Denali 50cc to 100cc (82cc) Bore Questions

[NCSCOOT]

Hi this is my first post on here but i been looking at everyone's posts on here for a while. A lot of everyone's questions and answers have helped me a lot over the past 3 years of scooter modding so i would like to thank you all for that!!!

Peace Sport 50cc to 80cc (72cc):
I've been modding scooters for the past several years and it all started with my Peace Sports 50cc. Very basic and more known of the 50's i decided to bore it out to a 80cc (72cc) displacement. I put on a performace exhaust, 20mm Carb (Jetted to 90) and a performance Variator with 5g rollers but did not touch the Torque Spring. I have also installed a Racing CDI.

It ran really good for over two years topping out at speeds of about 45 mph which is all i really wanted to push these little engines anyway. I really just wanted more pull off the line than anything else, top end really didn't matter. All of a sudden it just died on me after 2 years of boring it out. I am guessing i just pushed this little engine to the max with the bore and i just killed it as I've heard that the crankcase isn't designed to go over 35 to 40 for these little engines for longer periods of time, not to mention the crazy off the line starts.

Denali 50cc:
Anyway when tax time came around i got a new scoot and wanted to bore it out again simply because i could not go back to a super slow emissions controlled 50cc. I did ride it around stock for a while to break it in then after two months i got to 100cc (82cc) bore. At first i only wanted a 80cc (72cc) bore but the scooter shop messed it up and gave me a 100cc.

I bored it out with the 100cc bore put on my 20mm carb with a 95 jet and a 40 idle jet. I found it transitions the best from FT to idle with that size idle jet. I then put on the performance exhaust and variator, along with a better made belt and a Racing CDI. The exhaust i got has a really big opening too and sounds great.

Question:
My question is does a 100cc and 80cc bores really compare in difference? I really didn't notice much of a difference in speed and in fact i think its running a little slower. One thing i couldn't do was put on the performance head with the shorter valves because of rocker arm issues but i have heard that it doesn't really make a difference if i use 69mm valves or 64mm valves and i wanted to ask everyone here what their thoughts were on that issue.

Another thing is that i did put on a bit of weight. When i rode my Peace Sports 80cc bore i weighed about 190lbs and now i weigh 230lbs riding my Denali 100cc bore. Could the added weight make any difference?

In my personal opinion i think these engines just aren't designed for such a big bore on it. I've always heard bad things about these 100cc (82cc) bores, such as engine and crankcase's going out faster, etc so it does worry me a bit having installed this but it was the weekend and the scoot shop was closed so i just threw it in.

If anyone has any thoughts as to why it feels the same i sure would welcome any opinions or idea's.

Thanks