carb question on kit conversion

roots to wings /
massboy
Dec 12, 2020 11:56AM

going to put a 65cc airsal on a 79 maxi hi torque e50 that has a stock 12mm oem bing on it now (2.12a atomizer). it's for my 16 year old son and i want to "governor" it a bit so it maxes out under 40. I want him to have a little fun, but not too much. Can I run it with the 12mm bing? If so, what jet? I believe I have a 64 or 66 on it right now (58 is stock) it's got an estoril and hi flow metal mesh on it now with 16x45. I know a 15mm bing uses a 78 and 14mm bing uses a 72 with this setup, but not sure about the 12mm. thx for your help

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Re: carb question on kit conversion

Jay Rivett /
bjaockx
Dec 12, 2020 12:55PM

You can add easy speed restrictions. Over jet a little, or you can add some more air resistance to the carb airbox. Another one is to get a throttle cable just a bit too long so the slide cant open all the way up. Easier to make happen on a tomos/domino throttle vs a maxi/magura throttle.

Maybe you could put something to stop the slide on the top cap?

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Re: carb question on kit conversion

Overpriced Parts /
roffman
Dec 12, 2020 01:05PM

It could be be close to the same as a 14mm carb Run the 222 atomizer it works better with a kit that has boost ports and it could take a bigger jet around #68-72 jet especially if you’re running a unrebuilt engine with 41 year old seals you’re going to have some air leaking in mix

There is no set in stone jet size when you say a #72 jet for 14 mm carb it’s not always a 72# jet but for a piston port kit and small pipe yeah 72 could be close, reed kit and big pipe it could be a lot bigger jet, a estroil has a pretty big chamber also,

Time good in the low end of the specifications and then Jet from high size jet to low and try every needle setting and run a head temperature gauge to aid in the tuning and to keep from blowing up the kit

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Re: carb question on kit conversion

roots to wings /
massboy
Dec 12, 2020 01:49PM

thanks. pretty sure i can point to numerous posts where you recommend 72 on 14mm bing and 78 on a 15mm. i followed your advice in this forum laboriously when I put the 65 airsal on another e50 and it's finally running great (except for the broken throttle cable) once i got a real bing 15 and 2.17 on it with the right needle clip position. i was surprised to learn how much difference needle clip position made on a kitted bike. i understand every bike is a bit different and i may end up in a different place with this one. for example, i ended up on needle clip 3 on the one i have running (maybe i need more fuel to make up for my not rebuilt bottom end.

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Re: carb question on kit conversion

Ryan Graeme /
bigrvg
Dec 12, 2020 02:11PM

Don't put the 65cc kit on it would govern it better, surely?

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Re: carb question on kit conversion

Graham Motzing /
grahammotzing
Dec 12, 2020 09:31PM

If you run short gears and the stock pipe it will stay below 40 and run pretty well.

I'd still do the case seals at a bare minimum, you'll spend more time trying to tune around bad seals then you will rebuilding the engine

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