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Discussion Starter #1
I'm going to apologize to everyone in advance for the length of this post. The really important part starts in the 9th paragraph, but I wanted to have some background available to help anyone else who's experienced clutch/cvt issues.

I recently enjoyed a 5 week vacation with my family. When I got home I hopped on my 650 that's normally nearly daily-driven and it fired it right up. I have had 48,500 totally trouble free miles on it. As I started to pull out of the driveway I noticed an odd "slipping clutch" feeling then the bike suddenly changed to a high ratio- something like shifting into 4th or 5th gear. I eased off on the throttle and it engine braked normally then shifted back into a ratio roughly similar to 2nd and I was off. After a few blocks it was apparent something was very wrong as the bike kept continually wanting to go into a very high range, and with application of much throttle it would start to slip and change gear ratios quickly up and down.

I took it home and hopped in the cage to run my errands. When I got home I tried to diagnose the problem by riding around the neighborhood at different speeds in Manual, Normal and Power modes. The bike would slip if I applied much torque, and the CVT ratios were all over the place. The slipping became so bad after a couple of miles that I was worried about getting up the hill to my neighborhood, and put it in manual mode to gently climb the hill in a lower gear. The bike then gave me an F1 code - C58 which is reduction ratio disagreement. It only gave me the code once, and it was after repeated opening and closing of the throttle rapidly to see if the engine braking was working.

I spent considerable time researching the advice on this forum and others, and decided to replace the PPS as the problem seemed to be electronic and I had noticed that my PPS wasn't responding smoothly when the plunger was pushed in and out.

Once the PPS came in and I stripped the tupperware and broke yet another tab - ugh - to get to the PPS connector. I decided to test it with an ohmmeter and it appeared to be in spec. Uh oh. I put the new PPS on and took the bike for a test drive and the symptoms were all the same. I pulled the CVT stepper motor and turned the shaft and it was smooth. I turned the gears inside the CVT and they also turned smoothly.

My next target seems to be the clutch, and when I ran a clutch slippage test the results seem to indicate a problem with the clutch, but I couldn't figure out how that would cause the erratic CVT ratio changes. Another hour or so researching here convinced me that there's no way to tell if the CVT or clutch is slipping... The clutch is hooking up at 1700rpm, but then will slip smoothly toward redline. I also have a hard time believing that the clutch would fail from 5 weeks of sitting still when it worked just fine when I parked the bike. I left the bike alone for a day to do some more research.

Today I decided to take the bike out and put it on the centerstand with the switch "dangling" so I could experiment with the gear ratios without actually having to ride and try to listen at the same time. While getting my tools I saw a wasp fly in the exhaust and I wondered why it did that. When I climbed underneath I noticed a number of wasp nests (mud daubers) and thought to check the exhaust opening from the CVT. No sign of mud nests but I decided I would shine a light on the CVT opening and see if mud or dust or insects came out with the bike running.

I started the bike on the center stand and immediately the back wheel spun up to about 20mph. Odd... I pulled on the rear brake and the motor bogged down quite a bit until the clutch released. I heard the CVT changing ratios during idle - also odd. I put the bike in Manual mode and ran through a few gear ratios and the speedometer responded with normal looking rear wheel speeds... Good so far. I put it back in automatic and locked the throttle at about 5000rpm. The rear wheel started climbing toward 70mph and when I shined the spotlight at the CVT exhaust something shot out of the opening. I reached up to shut the throttle and turned it the wrong way (I was upside down facing the back of the bike after all...) Next thing about a dozen acorns come shooting out of the CVT as the rear wheel speed hit about 100. I flipped the kill switch and tried to avoid the acorns that were still coming out, mostly in pieces.

Now to the reason for this post - is there any way to clean out the CVT without having to remove the engine and pull the entire CVT apart? I'm specifically thinking if I could get a few parts off and get an inspection camera and small vacuum hose inside I could clean it. Having said that, I noticed that the manual calls for wearing gloves while working inside the CVT... I don't think the mice were wearing gloves when they packed the CVT full of acorns. Should I just plan on a CVT rebuild? (In that case, I most likely may have to park the bike due to time considerations and consider a different one and keep this as a parts bike!)

Has anyone else had to deal with this? I seem to remember seeing a thread quite some time ago about a CVT with a nest in it but haven't been able to find it. I would love to know what they did to clean the CVT.

If I do decide to keep the bike, I'm assuming I might as well rebuild the clutch along with the CVT as I'm still not convinced that it's not slipping. A clutch rebuild looks to be 100 times easier than the CVT. If I open up the CVT should I also plan to change the belt?

Any advice is greatly appreciated.
 

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Given the way the exhaust vent snakes across the top of the cvt housing before it turns down into the main part of the housing, I don't think you could get all the stuff out through it. That and the openings for the pps and shift motor are your only access points. I'm afraid you are going to have to pull the cvt.
 

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you almost have 50k miles on that scoot.

