Give'n an underdog sum bite wit a bit of the ol' BB displacement!!

[Ruger]

Hey y'all, please cut me sum slack. This is my first time wit a forum of anykind...ever. Also speakn of small bikes, nxt 2 any of u, I don't know sh•t! Here's the deal, I recently bawt a 1981 JR50X fur 40$. Sorta looks shot out, but sat only 2yrs since my lil cousins trashed the magneto components all ta h•ll. Other than the removed flywheel cover that likely caused the magneto fail, its entirely complete, plastics & all. Bawt it wit intentions 2 restore it slowly 4 my son Ruger who is now only 6mnths old. I'm a proud new dad & love mechanics so I had a good thing going..but sh•t went a way diff path. Hafta restore another mini after this'n 2 keep it right wit my son. I AM OFFICIALLY SICK WIT MINI FEVER! I strippd the lil jap f•cker all the way dwn & schooled myself a good bit online 4 a few days. By the end, the resto route went 180° & became a ridiculous high end custom rebuild & no real experience. Which doesn't bother me a dang bit, just crazy how wrapped up & interested I am n this. I'm like a kid that has just found out what porn is, by findn a big ol' box of dirty smut mags. GeezeO!! WHERE THE H•LL HAV I BEEN THE LAST 10YRS & Y HAVEN'T I BEEN WRENCH'N ON SIMPLE LIL BIKES?? Sorry guys bout the xtra long post of me all ranting, dragging on & what not. I'm just excited & don't know or have anyone I could convo wit bout tricked bikes of any kind....other than this interweb buisness. Plus, wanted 2 explain my circumstance n depth bein my 1st build/1st luv. Hope u veterans can feel what I'm saying. So on wit the point. I know JR's r made fur 5yrolds & r the no balled underdog of the bunch, but I like that. Better of an accmplshmnt, since excessive power & high performance is the main factor n my build. OK 1st Q.- I can bore my stck cyldr 2mm, but way +dsplc is needed ta reach the overkill JR status I want. Any good (from 49cc up to 82+) big bore & complete top end kits that will fit my JR? I've searchd a ton on the web. Found trusted setups, all mention'n they fit the other 3 main manufacturers. Nuthin bout z'yella fella. Even seen several scooter kits that go as big as 108cc witout mod'n the bottm end & casing. All I've found 4 Suzuki is the Wiseco performance piston kit 4 a stock cylndr over-bored to 42mm. Please share sum advice if it helps up dsplcmnt on my 'zuki JR & don't b a d•ck if I sound dumb. Here 2 learn. Thanx big time.

 

[eichkay]

Finding info on a JR50 build is going to be hard, We all ride 4stroke mini's on here and parts and info for that are in abundance. Anything can be bored up... You need to suss out what size piston your stock motor has and what your wall thickness of the bore is.

Then find the biggest piston you can to suit.. IMO you should just look at getting the bike running, the 49 2 stroke will be a heap of power for a young kid

 

[The_GDFP]

Hurts my head to read the prattle, but repost the basics, and I can help sort your JR. Been through a few of them.

 

[Ruger]

Yeah sorry bout all that. I can settle down now & cut 2 the chase... & I didn't know most of y'all rode 4str my bad. My story was how I got this bike 2 build 4 my son but now I'm crazy bout the build & wanna go all out. So 2 much power isn't a problem. I will build sumthin tame 4 him after.... Sorry again guys, I am serious & practical bout this build. Just A.D.D. & tend ta ramble. I NEED 2 FIND an aftermarket big bore kit /modified top end assembly that will bolt ta the original Suzuki JR50 engine's bottom housing. Increasing my displacement frm 49cc to 82cc or larger. I can only safely bore the stock cylinder another 2mm, up ta 55cc's & I want more fur my effort. I hav found several high performance kits/mods like what I am lookn 4 but they all fit every other minibike manufacturer, except 4 Suzuki. Even seen kits fur 49cc 2str scooter engines that go as high as 108cc, but nuthin at all 4 Suzuki models. Has anyone anyone seen a JR50 bored beyond 42-43mm or wit displacement greater than 55cc?? Maybe just the advertised kit even? That's me trying ta simply explain the basics LOL. Its hard enuff 4 me not ta ramble through the entire 2000 character limit, let alone write a 5 sentence paragraph & what not.Please bare wit me.

