80cc engines differ

Discussion in '2-Stroke Engines' started by blankbox7, Apr 2, 2010.

  1. blankbox7

    blankbox7 Member

    I bought my 80cc engine about a year ago, and my friend got one 4 months after. Both were purchased from the same place and I assembled both of them. I am on my 600th mile and everythings running great. Takes off smoothly, idles nicely, and has a decent top speed. My friend on the other hand, his has a whole lot of low end torque, a fast top speed, but his doesn't idle very well. Our bikes are the same, including carb and exhaust... What would cause his to be better? I'm not complainin, just very curious.

    (we use the same oil and gas too)

  2. augidog

    augidog New Member

    firstly, there is NO SUCH THING as an 80cc Happy Time.

    secondly, see above...inconsistancies in advertising & sales practices could explain the inconsistancies in engines that are otherwise "the same" :detective:

    edit: that said, if you KNOW they are the same, double-check the mixture settings.
    Last edited: Apr 2, 2010
  3. motorpsycho

    motorpsycho Active Member

    is his back sprocket the same size as yours? (# number of teeth)
  4. How could inconsistencies in advertising & sales affect the performance of an engine that is otherwise the same?

    Last edited: Apr 2, 2010
  5. augidog

    augidog New Member

    i said "the same" in quotations meaning maybe not the same. also note the OP didn't mention the source, so i replied with some generic but relevant info.

    since there's no such thing as an 80cc engine yet the OP states he has one, we can surmise the OP was lied to...where there's one lie there might be others. i've personally seen more than one case where 2 "identical" engines from the same seller turned out to be different versions albeit similar enuff to hoodwink the beginner. all it takes is 2 carbys from 2 different sources to have differences in performance in 2 otherwise "identical" kits.

    im(experienced)o, anyone still listing 66's as 80's is either an outright liar or just too dumb to know what he's selling...i recommend avoiding liars and dummies as common sense.
    Last edited: Apr 2, 2010
  6. give me vtec

    give me vtec Active Member

    there are a number of factories that make these things. Your vendor could have any number of suppliers offering "the same" engines. Very common.... they say you bought a grubee but it is actually a flying hoarse. Only way to tell is by the manufacturers plate or sticker that comes on the side of the engine. It tells you where and when the engine came from.
  7. Hawaii_Ed

    Hawaii_Ed Member

    Wow, that is helpful info there augiegod.

    It is true there are no 80cc, they are all 66cc. This guy is a newbie.

    There are many flavors of engines out there from many factories. Manufacturing tolerances vary greatly. I have ran 5 HT motors on various bikes. Each has different personalities.

    I can also say with professional race car engine building: You can build the exact same parts to the same specs, and still have one engine run differently than the other. It just happens sometimes :)
  8. augidog

    augidog New Member

    so you say i'm getting on blankbox for not knowing something?

    yes he is a newbie, so he didn't know until now that he'd been lied to. not his fault. since enuff peeps list and sell 66's all the day long, the guys who're still selling "80cc" HT's are lying tho they don't need to. but the target is the newbie/impulse buyer as a competitive strategy, said strategy being unfair & dishonest imo. it's also a great way for the "box-seller" to dump shabby goods.

    as you know, i have a personal stake in the info at MBc being as correct and as organized as possible, far as i'm concerned there'd be no OT here at all, plenty of members browse this place daily and never leave the garage/technical area.

    as you also know, we here in ocean park went through a lot of bicycle engines during MBcs' first 2 years, and we shared all we learned bluntly. shenannigans was proven on the 80cc was when we tore one down and discovered it for what it was, and posted it here in may '07, with pics: http://www.motoredbikes.com/showthread.php?t=5145&highlight=powerkingshop+rings

    3 years is long enough for this to be going on. the "80" anywhere in a listing should have faded away a long time ago. one month of seriously boycotting anything-80 and no more newbies will be lied to, ubetcha...and the reputable HT-suppliers who've come along will get more of what they deserve.

    since this forum subject-line will eventually be a "80cc" search result, any new newbies who click it will be clued in quick (unless you think it's ok for the seller to dupe a novice?) to the myth of the "80cc Chinese Super Bicycle Happy Time"...this is how consumers get things done, by telling each other stuff.

    blankbox7: now you know more than you did about your engines :)

    based on what you wrote:
    of course you don't need racing experience to realize engines do have personalities. however, the closer to production level 2 engines are, the more likely they can be made to run almost identically. if you're sure you're looking at 2 "identical" kits then different mixture settings would give the results you've described. it's not a promise, it's just my best guess based on some good experience. so if you haven't already, might as well have a look at the needle-settings...or, look for a tiny leak in one engine :helmet:
    Last edited: Apr 3, 2010
  9. arkives1

    arkives1 Member

    Engines are just like women, they all come from the same 'creator' and all have the same basic parts but WOW what a difference among them!:jester:
  10. Esteban

    Esteban Active Member

    I agree !

    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. ?
  11. blankbox7

    blankbox7 Member

    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.
    Last edited: Apr 4, 2010
  12. augidog

    augidog New Member

    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? :detective:
  13. chefdouglas

    chefdouglas Member

    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.
    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.
  14. blankbox7

    blankbox7 Member

    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!
  15. motorpsycho

    motorpsycho Active Member

    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.
  16. Skyliner70cc

    Skyliner70cc Active Member

    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.
  17. give me vtec

    give me vtec Active Member

    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),