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Post by stevo52 on May 27, 2012 13:09:24 GMT -5
So recently my vento has been making this vibrating or buzzing noise when the engine revs. Its not noticeable at idle. I thought it was either maybe detonation or something in the tranny. I took the head off and spark plug all looks good. I also took apart the variator and well that seems good too. Checked screws, everything I can think off. The sound seems to be coming from near the variator area or the fan area on both sides like maybe the crankcase area. I fear it might be something internal like crank bearings Also, my power has been lower and top speed has been varying alot too. It struggles to hold 40mph at times as it can't seem to rev and falls "off the pipe". Very strange. I was just gonna put it up for sale too! Anyone experience this before? Any ideas?
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Post by 90GTVert on May 27, 2012 15:03:52 GMT -5
Could be hearing the reed valves. I'd inspect the CVT though because of your other symptoms.
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Post by reveeen on May 27, 2012 16:14:40 GMT -5
crank bearing problems will be indicated by excessive heat where they live.
Rollers flat spotted, or a loose starter drive, is where I'd look.
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Deleted Member
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Post by Deleted on May 27, 2012 16:35:49 GMT -5
From my experience, a crank bearing problem is very obvious even at idle. I never heard a quiet bad crank bearing.
Chasing mystery noises is a pain!
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Post by stevo52 on May 27, 2012 17:08:05 GMT -5
I think its the CVT as well. I had the cover off and when then the variator starts moving the noise starts its like the rollers are jumping around but I didn't change anything I've had those rollers for 500 miles or so and its a malossi variator. The rollers are not flat spotted either they are ok. The noise is as loud as my exhaust. Lots of racket I'm scared to drive the thing lol. I pulled off the starter clutch (part behind variator with the three spring loaded rollers) the rollers fell out. I re installed and put it back no change still lots of racket. The starter gear and crank gear are wiggly with a bit of play but I think that stuff is all compressed when the variator is tighten down. I tried taking off the starter bracket but I was starting to strip the screws so I stopped. Needless to say that was tight. I had the fan cover off too. The flywheel was tight everything looked fine.
Its a mystery I guess :banghead:
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Post by Fox on May 28, 2012 1:23:47 GMT -5
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Post by stevo52 on May 28, 2012 9:36:08 GMT -5
I guess it could be the reeds although why would they just start making noise out of no where? And I think that would be more buzzy. I have the carbon fiber ones too that came with the bbk. I'll inspect them today though.
Haha no impending doom but it actually is not running good. I just rode it was slow struggling to go past 30-35mph. The motor is feeling weak it won't rev up. Idles smooth though but doesn't start too well sometimes cranks for awhile new battery too. I think its time to check compression although the 70cc only has 1500 miles on it :/.
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Post by stevo52 on May 28, 2012 12:23:23 GMT -5
I tried getting a compression reading from a rented gauge from autozone but I couldn't get a reading at all :stumped: . I ran the motor for like 10 minutes and held the throttle WOT while I cranked the engine by hand. Am I missing something here?
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Post by 90GTVert on May 28, 2012 12:29:24 GMT -5
You need to use the e-start and then kickstart to get a compression reading. Even by hand you should get some reading I'd think. Might be a gauge not sealing?
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Post by stevo52 on May 28, 2012 13:56:20 GMT -5
Ok same procedure used the e-start with engine turning at 1000rpm according to the tach and I got 60 psi yes that's it. Did it twice same reading. I could only get the screw in part snug but it had an o-ring so should be sealed.
So assuming that the gauge is correct then I need a new piston ring...the cylinder still has crosshatching and only 1500 or so miles WTF! Well at least I found the poor performance problem.
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Post by 90GTVert on May 28, 2012 15:28:57 GMT -5
If it's really 60psi you'd be lucky if it started and if it did you'd have horrible performance. Not a little different... horrible. You could try taking the o-ring off and installing the washer from a spark plug. I had better luck with that on my compression tester for some reason.
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Post by stevo52 on May 28, 2012 16:26:02 GMT -5
Well I can only go 30mph maybe 35 after a half mile. I use to do 50+ easily. 60psi does seem ridiculously low. I think I'm going to put the 50cc back on and see what compression number I get. There is only 1200 miles on the stocker should be fresh. Unfortunately the only thing else I can test the gauge on is my car and its a subaru WRX not easy to get to the spark plugs lol.
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Post by stevo52 on May 29, 2012 20:53:39 GMT -5
Update - I put back on the 49cc and the scooter runs awesome...and that stage 6 70cc kit was a waste of money...destroyed the ring in 1500 miles unbelievable. Anyways I'm actually excited about getting 60-70mpg again the reason I have the scoot in the first place.
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Post by 90GTVert on May 30, 2012 7:30:51 GMT -5
Which Stage 6 kit? If it's a single ring kit, it's not really meant for a daily rider IMO. As long as it's just the ring(s) you should be able to get a replacement and have it running like new again with the S6 kit if you wanted to.
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Post by stevo52 on May 31, 2012 3:26:05 GMT -5
Its the S6 Sport Pro single ring. I have yet to find just the ring. Seems like you have to a get a piston rebuild kit. Anyways not worth the money to me if it last such a short time and the bike has other annoying electrical problems.
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