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Discussion Starter #1
I'm fixing a bike for a friend. The bike will start and idle for a bit and then stalls. It will start up again and do the same thing.I have put fresh gas in it .Does this point to a carb problem?If I put the choke on it dies.Someone else has worked on it and cleaned the carb.

I've worked on bikes before but never one of these.I am just looking for suggestions,any help you can provide would be appreciated.
 

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Hi there – and welcome to the board ……..

It does sound like a carb problem – and for reference, you can find a variety of manuals here http://tw200forum.com/forum/technical-write-ups/70-service-repair-manuals.html

“If” the carb isn’t set up correctly, the amount of fuel going into the engine will out strip supply, running the float bowl empty. Once the engine stops, the float bowl continues to fill, until you start her up again, when once more the engine uses up more than is in the float bowl – rinse and repeat.

There could be a variety of reasons for this – blocked holes everywhere – float level incorrectly adjusted etc – but as someone else has worked on that carb you now have consider the area to be highly suspect – which means checking everything from scratch.

Before you strip the carb down – have you tried sea foam (we call it Redex over here) in the fuel ? This will sometimes shift the blockage, but needs to be tried and run for a couple of days to work properly. You may also wish to use a fuel filter in between the tank and the carb to stop any future contamination confusing the issue.

Should it turn out to be a carb strip down situation, there are a lot of little bits in there which need to be assembled correctly – don’t presume that the last person in there got everything the right way around - we’ve had a few instances of faulty re-builds being replicated. Proceed with a high level of suspicion – after all – it doesn’t work now, so if you re-build it the same way, no prizes for anticipating the end result. The carbs on these bikes are quite small, so even the slightest deviation will stop them from running properly.

It will help a lot to state the exact year of TW, in order for others to chime in in future – there are a lot of good people on here, but we need to know what we’re dealing with …………..
 

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I would first confirm that there is a good steady supply of fuel from tank to carberator. Those fine mesh filer screens in the tank can get clogged over time, petcock can get clogged, fuel line can get kinked. This takes but a minute to disconnect fuel line at carb, turn on fuel and hopefully confirm a steady stream of fuel. While I am mot saying this is likely your problem I only suggest you test all assumptions before drawing any conclusions like "problem must be CDI or carburator". Similary intensity and consistancy of spark can be quickly tested to comfirm or set aside concerns r.e. ignition issues.
Good luck oleschool, mighty nice of you to help fix a friends bike.
Certainly the fuel additives that dissolve varnishes and flush out carb debris can often work wonders on a bike that has been sat idle for some time.
 

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Hello and welcome! I would dump the tank, flush it out a bit, add FRESH gas and a double dose of Seafoam and run it for a bit. Let it sit overnight and run it again, let the seafoam do the work. After that, you may need to take the carb off for some cleaning.
 

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Discussion Starter #6
Well,I pulled the fuel line off and there's definitely good flow coming out of the petcock.I removed the carb and all of the jets and soaked them in a degreaser I've had good results with and then blew them out as well as the carb body.I reinstalled the pilot and returned it to the 2.5 turns out it was set at.I adjusted the float height as well as the fuel level.When I ran the bike it reacted the same as before.It will idle and eventually stall.Its better than before but is still not rideable.As soon as I touch the throttle to rev it it dies.The carb is cleaned and set to the spec in the manual.There are no mods to this bike.

The only other work that was done was the stator was just replaced.It has not run since.
 

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Have you checked the carb manifolds (inlet and outlet) for cracking ?

Air filter might be worth a glance too

And when you increase from idle – the HT circuit perks up a bit – check for leaks on the HT side (plug/coil/caps/cable)

Run it for as long as you can to give the sea foam a chance to work ......
 

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If I'm reading correctly the problem started after the stator replacement. Pull the left case cover and check the the wire running from the stator. Look for abraded insulation. These wires can be pinched when reassembling.
 

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Discussion Starter #9
If I'm reading correctly the problem started after the stator replacement. Pull the left case cover and check the the wire running from the stator. Look for abraded insulation. These wires can be pinched when reassembling.
If the wires were pinched would that still allow it to run?I'm just asking.I read that there were different assemblies,like cdis for the different year of TW. Could this be a problem with the new stator?Is it possible a stator from another year was installed? How could I tell?
 

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There are two different part numbers, pre 2001 and post.

Pre, for a 2000, would be 2YG-81410-M0-00.

2001 and on is 4WP-85510-10-00.

Might want to look inside and see if the part number is on it someplace.
 

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Discussion Starter #12
I didn't check the stator part number as it seems like quite a bit of work.I have however gone through the suggestions from post #7.
1- No cracks in the intake boots
2-Air filter is clean and oiled
3-Found the plug boot resistance was 9500 ohms so I replaced it,also measured the resistance of the coil and found the primary side out of spec.I temporarily installed one from another running bike but it made no difference.
4-I can't buy Seafoam where I live.

