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Post by bigmac on Jun 11, 2017 19:47:57 GMT -5
Near the end of a long ride (about 20 miles) my 50cc gy6 suddenly started to make a noise. Sounds like a rubbing/grinding noise. Luckily, I was less than a mile from home so it didn't run like this for very long. I didn't notice any difference in performance during this time.
I had a no spark issue about 175 miles ago which a new magneto and pick up coil fixed. I thought I had under tightened something during that job and it came loose causing the sound. However, everything was secure. Now I'm panicking at the thought of worn-out crankshaft bearings.
I watched this youtube video on how to locate noises on a gy6:
As the guy in the video suggests, I removed the CVT belt to reduce noise along with ruling out the clutch side of the CVT as the noise source.
Now, usually my starter motor cranks the engine over kind of slowly, especially on the first starting attempt. Then once the engine starts, it has a hard time idling until it's fully warmed up and even then it tends to stall at times. It's been this way for months and I assumed the starter motor had an issue and the carburetor had a dirty pilot jet.
When I started the engine without the CVT belt, it cranked over much faster, started easily and idled smoothly. actually, it idled a little too high, like the idle speed adjustment screw could be turned out some. As for the noise, still there but less noticeable and will fade away at about 2,900 rpm, granted that my scooter's tachometer is accurate.
It appears that when the belt is on, it puts enough load on the engine that it becomes hard for the starter to crank it over and even makes it difficult for the engine to stay on at low speed. Is this normal? Aside for the belt, I haven't inspected anything in the CVT. I've never taken it apart before so I don't know much about it, but maybe some of you here know all the parts in there and can determine which ones could possibly be making a noise similar to what I've described and possibly be putting extra load on the engine.
I'm hoping it's something with the CVT which is where the noise does seem to be coming from but I could be wrong and it could be a crankshaft problem. In any case, I am curious to know whether or not it's normal for the engine to start and run so much better without the CVT belt on. With the belt on, it's like a motorcycle with a clutch lever that can't be fully pulled in so it's in the friction zone while stopped making it necessary to ease on the throttle slightly to prevent stalling.
Scooter has slightly over 6,000 miles by the way.
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Post by tortoise on Jun 11, 2017 20:36:53 GMT -5
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Post by cyborg55 on Jun 11, 2017 22:12:08 GMT -5
This sounds about right
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Post by toddmaples on Jun 12, 2017 15:06:04 GMT -5
Check clutch springs, weak or broke clutch springs will cause this also as the arm will prrmaturely engage the bell, putting load on motor. |
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Post by bigmac on Jun 14, 2017 14:01:53 GMT -5
I was going to take it apart today and check the things that have been suggested I look into but couldn't get the nuts off.
As I said before, I recently replaced the magneto and to remove the nut on the crankshaft, I used a spanner wrench that holds the flywheel still so I can turn the nut without the shaft moving. I once again used that spanner wrench to hold the flywheel still so that the crankshaft wouldn't move while removing the nut on the transmission side of the shaft but even with two feet of leverage and banging it with a rubber mallet, the nut remains stuck.
I think I'll need an impact wrench to get this apart. I've always managed to get even the most stuck fasteners free with WD-40 and some good hits with a rubber mallet on the handle of the wrench but this thing was apparently put on by Hercules or something.
Edit:
Just to make sure, the nuts for the variator and clutch are not reverse threaded are they? I turned left (counterclockwise) while taking the nut for the flywheel off but is the threading on the variator side of the crankshaft opposite, so I should turn right (clockwise) to unthread it?
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Post by cyborg55 on Jun 14, 2017 22:00:09 GMT -5
No normal threads left off right on
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Post by onewheeldrive on Jun 15, 2017 0:18:01 GMT -5
6,000 miles is an EXTREMELY long time to not check your variator, if you haven't ever. Your rollers are probably beyond garbage. Have you (or anyone else) ever had the variator off before?
It also wouldn't surprise me if your variator is shot. Those 3 "v" guides on the variator back plate are hit or miss. Once they are cracked they don't last long, and it will destroy the variator if neglected long enough. It just happened to me again not too long ago.
Definitely check that out (CVT) before you start worrying about the crank. If you wipe your finger in the case and see really fine gray metal particles, it's probably metal to metal contact in the CVT.
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Post by bigmac on Jun 15, 2017 20:24:08 GMT -5
No, I haven't removed the variator before and I know the person who had it before me didn't either. I took the CVT cover off three times in the past. Twice to fix a problem with the kick start and once to replace the starter clutch. There is always black dust in the case from the belt, which I cleanup whenever I have the cover off but I haven't noticed any particles that appear to be from metal.
