49cc cylinder and piston?

[Frankenstein]

So the 49cc engine uses a 40mm piston and cylinder right? Where can I find a set of these and are the dimensions such that they are compatible with a 66cc bottom end?

I don't think it will matter if it's not compatible with a 66 bottom end since it's not going on one anyway, just getting some dimensions sorted out so I can frankenstein something together later.

 

[Frankenstein]

Also do the 49cc pistons have 2 versions where one hole hits higher than the other for the wrist pin?

 

[crassius]

haven't seen one in years, so don't know if piston has 2 versions - cylinder has smaller stud spacing that 66cc

 

[MotorBicycleRacing]

Also do the 49cc pistons have 2 versions where one hole hits higher than the other for the wrist pin?

Nope. There is only one 48 cc 40 mm piston.

 

[Frankenstein]

haven't seen one in years, so don't know if piston has 2 versions - cylinder has smaller stud spacing that 66cc

I thought so, but I wasn't sure, saw some pictures indicating a 42mm stud spacing which might make things easier actually..

Nope. There is only one 48 cc 40 mm piston.

I figured, I'd probably be doing an adapter plate so maybe I have to look around for a 40mm piston with a 10mm hole that's lower than where it is on one of those. Thanks!

 

[Steve Best]

I have a 48cc. Cylinder stud spacing is different.
Piston has an odd crown. Flat on outer edge and domed in center.

 

[Frankenstein]

I have a 48cc. Cylinder stud spacing is different.
Piston has an odd crown. Flat on outer edge and domed in center.

I saw that weird look in some Minarellis, possible there's a surplus of those pistons laying around and Cheep Chong Nong bought them at a discount so he didn't have to make them himself..

 

[Street Ryderz]

I saw that weird look in some Minarellis, possible there's a surplus of those pistons laying around and Cheep Chong Nong bought them at a discount so he didn't have to make them himself..

Like the 66's they too have evolved some over the years the older ones were a simular dome to the 66 piston then they went flat out at the edge and now the hole top is flat I can take some picks tommorow for you so you can see the wrist pin hasn't really changed the big end location is different between the 38mm stroke and the 40mm stroke.The best ones I have seen so far are the older star fire gen 2's they used a 17mm crank the castings were much better all around and have larger head and cylinder surface area and even put some out with a steel sleeve.

 

[Street Ryderz]

Here's some pic's of two different 48-50 cc 40mm piston I could'nt find a flat edge one like Steve referred to in the shop right now but I have two customers currently running them so I'm bound to see another one and will post pic if needed.Sorry it took a while but been busy lately.The one one the right is the domed 40mm and the left flat topped 40mm my son killed the one on the right with detonation not knowing he could'nt go faster down hill when the gear is already topped out.Then look at the casting differences between the star fire and the current skyhawk.The black one is the star fire you can see that there is alot more surface area for one and then the quality of the casting thick and straight.You can still find these engines online some times C/L ,Kijiji and such.