Do i need a exhaust for this??

[Evo]

So i found a big bore kit for my QJ1E40qmb engine. cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.m748&item=230659879322&viewitem=&_trkparms=clkid%3D2048080642072431271#ht_3150wt_708
The post says that i need a exhaust to use or it will overheat my engine. I am wondering if there are any other ways around this that you guys might know?

[90GTVert]

As long as it's tuned properly and the stock exhaust isn't clogged or restricted, it should be fine. I'm sure there are some 50cc tuned pipes out there with small stingers that retain enough heat to be a problem on a 70cc, but I wouldn't worry about a stock pipe. I've managed to use a stock 49cc pipe on a 96cc stroker with ported cases and cylinder. Certainly not my 1st choice, but it was OK. Another style of stock exhaust that I have was exactly the same as what came on my 89cc scoot stock.

[jmkjr72]

you can run an oem pipe you just wont have the performance that you would with an after market pipe
i know the yamah aoem pipe works well with bbk
or if you are trying to keep the stock look the sp3 is a good pipe too

[brandonscoot]

aww man i want that same kit really bad too! it looks nice, cept the coil, dont need that.

now if only i knew my wrist pin size :/

[Evo]

What size main jet should I get?

[jmkjr72]

go up 1 or 2 sizes on the oem mj or the current mj you have if you are sticking with the stock pipe