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Discussion Starter · #1 ·
I need a step by step with pics, if possible on how to bore out my stock carb. I want to bore it out to have a 20mm opening to a 14mm end. How do I do this? Calling out all O.G. Pocketbike engineer, Where are you at HOSS? And Once I bore out my carb, do I have to rejet it, if so how to?
 

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Well, you can get the IP2 Adjustable Jet kit and Tappered Needle... from adrenalin-racing but as for the bore i have no idea... i would like to do the same also...
i have the Big Bore kit on the way here..
 

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1. Remove all parts from the carb.

2. You will see the tube that goes all the way through the carb, the one that the air flows through. Its about 12mm (1/2") wide, drill it to 9/16". Hoss reccomends using a countersink bit rather than a regular drill bit. I think I know why. A regular bit has 2 cutting blades, both relatively sharp. In the soft aluminum, the bit will cut in too deeply and get caught. (am I right Hoss?) That could potentially hurt your hand.

3. Taper the inlet side. If you use a velocity stack I think its pointless to go above ~18mm, but if you have the stock filter than go as big as you can, but you should really get a new filter.

4. Widen the hole in the velocity stack. I'm not sure on the optimum width of it. Its ~14mm stock, which is now the size of the carb, so it definitely needs to be larger. I opened mine to 16mm, and I'm thinking of going to 18.

5. Widen the phenolic (black plastic) carb spacer. I drilled mine with the 9/16 (14mm) bit. I bolted it to the carb to be sure the tubes would be alligned properly.

6. Tune it. Somebody else write this part.
 

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I used a tappered drill bit, then smoothened it out with a dremmel and sandpaper. You can find them a any hardware store.
 

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Boring Out Stock Carb

HOW DO YOU TAPPER THE INLET? I AM THINKING ABOUT BORING OUT MY CARB BUT I REALLY DON'T KNOW HOW. YOUR POST HAS GIVEN ME THE GENERAL INFO I WAS LOOKING FOR. THANKS.




MikeM said:
1. Remove all parts from the carb.

2. You will see the tube that goes all the way through the carb, the one that the air flows through. Its about 12mm (1/2") wide, drill it to 9/16". Hoss reccomends using a countersink bit rather than a regular drill bit. I think I know why. A regular bit has 2 cutting blades, both relatively sharp. In the soft aluminum, the bit will cut in too deeply and get caught. (am I right Hoss?) That could potentially hurt your hand.

3. Taper the inlet side. If you use a velocity stack I think its pointless to go above ~18mm, but if you have the stock filter than go as big as you can, but you should really get a new filter.

4. Widen the hole in the velocity stack. I'm not sure on the optimum width of it. Its ~14mm stock, which is now the size of the carb, so it definitely needs to be larger. I opened mine to 16mm, and I'm thinking of going to 18.

5. Widen the phenolic (black plastic) carb spacer. I drilled mine with the 9/16 (14mm) bit. I bolted it to the carb to be sure the tubes would be alligned properly.

6. Tune it. Somebody else write this part.
 

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Get a tungsten-carbide bit for your dremel. Thats the best bit for removing aluminum and other soft metals.

I'm assuming you understand the definiton of the word 'taper' and which end is the inlet.
 

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You sound like you got it. As far as jet sizing just buy the welder tip cleaner tool. Home Depot. Do very little at a time. remember small motors + small increments = big change. Patience, take your time.

There is no 9?16 countersink bit. Drill out phenolic to 5/8 or even 3/4. Set needle at 5th position.

Lets get through these mods mentioned before moving on.
 

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HOSS said:
As far as jet sizing just buy the welder tip cleaner tool. Home Depot. Do very little at a time. remember small motors + small increments = big change.
???

can you tell me what exactly you are talking about? you are using the cleaner tool to mod the jet? how?
 

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Discussion Starter · #10 ·
welcome back Hoss....can you start a tread on making that conduit for the stock pipes with pics and instructions if possible. Thanks your the man HOSS
 

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ive got a stock carb to ive seen a pic of a bore out job on one it was on ebay , ive got one question tho if you bore it out a little bit is it a must u do the jet also ??
 

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have you even read the "how-to" at the top of the page?
 
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