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Discussion Starter #1
Hello everyone and I thank you for any direction you can give me.

I've read and read but none seem to fit my bill

I recieved a tw200 from my father after he passed. This 200 only has 1200 miles on it. I remember him saying that it would die after he rode for a bit. He thought it was cdi or stator

I pulled it out recently and installed a new battery. I also pulled the carb before I even attempted to start. The carb had been drained and spotless.. I blew every orifice with cleaner and was all clear.

After reinstalling the carb and battery. I used a test fuel tank (original needed cleaned)
The bike started instantly and ran for about 2 seconds then died. Attempting to restart it would try but never start. Come back 1/2 hour and exactly the same thing...
I tested the stator and I'm getting about .9 set at 200 ohms on my tester. Going to test again tomorrow with better tester.
I also froze the cdi to see if it changed anything. Nothing has worked so far....

It had a battery tender... is this something that could have prematurely effected the electronics
 

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Sounds more like a fuel delivery issue to me. You don't mention where you are located but before I did anything else I would attempt to find a known working carb from another TW and install it on yours. That would easily rule out the numerous other issues that could be possibilities.

You should also check the air box for critter nests. Under the seat and behind the battery is the air intake. If it is clogged then no go! Numerous other issues could be causing your problems but you have to start one thing at a time with things like you describe.

GaryL
 

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The stator and CDI are expensive parts - so start with the simple things first

I tend to agree with Gary - it sounds more likely to be a fuel supply issue .....
 

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Sounds like time to check the basic trilogy of internal combustion... fuel, spark and compression. Plus test any assumptions made so far.

I would confirm good consistant fuel delivery to the carb’s float bowl. Make sure test tank is vented and delivering a good stream of fuel. Then open carb float bowls drain and confirm a good consistent stream of fuel is going into and then draining out of carb....if not this indicates problem with fuel delivery which can be 1) clogged filter just on top of float needle seat or 2) sticking float needle or 3) problem with plumbing from test tank.
If passes this test then confirm proper static fuel level in float bowl....clear tubing attached to aforementioned drain fitting can act like a manometer tube and indicate fuel level.
If starter is engaged for some seconds a properly functioning carb should pull detectable fuel through carb and into intake and cylinder. You could check for this by first disconnecting plug so engine will not fire, engage starter, then pull plug and inspect for fuel moisture and/or odor.
Bike passes this test now? OK, perfect opportunity to put finger over that spark plug hole and spin starter to test for compression.
Bike passes this test too? OK, perfect time to inspect plug and test to see if a good spark can be ​consistently and repeatedly detected for a period longer than the stated maximum observed run time mentioned in post#1. This gives you some feedback on relative health of the whole ignition circuit.

I suspect somewhere along this chain of diagnosis you may find something amiss. Stay logical and systematic in your analysis.
 

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U may have already tried this but have u been keeping the choke on when it cranks? If not then try that. If it runs with choke but dies without the choke then you know it's carb related. I know u said the passages seemed to be clean but it may not be clean enough to let in the needed fuel flow for proper running of the engine.
 

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Discussion Starter #6
Hey thanks for the speedy and thorough responses.
Update: reinstalled stator and removed carb again.. absolutely nothing plugged. Pilot and main was clear. Pulled the idle screw and reset it at 2 turns out and removed the air filter to insure nothing plugged. Inspected diaphram and needle.
Carb looks like it's never had gas in it.

Reinstalled carb
Filled carb, drained with drain screw. Actually let run for a little bit to insure no blockage. .

Engaged choke hit start button and it fires instantly..runs for 2-4 seconds and dies as if the kill switch was hit. No sputter just dies. Hit start button and bike sounds like it's going to start then nothing when you disengage the starter.
Pulled spark plug boot then spark plug and it is moist.
Good compression
Grounded plug to check spark and it has decent spark.

I'm really leaning cdi box but what do you think?
 

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Have you tried different fuel. I'm thinking maybe it's stale fuel. Or try starting fluid after it dies & see if it runs on that.
Try adding Seafoam when you change fuel.
 

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I had a similar problem with a Bultaco trials bike I was fixing to sell.

When I pulled the muffler off for cleaning, about two cups of bird seed poured out. Some mouse or bird had quite a collection going!

Vacuumed it all out, and the bike then started and continued to run.

A long shot, but a blocked exhaust can cause your symptom.
 

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I had a rats nest in an exhaust once and Mike bike would run but wouldn't open up. Definitely check the exhaust system. I have heard if coils that when the started to get hot they would stop firing but just a few seconds wouldn't be heating up.
 

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You seem to have the fuel delivery good.
If it really seems to want to start, or actually is running while cranking, I'd start looking to see if voltage is present while in the on position and not cranking.
Tbe CDI can have intermittent issues but usually it's either good or bad. Not just weak. A coil on the other hand can become weaker or seems more prone to not working as well when it heats up.
Sorry to go back to the carb, but spraying starter fluid into the intake, and finding out an engine will run like that, has found out proven many of my carb issues.

You do have some previous history to go by, and the bike is very low miles, but don't assume the basics are good because it's basically new.

The way you describe that it will start, and run, for a few seconds, when totally cold, but not start the next times, would lead me turn on the key and leave it for a few minutes then try the starter. If some electrical part is heating up with current it might not start and you might have ruled out the carb.

I doubt 2-4 seconds, of running, is enough to push very tight valve clearances to the point of preventing the engine from running again.

Marginal spark could do that though. It's much harder to spark under pressure, so you need a very strong spark with the plug out.

I am a little cheap, so I would look for intake and exhaust blockage, as suggested, because it doesn't cost me much.

Sorry for rambling. I'm a little lucky in that I have two TWs and can swap parts to find issues.

