Upgrading from 125cc to 150 or 160 something cc ?

[Neil955i]

Mis-read that as 140 mph to begin with!...

 

[klaviator]

Everything else being equal, a 150 should be faster than a 125 but everything else is seldom equal.  How the engine is tuned as well as gearing make a big difference.  My Like 150i makes 13.5 HP vs 10.3 for my old Super 8 yet top speed seems to be about the same.  The Like does accelerate a bit faster.  My Yamaha Smax at 155cc was significantly faster than either Kymco.  The engine was liquid cooled and just tuned for more power.  Typically an Air cooled 2 valve engine makes less power than a 4 valve motor or a liquid cooled motor. 

Another factor is the rider.  On twisty roads I have run away from motorcycles with over 1000cc on my small scooters. 

[Kansas kymco]

Myself I like liquid cooling and FI and the HP they bring.  But everything is a tradeoff you get more weight and a little more complexity over air cooled.  I see different machines for different purposes.  125-150cc for around town and speeds 45 and under. 250cc and up more suited for secondary paved highways.  With the larger machines capable of main highway travel but at a cost of increased weight. But you know what they say about opinions, everyone has one.

[TBR125]

Have any of you upgraded a gy6 head to a four valve unit? I am curious of the actual difference all else remaining the same. Also, any thoughts on effect of increasing compression? minor increase.

[klaviator]

Have any of you upgraded a gy6 head to a four valve unit? I am curious of the actual difference all else remaining the same. Also, any thoughts on effect of increasing compression? minor increase.

My Super 8 had a GY6 with 2 valves and a carb.  My Like 150i has basically the same motor but with 4 valves and FI.  The difference is less than I expected.

[TBR125]

Probably not worth the high cost then. It quickly adds up to the cost of a non running Honda CB 750(my dream project bike).

[scooterfan]

Since my initial post the rollers at my Agility’s variator has been greased very slightly, and a new clutch has been installed on the same day. Since the grease on the rollers and new clutch I immedialy noticed a definite improvement on engine power when on dayly rides in our area. The engine does not loose power or RPM’s when I ride uphill any longer, and engine RPM’s are higher when I reach the top of the hills these days.
This difference in general performance made me realize that there is no need for an upgrade any longer - the current performance suits me perfectly. In fact - I now simply loves the Agility.

I now started wondering what is actually causing this power difference - the grease on the rollers, the new clutch, the new big spring on the new Chinese clutch kit, the new clutch itself, or a combination of all mentoned changes. I initially though that the grease on the rollers is causing the difference, but then realized the new clutch kit could play a role as well. 
Whatever the reason - if the grease on the rollers does not create problems in the near future, I think by pure fluke, and in an unexpected way I managed to find a way to create more power from my Agilty’s engine.

[TBR125]

Good chance grease would effect the shift rpm and increase variator response improving ride experience, however, how would greasing the rollers increase power at the wheel if that is what you are saying? I can't figure what power it could make available.

[scooterfan]

Good chance grease would effect the shift rpm and increase variator response improving ride experience, however, how would greasing the rollers increase power at the wheel if that is what you are saying? I can't figure what power it could make available.

I think maybe a combination of a better roller / variator response, and maybe a slight different clutch spring is causing the higher engine RPM’s during certain stages when I ride uphill. Therefore maybe a slight different “gear ratio” at higher RPM’s.

Maybe I should replace the new big clutch spring with the original clutch spring to see if it makes any difference.