big bore kits By mudmobster (Read 981 times)

[mudmobster]

I was thinking about putting a big bore kit on my wife's scooter 50cc.I'm not going real big just an 80cc kit ,what all would i have to do air fuel pipe wise to get to tuned correctly?

[Alleyoop]

you will have to re-jet the carb to at least a #88 maybe even a #90, also try it first with the air box on and see how it runs. If it needs more air take the restricting tubing out inside to allow more air if it still needs more air then you may want to go with a UNI Free Flow or a K&N filter or you can try adding some holes in the air box and if you put to many you can always cover one hole up at a time to get it dialed in. Also a free flow muffler to allow the exhaust to go out more freely BUT IT WILL BE LOUDER not quiet at all.
Alleyoop

[gy6139qmb2013]

on the gy6 139qmb 50cc. When installing this kit can the original head and valves be used?

[Alleyoop]

Ask MILLSC, he has done many 50cc bbks, he can tell you what works and what doesn't work. You may want to PM him.
Alleyoop

[millsc]

You can keep the airbox with 80cc 47mm kit, and run an 85-88 jet and stock pipe. The smaller kits work fine with stock airbox and stock pipe, the bigger 100cc 50mm kits work better with open airfilters. You will get better performance with an open airfilter on the 80cc kit with an 88 jet, the hipro pipe doesn't do much for the 47mm kits more or less just makes it louder. Use your stock head with the 80cc kit

[millsc]

www.ebay.com/itm/80cc-Big-bore-kit-chinese-scooter-moped-atv-139qmb-50cc-GY6-moped-bbk-47mm-/281115103637?pt=Other_Vehicle_Parts&hash=item4173c41195&vxp=mtr i usually put these on the scoots i do 80cc kits on its on ebay but from scrappys

[Alleyoop]

See what did I tell you MILLSC knows his BBKs, he has done lots of them.
Thank you MILLSC
Alleyoop

[mudmobster]

thanks guys my wife will be very happy

[mudmobster]

I'm having a hard time finding a 88 jet is a 90 going to cause a problem?

[ctpgs]

page down about halfway and there are main jets and have an 88 right above add to cart is drop down box to choose size
www.scrappydogscooters.com/Replacement_Parts.html

[millsc]

www.power-barn.com/servlet/the-1539/Keihin-99101-dsh-116-dsh-XXX-Main-Jet/Detail

[mudmobster]

thanks millsc.I ordered the parts should installing by wed. thanks again

[mudmobster]

I've got the bbk on and running carb rejetted,but it smokes like the devil.I tore it down and check the rings still smokes.Is this normal?