80cc engines differ

Okay first off, I'm not new to these 2 stroke engines. Why everyone assumes that someone who words things so everyone can understand them are called newbies, I have no idea. I know that the so called 80cc engines actually have a discplacement of 66cc, I just figured that that's what people would recognize it as. The two engines are 66cc skyhawk silver slant head engines, nowhere did I say they were grubee or flying horse, or a happytime. The two sprockets are both 44 toothed...


And Augidog, calm down, you sound like I was attacking you or something! To my knowledge, these engines are the same model, I've checked the carbs and jets, the exhausts are diffrent but we interchanged them before and had no significant diffrence. No, I have not torn these engines down as far as the crankcase, and that might be were the answers lie, but I am not new to all of this...

Anyway, thanks for all the responses, I just couldn't figure out what gave my friend the edge, but soon or later I'll have an answer. I thought the power diffrences could have been from better port polishing (if there is any) or just upgraded parts.
 
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if you thought i thought you "attacked" me, you thought wrong. this was merely a forum-situation that called for clarification. reading the words i was given to read, i wrote some words in response, it seems to me you didn't really read what i wrote & misunderstood my intention.

however, IF you knew more than your OP communicated, then you sold this group short...MBc has been on the edge of this stuff for years..."just the facts, ma'am" works best for the best answers and discussion.

and, let's face it, blankbox...IF you were the noob your OP led us to believe, then you'd be glad to have this new info, right? :geek:
 
Simple answer that may be it- the jets even if marked the same could have been drilled/molded (what ever) 6 or 8 months apart and the tolerance changed due to wear. The piston could be loner or shorter due to the mold used. Quality control is done by eye not caliper so the same engine from the same factory on the same day could be just enough different to feel let alone months later. These are fun engines not BMW or Honda.
And Augidog, calm down, you sound like I was attacking you or something!
I don't know Augidog personally but I've read probably 1000 posts by the guy and his passion helps us all and the sport. Personally I listen to him.
P.S do you and you buddy weigh the same, do you have the same amount of grease in the wheel bearings, are one of you missing a screw in the air filter,etc to many variables to ever know.
 
Thanks all for the suggestions, I haven't checker the jets yet, and I still want to take a better look at the ports, just to see if there's anything I can do to equally match his.

We both have the same weight, maybe only a pound difference, his engine was put on the same bike I got, knowing the kit would fit... The two bikes don't look the same though, his having stock paint and apehangers, mine w/a black & red paint job and banana seat w/ sissybar, I'm uploading pics soon hopefully

I haven't read or posted here at mb in a while, sorry for the 80cc listing, was not intentionally done to make me look noob, but thanks everyone for posting!
 
well, a lot of times the "same" engines can be built with very different end results.
every once in awhile you will get an engine (car, truck, motorcycle, 2 stroke...whatever) where all the parts are perfectly matched (by coincedence) and you get an engine that makes more power.
i have seen this many times with cars...2 exact engines, built with the exact same parts, same tuning, same oil etc. ran on dyno's
one engine will make a significant amount of power and torque over the other engine for some reason, or both engines will be very close in h.p. and torque.
sometimes you get lucky, other times you get a lemon.
 
I wish they were all the same. I've got 3 in my spare parts bins that were weak engines that never made it onto customer bikes. I won't sell a bike until I put a 100 miles on it to ensure it is producing sufficient power and runnning correctly.

My favorite engine of all time was a Kingsmotorbike.com engine (bushing engine) that I purchased about 5 years ago. It would climb the steepest hill in Colorado with a 44 tooth sprocket (stock size). Today, I can't climb the same hills even with a SBP shift kit. That engine (no slant head either ) was so torquey and powerful. I regret selling it and the bike it was one after 3 years of hard use. I never had another engine like it.
 
What would buyers do if they bought a car that was supposed to have a V-6, but it turned out to have a 4 cyl. ?

kick themselves in the *** for not knowing the difference between a v6 and a 4 cylinder when they open the hood (that a bonnet for those of you in the UK),
 
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