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Post by lansingscootguy on Dec 15, 2014 18:46:44 GMT -5
Hey everyone, New to the forum. I just bought a 2014 tao tao thunder 50cc moped. Rode it for 268 miles then had a 80cc bbk installed. Now keep in mind this came stock with the 1P39QMB motor. Correct me if I am wrong but that's a 67mm piston right. Anyway this scooter has what I think are serious issues. For instance before the kit it wouldn't get over 30 after kit it won't get over 37-40. So I got a new coil,cdi and changed the spark plug. Now 4 weeks later with almost 700 miles on it I am looking at a performance variator and final drive gear upgrade. I have done a oil and differential oil change. I pulled the spark plug today and it looks like it is dry fouling. From what I have been told this scoot should jump right up to 40 with no problem but it takes forever to get to 35. Anyone from the Lansing Michigan area?
Help!!!!!
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Post by niz76 on Dec 15, 2014 19:01:37 GMT -5
Welcome!
With the 4t 139qmb you're actually doing pretty good at 40mph! Stock piston is 39mm and your 80cc bbk (72cc) is 47mm...
Tons of info here for performance!
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Post by birdman on Dec 15, 2014 19:25:14 GMT -5
Sounds like its running about right.. Perhaps you should have opted for a larger size scoot like a 150cc. Or maybe do a 150 swap wootwoot!! Or maybe a two stroke 50cc would make you happier than that 4t. Anyhow Welcome to this wonderful corner of the interweb
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Post by lansingscootguy on Dec 16, 2014 8:43:24 GMT -5
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Post by lansingscootguy on Dec 16, 2014 8:45:07 GMT -5
I have a 2007 that will throw me down the road at 50 miles an hour and it's 100% stock not understanding why I'm having issues getting over 35 with one that's brand new and has a big bore kit on it
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Post by 90GTVert on Dec 18, 2014 11:38:01 GMT -5
Could be a little out of tune, either the carb or CVT perhaps. www.youtube.com/watch?v=K5j8gHg5kMcVariator may help some. Not sure on the quality/longevity, but the DLH should work better than stock. Maybe the gears in your scoot don't allow it to get up to higher speeds without over revving? If you know what RPM you're seeing that may help us to help you. I have a 2007 that will throw me down the road at 50 miles an hour and it's 100% stock not understanding why I'm having issues getting over 35 with one that's brand new and has a big bore kit on it Possible the older model is actually a 72cc? For a while there were quite a lot of stock scooters coming in 63-72cc, sold as 49/50cc.
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Post by lansingscootguy on Dec 18, 2014 17:22:06 GMT -5
The 2007 is a stock motor. I changed the jug on it. Not really interested in riding it right now as I have a new one.
If it ever quits raining and snowing I am going to try adjusting the valves to see if it helps.
If I didn't have 1200.00 wrapped up in this one I would sell it.
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Post by Elektrey on Dec 18, 2014 18:21:25 GMT -5
I think it's out of tune/restricted in some way or form but it's hard to say without looking at it.
I think an 80cc 4t should get you to 45-50 but to expect any more out of it you might be better off getting a 125/150cc
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Post by niz76 on Dec 18, 2014 18:53:18 GMT -5
When I installed a 50mm BBK on a (all stock) 4t it didn't do much for top speed. I even tried to "detune" it a bit by adding heavy (for me) 8g roller weights and still never got much above 40mph. Had plenty of torque for a nice takeoff and hills though...
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Post by Elektrey on Dec 18, 2014 19:59:17 GMT -5
Remember gearing plays a big part in top speed.
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Post by niz76 on Dec 18, 2014 20:06:31 GMT -5
Remember gearing plays a big part in top speed. It does?? lol j/k Just sounded like you were saying one could just toss in a BBK and expect upwards of 50mph on a 4t... "I think an 80cc 4t should get you to 45-50..."
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Post by scooterpimp on Dec 18, 2014 20:14:33 GMT -5
Put 80cc (72cc) bbk on 3 didderent 139 qmb scoots , all 3 had great take off power but maxed around 42-45 mph . Before i did other mods , sliders,springs , timing , jetting etc. Got one to go 51 mph after mods ,but 50+ on 10" wheels is sketchy. Im more into the launch & rapid acceleration vs hi speed.
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Post by lansingscootguy on Dec 22, 2014 10:05:28 GMT -5
I ordered a performance variator,rollers 49/17 final drive gearing and a exhaust system today so let's hope this does the trick. Will keep everyone updated. P.S. it's on 12" wheels....
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Post by lansingscootguy on Dec 22, 2014 10:15:30 GMT -5
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Post by iwannascoot on Dec 22, 2014 12:17:23 GMT -5
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