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I would buy the new carb first or at least look around for a loaner carb known to be working right and see if the bike fires right up with it. The CDI requires the removal of the case cover, a new gasket and while in there you might as well swap the front sprocket if there is any wear at all. I am willing to bet the different carb will be all the difference.

GaryL
 

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Discussion Starter #22
GaryL. Unfortunately I don’t know of anyone that has a spare carb. Would it be an option to take the carb off and simply spray starter fluid into the head and see if it runs okay?
 

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GaryL. Unfortunately I don’t know of anyone that has a spare carb. Would it be an option to take the carb off and simply spray starter fluid into the head and see if it runs okay?
NO! Bad idea and could blow you and the bike up. Any engine will run on the highly flammable starting fluid which will tell you nothing.
Fill in your member profile telling us where you are located and maybe another member lives close who can help you. In my post above I wrongfully stated the CDI is in the side case which it is not. The stator is in the side case. I have never had a CDI or a stator go bad which is why I am pointing you to the carb being the #1 issue.

GaryL
 

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You can use a small amount of gas instead of starting fluid. Keep in mind that this is not a conclusive test, as you've previously mentioned that it "sort of" runs. If it's hard to start by normal means, and it easily starts when you insert gas directly in the cylinder, it may point you to a fuel problem, and not an electrical problem. I think it's worth investigating.

The CDI is easily accessible under the right-side plastic cover. You can unplug it and reinstall it in under a minute.
I'm not an electronics expert, but I'm guessing the CDI is manufactured to withstand a pretty large temperature swing, including freezing temperatures. ...But if you're unsure, don't listen to me.
If you decide to do it - The freezer test is simple and easy, and may help you eliminate that piece from the puzzle.

For the long term, if you're not already using non-ethanol gas, it's time to make the switch. Your bike will run better, and will be less prone to carb problems in the future.
 

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Discussion Starter #25
Well, I got GaryL's advice a little late. I ended up spraying starting fluid in the airbox snorkel under the seat, opened the throttle a bit, and the bike started and ran strong for about 30 seconds. Then it faded and died. I also unplugged the CDI and stuck it in the freezer for an hour. Plugged it back in and tried to start the bike and no luck on this front. This leads me to believe that GaryL is correct and that it is a fuel issue and not the CDI. So I took the plunge and ordered a brand new carb (ouch! $325 was pricey) so I'm hoping to swap that out by the end of next week. I'll definitely report back.

With that said, if it is the carb and idle is so lean (which is why it requires 4 turns out of the air mix screw), is there a passage other than behind the air mix screw and slow jet that I'm missing that I should be cleaning?
 

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Just curious, did you ever pull out the air/fuel mixture screw and inspect the O Ring on it?
 

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Well, I got GaryL's advice a little late. I ended up spraying starting fluid in the airbox snorkel under the seat, opened the throttle a bit, and the bike started and ran strong for about 30 seconds. Then it faded and died. I also unplugged the CDI and stuck it in the freezer for an hour. Plugged it back in and tried to start the bike and no luck on this front. This leads me to believe that GaryL is correct and that it is a fuel issue and not the CDI. So I took the plunge and ordered a brand new carb (ouch! $325 was pricey) so I'm hoping to swap that out by the end of next week. I'll definitely report back.

With that said, if it is the carb and idle is so lean (which is why it requires 4 turns out of the air mix screw), is there a passage other than behind the air mix screw and slow jet that I'm missing that I should be cleaning?
I will suggest that you give up on the old carb for now and wait for the new one to get there. When it arrives you immediately pull the plug out of the pilot screw hole so you can see the flat blade screw head. With a small screw driver you turn the screw all the way in until it hits the bottom lightly. Then you turn it back out 2 full revolutions and leave it there. Install the carb, install the air filter and fuel lines so everything is completely sealed including the air box filter cover. Make sure the carb boots are all in place and tight. Fire the bike up and go for a ride.

IMG_1841.JPG

View this picture. The straight slot in the screw head must go around twice to equal one full revolution. You need to go 2 full revolutions so turn it to the half mark and then to the #1 mark and do it again and that is 2 full revolutions. Turning the screw in is clockwise and out is counter clockwise. This is the starting point and you might have to turn it out a little more after the engine is hot to find the exact right setting. With the carb installed you will be turning the screw to the left, counter clockwise to find the final exact setting and it will be somewhere around 2 1/4- 2 1/2 turns out. You started at 2 full turns and probably won't have to go another half turn before you find the right spot. These final turns are very tiny so just a slight twist out is all you do and then take a ride. The bike should go through all the gears smoothly with no hesitation and in 5th gear it should run smooth with no slight bucking. You are done!

On another note, I hope you did not spray starting fluid through the snorkel with the new air filter element in place. Starting fluid will melt the foam. If you ever need to spray starting fluid in you do it with the filter removed with the air box cover off, direct into the carb intake side and with the twist grip throttle opened a little so the slide moves up allowing the fluid to go direct into the cylinder. As I already said, any engine will run with a direct shot of eather but that is no good for any engine.

After you have the new carb and the bike running with it you can decide what to do about the old carb. I bet there is nothing wrong with the CDI or the stator and the new carb will have you up and running.

GaryL
 

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One other thing comes to mind. If your fuel tank only has a little gas in it then always turn the petcock switch to the reserve position so it is getting full flow. Think you said you were using an external fuel supply so this won't matter.

Go to this thread in the tech write up section and find the picture of the carb bottom. This is actually the newer style carb but the same on the bottom of the old style carbs. The pilot screw is outside the float bowl and the pilot jet is inside.

https://www.tw200forum.com/forum/technical-write-ups/881-tk-carb-photos-parts-identification.html

GaryL
 

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Discussion Starter #29
Well I finally received the new carburetor and slapped it on after turning the pilot screw out 2 turns. Fired right up on choke, warmed up and unchoked and it everything works 100%. Before putting it on, I compared the two and noticed that the prior owner had adjusted the float. I'm going to adjust the float to match (I assume it should be set to a level of 25mm) and swap it on to see if it resolves. Either way, I'm back on the road. Thanks to all for the help. Now for lessons learned:

1. Check the float when you clean the carbs.
2. Checking the CDI is easy and can be done prior to shelling out money for the new carb if that's what is needed.
 
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