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Discussion Starter #1
After riding for a few hours today, I noticed that when in gear, didn't matter which one, at the bottom of the RPMs when the throttle was completely loose,the engine would stutter right before acceleration. I need help diagnosing this. Thanks for any help.
 

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You might first try to clean it with 1-2 oz Berryman's B12 Chemtool or Seafoam/gal of fuel in the tank and run it through and see if that helps.
 

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It takes about 5 minutes to pull a carb off of these bikes with a #2 phillips screwdriver. Then you need a small flathead screwdriver to remove the pilot jet. And then you need an appropriately sized stiff wire to poke through the hole in the pilot without gauling or enlarging it.



Mine was plugged up when I got the bike. I ran wire through it and carb cleaner to flush it out.







You need to be able to see daylight through it.. The hole is pretty tiny.



.4mm I am guessing given the #40.







This one item in tandem with the adjustable mixture screw under the carburetor is responsible for idle and up to about 1/4 throttle. (Also the enricher/choke if the bike is cold is usually involved.)
 

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Discussion Starter #7
Thanks for all the great help. I followed your advice and ran a wire thru the pilot jet. Didnt seem clogged at all. Ill put it back together and run it tomorrow and see whats up. Is it possible it is running too rich now that the temps are getting warmer? I have been running it all winter in sub freezing temps and this problem arose once I ran it all day in warmer temps.
 

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With the factory pilot jet, I find it hard to believe the bike will ever idle rich at 1000 feet above sea level, where I live, haha
They send these things to the USA so lean that they hardly run right. But maybe in your case. If it started and ran easily in really cold temps and now it doesn't want to run, my guess is that it's getting too rich on you. The simplest check is to make sure there's not a mouse nest in your airbox or something restricting airflow into the carburetor.
 

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Discussion Starter #9
With the factory pilot jet, I find it hard to believe the bike will ever idle rich at 1000 feet above sea level, where I live, haha
They send these things to the USA so lean that they hardly run right. But maybe in your case. If it started and ran easily in really cold temps and now it doesn't want to run, my guess is that it's getting too rich on you. The simplest check is to make sure there's not a mouse nest in your airbox or something restricting airflow into the carburetor.


Nope, no mouse nest in there haha



I checked the spark plug and it does have slight black deposit on it and the symptoms are it hesitates when I open the throttle. So adjusting the pilot screw will alter it from rich to lean?
 

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The pilot jet screws in tight. The pilot screw on the outside of the carb on the bottom will lean up the mix the more you screw it in.



I believe they come from the factory turned out 1.5 turns from seated. Most people are running them 2-3 turns out just to make their bike idle though. Maybe yours is turned out too far. A black plug would definitely be too rich or mean oil is getting past the piston rings.



You might just change the plug out since they're cheap and see if the bike runs better just from that. I think I bought all five D8HA sparkplugs my store had in stock when I got my TW200, haha.
 

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Discussion Starter #11
Just to clarify, this is my first bike and first time tinkering with engine mechanics, so I appreciate all the help you guys provide.



I tried several positions with the pilot screw and still the same symptoms.



So the pilot jet is responsible for the fist quarter throttle? And what I'm experiencing is a stutter right in that range, is that considered a "lean surge" or did I make that up?



When you shim the needle does that allow more fuel to the pilot jet in that first quarter throttle? Or should I just keep trying with the pilot screw? Cause damn, this all started happening since it got warm out!
 

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After riding for a few hours today, I noticed that when in gear, didn't matter which one, at the bottom of the RPMs when the throttle was completely loose,the engine would stutter right before acceleration. I need help diagnosing this. Thanks for any help.




Have you or someone else rejetted the carb?.
 

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Discussion Starter #15
Have you or someone else rejetted the carb?.


Me, no. As far as the previous owner, not sure. The bike ran beautifully in the winter tho, only when the temps warmed up above zero did this problem begin.
 

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Just to clarify, this is my first bike and first time tinkering with engine mechanics, so I appreciate all the help you guys provide.


Since you are learning. Take it slow, don't get too frustrated. Here is a good animation that illustrates how our 2001+ bikes with cv carbs work.

[media]http://www.youtube.com/watch?v=wyspAHrMbb8[/media]



Here are a couple of written explanations to go with it: http://www.drpiston.com/Cvcarbs.html and http://www.battlescooter.com/1.html.



Of course, be familiar with the specific carb threads from our site: http://tw200forum.co...identification/ and http://tw200forum.co...47-carb-tuning/



How old is your gas? If it's not fresh, change it out. Have your checked to make sure you don't have a vacuum leak, especially around the rubber boots around the carb. Definitely change the plug, it's cheap. If the jets in your carb are stock, about 2 turns on the pilot adj screw should have you running (clockwise until it seats, but don't crank on it, then counter-clockwise two 360 degree turns). You can get a small screwdriver, like a flathead from a Stihl dealer, then cut off all but 1/2" off of the orange handle, then you can reach up and adjust the screw to fine tune it while the bike is running. If you still can't get it going right, do a full carb breakdown and cleaning.



Good luck.
 

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When you shim the needle does that allow more fuel to the pilot jet in that first quarter throttle?


Nope, shimming "the needle" allows more fuel to enter from the main jet into the main intake passage where it mixes with air.



Since you're in Manitoba, you might want to think about learning all you can about the carb and the rejetting process. Your bike may need different jets, i.e. one set for the winter, one set for the summer to run as good as it can. You also might want to check to see which jets are in it now. Maybe a previous owner put in a larger main jet which made it richer and helped how the bike runs in the winter, but as the weather warms up it is running too rich and needs a smaller jet. Hard to say without that info from you. Again, good luck.
 

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Discussion Starter #20
Some excellent info there, thanks a lot.



I have a 128 main jet and the pilot jet has number 31 on it. When I took the pilot jet out, I didnt see the spring, washer or O ring. Are those suppose to just pop out when you unscrew the pilot jet? Or are they accessible from the vacuum diaphragm on the outside?
 
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