You seem to be following the right path for diagnosing the problem.

You have done the PPS deal and I doubt that made any difference. I did the same thing at first and it turned out to be a worn out clutch, with the engine reving high from a sand still...

My CVT gave out after I rebuilt the clutch.

don't see what you would be accomplishing by trying to clean the CVT, as I doubt you would gain anything.
you won't know until you drop the engine and crank open the CVT, hopefully the primary pulley bearing and the pulley
itself are in good condition. If you do open it up, replace the primary pulley bearing.

here is a picture of the CVt split open, imagine it put together, there is next to no room to get in there through the exhaust to do anything except to take a close look via a flexible cam.



Take your clutch apart and examine the plates, there is a good chance that they may have worn out.

If the problem isn't there it could be inside the CVT, a belt that is worn out and is on its way out. Mine totally disintegrated.





my rebuilt scoot, with a new PPS, clutch and CVT is running rather well thus far with close to 3k miles on it since the CVT job.

good luck.
 

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Over the last few years I have bought 15 Honda Big Ruckus scooters and have sold most of them . One of them a 2006 had a little over 350 miles on it so I know it had been sitting . It drove fine when I test drove it , but when I opened the CVT up to install a Jcosta racing variator , it was packed with some thing that looked like bird seed . There must have been nearly a pound of the stuff in there . My neighbor a former motorcycle mechanic and retired military guy who is also certified on jets was over at the time , said he never saw any thing like that . Me neither . I also had a baby possum hiding in my garage for over a week last year , I knew he was there because I saw his little foot prints all over my bikes . I searched that garage high and low and couldn't find him . One night about every hour I would open the door and turn the light on as fast as I could and finally caught the sucker . Bottom line is varmints can do a lot of damage .

TheReaper!
 

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Discussion Starter #6
Black Cat: PPS = Pulley Position Sensor. It's how the computer knows where the primary pulley's movable half is located. Using that and some other information it sets the width of the front pulley to be in the right ratio for a given speed and throttle position. I have had my head so far into the inner workings of my scooter this weekend that I'm starting to babble in TLA's (Three letter acronyms...)

Thank you everyone for the replies.

I went out to the garage this evening somewhat bummed about having to rebuild the CVT and decided that the cooling fan in the CVT must pump a fair amount of air, and since it's connected to the secondary it must spin proportionally to the rear wheel. MPH = CFM... I removed the intake filter, started the bike and set the RPMs at 7000-ish with the manual mode in OD. At 120 indicated the CVT was blowing out dust and acorn pieces like a leaf blower. I kept it up for 15-20 seconds until it was blowing clear air, then hopped on for a test drive.

I bumped the throttle to get moving and did a little burnout in my gravel driveway like I normally do. It couldn't do that earlier today. When I pulled out gently onto the road it accelerated smoothly. I then got a little more aggressive and it's still "shifting" a little rougher than usual at slow speeds, but the slipping is gone above 20mph. I can still make it slip, but only with a fistful of throttle and at lower speeds. I am more convinced now that the belt is slipping - possibly due to the secondary pulley not properly tracking the primary.

I am going to put the bike back together and take it on a longer ride, staying within range of a quick "rescue." I imagine the CVT is probably on borrowed time at this point, so I will also start clearing a spot in my garage for a big mechanical project. I'll start by rebuilding the clutch since that's probably going to need to be done anyway and it's easy to get to.
 

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There's no doubt in my mind that you will end having to pull the CVT and tear it apart to see what is gonna need replacing. Personally I think with that mileage you should replace the drive belt and input bearing along with the necessary seals. Hopefully you don't have some rodent guts everywhere.
 

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The best value for your $$$ is to see what you can get for the bike on a trade now while it still operates. Alternatively, what you can get by parting it out.
 

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My guess would be that all that stuff bouncing around in there has damaged the face on some of the aluminum links in the belt. That could be a cause of the slipping. Hopefully there is no damage on the pulley faces.

If you can get by without having to replace one or both pulleys then all you are looking at is the cost of a belt and some seals and gaskets. That is what I did on mine and the cost was only a little over $300. Of course you will need to inspect the bearings and determine if any of those need replacing.
 

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Whay I do is blow 100 psi with a blow nozzle, every time i do a CVT filter clean, I blow it in both the exhaust, and the intake and it usually blows out some crap
 

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Discussion Starter #12
Thank you everyone - great ideas. I will not be trading in my Burgman though... I will ride it until it needs something rebuilt or I can part it out.

Yes Ledude, I definitely plan to add the screening to the CVT exhaust. I will do it with smaller mesh to keep the darned mud-daubers out too. I have been fighting them on my RV for years. They get in and build mud nests in the AC if I leave it sitting for more than a few days.

The other thing I will do is go back to riding daily... Then it's less likely that anything will build a large nest in my scoot! This time of the year it's too hot to drive to my business appointments, but I can usually find an excuse to run my errands in the evening when it drops below 100 and the sun is down.
 
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