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Discussion Starter #1
Rebuilt the carb on my 2003, full acid dip treatment, etc. I also replaced the fuel line, added the filter and did a bunch of other "non-fuel" stuff that I'll cover in a different post. Since doing so, I get no fuel going to the carb. I can fill the tube to the carb with some squeezing and flicking, but I'm pretty sure that carb bowl is bone dry. Nothing comes out when I remove the drain screw (assuming that's the one on the bottom of the picture below, right below the idle adjuster).

The petcock is on reserve and I'm fairly confident the guys who did the carb rebuild are competent, although anyone can make a mistake. I've tried the choke in all three spots, with no throttle and full throttle... seems to make no difference. She doesn't even *cough* when I try to start her. Fuel does flow when I disconnect the line from the carb.

Before I pull the carb apart again, what should I check? If I do have to pull the carb again, what should I be looking for? Thanks!

CarbCompressed.jpg
 

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Is the float stuck? Try tapping the carb with a rubber mallet.
 

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Here's what I would try first. Take the sparkplug out and squirt a little gas into the cylinder. Replace the sparkplug and then try and start the engine. The engine should fire for at least a few revolutions. If it keeps running, great. If it runs briefly and then dies, then your float valve is probably stuck closed. Try Tommy's trick to see if that frees it up (but don't whack it too hard).

If that doesn't do any good, loosen the clamps securing the carb to the intake manifold and air box enough so you can rotate the carb enough to access the float bowl screws. Turn off the gas at the petcock. Remove the float bowl and ensure that the float is able to move up and down freely and that the needle valve is moving up and down with the movement of the float. If it is, let the float drop to the down position and then slowly open the petcock and see if the gas flows out. If it does, the problem should be fixed. If it doesn't, come back and let us know.
 

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Personally, I would remove the hose at the carb inlet after closing the petcock and see if you get a steady flow when the you open it with the gas cap on and tight. If not a steady flow or very little fuel continuesly flows thru. I would try cracking or totally removing the gas cap to rule out a venting issue.

If still no flow with the petcock open, I would inspect the petcock to see if it somehow it became clogged some type of residue or possibly loose rust which may have came loose inside your tank and settled to the bottom while it was "off" during your recent re-build ? You may also blow back up thru the supply tube and petcock at this point ( before actually removing it from the tank ) to possibly clear the petcock screen a small bit to get it flowing some..... if it does work or if you fail to be able to blow clear thru back into the tank, then remove petcock and clean or replace screens or entire unit as needed after insuring the fuel line is open and in good shape with no kinks or cracks.

Barring either abive situation, :rolleyes: then as has been suggested, I would be thinking that's it's carb and float diagnosis time.

Just my $ .02 and possibly not even worth that ?:unsure:

excalibur
 

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Personally, I would remove the hose at the carb inlet after closing the petcock and see if you get a steady flow when the you open it with the gas cap on and tight. If not a steady flow or very little fuel continuously flows thru. I would try cracking or totally removing the gas cap to rule out a venting issue.
+1
Ditto
 

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Discussion Starter #6
Sounds like good advice... I already tried a bit of mallet smacking, that had no results. Fuel flows freely when removed from the carb inlet. I won't have time until later this afternoon to check the spark plug trick or remove the bottom of the bowl, those are next on my list.

I suspect the float is stuck up... "How stuck" is probably the question, which I can hopefully get to tonight. Thanks all, I'll keep you posted!
 

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Needle valve is stuck, I bet. Either "the guys who did the carb rebuild" are not "competent" or they made a mistake. Why are you not calling them?
 

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Discussion Starter #8
Either "the guys who did the carb rebuild" are not "competent" or they made a mistake. Why are you not calling them?
Not calling them because they did me a favor... as in "free", it's a school. My parts, my installation, their acid dip and rebuild and a few extra days time to show everyone how an old school carb works and what needs replacing on one. Sure, sometimes you get what you pay for... but even if I end up having to redo the entire carb myself I'm still ahead just because I didn't have to deal with the cleaning and acid and my friend has now seen and reassembled the guts of an old school motorcycle carb. If I can find out what's wrong, I'll show him and he'll go ask his teacher what to do to make sure that doesn't happen the next time he's dealing with one.
 

