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 Newb looking for bore kit advice! 
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Joined: Thu Sep 06, 2018 2:00 pm
Posts: 1
Post Newb looking for bore kit advice!
Hey! First time posting to this forum. So first off, glad to be a part of this community!

Now to my question.....I have a 2012 Yamaha Zuma 50 4 stroke, or Yamaha BWS 50 where I'm from and to be honest its just not kicking it like it used to.
To be fair I have not been all that kind to it but have done the regular oil changes along with spark plug and air filters. I have about 8800 km on it at the moment and it's just sluggish. I know this is most likely from poor upkeep, but I have been interested in increasing the bore size for years now but havn't had a good reason to till now.

So what I'm asking is would anyone recommend a big bore kit that i could order online to install myself? nothing crazy, even 70cc would suffice, as well as what I would need to do in order to get the proper performance out of it? ( i know about the restricted CDI but dont know to much about it, etc.)

Also, the belt has never been changed before, would this help with performance at all if i put in a new one???

Thanks to anyone that has a reply to any of these questions!!

Thu Sep 06, 2018 4:11 pm

Joined: Wed Sep 05, 2018 9:39 pm
Posts: 5
Post Re: Newb looking for bore kit advice!
Welcome to both of us. ;)

Thu Sep 06, 2018 8:17 pm
Scooter Addict

Joined: Fri Aug 31, 2018 5:18 pm
Posts: 190
Location: Fox Valley Wisconsin
scooters and mods: 2 2004 Vinos 2004 Zuma
Post Re: Newb looking for bore kit advice!
I can speak for the belt on both bikes ,A end of life belt would hurt performance use a oem yamaha belt it is as good or better than anything else.
On the 2 stroke if you are looking for biggest bang for buck you can grab a cast iron sport bbk polini or malossi around $150 bucks if you want to step up a notch in price and performance from there the sport verions bbk top trophy or the street race pro are still very reliable and forgiving and are in the $200 range .
I prefer cast iron over aluminum .
You have to be prepared to upjet the carburetor on all of these you also may have to adjust the cvt variator weights .
If you decided to add a pipe you may have to upjet the carb further and dial in the cvt for the new power band .
Very important to use the same brand jets .
I had to use mikuni jets since I could not find TK jets and i had to buy a set 6 sizes higher to find the right range .
The 4stroke upgrade kits are spendy .

2004 Vinos Derestricted exhaust and variator stock carb with mikuni 75 main jet needle down 1 clip 40 mph
2004 Zuma Malossi sport 70 cc breaking in with stock pipe then Technigas next r polini 107 mm clutch polini green springs high speed variator 84 main jet 46 pilot jet needle 1 clip rich
2005 eton beamer airsal sport 70cc 9200 peak rpm top speed 40 77.5 mikuni jet needle 1 clip rich

BBKs all around on the way

Sat Sep 15, 2018 8:26 pm
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