TTR230 Dead Spot just off Idle

So Im not new to dirt bikes. But I am new to 4 Stroke bikes. A couple months back my girlfriend and I got in to some dirt bikes. Mine runs flawlessly thanks to the FI that Yamaha has gone with. My girls TTR runs great too, but..... it does have a dead spot just off idle. Makes no difference if the engine is cold or up to temp. If you try and smack the throttle open it will just die if you hold it open. So you really have to be gentle with the first 1/8 of a throttle. Im suspecting the the slow jet (pilot jet) is too rich maybe? Or maybe the clip on the jet needle needs to be adjusted? But before I go digging into it I want some informed opinions on what the possibilities could be. No I don't have a manual for it yet. Yes Im going to get one for it, and my bike. But $160 is kinda steep for the pair. And until some other problem rears its ugly head Im just gonna keep up on common sense maintenance.

Hers: Its a cute little bike and has lots of spunk and potential. I just want to make it better.
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Mine: Its a sexy beast and kinda scares me. But I know how to keep it in check.VZM.IMG_20160428_170823.jpg
 
From your description it seems like a lean bog to me, but I'm not there. Id adjust the mixture screw first to see if that makes a difference, if not, I'd definately go thru and clean that carb thoroughly and check float height, as far as an informed opinion I havnt worked on any of the ttr's but my first thought would be a malfunctioning accelerator pump, if that carb is equipted with one.
 
The ttr's and the street going serow i have been around do not have accelerator pumps, though the air shutoff diaphragm get mistaken for one sometimes. If that critter is cracked it will give a similar symptom that will also include popping on deceleration. I would start with the fuel screw and see if you can get it tuned more to your liking. small bore, heavy crank and flywheel doesn't get the thing moving quickly to begin with, so some careful throttle aps my be in it's future, but the fall on it's face syndrome is there largely by the legislative process. Slide cutaway has all but been eliminated as a way to tune this out.
 
The ttr's and the street going serow i have been around do not have accelerator pumps, though the air shutoff diaphragm get mistaken for one sometimes. If that critter is cracked it will give a similar symptom that will also include popping on deceleration. I would start with the fuel screw and see if you can get it tuned more to your liking. small bore, heavy crank and flywheel doesn't get the thing moving quickly to begin with, so some careful throttle aps my be in it's future, but the fall on it's face syndrome is there largely by the legislative process. Slide cutaway has all but been eliminated as a way to tune this out.

Well it does not make any popping on deceleration. So maybe I could possibly eliminate the air shut off diaphragm. As for adjusting the fuel screw. Ive looked and looked and cannot find any type of adjustment screw. Like one that Im familiar with on a T2 carb that would have a tension spring on it. Maybe I need to look a little harder.
 
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yep you do. in most cases you WON'T find the low speed screw in the same place, the exception being that lots of bikes had mikuni carburetor conversions in the past and the VM models had the low speed controlled by an air screw as opposed to a fuel screw. fuel screws are located on the head side of the carburetor and your tt has it under the spigot just behind the rubber intake flange. it works backwards to an air screw, meaning you turn it out for more fuel in mix, and in for less.
 
I ran into the same issue on a pair of 230s last year. The pilots get clogged really easy. Clean the carb twice and once more for good luck and to keep the schmuts to a minimum go to Homedepot or lowes and get some little bottles of premix oil with stabilizer. Mix 1 little bottle with about 5 gals of gas and you won't have anymore issues. I've been doing that to all my small engines for the last year or 2 and have had no more issues.
 
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