carburetor boring

Ok, I am basically a newb for mopeds, and I have been working on

my puch maxi for some time now and it is running ok and I just

bought a 70cc TCCD and it should be arriving shortly. I currently

have a 12mm bing and it might take awhile before I can buy the

one I want (19mm dellorto racing) and I was curious as to the best

way to bore a carburetor? Should I just get a brake hone and hone

the tar out of it...or should I hand hone it with a dremel and then

use the cylinder hone to make everything even? And what is your

best estimate as to how much I can bore it? thanks

Re: carburetor boring

I took my 12mm out to around 15mm using a drill bit. I put the carb in a clamp and lined it up and drilled right on through. I think I used a 9/16" or a 5/8" drill bit. Make sure you take EVERYTHING out of the carb body and take it slow. Let the weight of the drill do the work and you'll be ok.

Re: carburetor boring

yeah, use the 5/8er and use plenty of cutting oil(any oil will work, or even wd40) to keep your carb and the bit cool. Otherwise you will bind up, fuck shit up, and maybe warp your carb if it gets too hot.

When you are finished, make sure you sand away any high spots or burrs by the slide.

And take out the emulsion tube as well as the jet. You drill into the tube, you are, Le Fucked.

Re: carburetor boring

True about the heat. I forgot that part. I have an oval intake manifold from trying to go way to fast and hard.

Re: carburetor boring

Also, when you take the carb apart to bore, do you bore straight through to the other side, or does the air intake side need to be smaller than the side going to the engine intake? And do I need to epoxy or weld anymore metal to make sure no leaks or just play it by ear? thanks

Re: carburetor boring

I went straight on through. If you use a 9/16th bit and go straight, you shouldn't pop out anywhere, it just makes a bigger passage way through the body. I don't know about going from either side, that seems like it would be harder to line it up perfectly. Stright through ensures there is a single column of air the same size all the way through. Just take your time and make sure you are lined up as perfectly as possible when you start to dill and you'll be fine.

Re: carburetor boring

Ifou can have someone stand back and eye whether you are starting the larger hole at an angle that helps. The helping person would be telling you to raise or lower the drill. You would be monitoring the other axis alignment. If you use a drill press you could fix the carb in the vise by putting a 12 mm bit or thereabouts in it first just to line it up perfectly. 5/8ths is about15.5mm 9/16 is about 14mm

Re: carburetor boring

Thank you so much!

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