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Post by lostforawhile on Jun 23, 2017 2:58:57 GMT -5
Ok I've got to get a little more power for my commute, just for the sake of climbing a couple of hills, at the minimum, I'm showing an average speed of 34 mph on my ten mile leg each way, I ordered the variator lock tool, removing the restriction ring is straight forward, I also ordered the unlimited CDI, which is also easy to swap, what kind of gains am I looking at from those two modifications on a gy-6? and what would be my next step? i need to figure out this suddenly squirrelly front end, but I'll take a look tomorrow.
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Post by lostforawhile on Jun 23, 2017 3:03:06 GMT -5
Also on these generic gy6 engines, is a Keihin carb standard? I thought they were mostly unbranded chinese carbs, I was surprised to see a Japanese carb on mine
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Post by 90GTVert on Jun 23, 2017 7:48:18 GMT -5
34MPH is a good average speed for these scoots. I expect little to no gain from the mods you've ordered unless you've already verified that you have restrictions.
Big bore kit is my #1 choice if I want to speed up a scooter and am not concerned with sticking to 49cc. 72cc is a good gain in power without as much stress on the crank as larger bores tend to have.
Keihin carbs are not standard stock. Some scooters have them though.
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Post by lostforawhile on Jun 23, 2017 8:16:43 GMT -5
34MPH is a good average speed for these scoots. I expect little to no gain from the mods you've ordered unless you've already verified that you have restrictions. Big bore kit is my #1 choice if I want to speed up a scooter and am not concerned with sticking to 49cc. 72cc is a good gain in power without as much stress on the crank as larger bores tend to have. Keihin carbs are not standard stock. Some scooters have them though. you can tell the CDI is restricted, from listening to it, and for 6 bucks, no loss, I have a spare if nothing else, the variator tool has many good uses other them removing that ring |
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Post by 90GTVert on Jun 23, 2017 8:46:57 GMT -5
I don't think I've ever heard of a 139QMB that is restricted and averages 34MPH. You've got a really strong runner there if you're correct about the restriction, or it's barely restricted... like a rev limit high enough that it has hardly any effect. Either way, you aren't out much and that tool is nice to have. Hope it works out and you do get more from it.
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Post by lostforawhile on Jun 23, 2017 10:40:02 GMT -5
yea I run a speedometer recording app on my phone, I will swap out the CDI and do my usual run to work and see if anything changes, it might be the gearing, as it's terribly slow starting out, but seems to have a higher top end speed, it was running obvious rich when I got it, then I took out the airbox inlet restriction, 4 1/4 inch holes, and it picked up several miles an hour and quit smelling of gas constantly, so it's possible maybe someone swapped a carb or something
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Post by lostforawhile on Jun 23, 2017 10:53:50 GMT -5
I wonder if aerodynamics have any role? this particular bike has a pretty aerodynamic shape, VS. something like a flat front Vespa, I also had a huge amount of buffeting with the non full face helmet and goggles, which pretty much went away with the full face, aerodynamics get more important the lower the horsepower
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tito
Scoot Member
confused, very confused
Posts: 32 
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Post by tito on Jul 12, 2017 7:18:01 GMT -5
Curious for a followup, in the process of ordering some upgrades myself.
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Post by humanshield on Jul 12, 2017 7:58:54 GMT -5
"Average" speed of 34mph on a 10 mile leg does sound good for a 50cc scoot.
Like Brent said, your scoot is probably running pretty good and I agree you won't see much (if any) improvement with those changes. It takes a big change to make a noticeable difference and again, like Brent said a Big Bore Kit is the number one way to do that.
Personally I run a 50mm kit and have for over 4,000 miles now with zero issues but the 50mm kit requires more expertise during installation and break in IMO.
But consider this....
I do have a 50mm BBK, cam, some porting, a larger carb, intake mods etc...and I STILL will only go about 35-37mph on a long ride (10 miles or more)
That's because the gearing isn't set up for more speed even though I can push it to 47mph. It just revs too high and puts too much stress on it imo.
Doing those mods AND THEN changing the final drive gear ratio is the only way to have a more "comfortable" top speed on a QMB139 as far as I can tell. Others might tell of another way.
Oh...the ONE THING you ALWAYS want to make ABSOLUTELY SURE OF........
The tire air pressures....I keep mine around 40psi....but 35psi is good. NEVER let your tires get low on air. The motors on these scooters just don't have to capacity to fight low tire pressure and it will overheat the engine.
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Post by jackrides on Jul 12, 2017 12:20:46 GMT -5
A full face is a little more aerodynamic and a lot safer. Your body is the biggest resistance and drag factor. About the only improvement is to wear a jacket that isn't oversize and floppy.
Check your steering head bearings as follows. Sit on your scoot, hold the front brake, and rock the scoot back and forth. If your feel movement or hear a small knock, the bearings are loose. Tighten them with the front wheel off the ground; and check that the front end will Freely turn from side to side. Check the axle nut for tightness.
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Post by jeff84 on Jul 12, 2017 13:25:17 GMT -5
overinflated tires, will help a tiny bit. its not dangerous just a harder ride, and possibly faster tire wear. I run 40 psi even though recommended is like 29-32. less rolling resistance. friction is a huge factor especially with such small engines. weather its wind or rolling resistance. that's why typically doing a ninja tuck will get you a couple of mph over sitting straight up
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Post by jackrides on Jul 12, 2017 21:01:17 GMT -5
Second thought, aerodynamics has no meaningful effect below 40mph.
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Post by lostforawhile on Jul 12, 2017 23:27:50 GMT -5
Second thought, aerodynamics has no meaningful effect below 40mph. that's hard to believe, going from a non full face helmet where the wind was knocking my head around, and you could feel the drag, to a closed face helmet, drag is drag, the more aerodynamic the object the less drag, and less power is wasted overcoming it. a scooter with a good aerodynamic shape, is going to have far less drag, then a scooter with a wide flat front eg vespa, |
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Post by lostforawhile on Jul 13, 2017 0:11:20 GMT -5
ask any bicyclist if aerodynamics don't have an effect below 40, and I used to be one before i got run over
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Post by jeff84 on Jul 13, 2017 0:13:06 GMT -5
the less power you have on tap, the more aerodynamics play a role. with more power you can easily overcome lack of good aerodynamics to a point. an you have to pretty fast before you reach the that point.
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