I wouldn't be too happy to start buying random parts.
Stick with it. It's just mechanical and can be fixed.
 

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I know carb has been beat to death, however my first experience with a TW200 repair for a local fellow was very much like this one. On top of the needle seat is a fine mesh filter that can be easily clogged... your comment about needing to clean the tank points to this being a possible problem. The filter would weep a small amount of fuel when sitting and fill the float bowl , however it would not feed enough to keep the engine running.

In the link , zoom in on the diagram at item 25 and you'll see the small dome shaped filter. Also I find it best to simply replace the pilot jet when ever working on a problem like this so you can 100% say it's not the issue, the orifice is so small that I have many times seen them were compressed air does not clean it out.

** never mind , I can not post a link ,I'm to new ... pull a diagram and check out what I mean, its a wear item and is 15 buck so I would replace it anyway. **
 

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Good idea, however Twisted Throttle already confirmed he has good fuel delivery through the float needle’s filter screen by observing good fuel flow through carb and out card drain fitting. Thus no clogged screen may be assumed with very high confidence.

Now if this was my decrepit thirty year old Dodge I’ld say check the ignition ballast resister, however TWs don’t have them.:) Vehicle would start but stop once ignition key was released. Sorry misc rambling not helpful to the problem at hand.
 

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A while back we had another member experiencing this same problem. I had a brand new OEM spare carb sitting on the shelf and offered to ship it to him just so he could try and see if the carb was the problem. He did it and his bike roared to life. So happy he ended up buying that new carb from me because he didn't want to disassemble it all again. New carbs are available for around $260-270 and it is my opinion from what you describe the carb is the issue. Wish you had a donor working carb just to make the switch and eliminate this as the issue. As mentioned before, these carbs are old school and just a tiny clog anywhere is all it takes.

Quick story. My first TW, 1991, had this same issue. I worked on that carb for almost 2 weeks to no avail. Finally broke down and bought a new one and the bike was great. Once the new carb got me going I again disassembled the old carb to try to find the culprit. The old carb had been rebuilt by the dealer just before I bought the bike and each time I took it apart I put it back together the same exact was I took it apart.

Along comes member JBFLA and all his great pictures and assistance. Turns out the dealer mechanic had a tiny spring in the wrong place and I kept putting it right back in the wrong place. There is a rectangular connecting block between the slide and linkage. The tiny spring goes inside the block between the two pins. I don't think the newer carbs after 2001 have this same set up but just one little mistake sure can cause fits.

GaryL
 

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Discussion Starter #16
Update. I sprayed with starter fluid and it changed nothing. The bike did the exact same thing. Started perfect ran for three seconds.. died and would not restart.

So let's put the carb to the side for a second. If this were electrical where would you start. ..

Wish I had a spare cdi lol
 

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Update. I sprayed with starter fluid and it changed nothing. The bike did the exact same thing. Started perfect ran for three seconds.. died and would not restart.

So let's put the carb to the side for a second. If this were electrical where would you start. ..

Wish I had a spare cdi lol
In post #6 you stated that you had decent spark at the plug. . Not beating a Dead Horse , but I'm still leaning towards a fuel issue.The starting fluid should be sprayed AFTER the engine dies & if/ when it does , see if it'll stay running with short bursts of starting fluid in the intake.
Its not ment to be a repair. Just a test to diagnose fuel / ignition issues.
Keep a fire extinguisher handy when working with fuel . A backfire through the carburetor could ruin your day in a hurry if you can't snuff it out with a rag .
Good luck .
 

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My "speciality", at least with Sportsters, is electrical.
It is a very common comment that most carb problems are electrcial. ;-)
However, after reading and re-reading this thread, it does seem to be a fuel delivery issue.
After running 2 seconds, spraying a small squirt of starter fluid will probably give it another 2-3 seconds of life.
If that is correct, then look deeper into fuel delivery.
Good info from GaryL, Bobo 413, jacmmaxwell and Phelonius, as well as suggestions about a blocked exhaust.
 

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Discussion Starter #19
My "speciality", at least with Sportsters, is electrical.
It is a very common comment that most carb problems are electrcial. ;-)
However, after reading and re-reading this thread, it does seem to be a fuel delivery issue.
After running 2 seconds, spraying a small squirt of starter fluid will probably give it another 2-3 seconds of life.
If that is correct, then look deeper into fuel delivery.
Good info from GaryL, Bobo 413, jacmmaxwell and Phelonius, as well as suggestions about a blocked exhaust.
This is exactly what I did and it still died. Never even acted like it wanted to run better. I feel like if it were a carb issue. It would have to be a vacuum lock on the intake side somehow somewhere. I don't think it's running out of fuel because of how quickly it dies.. not a running out of fuel but like a kill switch engaged

I want it to be a carb issue but don't know how it could be at this point.
 

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You're not going to get a vacuum lock until at least the thirty second mark, possibly more

Running for three seconds (more or less) indicates a major fuel supply fault. You couldn't even run the float bowl dry in three seconds

However - (another word for "but") - if there's a bit of sh*t in there that's blocking flow, you will get a (passive) three second run, then the fuel flow is blocked again

The odds on an electrical failure manifesting itself within that consistent time frame is minuscule - forget the HT for now, unless you want to spend 100's chasing a fault you can't see

If you don't believe me, stick your finger on the plug cap and turn the engine over - electricity is a fickle mistress, and will always follow the path of least resistance, eg to the plug, not to your finger

If you get a shock, you've found the fault - if you don't get a shock, change the jets for new ones - don't even bother trying to clean them - just change them

It's cheap, and it's cheerful - until then, it's a guessing game .........
 
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