The bike will start and idle but will only stay running a couple of minutes and stall.If I try to open the throttle at any time,it stalls.

I've had a the carb apart quite a few times and can't figure this out.

Any help would be appreciated.
 

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OK – so this is either a carb issue – or an HT issue (fuel or spark)

Can you confirm you have a strong spark at the plug when cranking it over – and when it stalls, what does the plug look like and smell like ?

Have you had the pilot jet out and cleaned it – and how many turns out is it set at ?
 

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Discussion Starter #15
I have removed all jets and can see through all the holes in them.I have blown air through all orifices in the carb body including the "bleed ports" in the circumference of the intake side.The pilot is set at 2.5 turns out.I'm wondering if the spark is too weak.I took a coil from another motorcycle which runs well and tried it but the issue remains.I've even removed the needle and seat and cleaned all passages in the carb.

While its running I've monitored the fuel level in the carb to confirm its not running out of fuel,it is not.I can hit the e-start immediately after a stall and it will fire up after a few revolutions. The new plug it black.It eventually runs without the choke but stalls the moment I apply throttle.Even trying to adjust the idle screw causes it to stall.As it is running I can feel a good flow of air thru the snorkel under the seat.


How could this be related to the ignition side of things? I'm going to do some resistance checks on the source coil and pick up coil.Could either of these be responsible for this problem?
 

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Either the heat value of the new plug is wrong — or you’re getting oil in there somehow. Let’s start with the things that don’t cost money …….

Check the foam filter oil content (wet, but squeezed out thoroughly), also you can eliminate this as a problem by simply taking the foam out completely and seeing if it makes a difference.

Spark plug heat value: - The plug you should be using is listed as

Capture.JPG

If that’s not what’s written on the side of the plug, you need to change it before going any further.

Other possibles are:
Pilot jet — Even if it looks right, it may not actually “be” right (replace jet)
Coil is breaking down resulting in weak spark (replace coil)
Fuel tank may be contaminated with oil when it was laid up (try it with a known “good” tank)

Is the exhaust smoking when it does fire up ? — this would indicate oil in the fuel (though not where it’s coming from) ………….
 

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Discussion Starter #17
I just checked the resistances as per the manual and have found that the source coil is way out of range. 50K ohms and it should be around 450 ohms.I would think this would be it.What exactly does the source coil do?

I am using the DR8EA and the fuel is brand new.The exhaust is not smoking.

I had the exact same symptoms with a temporary replacement coil,that I tried yesterday.

Unfortunately I live in a remote community where almost everything related to bikes is a special order.When I order something its usually 2 weeks or more.
 

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I just checked the resistances as per the manual and have found that the source coil is way out of range. 50K ohms and it should be around 450 ohms.I would think this would be it. What exactly does the source coil do?
Basic Operation
As the motorcycle's engine runs, a notch cut into the side of the magnetic engine flywheel passes between the source and pickup coils. The sudden drop in the magnetic field triggers the source coil, allowing a 12-volt current to flow into the CDI box. The current amplifies to a higher voltage, usually between 400- and 600-volts, and is stored within the capacitor. A drop in the magnetic field triggers the pickup coil and the capacitor discharges its stored current into the ignition coil. The current passes through a tightly wound wire within the ignition coil, called a primary coil, where it is amplified further to an excess of 10,000 volts. The final output current feeds through the ignition coil spark plug cable and into the spark plug, where it discharges within the engine's combustion chamber. This cycle repeats itself at every revolution of the engine.

How Does a Motorcycle Capacitor Discharge Ignition Work? | eHow UK

Powers the CDI basically — (took me ages to find that link) …………….
 

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And in anticipation of your next question – “where is the source coil located” – it’s part of the stator assembly.

You have two choices:
One – locate a replacement source coil and solder it in. Rex's Speed Shop - Sales 01580 880768 for example will be able to help, but I’m sure there’s someone closer to you.
Two – eliminate the need for it (go DC) - http://tw200forum.com/forum/performance-customization/4950-ignitech-programmable-dc-cdi.html

Unfortunately, both pricey ($100+) options

Might be wiser to check the integrity of the wiring first (hell of a lot cheaper) – run a continuity meter down them – I find it curious that replacing the stator didn’t work for the previous owner …………
 

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Discussion Starter #20 (Edited)
Ok now I'm confused.The source coil in my manual shows a separate unit that is held onto the stator with two screws.I just looked it up online and the only external coil on the stator is the pulse coil.The stator on this bike was just replaced.

This is a Cdn bike. Are there differences between the bikes for different geographical areas?

I posted this before refreshing my browser...hence the question after the answer...
 
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