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Dr350s CV Carb Rich - Pinholes in idle fuel reservoir OEM?

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Background: I recently acquired a 1993 dr350s and I cannot fix a rich condition; I am  about to purchase a TM33 pumper carb off of eBay but I hate when I am not able to figure something out.  Hopefully someone here is able to give some insight!

Tried: The bike is 100% stock. I have replaced the vacuum petcock with a standard one, and replaced every jet and rubber piece float and needle with OEM Suzuki pieces, triple checked float height, the idle, main jet, and choke valve and seat surfaces appear to all be in perfect condition, etc.

Symptoms: With the bike fully warm and choke off, the bike idles highest with the idle mixture screw all the way lean and dies if any choke is applied. It also smells rich, does not hot start, spits black soot, and pops on deceleration, low power, etc.

The only unusual thing is where the idle mixture screw pulls fuel from there are three little pinholes drilled straight through into the throat of the carb.

They do not look OEM, and I tried to epoxy them shut but I think I rushed it and the gas ate my JB weld... are these factory or did someone try to correct an old vacuum leak with this?


Thank you!



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  • 11 months later...

Just an update in case anyone else was having the same issue.

The pinholes are set at the factory.

I ordered a 37.5 pilot jet that fit fine, but for some reason was entirely different than a genuine mikuni one and allowed way more fuel in at idle even with the screw all the way closed.

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