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need help DR.DRZ carb question????

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i got the sudco carb off u awhile back and a need alittle help dialing it in. Mid to top end feels good but the bottum end needs some work. I have the needle that comes stalk in the two brothers carb. I put the clip all the way to the leanest position. when i rev it and let go it doesn't snap right back to idle, kind drags on alittle. Also the air fuel screw is turned way out to 3-4 turns (which leans it out the more u turn out) I know this isn't a two brothers carb and it looks different to yours ie(choke assembly, and main jet size) , I put the 50 pilot jet back in itfrom a 55 , helped alittle. Any suggestions olly

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The quick return to idle is not affected by the needle, only the pilot system. The pilot controls from no throttle to about 1/4 wide open throttle (WOT). The needle controls from 1/4 to 3/4. The main controls from 3/4 to WOT.

When you rev it up and chop the throttle to closed, only the pilot system is involved. The pilot screw turns out to richen, not to lean. The pilot screw adjusts an air flow, but it is an air flow that is driving a fuel flow. When the screw is out there is more air flow which pushes more fuel flow which richens the mixture.

Start with your 50 pilot jet in. Put the needle back in the middle position. Put the pilot screw at 2 turns out. Let the bike warm up. Do the idle drop. What you are looking for is the leanest setting of the pilot system that allows a quick return to idle. If it is hanging up, open up the pilot screw by turning it out. If you get to 3 turns out and it is still hanging up, the pilot jet needs to be increased in size.

I will go see if I have a 52 pilot jet in my set of jets. The reason they are hard to get from Sudco, is that they send their carbs out with a 52 and, therefore, all their customers always have a 52.

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I checked my set of jets and couldn't find a 52. Now that I remember it, I recall trying to get a 52 pilot and couldn't. You can forget my previous comment about Sudco sending their carbs out with 52's.

I tried a 50 and it was too lean. From idle, the bike would just rev up all on its own, after it warmed up. After unsuccessfully trying to locate a 52, I put in a 55. It seemed to work just fine. However, I have the opened up intake, aftermarket exhaust, 145 overbore kit and upgraded cam. Those upgrades would tend to lean out the mixture, meaning that I should need a bigger pilot jet. However, I am at 7,000 ft elevation, which would tend to richen the mixture, meaning that I should need a smaller pilot jet. The effect of the upgrades tends to cancel the higher altitude effects. All that to say, I think that a 55 pilot should be good for most people. If you have some upgrades and are at lower elevation, you might need to go to a 58.

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i have all the mods u mentioned, big bore, cam, open intake,... so maybe the 58 is the key to my answer. It's really close to being where i want it, i'll keep tring till i get there, thanks for your help olly

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