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Post by boarder4life501 on Apr 11, 2011 2:21:39 GMT -5
I bought this 50 cc 4 stroke Chinese scooter about 4 years ago not really knowing much about scooters and what scooter would be good to buy.  Now I decided that I was going to make it better and faster. Not know much about scooters I had to learn the hard way. The upgrades I have put in it so far are.  - K&N Fuel filter - Racing Cdi - Performance exhaust - performance air filter - Performance carburetor - 50mm bore kit... haven't installed 50mm big valve head yet but am about to. Just using the stock one right now. - New Kevlar belt - New Rollers that came with the 50mm kit  I am about to put on some new tires on it too. I am having some issues though. Before i put on the bbk I was able to hit 30-35 slowly but was able to hit it. Now after the bbk I defiantly notice the difference in the acceleration, but I hit 35 and just sit there sometimes maybe 38 but if I'm not going down hill it will not go any faster. I am just confused on what to do know to get it to go faster? Any help would be good. |
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Post by speedy1125 on Apr 11, 2011 2:44:37 GMT -5
What is the weight of your rollers? Are you getting full belt travel on the variator? stock contra spring or other?
Sweet Ride!
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Post by boarder4life501 on Apr 11, 2011 3:06:09 GMT -5
I do not know the Rollers weights actually. I do not know if I'm getting full travel. how could i check that? and ya stock spring. I haven't changed any thing in the cvt other than the rollers. I am a bigger guy so what would be the best weight i was going to get some 9gm rollers. thanks I like the way it turned out looking.
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Post by speedy1125 on Apr 11, 2011 3:43:44 GMT -5
Its pretty easy to see the wear marks on the variator drive face when you take the cvt cover off. if you see a dull area around the perimeter outside edge then shiny just below it then the belt is not traveling all the way up to top gear which means you most likely need heavier weights. As for the right weight, that is something you will have to determine through some tuning. I have seen box sets of rollers that come in several different weights, you can mix and match them to change the total mass to many different total weights.
A quote from another thread concerning weights and acceleration etc.. by RocketDog-
"In order to get the best acceleration you need the engine to accelerate through the gear range at the maximum peak torque. On a stock 50 I think it's approximately 6500 rpm. Does that sound right Jeremy? On a 72 it would be a little lower. In order to be able to do that, your going to need an accurate tach. Stock ones usually aren't. The tiny tach seems to work well and it's inexpensive.
So, you hop on the ole scoot and take off down the road with the throttle pinned to the stop to see what your rpm is before you reach top gear. Of course as you do, reach top gear, the rpm will climb higher. So if your running a steady 7500 through the range, raise the weights a gram and see what you get.
If what you want is the best possible gas mileage, you should go with a bit less rpm. This system has worked for me.
RD"
He explains it better than I can.
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Post by boarder4life501 on Apr 11, 2011 4:21:16 GMT -5
thanks i will check into that. I did just change my jets. I was trying to figure out which was the best and put in some bigger ones and i hit 37 on gps. but i will look to see if my belt is traveling all the way. thanks
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Post by 90GTVert on Apr 11, 2011 8:08:34 GMT -5
What jet size are you at now?
An easy way to see if the belt gets full travel is to mark the vari with a marker, then run it to max speed and see how much marker is left on the outer edge.
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Post by speedy1125 on Apr 11, 2011 16:21:32 GMT -5
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Post by boarder4life501 on Apr 11, 2011 22:22:47 GMT -5
My jet size is #88 now thanks.
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Post by 90GTVert on Apr 12, 2011 6:18:04 GMT -5
Shouldjn't be a lack of fuel keeping it in the 30s then. Dunno if that's the perfect jet for you, but it should be close enough not to rob you of much speed.
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Bong
Scoot Enthusiast
Posts: 235
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Post by Bong on Apr 12, 2011 15:32:21 GMT -5
Can I ask what Exhaust that is??? How Loud?? Looks really good and I love the black color scheme!!!! Great Job !!!! Is that a QMB139 engine? I only ask because I used the same Air filter you have pictured on my QMB. It looks really cool but, I had better performance with an UNI directly on the carb. Just a thought and my $.02 |
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Post by boarder4life501 on Apr 12, 2011 17:10:40 GMT -5
um i don't know exactly what exhaust it was actually the first thing i bought a while ago because my friend had it on his ruckus. its not extremely load kinda sounds like a small harley lol yes its a QMB well i could go pick up a uni if it will make a difference. I am going to check my belt travel today because its a great day to go riding and ill get back about the belt travel after i have rode it for a bit.
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Post by boarder4life501 on Apr 13, 2011 3:33:34 GMT -5
lt travel and it is getting full travel. What jet size should I be using? Also would my stock head be restricting performance should I go ahead and install my big bore head?
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Post by 90GTVert on Apr 13, 2011 6:41:09 GMT -5
The stock head should be making it feel really torquey from having a bunch of compression if you didn't open up the combustion chamber. If your big bore head doesn't have larger valves or ports, you'll probably get more from the stocker from the compression boost as long as you don't start having overheating problems or detonation.
Jet will probably need to be 88-92 I'd think.
Any idea what the max RPM is?
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Post by boarder4life501 on Apr 13, 2011 13:06:06 GMT -5
my stock tachometer reads right around 9,000 but thats stock so i really don't know until i buy a aftermarket tach
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