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

[sc00ter]

I have never done, or know anyone, who has done a bbk on a 50cc 4 stroke. Everyone in my neck of the woods swaps out the 50cc and drops in a 125-150cc stock motor out of a wreaked scooter instead. Whats funny is none of these guys even know how a motor works, so when it stops running for whatever reason they are totally lost. Congrats on you for learning! I did a 125 to 155cc cylinder swap (along with injector mods for fuel) and it made a big difference. Used a no name bbk from Taiwan. The scooter was a Zuma 125.

[NCSCOOT]

Originally Posted by sc00ter

I have never done, or know anyone, who has done a bbk on a 50cc 4 stroke. Everyone in my neck of the woods swaps out the 50cc and drops in a 125-150cc stock motor out of a wreaked scooter instead. Whats funny is none of these guys even know how a motor works, so when it stops running for whatever reason they are totally lost. Congrats on you for learning! I did a 125 to 155cc cylinder swap (along with injector mods for fuel) and it made a big difference. Used a no name bbk from Taiwan. The scooter was a Zuma 125.

Yeah the Taiwan kits are built a lot better, i could tell just from holding it and looking at the material. My first BBK i installed was a cheap $40 Chinese off of eBay and I am guessing why it contributed to my first bike failing after 2 years.

I too knew nothing about small engines lol, but i wanted to learn and i did it coming here to this forum and watching YouTube. Eventually over time i knew how to do everything with these small engines. Watching people do those BBK's on youtube, they made it look easy haha. When i tried it on my first bike it was a utter nightmare. Come to find out i did everything right i had just forgot to connect a simple ground wire to the top of the head. I still do make simple mistakes like that but eventually over time i want to become small engine certified. I found a passion for these little bikes i guess you could say

Now for the difference in the 80cc (72cc) kit and the 100cc (82cc) kit:
On a flat roadway i got my new Denali with the 100cc kit up to 45mph, maybe a little bit over. I normally don't push these bikes over 45 no matter what bore i put in them i just wanted to push it a couple times to see if i could feel a difference with the 80cc and 100cc kits. My last bike i got up to 45mph on the same road and it was with a 80cc kit. Now i do notice that off the line my 100cc kit does have a bit more pull to it.

I am also doing a oil change every 200 miles instead of 300 miles because it runs hotter with this type of kit. I use Shell Rotella 15w40 diesel engine oil. The added weight of the oil helps with better cooling in these small engines. I used to use Performance Synthetic Motorcycle oil but i find it to be too thin and i think that oil may have also contributed to my last bike failing. I am really sticking to what works this time, WHICH IS NO SYNTHETIC engine oil lol. I know a lot of people by cheap walmart and put it in these things but your bike will love you if you use a "brand that works" kind of oil.

I am thinking that it might be either my added weight that i put on, since i did put on almost 40lbs. Or it might be the Variator/Clutch limiting me somehow. I think i might of used the stock variator with my 5G sliders instead of the performance one, I've heard that the Stock Variators are heavier than the performance i might try to go swap it out with my 5G sliders.

I am going to try messing with the variator in a bit and i'll let you all know..

Any other suggestions/comments would be appreciated, thanks