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Post by forkyleigh on Jul 23, 2014 23:05:48 GMT -5
Ill give the best background I can. It was running great with stock cvt parts. I changed to heavier rollers and it was still running great. I then stopped at a shop to get a different torque spring. They only had a 2000 rpm spring. It is much to big, I know. But, the thing ran like a raped ape.
The bike sat for a bit. Then when driving it, I could pull out of the driveway like a raped ape, but the next time I had slowed for a corner/stop I could barely move.
I have tried adjusting the cvt. I have tried heavy rollers with the 2k spring. I have tried lighter rollers and now a 1k spring.
It almost feels like it is slipping after the first take off. The one thing I have not adjusted is the clutch springs. They have been a constant and I believe are 1k.
Again, it seemed to be working find for a few days, now only when you first start it and take off.
It doesn't seem to be fuel related, as I don't my plug shows a light brown color.
2005 Vento 70cc BBK Leo Vince zxr Stock 19mm carb Snorkel Delete Belt only has about 300 miles on it CVT details are above.
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Post by 2TDave on Jul 24, 2014 4:45:12 GMT -5
I'd try heavier clutch springs. Sounds like it may be slipping. It may have got glazed and then the slipping got worse.
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Post by chehystpewpur on Jul 24, 2014 7:30:52 GMT -5
+1 ^ possibly it is a hair lean. When we had the crazy temp swings where I'm at it would do the same it was rich when the choke was still on then when it shut off after the 1st launch it would take off like crap. Sometimes when the cvt gets hot it performs like crap too. How heavy of weights do you have? I'm using 2k springs right now with 4.5 gram weights to have a good takeoff. From my understanding the minarellis hate heavy weights. And for some reason they do absolutely nothing for you either. I have almost every increment of them up to about 7 then a set of 9 gram sliders and I go faster with the 4.5 gram rollers than any other ones... The 5 gram sliders might be better but I haven't tried yet cause I feel as though the same thing is gonna happen. Higher rpms and less top end.
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Post by forkyleigh on Jul 24, 2014 7:50:50 GMT -5
My onky thought is that things were fine with the stock springs.
Also, it seems i am getting rpms just not going anywhere fast.
I have a 90 jet in it. I have the needle one step rich.
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Post by chehystpewpur on Jul 24, 2014 8:34:14 GMT -5
Things were fine with the stock weights too though. A 90 jet seems huge btw. Do you maybe have an air leak thats messing up your performance after it warms up and the gasket splits? I have like a 70 or 75 main jet with a 70cc Bbk the only time I ran a 90 was when I puked a gasket and half the fuel was spraying out. Clutch springs with a higher stall should do nothing but improve takeoff due to you being closer to or in the power band. Does your bike have a restriction washer? Possibly removed but not put back in? You never said what weight was in the variator. That would be pretty helpful. Are the variator guides good and the clutch opens all the way and closes with no binding? Is the copper or brass bushing in the variator where its supposed to be? Mine came dislodged and was holding the variator open sometimes but not always and destroyed my takeoff for a little while. I see that and fixed it and now its back to normal.
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Post by forkyleigh on Jul 24, 2014 10:02:09 GMT -5
I have tried 6.8g, 3.5g, 4.5g, 4.0g and a combo of the 4.0 and 6.8g. I double checked my jet. It is an 85. Apologies for being incorrect. I took the cover of the cvt and ran it for a short bit with the rear wheel in the air. The both seem to be opening and closing. Is there anything else I should look for? When I started, the variator was open and the clutch side closed. As I made it accelerate, they both changed.
Should I have changed the pilot in this carb? Ive tried to let it idle and it doesnt seem lean? I have check for air leaks using carb cleaner. There was no change to the rpm.
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Post by 90GTVert on Jul 24, 2014 10:33:59 GMT -5
It sounds like something is slipping to me since you've got the revs, but no power.
Take the clutch bell off and look for glazing of the shoes or bell. Sand both with emery cloth or something around 220grit sandpaper. Clean them with brake cleaner after. See if that helps.
Any black marks on the drive faces or excessive belt dust? Is the belt in good condition? Does it measure near it's specified width?
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Post by forkyleigh on Jul 24, 2014 11:06:20 GMT -5
90GTVert The belt has about 300 miles. I would hope it is still good, but I havent measured to be honest. There are black marks on the variator face. Two separate rings. It seems to only happen under load, as I had the cover off with the rear tire off the ground with no issue.
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Post by chehystpewpur on Jul 24, 2014 12:43:12 GMT -5
What type of belt did you buy? Its possible it is slipping if its not quality or it wore down quick. I've had both happen from cheap belts. I only buy Bando belts now. Everything else is a waste of money with my set up. Maybe sand the variator face a hair to scuff it up so it isn't smooth and letting the belt slip. Try to not remove material just scuff it up. Pilot jet you should be fine with stock if it doesn't seem like thats lean or rich. What rpm does your back tire start to spin at with it on the stand?
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Post by 90GTVert on Jul 24, 2014 13:01:05 GMT -5
Belt or clutch slip usually do only happen under load. It's easy for them to grip well enough just to spin the tire. Takes a lot more grip to accelerate a loaded scoot without slipping.
Are you seeing thick black marks, like an accumulation, or just minor coloration? If they're thick your belt may be slipping bad.
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Post by forkyleigh on Jul 24, 2014 13:54:05 GMT -5
Maybe I should just pull the cover off of the cvt and take it for a spin. I only have to go a few houses down the road and I will already have the issue. I could also take a photo of the black marks on the variator. Everyones definition of thick will vary a bit!
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Post by chehystpewpur on Jul 24, 2014 22:38:29 GMT -5
Is there a possibility the belt isn't riding far enough down in the variator for takeoff? If you could get one of the variator shims it might make it a hair wider and let the belt ride lower in the variator when it heats up. That way your takeoff would be closer to normal and might not have much of an effect on top speed. Or possibly the spring for the rear pulley heats up and gets too soft. An new one or slightly stiffer one might keep the belt up where its supposed to be when everything softens up from heat. If you take it out with the cover off check and see if the belt is in the same position when you first start it and drive it vs when its hot and acting up. I know you said its a new torque spring but sometimes parts are not always up to spec or dont hold spec after some use. Or maybe the clutch springs stretched or wore out and are grabbing too soon. With heavy rollers thats a possibility due to belt speed being alot higher at idle in some cases. So they would get worked more in a sense.
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Post by niz76 on Jul 25, 2014 0:52:11 GMT -5
Is the CVT cover hot after riding a bit? Like too hot to put your hands on?
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Post by forkyleigh on Jul 25, 2014 12:14:36 GMT -5
This happens in the first 60 seconds. I can't imagine it gets hot by then, but I will check. I am leaning towards something slipping, but I just need to figure out what.
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Post by forkyleigh on Aug 3, 2014 21:09:29 GMT -5
Update for everyone.... I finally had some time to play with it. The RPMs are not going up. It is just real sluggish until I hit about 35mph.. Then it feels like you hit the nitrous button and it just wants to freaking go.... But getting to 35mph is not near the acceleration it should be. Belt is worn to about 16.1mm. That seems to have worn exceptionally fast. Also, it is not a big fan of hills. I think it comes down to tuning the CVT better.
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