Slightly Underpowered

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Hey everybody... you could say I'm new to this forum but I've been reading here and taking advice for a year or so... I'm no newbie I'm on my second 80cc 2 stroke bike and I do have a basic understanding of how engines work... but what I'm wondering is why does my new bike feel slightly underpowered? I used to run my old motor on a chopper frame and keep up with my buddy. Sometimes slightly faster than him. now I have a mountain bike/cruiser style frame and a new engine he has his same old bike and he'll slowly pass me if he wants to... we have almost the same bike all stock except we both have a bbr tuning stage 2 cdi (just for the keyed ignition little theft provention) and I run the viper flexible exhaust he runs stock exhaust with a gasket leak. He will pass me up but we virtually have the same bike I just have a slightly better exhaust... is his exhaust leak causing him to run faster than me or what? I'm baffled I have my carb tuned, spark plug gapped to 25, a decent exhaust, I check my plug regularly and it's always the right color. He doesn't doesn't care about any of this stuff but his bike will slowly pass by me on the top end and I'm the one taking the time to actually tune mine and thats irritating.
 
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I'd you'd like a picture of em I can deliver on that.. my bike is the blue his his black.. all mine has received since this picture is spring load chain tensioner, carb cleaning and tuning, and the viper exhaust my buddy (gray bike) he has had no changes since this picture..

Screenshot_20210928-023438_Snapchat.jpg
 
Local time
7:23 AM
Joined
Sep 28, 2021
Messages
30
Hey everybody... you could say I'm new to this forum but I've been reading here and taking advice for a year or so... I'm no newbie I'm on my second 80cc 2 stroke bike and I do have a basic understanding of how engines work... but what I'm wondering is why does my new bike feel slightly underpowered? I used to run my old motor on a chopper frame and keep up with my buddy. Sometimes slightly faster than him. now I have a mountain bike/cruiser style frame and a new engine he has his same old bike and he'll slowly pass me if he wants to... we have almost the same bike all stock except we both have a bbr tuning stage 2 cdi (just for the keyed ignition little theft provention) and I run the viper flexible exhaust he runs stock exhaust with a gasket leak. He will pass me up but we virtually have the same bike I just have a slightly better exhaust... is his exhaust leak causing him to run faster than me or what? I'm baffled I have my carb tuned, spark plug gapped to 25, a decent exhaust, I check my plug regularly and it's always the right color. He doesn't doesn't care about any of this stuff but his bike will slowly pass by me on the top end and I'm the one taking the time to actually tune mine and thats irritating.
Also by carb tuning I don't mean jets... I do have jets just haven't used them because the plug looked a good color after just putting the needle clip on leanest setting. (all the way to the top of wider end of needle) I run 40:1 with full synthetic oil maybe too much but the spark plug being light brown seems to tell me it's okay... plus honestly if rather run rich than lean I'd just prefer the perfect tune.
 

Frogslayer

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Also by carb tuning I don't mean jets... I do have jets just haven't used them because the plug looked a good color after just putting the needle clip on leanest setting. (all the way to the top of wider end of needle) I run 40:1 with full synthetic oil maybe too much but the spark plug being light brown seems to tell me it's okay... plus honestly if rather run rich than lean I'd just prefer the perfect tune.
What are the vibrations like on this engine? Maybe your crank isn't balanced as well as your old one?
 
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Your buddy could be running hot and lean with that gasket leak. That actually might be what is causing his to be stronger in power. Its bad though, a leak right at the port is very bad. Will eventually cause him problems and maybe a need for a new engine sooner rather than later.
I was trying to tell him that and he isn't listening but hey not my bike if he wants to wreck his motor I can't stop him
 
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Sounds exactly like my buddies. Lol. They can't figure out how I made a motor last over 4k miles now. I tell them " its called proper set up and maint.".
I baby mine and he doesn't care about doing the same... at first it really sucked cause I'd still be the one broken down but with how it's going this time shouldn't be me pedaling home
 

Chainlube

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I'd you'd like a picture of em I can deliver on that.. my bike is the blue his his black.. all mine has received since this picture is spring load chain tensioner, carb cleaning and tuning, and the viper exhaust my buddy (gray bike) he has had no changes since this picture..View attachment 158480
Can't tell from the pictures, but it could be as simple as his bike has a 42 tooth sprocket and yours is a 44. Count the teeth.
 

mark20

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as mentioned above he's running leaner with that leak, honestly, if you want more performance run an NGK B6HS and sand the head down (or for 35$ you could run a puch head or a 5.5cc cooling head) since it covers more area in the chamber and will give a slight compression bump.

You could be running a bit rich as well, and unfortunately, that viper exhaust isn't really doing you any top-end favors (you honestly might have lost some top end due to the header length) a proper pipe (like a jog pipe for example) as well as porting (or hell, cleaning) would benefit top-end performance (since these engines vary wildly, you could have chamfered ports causing poor performance)

hope this helps!
 

Street Ryderz

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Did you just start using the flexible exhaust on this engine? The picture shows stock exhaust on both, but I can tell you that the flexible exhaust is junk, it's too small even for stock ports to breath properly it ends up getting hot and losing more power as you ride on it! If you were to gut the stock exhaust it will be faster than his with no cost to you but your time and effort.
 
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