What do you do to the carb after you put on a big bore kit?

by Sean

I just put a big bore kit on my scooter and for some reason it burnt a hole in the top of the cylinder and the mechanic's telling me that it was because the fuel jets were too small.

I was wondering what size I am supposed to put in? I have 49cc 1PE40QMB motor which I put a 70cc kit on.


Comments for What do you do to the carb after you put on a big bore kit?

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Jul 08, 2010
by: Anonymous

Are we talking a two stroke motor or four?

For a two stroke:

If your main jet stock was, let's say an 80 (should be stamped on the jet itself), try around a 90 jet. There is tons of wonderful info about two stroke engines on the internet.

Try searching by two stroke tuning. You will have to do some plug chops to get it right. Plug should be a medium to dark brown color. Black color means too rich, no color or white means to lean.

Jun 13, 2010
by: Jim Zeiser

Look up Enviromoto.com on your search engine and ask Jeremy about it. Or Jim Martin at Rapid Repair.com. Either one of these guys are ace mechanics and should be able to tell you what main jet to use.

Jun 12, 2010
Rejetting the carb.
by: Izzy

I would tell you to go to www.partsforscooters.com. Get the phone number and call them. They will be able to tell you what size you would need. They have been great to me.

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