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intake boring???

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hey i have a xr70 with a lifan 125cc engine on it it has a 20mm carb and intake and i was wondering if i took a dremal tool and put a grinding bit on it and bored the inside of my intake out if it would work or if it is a stupid idea please reply i have a pitbike race commin up and if it is a good idea i need to do it to win thanks Danny

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Well have you ever ported and polished before? You could you really don't need a metal boring bit . Use the sand paper bit and also get some grits that go up.One is match porting. It's when you make the port of the intake or exhaust the same size as the pipe. Then smooth it out making the air flow smooth and have less resistance. I read somewhere awhile back and this mechanic was making strategic gashes in the intake to create turbulence so the air flowed in a certain way to help make the rate of the fuel and air combust more efficently.

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I read somewhere awhile back and this mechanic was making strategic gashes in the intake to create turbulence so the air flowed in a certain way to help make the rate of the fuel and air combust more efficently.

Thats what a power now does on the big bikes, splits the air flow so it flows differently creating more power

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Matching the intake isnt going to allow you to pull even a second off your lap time....

you might as well just practice more

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There are times when intake boring can help, and others where it can hurt. Many of the 125cc engines come with 26mm intake ports at the heads and usually a slightly smaller intake to match a 24mm carb (velocity gains). In my case, the previous owner used a 22mm intake and an 18mm carb from the replaced 50cc engine. This was absolutely stifling any potential outside of low end torque. My Zongshen's intake at the head was 25.5mm and the new carb I bought was also 25.5mm. While the carb alone made a huge improvement, opening up an upper rpm band not obtainable before, boring the intake from 22mm to 25mm and port matching the flanges made the transition from mid to high less peaky and improved the overall top end. Keep in mind that the inside surface of the intake is bumpy which causes a bit of turbulence, impoving bottom end (atomization). Porting aluminum usually ends up in a much smoother surface which can hurt your low rpm band. As for the heads, I'd leave the intake port alone.

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i would match them and put a rough (but straight) finish on it. Other than that, going bigger won't help if your head and carb aren't any bigger.

i wouldn't do it if you havne't had experience porting.

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Matching the intake isnt going to allow you to pull even a second off your lap time....

you might as well just practice more

So your saying what?That's like saying 20mm and 22mm carb it the same. Well as far as lap time that's up to you. Anyone can improve lap time without match porting. Shit you don't need andything just practice.

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