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Post by bigmac on Jul 4, 2017 12:04:10 GMT -5
With a 1/2 inch drive impact socket, 5 foot long pipe for leverage, spanner wrench wedged against the floor to keep the shaft from turning and a 210+lbs man sitting on the scooter to keep the scooter from lifting up off the floor by the spanner wrench's handle while turning the nut loose (which was still almost not enough to weigh it down), I was finally able to get the nut off.
Now I can take it apart and see what's wrong.
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Post by toddmaples on Jul 4, 2017 17:14:02 GMT -5
With a 1/2 inch drive impact socket, 5 foot long pipe for leverage, spanner wrench wedged against the floor to keep the shaft from turning and a 210+lbs man sitting on the scooter to keep the scooter from lifting up off the floor by the spanner wrench's handle while turning the nut loose (which was still almost not enough to weigh it down), I was finally able to get the nut off. Now I can take it apart and see what's wrong. I would have invested the $20 into an impact. Makes pulling car tires alot easier too for regular maintenance/inspections. Check for all the above and report back please.. |
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Post by bigmac on Jul 5, 2017 21:30:49 GMT -5
Aside from being a bit dirty, nothing on the variator side of the CVT looked worn-out or broken. The only thing wrong from what I could tell is that most of the roller weights have flat spots so I'd like to get a new set of them. I don't know what the weights are when stock. Whatever I have now works well for me and seem to give a good middle ground between having decent acceleration and top speed. Most ebay sellers have 8.5g rollers.
I have a gy6 service manual that says the drive belt should be 18mm in width and should be replaced after it goes beyond 17mm. Mine is at 16mm so I'll like to get a new belt. I currently have a Gates Power Link which I heard is a good brand for these gy6 CVTs so I'll get another one.
$20 impact wrench? I didn't look around a whole lot but the cheapest one I came across was a $35 air powered one with pretty lousy reviews. And it didn't even come with an adapter to hook it up to a compressor. I was about to get it anyways but changed my mind after seeing this video. The guy said he tried both an electric and air powered impact wrench on the nut with no luck. Eventually, he got it free by basically doing the same thing I did. Plus, I already had all the stuff on hand but the impact socket and 1/2 drive socket wrench which I just borrowed from my brother so it didn't cost me anything.
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Post by 125scooterbro on Jul 6, 2017 2:48:45 GMT -5
Aside from being a bit dirty, nothing on the variator side of the CVT looked worn-out or broken. The only thing wrong from what I could tell is that most of the roller weights have flat spots so I'd like to get a new set of them. I don't know what the weights are when stock. Whatever I have now works well for me and seem to give a good middle ground between having decent acceleration and top speed. Most ebay sellers have 8.5g rollers. I have a gy6 service manual that says the drive belt should be 18mm in width and should be replaced after it goes beyond 17mm. Mine is at 16mm so I'll like to get a new belt. I currently have a Gates Power Link which I heard is a good brand for these gy6 CVTs so I'll get another one. $20 impact wrench? I didn't look around a whole lot but the cheapest one I came across was a $35 air powered one with pretty lousy reviews. And it didn't even come with an adapter to hook it up to a compressor. I was about to get it anyways but changed my mind after seeing this video. The guy said he tried both an electric and air powered impact wrench on the nut with no luck. Eventually, he got it free by basically doing the same thing I did. Plus, I already had all the stuff on hand but the impact socket and 1/2 drive socket wrench which I just borrowed from my brother so it didn't cost me anything. good to hear, usually the first thing can wear off is the weight rollers and there comes the bad sound from the cvt, il suggest to make a tool for removing the roller box because you will need it in future or just get one from ebay with 10$ much better than the impact gun if you ask me |
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Post by pistonguy on Jul 6, 2017 6:14:30 GMT -5
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Post by pistonguy on Jul 6, 2017 6:24:17 GMT -5
Electric Impact www.harborfreight.com/12-in-heavy-duty-electric-impact-wrench-68099.htmlThese are almost always on sale from a weekly flyer for $39.00 and they Always have a 20% off coupon you can use on top of that. I own one and She has some Snots. Other than anything on the scooter, Car and Even Big Blade Brush Hog 1-1/4 Nuts. That dude in the video is a joke, another squid just providing misinformation. barn yard butcher with a pry bar. Both my USA made Chicago Pneumatic or Ingersall Rand will Shear the end of the Crank off with Nut Impact if I wanted to. The Electric impact I'm using is Overkill for such a small nut on the end of the Crank, I'm more concerned of busting it off as this Impact has no adjustment as I do on conventional air |
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Post by bigmac on Jul 6, 2017 14:36:31 GMT -5
The gy6 service manual I mentioned before says the torque spec for this nut is 28ft lbs. That isn't all that much, especially compared to how tight it was on before. What do you guys usually torque it down to? I want to make sure it doesn't come loose when I finally get it back together.
Motonosity, a youtuber I often watch did a Honda Ruckus build series and he had this nut come loose.
You can hear about it at the 15:45 mark of this video.
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