Well upon riding my neighbor's 49cc pocketbike and realizing how obnoxiously slow it is, i've decided upon my summer project, and was wondering if there was anywhere that you could pick up like a yz, cr, or rm 85 engine/tranny without buying the whole bike.

Last year, me and my buddy did a full build on his bro's 95gsr (f thieves btw), so we need somethin to keep us busy this summer.

SOOOOOOOOOo...

the plan was...



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Also: Does anyone know where one could buy a pocketbike minus the engine, cuz if i could, i'd imagine it being cheaper...iono

I realize that not only will the damn thing be a royal pita to get to work/fit/run. But i've got all summer, all necessary welding tools, and my crazy *** to get it fitting.

But holy goddamn, think aboot how absurdly fast this thing'll be

 

.......I have a 49cc bike, been thinkin' about the same project.
keep us updated..

 

hi! devlin do you want more speed in your 85cc motorcycle?replace your piston in to bigger one.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ttlandii &raquo;</TD></TR><TR><TD CLASS="quote">hi! devlin do you want more speed in your 85cc motorcycle?replace your piston in to bigger one. </TD></TR></TABLE>

i think he wants more speed outta a 49cc pocket bike..

but anyways, let us know if you figure out a way.

 

Yeha, i'm keepin my yz85. ****'s FULLY built, my dad's boss's son used to race the bish, and i bought it off him right after a rebuild. Thing's obnoxiously fast.

And its the pocketbike thats gotta get faster...

After deeply thinking about it, i was considering switching to maybe an xr100 motor instead, partially because its air cooled, which would make the whole overheating thing not much of a prob....

But goddamn a 2-stroke 85 would be soooooooooo fast.

Now all i've gotta do is find somewhere i can buy wrecked dirt bikes....

 

Pocketbike engines are SMALL. I doubt you will have much left of the original frame left if you chop one up enough to fit a yz85 engine in there. And the idea of using a xr100 engine would defeat the whole point of doing the project in the first place.

I would just buy a water cooled blata if you want to go fast. You can make the factory equipped engine go faster than is safe for the bike. My buddy has one that goes over 65mph! Maybe there are some other brands out there that make good power out of the box also? anybody?

If you find a way to make your project work out, damn. I can't imagine how it would feel to go yz85 fast on a pocket bike. Welp, if you decide to try it, good luck!

BTW that arc welder isn't the greatest thing for welding up tubing.

 

And i realize that arcing tubing blows...i built a go-kart frame last summer...

But i'm wayyyyyyy too poor to get a good mig/tig. And i got this for $50 so

And the xr wouldn't completely defeat the purpose, it'd be a different feel. It'd be wayy more torquey than the yz would be...

And i realize that i'm gonna be doing a bit of hacking...i might go with a bigger frame instead of the super uber small pocketbikes, go with one maybe like 1' tall

Still ironing out details.

And in response to "you can make the factory equipped engine go faster than is safe for the bike":

I don't want a bike that has an engine thats faster than is safe for the bike. I want a bike thats faster than is safe period. Like, defies sanity fast.

AND no one else has done it...and i'd like that

 

Just look at an Auto trader or something and find an old 80 that needs work. There should be plenty of 80cc motors on ebay as well. Have you ever thought of stroking the 49cc? I'm not too familiar with the pocket bike motors but they do make stroker kits for 50cc bikes of other kinds. Just bore and stroke that bish, you should be able to make it close to 100cc.

 

I'd let you use my TIG setup, but im way down in socal. Sounds like maybe something larger like the ticeman.com ysr450 would make you happy? Maybe not mini enough for you though.

Have you seen this clip:
http://home.mindspring.com/~va...a.avi
Its my buddy on his 65+mph blata...its modified. I'll ask him what he did when I see him.

You probably already know this- fitting an aircooled motor is simpler, maybe an old aircooled 80 2stroke would be cheap used, but the water cooled engines have more potential. Not sure which way I'd go if I were doing this type of project...

 

i just got my 49cc pocket bike today too. Man i wish it had a faster motor...its starting to feel really slow

 

Look into the ZPF model pocket bikes! I had a ZPF pocket bike that was built in Italy. That thing was freekin fast! Did about 70 mph plus! It was so freekin fast You could not stay over the bike w/ out it wanting to flip over. It was a 50cc 2 stroke w/ a ported and polished head, it made 13hp! All i have to say is that thing was scary

 

oh man that would be badass if it did 70mph...a little scary but it'd be nice to know it was taht fast just in case. Mine does like 30mph...i want it to be at least 50mph+

 

The one in the vid is good for around 70. Hes hard on the brakes in that vid, but its the only clip I have. You can tell if you compare the speed at the begining of the clip with the speed at the end. I'll dyno it next month and see how much power it makes. I'm sure its more than 12.

 

I"m not going to just bore/stroke the oem motor, its like trying to build a b18a to 200hp n/a. you CAN do it, but it'd be WAAAAAAYYYYY cheaper and for the same amount of money you could make a b18c go just as fast.

I think that i'm going with the yz, and i'll figure out SOME way to rig the radiator. I might up running a rc51-style and put it on the side

It'll work. And its not top speed that i'm concerned about. The yz85 tranny peaks at like...what...80ish? Its the insane pee-your-pants acceleration UP TO 80mph that i'm lookin fo

 

try dropping the exhaust on your 49cc bike............that'll help out your top speed.
I got mine to hit 55mph.

 

were putting a cr125 on a '85 atc 70 3 wheeler, gonna scare all the little kiddies on there pep boy special bikes with this one