Check the air filter. If stored, sometimes mice get in and stuff it with food or bedding materials. It's happened to me 3 or 4 times with motorcycles, generators and other items that are stored for months without being used.

 

Should have mentioned, that I also checked that and it looked perfect. Thanks for the suggestion.

 

Ashamed to mention it, but is your choke knob in/off?

 

Tested last night, the same symptom applies with choke at every position.

 

Since you have a low post count, I'm going to suggest double checking your work against a carb exploded part diagram and verify that all the tiny bits and pieces are accounted for and in their proper places. Did you work on the carb in the bike or did you remove it completely from the bike? Can you get to >3/4 throttle? Check for air leaks? Boots sealing properly?

 

Carb in the bike. Carb was also never broken down fully.
Not able to get to 3/4 throttle.

 

Mine sat this summer for 3 months and I had no issues with anything. Went out pulled the enricher knob half way and it started right up. I was expecting at least a plugged idle jet.
I do put sta-bil in the fuel and also use a filter in the funnel after seeing all the crud in the bottom of the 5 gallon fuel jug.

 

Double check the float adjustment. Sometimes this gets screwed up when taking the float bowl off and on and can cause you to go lean under throttle if it is restricting flow. Doesn't take much to throw this off. I've done it a few times over the years by catching the float when pulling the bowl off.

 

The pilot jet (idle) has nothing to do with 1/4 to 1/2 throttle. Thats the job of the needle and main jet. (mid range) Did someone adjust the height of the needle? Theres notches in the top of it and a small e-clip to raise or lower it. Raising it will give more fuel at 1/4 to 1/2 throttle, lowering it will do the opposite. Check to make sure the diaphragm at the top of the carb is sealing and the slide is raising the needle. Maybe the slide is sticking.

 

Not actually true. The jets are cumulative. Meaning, the pilot jet is in circuit from zero to full on the throttle. At 1/4 to 1/2 throttle, the needle kicks in, added to the pilot.
Also, the TW200 needle does not have a e-clip with an adjustable needle. Any street legal motorcycle doesn't as far as I know. Only off road motorcycles have an adjustable clip position needle. In the case of the TW200, users use a shim washer of .1mm thickness on the needle to simulate moving the e-clip down in order to effect a richer setting.

 

If it ran good before I would take it out and clean it good. make sure the slide is not stuck and moves easy as it moves under vacuum

 

Before tearing into the carb....try and pour in a little Sea Foam into the tank, and let it idle a bit. There could be something more, but try the easiest to start.

Had similar happen on my '09'er during first year I had it. Ran perfect. It sat for around 3 months, then it finally started and idled fine, but had the same bog when given a little throttle. Little Sea Foam, and poof!....it was running fine. Never any issues on-going. I then made sure to not let it sit too long before starting it periodically, or adding some fuel stabilizer.

 

1. Is needle jet right side up? (see JBFLA's photos)
2. Is diaphragm lifting slide and needle properly? (if diaphragm removed, was it reseated fully?)
3. Color of spark plug? (showing lean or rich?)

 

It could be bent too is someone had it apart before.

 

The basis for the 3 questions before speculating further is this:
At the throttle positions in question, is it running out of fuel, therefore too lean or is it getting too much fuel and therefore too rich.

TK Carb Photos and Parts Identification

Teikei CV Carburetor Photos for TW200 (2001 and newer) These photos are for informational purposes only.

www.tw200forum.com

 

Since I am leaving for a ride (with another veteran on veteran's day) and logging off soon, a few comments:
A vacuum leak would create a lean condition, but be more apparent at idle.
If the fuel cap/tank is not venting or bowl not venting, the result would be fuel starvation, bur be more apparent at higher RPMs
If the needle and/or needle jet is damaged, it would affect mixture, more so mid-range
If the float level is low, it would been lean, but more apparent as RPMs increase
If the enrichener is leaking or not seated, most likely richer, but more apparent at lowere RPMs
If the vacuum diaphragm is not seated or torn or pinhole, the slide would lift less, allowing less air and less mid-range fuel, so primarily a HP reduction.

