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Murphy, I dont know too much about tuning a big bore kit. But what else did you do to the bike ?

You have a bigger carb and cylinder, did you increase your air intake and increase your exhaust also. The all play and integral role.

This super 8 forum is practically dead, but maybe if you list all your mods, someone can chime in. I would think but no sure that you would now need to open up the air intake a bit and add a performance exhaust to go along with the increased carb and cylinder.

What Stig says about the holding tool is the best advice on this thread. 6 point sockets are a must and 12 points should be actually banned from this world.

Make sure you use the holding tool on a solid surface as it will dig into the grass. Its tricky to use. A big pair of vice grips should do it if you can stop the rotation properly. I would suggest a nut splitter but it could also damage the threads. You did put a tiny bit of grease on the threads so it can be properly torqued and easier to take back off ?

Also people that have installed upgraded variators also are posting about their shredded belts and the is no clear advice on using you stock boss or the boss that came with the variator.

Kymco new scooters (they have done away with the 2 strokes) are not highly regarded for speed and I would not buy one for that reason. You need an expert with all sorts of sources of aftermarket performance parts and knowledge to derestrict one. Kymco is really tightening the screws now on the ability to derestrict. Your dealer did what it could but has other scooters to care for and probably doesnt have to knowledge or resources to derestrict your scooter properly. You dealer is a Kymco dealer but doesn't specialize on just Kymco bikes and new models will throw them for a loop.

I cant say it is what it is but you need a person of higher knowledge, time, and resources to derestrict these new kymco 4 stroke scooters or to get in touch with another who has one and you can follow what he or she has done.

Juts realize by increasing RPMs and making the scooter go faster, you are increasing the stress of the internal engine components that they may not be designed to handle and can shorten their life. I just found this out after having a wrist pin bearing and clip failure after 8k miles. But that was a hard 8k I put on my bike in 4 years and cant fault Kymco and actually should praise the fact I got 8k mostly full throttle miles off the bike. I may detune it and throw in heavier sliders now that I have it back up and running.

My CV mods were new DR Pulley sliders and purple Malossi torque spring with a torsion controller and that was it and all I knew that would give better performance.

On my 2013 Super 8 2T, I just installed a new complete top end. So far 21 nice miles with it.

My old stock cylinder is scoured from the circlip/wrist pin bearing failure after 8k miles. Would it be worth to send this cylinder out to get resleeved if its possible and fitted with a new piston so I can have a spare top end in case of another failure or maybe swap it out after a few years of wear and tear?

The SSP-G HOCA kit I used costs $150 and I cant really compare it to the stock top end.

http://www.partsforscooters.com/169-404-Hoca-39mm-Kymco-Air-Cooled-Cylinder-Kit

Also, do people change their piston and rings after a certain amount of miles as a regular maint thing ?

I'm not too sure how long the SSP-G Hoca kits last and do know bike racers replace top ends every 25 hrs. I rode pretty hard for 8k trouble free  miles and can't fault Kymco in any way. Maybe I need to pull back on the throttle a bit more instead of always keeping up with traffic and let cars pass. Also, I may put on heavier sliders to decrease RPM's.

One note to the 2-stroke riders: The damaged piston and chamber was as clean as a whistle. Hardly a speck of carbon from using amsoil 2-stroke oil.

Keeping my fingers crossed. Put in the SSP-G kit and it started right up. Exhaust gasket didn't fit over male end of exhaust muffler ID too small but fit snuggly into female exhaust port but used it anyway as it it pressing up snuggly against the gasket and sounds OK..

Will have to break it in slowly and maybe detune it a bit with heavier weights to decrease RPM's and stress on connecting rod.

My piston kit came with G shape circlips. Should I cut off the ears (G part) to reduce chance of failure ?

After 8k perfect miles running spectacular, one of the circular spring clips that hold the piston to the rod broke off and ended up in the cylinder probably via a port. Thankfully it was a half mile from my home and I was going to take it to work the next day.

So I need a new cylinder and piston. Does anyone know where to get them sent to Connecticut, USA ?

I may have small piece or two in the what seems like sealed crank case but I doubt they will can any major issues.

I may be able to salvage the head as it just has a few beads of molten metal fused to it.

Thanks

Have you checked the reed valves?

Also.

I think the throttle has to be held wide open when kicking the motor for the compression test.

Per your recommendation I'm ordering the D-socket.  My carb has been cleaned numerous times but I've never removed or adjusted the air screw (I thought it was a plug).  What changes can I expect by removing the air screw, cleaning if necessary and adjusting the screw?

Mainly some low idle fine tunning of the carb they may help with idling and acceleration from low speed.. This is an air screw. I don't think it affects full throttle air mixture but I could be wrong.