you can drop in a 150cc engine!!
This is a discussion on Gy6 Performance Upgrades? within the GY6 scooter forums, part of the Scooter Forum category; SO i have 50cc GY6 it's called a Bronc Rally had it for a year and wanted to spice it up a little bit because ...
SO i have 50cc GY6 it's called a Bronc Rally had it for a year and wanted to spice it up a little bit because as it stand depending on the weather i can wrap the speedo to 50 so i only need a little boost.
Any who i see they are selling CDIs on ebay supposedly the stock one has a rev limiter. My guess is, is that if it's true it holds it at 6k cause unless i go down a really steep hill i tend to stay at 6k. Do the aftermarket CDIs really do any thing or are they snake oil?
I managed to find a cam that ads to mid and top end so i think i have that covered but, am not sure if i need to buy any gaskets for the swap?
I have seen plenty of carbs a lot look like snake oil cause i'm sure real Kiehin is worth more than 38 USD shipped. one ad claimed the gy6 50cc has a stock carb with an intake of 17mm and that the 20mm carb is better and another ad says it has a stock intake of 20mm and the 22mm is better. I found a 24mm but, requires modding the air box or a cone filter. is 24mm to much cause that sounds like quite a bit i remember my lifan 125 iI had in my Z50 at point had 20 something mm carb in it.
you can drop in a 150cc engine!!
I could but, it would be very noticeable and above the legal 50cc and to much power, I have a race bred 160cc pitster pro engine in my 1974 Z50 for that it goes 70mph. All i need is a small boost. I was figuring some one who has used or bought some of the above mentioned parts may know. Its seems most people just drop in a bigger engine rather than upgrade the stock 50cc witch is what I want to do since i know i can hit the mid to upper 30 mph at least, if not 40 mph and mild upgrade should really help out and possibly add another 5 or more mph. I know what a bigger engine can do from experience so i'm interested in spicing up what I have it's my commuter so I know it well and am interested to see what mild power adders will make it feel like.
So after hours and hours of research i have learned quite bit about the gy6. I'll probably make a new thread on the install after i get all my parts. The CDIs remove the rev limiter and advance the timing. I got 24mm carb so i know for sure it will bigger than what i have. The variation slider and roller and clutches are significant mods and change the power band and top speed at the rear wheel. The CVT setup is rather significant and mods do make significant difference.
The next step is to get technical thread going I have found plenty of resources on the GY6 from timing and tappets to CVT and CVT cover mods.
I have never seen a CVT scooter hit a rev limiter... EVER. The upgrade CDI is snake oil. The best thing you can do carb wise is get something with an accelerator pump. Lighter weights get you more acceleration and heavier weights give you top speed.
In the end, there is no replacement for displacement.
yup i'm pretty set on 60cc jug a high perf. head, already have carb and intake and complete tranny kit miuns the weights and springs that come with it. I also will do some of my own mods like ventilating the CVT cover and lightening the fly wheel.
Something like this
The stock sheaves limit your top speed. Granted the one in the video is a 150 but, i'd imagine the concept is still the same.
So i finally did it. all those upgrades they advertise suck and rob power. The bigger carb is kind of pointless and as far as the CDI we couldn't give ita fair chance as supposedly they only work if your scooter is top witch it wasn't running the hotter cam as the cheap Chinese quality control doesn't ensure the gear is pressed on right. Thats right the timing on these cams is probably wrong i lost power a really noticeable amount till i put the stock cam back in.
So here is what whent down, raised the the intake roof and deleted the valve guide then put 2 extra valve spring shims in and set the valve lash to 1 1/2 and 2 1/2 thousands.
I have had pretty good luck with the GY6 150 engine in the Double cross side by side.
I opened the intake and made a less restrictive airbox along with made a new pipe.
I really want to try the crank and 4v head .
I also agree with some of the stuff being hit and miss, I would also think on the smaller displacements that some mods are like going backwards.
Well I may bore out to 60cc. I like the idea of keeping a small displacement and making my own power. I fails to mention we kind of porta the the header too it nasty bug ugly weld join in there then they wrapped some asbestosis like stuff around the pipe i guess it's old school but, the principle is keeping the pipe hot allows it to flow better. I noticed Enviromoto has this new 139qmb HD crank by Naraku. kind of pricey not sure if i will ever get it or if i a even need it. I am looking forwards to getting a whole CVT kit. I did 50 mph down hille the other week but, at 9k witch means ratio was tapped out on the CVT. I would also possibly like to weld a bigger pipe to the stock can as i prefer the hush hush power, less likely to stick out or attract a cop's attention.
72cc top end kits are cheap power upgrades. I built one this past winter with a stock carb (rejetted), aftermarket exhaust, K&N style air cleaner and changed the variator wts. It now burrys the spedo (60kph) and keeping the stock carb size and variator wts kept the bottom end from dissapering.
County Line Cycles Grovertown, IN
Annnddd that is EXACTLY how you do it, none of that B.S. hotrod ultra hot coils and bigger carbs. I have collaborated with a friend and figured out how to use a 44mm (63cc) cylinder kit with the stock head to not only bore up but, gain compression. I'll probably go a head and port out the exhaust since the intake is ported already.
Last edited by cdoublejj; 08-07-2013 at 01:35 AM.