 

Thanks for all the responses yall. I had done the sea-foam treatment and have ran her multiple times to see if it would burn off some junk. I think my next course of action is to check and replace the slide and needle components if needed. Also I will look into the float needle screen.

 

Helps to jump in the “way back” machine to where it ran good and what changed. It sat, then hard to start. Presumably a constriction in the pilot circuit. But didn’t run better with cleaning, though started. That’s telling you what you need to know. I myself have a difficult time doing an effective carb cleaning without removing the carb. Pretty smart to follow other’s lead on enriching the mixture but smarter to get to where you started before tossing more on the pile.
A plugged vent line, tight valve etc could also be an issue as is time of year.
Do the CV carbs still have a plug over the pilot adjust? How did you remove that without removing carb? I’ve found it too tight myself. I find it challenging to read spark plugs with todays clean burning fuels.

 

Do the CV carbs still have a plug over the pilot adjust? How did you remove that without removing carb? I’ve found it too tight myself. I find it challenging to read spark plugs with todays clean burning fuels.

Yes, EPA still requires caps.
Easy to loosen both clamps, rotate carb (~80 degree max) and remove cap.

How do I "read" a spark plug? - NGK Spark Plugs

Learn how to analyze your engine's overall operating condition just by looking at your spark plugs. Find this and other DIY tips on our resource page.

ngksparkplugs.com

 

The best stuff for cleaning carbs, injectors etc believe it or not is Hoppes Gun Cleaning Solvent. Soak the jets or injectors in it for 4-6 hours than hose them out. They will come out looking brand new. Plus, they will smell great.

 

I have never tried that suggestion - but it makes good sense. The bonus is, that I love the smell of Hoppes solvent. Been around forever,

 

Women should use it for perfume.

 

It doesn't work on me, I'm now nose-blind to the stuff as I use it often.

 

My condolences, SP3, as Hoppes has a delightful and endearing aroma.

 

Don't be too quick to start replacing carb components. If your bike is a '21, I can almost guarantee you all the parts are physically fine. Brass doesn't corrode or get deformed in one year without something serious going wrong. It could get plugged up by debris in the tank, or bad gas sitting, but that can all be resolved with carb cleaner and physical cleaning. Replacing carb components might do more harm than good.

Couple tips for you--these are all mistakes that delayed me for weeks if not months messing around with my own carb:
-Try putting the original carb parts back in. Unless you buy OEM, aftermarket replacement parts may not be identical and can cause gremlins. That one literally cost me months of riding time as I didn't realize that the aftermarket main jet holder was not identical to OEM and that's why I could never get it to run right. Could only tell the difference on a very careful visual inspection.
-Check the float level in the float bowl. You can check it with a piece of transparent rubber hose, Google search how to do it. It's adjusted by bending a little metal tab, if that happened by mistake you could have too low a fuel level in the bowl which could cause all your symptoms.
-Impurities in the fuel are awful and can cause symptoms all through the system. I got screwed by a rusty tank for ages that kept putting rust particles in my fuel line after I thought I had cleaned it thoroughly. Add an inline fuel filter. Clean the living shit out of your carb with carb cleaner. And only run ethanol free gas if possible
-When in doubt, back everything off to factory spec and then try adjusting again. Factory pilot, factory main jet, no shims in the needle and mixture screw backed off 1.5 turns. Then, one adjustment at a time, try walking everything back in. You'll probably want the mixture screw more like 2.5 turns, start with that but just do half a turn at a time.

Good luck! With carb issues, always take it slow and don't change multiple things at a time.

 

Some minor elaboration to clarify previous posts:
Indeed the pilot jet does contribute, and effect fuel delivery throughout the RPM range on our CV carbs. This simple animation explains well.
CV Carburetor

While the OEM carbs do not have notches on the needle the replacement Chinese carbs I have seen do have the notches for the e-clip adjustment. This is another bonus for the $30 clone; use as is, or consider buying one a parts donor. Needle swap is easy.
For OEM carbs we add shims under needle retainer to accomplish same enriching effect of raising the needle.