Carb Question--- needle/diaphragm w/pic

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Carb Question--- needle/diaphragm w/pic by: onewheeldrive - May 29, 2014 18:15:46 GMT -5

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Post by onewheeldrive on May 29, 2014 18:15:46 GMT -5

Just popped my carb off my new engine to check the main jet (which isn't stamped).

Anyway, I took the top cap off of the diaphragm and looked down, and to my surprise I saw this. Is this a restriction--- I mean obviously you can't move the needle, but besides that? It's rather annoying if you ask me.

The needle will not move at all because it's screwed down. You can see the needle, which doesn't pass through the white guide like all my others did, right next to the screw.

Tempted to just pull the main jet out and put it in my old carb and use my old carb. Keihin carb in the pic here. Thanks again guys, as usual.

Last Edit: May 29, 2014 18:27:29 GMT -5 by onewheeldrive

2005 Tank Urban Sporty
139QMB engine

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Carb Question--- needle/diaphragm w/pic by: alleyoop - May 29, 2014 19:38:58 GMT -5

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Post by alleyoop on May 29, 2014 19:38:58 GMT -5

Actually the old one you have with the plastic holding the needle are the CRAP ONES(HAHA). that one in the picture are the best the needle will probably have about 5 slots and the "C" clip will usually be in the middle so you have 2 up and 2 down to adjust for any mid-range problems.
Alleyoop

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Carb Question--- needle/diaphragm w/pic by: onewheeldrive - May 29, 2014 20:36:21 GMT -5

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Post by onewheeldrive on May 29, 2014 20:36:21 GMT -5

Oh lol. Cool thanks. I've never seen that style in the forums before, probably just missed it is all. It said made in Japan so I figured it was good quality, just not satisfied with the diaphragm/needle part(at first!). Not sure why the jet isn't stamped, unless it wasn't engraved or lasered and just rubbed off--- unacceptable either way, IMO. I even cleaned it and used a magnifying glass to double check.

I threw my old carb on (didn't change jets) and it took off like a bat out of !!! Just like how I wanted it to. It went from what felt like a 63cc to a 72cc with just the carb swap--- probably a tad fuel starved. So I'm guessing the main jet in the new carb is a bit small, and the needle position could be a factor. EDIT: Plust the top speed shot up by at least 8 mph, way more power.

So I'll try this instead: I'll take the main jet out of my old carb and put it in the new carb in the pic above and retry that carb, and see how it reacts. Possibly tonight. Maybe even toy with the needle a bit if I feel frisky.

Last Edit: May 29, 2014 20:55:34 GMT -5 by onewheeldrive

2005 Tank Urban Sporty
139QMB engine

Carb Question--- needle/diaphragm w/pic By onewheeldrive (Read 420 times)

Post by onewheeldrive on May 29, 2014 18:15:46 GMT -5

Post by alleyoop on May 29, 2014 19:38:58 GMT -5

Post by onewheeldrive on May 29, 2014 20:36:21 GMT -5

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