger than the VARIATOR FACE. Belts on any CVT will only climb as high as the SMALLEST CIRCLE which is your Variator. Alleyoop
Here is a very good example of what happens. But in this video he has taken the BENDIX out so it does not flop around and grind on the drive face. This is a STOCK variator on this scoot notice how much smaller it is compared to the Drive Face that is a STOCK VARIATOR. Notice how the belt Climbs all the way to the EDGE of the Variator but because it is stock it will Just miss NOT hitting the Bendix Gear. But you put in performance Variator which are a few MM bigger in diameter the BELT WILL reach the Bendix and start to tear up due to hitting the gear on the BENDIX. Alleyoop
Post by moddersunited on Mar 20, 2015 2:32:04 GMT -6
Got back online a bit late today
My SYM is mildly modified: derestricted Dio Goshi exhaust (great low end torque) NCY variator (The orange ptfe coated version) NCY lightened clutch bell I was also running the Ncy clutch but went back to stock
cyborg: Thankfully it was only an optical illusion from the belt markings. I was worried about that as well when I pulled the drive face. After cleaning it up and taking a few measurements It turned out to be properly machined.
The belt doesn't show any signs of abnormal wear or markings on either side or outer face.
I did a few tuning runs today. First I replaced the contra with a stock spring and ran it. No markings above the flat ring on the drive face.
Second I replaced the contra with a 1000rpm and jumped up to 10.5g weights, bike ran alright, acceleration declined but still managed to reach top speed. Again no marks on the drive face.
I decided to go back to the stock setup as I didnt benefit from the 1000rpm contra and its a pain in the A** to open the driven pulley to seat the belt for reassembly.
Alleyoop: I'm going to test the Bendix this weekend. Just to clarify wouldn't I want to add weight to lower the rpm?
I'm starting to think this is more of an isolated incident. The dark ring the in the original post was made while I was up in the mountains and was hammering it a bit downhill. After I posted the thread and went for another tuning run I noticed the same ring only not as dark. Today I took it easy on the downhill parts of my "test course". I'm starting to think my issue may be the lack of resistance going downhill at WOT
Post by moddersunited on Mar 20, 2015 3:24:59 GMT -6
Didn't bother to wait on testing. I took out the bendix and noticed I good bit of belt residue on it, didnt see any scuff marks where it may have impacted but the case has doesn't allow much room for that
Got everything bolted back up and ran it around the block. On my downhill portion I laid into it and hit 50. When I got back sure enough there were rings around the drive face teeth.
So I guess that solves that, Don't WOT downhill and no problems will be had.
Sidenote/unrelated: Dio centerstand rest is on the muffler. Had a helluva time trying to pin a rattling noise that seemed to happen sporadically, I found out the extra "mount" on the goshi was actually the hole for the rubber stopper.