 

[loace]

Maybe just restore the jr for the lil fella then buy a proper mini for ya self ,if you are getting this excited over a jr 50 imagine what it'd be like wrenching/riding a dhz 160 or watever,

Even if you got the jr up to 80-90cc what do u plan on using for suspension or to stop it ,will it be reliable
Fair enuf u paid 40 bucks for it ,but how much is all this Gunna cost ya,
At the end of the day my opinion means squat,but good luck with it be interesting to see some pics

 

[The_GDFP]

Bigger isn't gonna happen, and more power is just gonna overtax the sketch suspension. Basic engine isn't sturdy enough to go way big. 50cc, lined up, will pull fine.
BBK's don't exist.

Get running decent with what ever bore cleans up scratches.
Remove factory restrictors.
Limit injector pump, use premium oil.
Mill head 1.5mm
Port cylinder
Mod airbox

Aftermarket pipe just adds to the poor bang/buck ratio and makes it hard to ride.

At some point, you'll realize the futility, and sell it at a loss, and get him a competent platform.

It's been done, but only for the sake of being able to do it:
Barsnake: World's Trickest Suzuki JR50

 

[Ruger]

Hey loace, thanx bud. I get what u mean. Kinda just found out exactly how wrong the JR50 is 4 the type'a project & mind set that it pushed me towards n the 1st place. Findn out more each day as I research, how little the performance Ind. offerssmall 'zuki 2 strokes(esp. jr models). I've also learnd that I can search forums like the tech threads here on MR. pretty embarrassed I made a thread(thinkn it was the only way I could ask Q or learn by forum) & went on like a clown bout it all & what hav ya. Coulda just kept quiet, not gone on wit my unneeded overexplinations, read what was needed 2 KNOW. But its whatever, I know I'm of the po-dunk trashy sort & far as can b frm bein interweb savvy. Anyway from this post on I'm gonna follow by example. Keep it simple as I can & only if needed by me or others. Also gonna keep the 'zuki a resto fur my boy. Which is good & the reason I hav it n the 1st plce. Need 2 find me a new junker mini as a cheap project platform. Crazy custom mini build here I come. I'm still hooked. Thanx again & take'r sleazy.

 

[loace]

sites like these and asking questions is how we learn mate, so don't be embarrassed ,i know myself its easy to get caught up in what you have in front of you, then step back and go why am i doing this?
if you end up with a 4t pit bike build of whatever brand you will find a **** load of hop ups parts and know how from these guys here on this site ,

 

[Ruger]

The_GDFP... hey man, kudos on the term "futile". That's exactly the word I was try'n ta think of, 2 describe what I was after this whole time. Whatever.. inexperience at its finest. Gotta start sumwhere, skill & passion begins wit an idea. Even bad ones.
I know bout the frame/suspnsion quality now 2 & completely understand how it affects what i had n mind. Appreciate ya fur the advise on what mods were safe. Not doing more than the 2nd gear, carb jettn, & basic tune mods beyond a plain resto tho. Yeah that barsnake bike has sum bada•• ideas, but that was one of the first links 2 lead me dwn the wrong path. Took me a "while" ta figure out, its pretty much the only custom JR of that caliber, a ridiculous lead for that matter. ("while"= a dozen dumb Q,20 dozen more Google searchs,& 2 bleedn eyes worth of time spent.) LOL God I suck.

 

[Ruger]

loace.. thanx fur the reassurance bud & appreciate'cha bein cool & humble ta me like that. I'm gonna good at this & now that I'm inspired, I will build an impressive custom mini. Even if its my 1st project & it will take alot of time, trys & f••k ups 2 complete. As long I'm practical bout it from the beginning. 1st mistake learned LOL.
Is (4t) an abbreviation fur 4 stroke? I might decide on a 4 stroke...idk. Definitely looks 2 b easier & more conventional, having an huge amount of mod/performance options.

 

[loace]

No wrys bro,
Yeah 4t means 4stroke,
All The pit bikes we ride and race are 4t, the only ones you will find that are 2stroke will be like pocket rocket kinda bikes and some off road kinda lookin ones but are really ****,

 

[bulldog93]

Or motard. They race the 2 strokes...

Welcome to the forum.

 

[The_GDFP]

I don't know how popular they are for Motard in AU, but here, a good dinger gets around the track nicely. I'm selling this one right now for $1500. Even the BarSnake JR would be left in it's wake