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Post by hardwire on May 18, 2010 19:07:19 GMT -5
Well, I wouldn't exactly call these "high" speeds. When my speedometer hits 55 (which is 44mph on the GPS) my scooter seems to bog out and slow down. It simply refuses to go any faster. I have replaced the jets with larger ones, and replaced the fuel pump with a Mikuni, and installed a Uni filter. Any ideas what may be causing this now? This is a really slow ass scooter. I weigh 190, and this 150cc shouldn't be this slow should it?
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Post by qwertydude on May 18, 2010 20:30:52 GMT -5
55 on the speedo is about as good as you'll be seeing. Mine tops out gps confirmed at 53 or so and I only weigh 130. The air filter is not as big a restriction as people make it out to be. Replacing it with a uni at most gives you a couple mph on the top end assuming you've tuned it correctly so this makes tuning critical. Also it may be that you need to put lighter weights in your variator so the engine can rev up a little more to make power and push you faster.
Just simply throwing in a larger jet is not going to cut it. You may be running rich in the midrange and leaning out on top. Which is why it feels like bogging in which case you may need to drop the needle down a notch and go up one jet size again. Only way to verify is to run a plug chop. But to repeat your scooter sounds like it's performing as normal.
Theses 150cc scooters may have 3 times the displacement as a 50cc but it doesn't mean you get 3 times the power. A well tuned gy6 50cc makes about 4 hp. A stock 150cc gy6 will make about 8 hp. And according to aerodynamic principles doubling the power will only gain you about a 25% speed increase. So compared to my 45 mph 50cc my 150cc's predicted top speed should be about 56.25 mph, accounting for inefficiencies in the larger transmission and tires my 53 mph makes sense and with you weighing more your 44 mph sounds about right. My best advice is experiment with a couple more jet sizes. Go one up in size and see if you feel more power and the plug looks nice and brown on a chop. Also changing out the roller weights to lighter, 12 grams should be about right, weights should help in the acceleration and top speed department if you're not in the maximum powerband at 44 mph which it sounds like.
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Post by mthomas on May 19, 2010 8:53:08 GMT -5
Sounds like you have an air leak. Mine had a hole in the stock air filter hose and I could not see it. It made the bike bog at about 40 mph and giving it full throttle. What was happening is the carb was pulling in air through the hole and causing the bike to run lean hence the bog. I fixed the hole in the hose with some silicon sealer an now the thing runs like a champ, carb adjusts right, plug burns better. Mine gets my 247 lbs. to 55 and 48-50 up hills according to the speedo not GPS.
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Post by qwertydude on May 19, 2010 13:18:03 GMT -5
He changed to a Uni filter so I don't think the air leak applies. Plus 50 mph on the chino speedo is in reality about 43 mph in real life. So you're right there with him in terms of speed.
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