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Since OP states that "fuel does flow when...disconnect line from carb" so this observation seems to eliminate any tank, petcock, fuel line, fuel level, or fuel filter issues. No fuel draining from carb trail line thus seems to indicate problem lies within carb.
I would remove carb float bowl and then open petcock again and confirm if fuel making it's way past float needle assembly. It is possible to have a clogged filter that resides atop the float valve seat.
 

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Not sure about your year TW, but my 2013 has a FAKE nipple that I accidently hooked the fuel line to. I could not figure out why fuel was not getting into the carb. I took the carb off several times, even removed the floats. (Hard to do without breaking one of the pin tabs I'll tell you...)
Finally looked at another TW and realized my mistake. Duh!

BTW, the correct one is the silver one, not the brass one. The brass one has a hose that goes up under the tank. When I put my tank on, it got folded up and I didn't realize a second hose was even there!
Check by attaching a hose and blowing into it. If it will pass air, it will pass gas. Ha!

 

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Not calling them because they did me a favor... as in "free", it's a school. My parts, my installation, their acid dip and rebuild and a few extra days time to show everyone how an old school carb works and what needs replacing on one. Sure, sometimes you get what you pay for... but even if I end up having to redo the entire carb myself I'm still ahead just because I didn't have to deal with the cleaning and acid and my friend has now seen and reassembled the guts of an old school motorcycle carb. If I can find out what's wrong, I'll show him and he'll go ask his teacher what to do to make sure that doesn't happen the next time he's dealing with one.
Honestly, I feel your pain. I am sure they did their best. However, you need to understand a couple facts:

1) The TW200 "CV" carb is not "an old school" motorcycle carb. In fact, it is a piece of crap. It was designed to eliminate the raw and un-burnt fuel that results when a "pumper" carb's throttle is "opened".

2) True "old school" pumpers squirt gas down the carb throat when the rider wants to go. The CV? No! Watch this YouTube viedo to help understand how a CV carb works:

3) The "choke plunger" is not a CHOKE. It only opens up an auxiliary passage so gas can flow into the cylinder. That passage has to be CLEAN.

4) In fact, the whole thing needs to be very clean. I use the old school carb cleaner that one dunks and soaks the parts in. CAUTION it is very toxic and eats all rubber, plastic, neoprene, and anything else that is not metal. Others here have good results from ultra-sonic cleaners. But, the point is, I have always had to work extra hard to clean a CV carb. They have to be spotless.

We have all been through this exercise. Welcome to the club.

You might think about showing that video to the students while explaining that the old days are dead and gone.
 

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Discussion Starter #13
I finally got to this today... I forgot yesterday was stoopid bowl, so that squashed any plans to smell like gasoline all day. :)

Is the float stuck? Try tapping the carb with a rubber mallet.
Tapped enough to knock off the cup of gasoline I forgot that I had under the carb when I was testing the petcock (that was fun), still nothing.

...Take the sparkplug out and squirt a little gas into the cylinder... The engine should fire for at least a few revolutions... Remove the float bowl and ensure that the float is able to move up and down freely and that the needle valve is moving up and down with the movement of the float.
I got nothing from the gas in the cylinder, but I don't really know what "a little" gas is. I think you might have been wanting to know if there was spark, so I took the plug out, clamped it to the cylinder casing and verified that it does indeed spark when I hit the starter. I'm going to say I'm not dealing with an electrical/ignition issues.

The float moves up and down freely. The needle valve appear to not be moving and no fuel flows when I raise the floats manually. That's probably the source of my issue. So... do I take the whole carb out to clean that and and everything else, or is there a trick to getting that out without the carb coming out and then I get to hope everything else is fine? I'm kind of leaning towards take it all apart and clean everything by hand, but there's a small chance I'll break or lose something in the process, which is why I didn't really want to tackle that from the start. No biggie... I'm okay with attempting manual cleaning if I have to.

Not sure about your year TW, but my 2013 has a FAKE nipple...
My '03 has only real nipples. :) I'm plugged into the one with the bend in it, see initial picture.

...I am sure they did their best... The TW200 "CV" carb is not "an old school" motorcycle carb. In fact, it is a piece of crap...
It was just a figure of speech... to a 19 year old, it's very "old school".

