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Discussion Starter #1
I have a 2003 v star 650. I recently changed to V&H cruzers, a k&n air filter, and rejetted. Since the rejet my bike hesitates when I apply throttle and still pops on deceleration. I've read many forum posts though finding this specific problem is harrowing. I've heard mixture screws should be turned more (they're out 3 turns), disabling the AIS (haven't done so yet), sea foaming (I cleaned the carbs and float bowls when I jetted). I really need help guys. My bike sounds amazing, I want it to run that way too. There are no leaks in hoses or vacuum tubes, I can't think of anything else...
 

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That was gonna be my next move but I wanted to consult fellow riders first. Thanks I'll see if it helps
You could also go the next step up on the pilots.... but removing the AIS is probably the easiest.
 

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First, this problem is far from "harrowing"...it's just a matter of knowing what the heck you are doing when you mess with bike...or taking the time to learn how these thihgs works. These Mikuni carbs are probably the simplest, most basic and trouble free carb ever produced.

So....lets see exactly what we have.....

You said the bike had be re-jetted. That is a term used so loosely these days to mean anything from taking the carb off the bike to actually changing something and hopefully getting most of the pieces back in the right places. Usually if something was changed in a "re-jet" it was the main jets. But telling us it was "re-jetted" really means nothing to us at all other than there is a possibility that the carb internals might not be put back together right.....

There are 3 separate fuel circuits on these Mikuni's. Idle, needle and main jet. They work at different throttle positions. Find the throttle position with the issue and you've found your problem area. Then you just need to figure out if the problem circuit is rich or lean and make a simple adjustment to make things right.

So..... to do this right, please tell us the size of your current mains and pilots and the throttle position with the issue....and we may be able to offer a little advice.....without that, it's all just making wild guesses and assumptions.
 

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Discussion Starter #7
Ok mick. Rejetted means I changed the jets. A main jet to part cj086 I couldn't find the "size" online it just says part number, changed from stock. Also changed the needle to dn0470. I followed the instructions in the jet kit to a T. That's why I asked if the slot position was ok or if it should be moved before I remove the tank and air system again. The thin rubber bladders were replaced in the same position, as were the float bowls after being thoroughly cleaned.

My bike idles fine when I start the bike. The problem I have is when I start off down the road and shift gears. Up or down, it hesitates a little before the throttle jumps back on. It doesn't jar me on the bike, but it isn't as responsive as stock. Also there's still popping on decel, though not NEARLY as much as before I "rejetted". So I was asking what needs to be tweaked.

I'm trying to address everything you said...pilot jets were untouched... The carbs and airbox were put together correctly, I even consulted service manual. There is nothing wrong with how it's put back, I just need some tweaking and don't know exactly what to do first off. So thank you for your time, and I am eager to learn.
 

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Those numbers are a start, at least we are getting close to figuring out what you have. However I can't tell what size those jets are from that number. Are they Dynojet? If so, you can take that jetting info over to the V Star 650 CC&D forum on Delphi and I bet the guys there can get you figured out.
 

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My first bike was a Yamaha r6 and I put in a dynojet kit in it and it had the same annoying hesitation as your v star. I suspected that it was running too rich because it seemed as if it had to burn off extra fuel before it really shot off. When I jetted my v star I used a non-dynojet brand and I turned the pms screws 3.5 turns and it runs good at this setting. I don't know what main jets you're running but the recommended jets for the k&n pods were 172.5 from sscustomcycle.

Edit...I just realized you have a 650 so the jet recommendation might be different. I would then just change the pms setting and see what works since that's the easiest thing first. If that doesn't work I would look into the pilot jets.
 

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Discussion Starter #10
Those numbers are a start, at least we are getting close to figuring out what you have. However I can't tell what size those jets are from that number. Are they Dynojet? If so, you can take that jetting info over to the V Star 650 CC&D forum on Delphi and I bet the guys there can get you figured out.

They are dynojets. Still can't find the actual size for that part. But ccnd is saying the needle position is 4 slots when the kit instructions told me two slots. Maybe I'll buy a new main jet separately so I know exactly what I'm getting and not part of a kit.
 

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The size number is usually stamped right on the jet. But you'll have to look really close.
 
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