Big bore question

[abansb]

I just got this Saturday I am so exited to get this install



It is the 100cc kit I know it is not a true 100cc kit it is a 50mm piston I do believe

But to me it is not to much of a size difference beside a stock 49cc piston here is a pick of them side by side one I have that is froze on a rod



could this be the 50mm piston? I have no way of checking I want to know before I even attempt to install this on my scoot

[90GTVert]

Don't have a ruler? Even if you can only measure inches you can convert. 50mm is basically 2 inches (1.97").

You definitely got a big bore (at least for most motors), but it looks the same size as what you had. I've never heard of the GY6 50s coming with a 50mm bore stock. Heard of 44mm and 47 or 48mm (I forget which it is ATM).

[abansb]

yes I have a tape measure lol I just didn't know how to convert it thanks

[abansb]

ok I measured the stock piston 1 inch and 3/4 the new piston is 2 inches

I just figured it would be a lot bigger

[felliott]

The stock engine comes out to be a 63 ccs right from the factory.

[peteyparado]

the stock 1 you said is 1"3/4 thats a 44mm bore!!! an 50mm for the new one you just got!!
Have fun installing it!!! i just did a 50mm on my scoot an i love it.. 55-60mph all day

[Deleted]

Apr 5, 2012 16:49:33 GMT -5 peteyparado said:

55-60mph all day

Is that GPS verified or..paced by an automobile?

[peteyparado]

GPS!! on an old airport maintenance road took a while to dial in the tuning but i think i got it..
when i changed my gears from 17/51 to 17/41 made the biggest difference on the top end..

[abansb]

ok thank guys I am hopefully going to start installing this tomorrow if weather permit's

[abansb]

Ok I install the Big bore first crank she fired up but it smoked like crazy I figured the oil rings had turned on me well I ripped her back apart and realigned the rings like they suppose to be and put her back together and same thing still smokes like crazy anyone know what else could cause this?

Also she has a lot more power and climbs hills a lot better just got to get her to stop smoking

[peteyparado]

that happen to me b4 i had a stock old exhaust an there was rubbish in there an it smoked till it was all burned up.., could be the same for u?
hows the speed how much more did u gain?

[abansb]

well the diagram I used I think was wrong Top ring 12 o'clock 2nd at 9 o'clock 3rd at 3 o'clock and last ring at 6 o'clock

another diagram I just found which Top ring at 12 o'clock 2nd ring at 6 o'clock corrugated ring at 12 o'clock one thin ring at 3 o'clock and the other thin ring at 9 o'clock.

This is the ebook I referred to GY6 BIG BORE KIT
AND TOP END REBUILD GUIDE now I may have to tear her back apart and readjust the rings again if the top one is not right

[larry001964]

Hi abansb,
I would start with a compression check, could have bad valve seals but the compression check I think should be first.

[abansb]

Apr 6, 2012 17:08:43 GMT -5 peteyparado said:

that happen to me b4 i had a stock old exhaust an there was rubbish in there an it smoked till it was all burned up.., could be the same for u?
hows the speed how much more did u gain?

I am not for sure how much more of a gain I have gotten but the feel of it and climbs hills like nothing as soon as I get the smoking problem figured out I will post my speeds

Another question I do have stock carb on her but I have a 150 carb I am wondering if I can use the 150 carb instead of rejetting my stock I was going to trow it on and see if it would work

[abansb]

Apr 6, 2012 17:32:17 GMT -5 larry001964 said:

Hi abansb,
I would start with a compression check, could have bad valve seals but the compression check I think should be first.

I am using the valves that came with the kit