Anyway, after pulling off the bowl, removing the drain screw and checking a few other bits, I definitely got what I paid for. It's nowhere near as clean as I think it should be.
With all of the above in mind, I think my best bet is to pull the thing back out, clean everything by hand and put it all back together. I'm happy to take an last minute advice before I start that journey.
I'm going to ask in advance that you all don't give up on "the village idiot". :) I'm a computer geek who rides... I don't "get" how carbs work and I'll never remember what all those little fiddly bits do. But, I can follow directions! I'll have potentially stupid questions if something doesn't seem right to me along the way. I also have tools and I'll get the right ones if needed (like the set of carb cleaning wires that I ordered because I figured I'd eventually have to do this anyway). I just need to know what not to do in order to avoid breaking delicate parts. In the meantime, I'm headed out to get some carb cleaner and find some metal bowls.. and order a new drain screw. I don't like the one I have and the rebuild kit didn't come with one.

Thanks all!
 

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So to paraphrase: No fuel flows through the float valve assembly ( needle valve) when the floats are lowered (raised) ? And this assumes carb inlet is succesfully being fed gas from tank?

If so then fuel delivery problem is likely isolated to the float valve assembly which consists of the moving needle, the seat assembly,an o-ring to seal seat to carb, and the ever-so-fine and ever-so-easily clogged nylon filter that resides atop the float valve's seat. That darn filter only has a couple hundred holes and does not tolerate ethanol film sludge very well. If you have an aftermarket inline filter then the carb's internal filter can be discarded unless you like triple redundancy afforded by a hard to service small surface area filter.
Removing the float valve assembly to inspect, clean and/or remove that pesky secondary filter can damage the o-ring on the seat. Be careful pulling out old seat or plan to replace with a new float valve assembly.
I should follow my own advice and have a spare needle valve assembly on hand. Instead I have a complete spare CV carb:p
 

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So to paraphrase: No fuel flows through the float valve assembly ( needle valve) when the floats are lowered (raised) ? And this assumes carb inlet is succesfully being fed gas from tank?

If so then fuel delivery problem is likely isolated to the float valve assembly which consists of the moving needle, the seat assembly,an o-ring to seal seat to carb, and the ever-so-fine and ever-so-easily clogged nylon filter that resides atop the float valve's seat. That darn filter only has a couple hundred holes and does not tolerate ethanol film sludge very well. If you have an aftermarket inline filter then the carb's internal filter can be discarded unless you like triple redundancy afforded by a hard to service small surface area filter.
Removing the float valve assembly to inspect, clean and/or remove that pesky secondary filter can damage the o-ring on the seat. Be careful pulling out old seat or plan to replace with a new float valve assembly.
I should follow my own advice and have a spare needle valve assembly on hand. Instead I have a complete spare CV carb:p

...and this carb has real nipples. ImaPoser.gif Sorry smthng, I found some of this funny. I suppose to a 19 year old a carb is old school. Side splitter.

I think you got this about figured out but just in case. pope.gif Fred's got some good paraphrase advice. Hope your next post is telling us it's running like it should. Good luck.
 
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I think the carb needs to come off the bike to do the kind of service you need to do. This write up from jbfla tells you everything you need to do and it has some of the finest photos and documentation I’ve ever seen. I just removed mine today. THANKS JBFLA!

http://tw200forum.com/forum/technical-write-ups/810-lazy-mans-teikei-tk-carb-cleaning.html

Nobody thinks your an idiot. I still get fooled by the neutral, kickstand and other safety switches and have cranked my starter til the battery throws up a white flag. You’ll get it.
 

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Instead I have a complete spare CV carb


Fred - you’re giving everybody carb-envy

Cheers buddy
 

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You can still put a hose on the carb and blow into it. Should easily flow air if the float and needle are working.
No air, then that's a good place to start.
These carbs are very touchy to anything not gas. Especially the pilot jet. Looking forward to seeing what you find.
 

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......."..

The float moves up and down freely. The needle valve appear to not be moving and no fuel flows when I raise the floats manually.......!

There's the problem.

The wire on the end of the float needle is not connected to the tang on the float......can be tricky to do.

jb
 
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Discussion Starter #20
The wire on the end of the float needle is not connected to the tang on the float......can be tricky to do.
What do you mean by "connected"? None of the pictures or diagrams or anything I've found says they should be connected... I was under the impression that the needle valve sits on top of the float tang.
 
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