GY6 MODS By thecrid (Read 1,691 times)

[thecrid]

I bought a new Solil moped with a 49cc gy6 qmb139 engine. I can only get 45MPH out of it I weigh 200 lbs. Here are my mods.

50mm BBK
50mm head with 23MM Intake And 20MM Exhaust Valves with 64mm Rocker arms
20mm carb with a 90 jet
A9 cam
racing cdi
performance exhaust

I have thought about gears but don't want to loose my low end power.

I have checked my plug and it is light brown almost tan so I think the jetting is correct.

Any thoughts? 

[Guitarman]

Yep. One thought. Buy a bigger bike.

[richardv]

There's no replacement for displacement.

[tvnacman]

Go with taller gears , larger diameter variator , and then work on the roller/slider weights .

John

[Alleyoop]

Aug 12, 2014 1:36:47 GMT -6 thecrid said:

I bought a new Solil moped with a 49cc gy6 qmb139 engine. I can only get 45MPH out of it I weigh 200 lbs. Here are my mods.

50mm BBK
50mm head with 23MM Intake And 20MM Exhaust Valves with 64mm Rocker arms
20mm carb with a 90 jet
A9 cam
racing cdi
performance exhaust

I have thought about gears but don't want to loose my low end power.

I have checked my plug and it is light brown almost tan so I think the jetting is correct.

Any thoughts? 

45mph from 30mph is about all your going to get that is pretty damn good. What mph did you expect out of a bored out 139qmb motor? You do realize a 150cc stock is only good for 50-55mph. It takes power to move weight, your at 200lbs that is quite a lot of weight to move.
Alleyoop

[jct842]

Your 15mph faster than it was designed for, as others say if you want faster sell it and get a bigger scooter. I would not look at a 150 because you are going to try to make it go faster too, look at a 250. Making them go faster is a lot more cost than to just buy the size you need to go how ever fast you want to go and keep it stock. Stock or close to stock scooters last a whole lot longer than hot rodded ones.

[Bashan]

Do you know how many cc's are in a 12 ounce coke can? 355cc's. So to get the kind of power to hit around 40 with a 200 pound load with a displacement of a 1/4 of a coke can is great. The pistons on 250's look tiny to me. I'm always amazed at what they can do. But it is so true, there is no replacement for a huge piston and a stroke as long as your arm! Or something like that.

[thecrid]

Wow you all have good really good points. I live in Hawaii and you don't have to register it if it is less than 50cc so as far as the state knows it is legal they treat it like a bicycle. Yes im pretty happy with the 15mph gain but it is just something to fool around with. It is fun just seeing what I can get out of little motor.

John I probably will go with larger gears the 17/49 set should give me about 8 mph if my math is correct then start playing with the variator and rollers.

[Guitarman]

Where in Hawaii do you live? Or from kama'aina to kama'aina;

'eh, wheh' you stay?

[tvnacman]

If you go with the taller gears , then loose bottom end . Lighter rollers/sliders can bring back the bottom end . Just watch your rpm . Keep in under 7500 or 7800 .

John

[jct842]

You may not be able to go faster with taller gears if you do not have enough power to turn them.

[thecrid]

John,

I will order the gears and update this post as I go thanks for the advice