[TW_in_BC]

So I FINALLY receive the parts I need to repair my pony...you may or may not recall that the SOURCE COIL on my ignition system fried itself two weeks ago, just before a big group ride.

Dealer had no part in stock, so it had to be ordered from Japan, and it arrived yesterday after what seemed like an eternity.



Here is a pictorial as to how it went back together. If I can do it....anybody can!

...and before ANYBODY asks if I was CERTAIN that the problem was the source coil...I'll say it again: YES! I measured the resistance at points A & B as shown...

New coil (on the left) = 700 ohms

Old coil (on the right) = 1,200,000 ohms.

Everything goes back into the same location it came from. This is what it should look like when the Stator and Pulse coils are remounted. Note the brackets that keep the wires out of harm's way. I highlighted the bolt that broke off in the case...and it didn't even have to be removed!!!!

While I wait for the loctite to set up, I move onto other points...

Here is a look at where everything goes...as well as the NEW front sprocket. When you change sprockets, make sure that you clean all the gunk, dirt and assorted crud from around the output shaft.

A look at the whole thing, including the NEW rear sprocket! I went with a 14/47 combination this time. A 6% gain in top speed, but a 6% loss of bottom-end torque as well!

NEW O-ring chain installed too. Note the direction of the Master-link clip.

About 124 links gets it to mid-stroke on the adjusters...should be good enough!

A new gasket for the crankcase cover...I smear a light coating of synthetic grease along the mating surfaces; that way, if I have to split the case in the near future (heaven forbid I messed anything up!) the gasket won't get ruined and I will probably be able to reuse it.

Just in case though...I already traced this one out on gasket-stock!

Before, re-assembling, I use some compressed air to blow out all the crud from inside the engine. She's been apart for two weeks now, so I won't take any chances.

Once reassembled, it should look like this!

Torque down all the bolts in a criss-cross pattern to avoid warping the cover. Now, I fill the engine with oil and start re-routing the cables and re-connecting all the wiring. The battery has been on a trickle charge all night, so she should be fully charged by now.

Before replacing the fuel tank, I test the ignition system for spark. Much to my chagrin, I can see none!



Was this all for nothing? Now I'm starting to get pissed!

I do a couple of other tests, try a few different plugs, wiggle some more wires...nothing. So I get right down near the engine and have a close look...well waddaya know...it IS sparking...but strangely!

There is a nice, clear spark when I first turn her over, and when I stop...but nothing in between. WTF???



Thinking that this might be enough to get her going, I replace the fuel tank and fill her with some nice 90 octane. I crank and crank and crank but nothing doing...

I can tell that she is TRYING to fire, because she turns over faster when I twist the throttle, and slower when I release it...so SOMETHING is going on...



After 15 or 20 minutes, she eventually "catches" and sputters to life. While she is running, I check around for leaks, drips, or funny smells...the rectifier seems warmer than it should be...I can touch it, but I can't leave my hand on it for too long. I assume this is because of all the cranking I did and the drain on the battery.

I let her warm up for quite a while before shutting her down to drain the oil; just in case I didn't get ALL the crud out with the compressed air!



With fresh oil and a clean filter, I try her again...still a bit tough to start, but she catches within a few seconds. I let her warm up completely before taking her for a test-drive. The new sprocket combo is nice on the street, we'll see how it works out in the bush.

Everything SEEMS to be OK so far, although I am concerned about the whole spark thing and why it took so long to get her started again. I know that these bikes NEED TO be started at least once a week...but I don't understand WHY this is.



Hope this is helpful...

 

[srs713]

Torque down all the bolts in a criss-cross pattern to avoid warping the cover. Now, I fill the engine with oil and start re-routing the cables and re-connecting all the wiring. The battery has been on a trickle charge all night, so she should be fully charged by now.

Before replacing the fuel tank, I test the ignition system for spark. Much to my chagrin, I can see none!



Was this all for nothing? Now I'm starting to get pissed!

I do a couple of other tests, try a few different plugs, wiggle some more wires...nothing. So I get right down near the engine and have a close look...well waddaya know...it IS sparking...but strangely!

There is a nice, clear spark when I first turn her over, and when I stop...but nothing in between. WTF???



Thinking that this might be enough to get her going, I replace the fuel tank and fill her with some nice 9

I'm gonna put my bet on battery problem. My old battery would seem to take a charge from my Battery Tender, and show 12.4V on a meter. It would also light up the headlamp. But it would not crank the starter.



Turns out there is a way for a battery to seem OK but have few or no cold cranking amps... it does not work under load. Any auto parts store should have a tester that will check it for you.



The reason I think your problem is battery is that when you first start cranking, there would be a short time when enough power would get to the coil to fire the plug, maybe only once. And then when you let off the button the starter stops pulling power, but the flywheel keeps going for a turn or two, and there is enough power in the system to fire the plug. If you had a kick start, it might fire up easy.

 

[PJungnitsch]

Nice pictorial!



On the not starting thing, that's where a kickstarter is nice. If mine sits for any amount of days the kickstarter will fire it up much easier than the starter button will, I think because full power is going to the ignition and nothing is being 'robbed' by the starter motor.



Mine also will show no visible spark on a spark tester when I crank with the starter, which I've never seen on an engine before.

 

[TW_in_BC]

I'm gonna put my bet on battery problem. My old battery would seem to take a charge from my Battery Tender, and show 12.4V on a meter. It would also light up the headlamp. But it would not crank the starter.



Turns out there is a way for a battery to seem OK but have few or no cold cranking amps... it does not work under load. Any auto parts store should have a tester that will check it for you.



The reason I think your problem is battery is that when you first start cranking, there would be a short time when enough power would get to the coil to fire the plug, maybe only once. And then when you let off the button the starter stops pulling power, but the flywheel keeps going for a turn or two, and there is enough power in the system to fire the plug. If you had a kick start, it might fire up easy.

I don't think the battery is the problem as it is NEW (June) and I have done a load-test on it and it passed. I can't see how a battery would have enough juice to crank it over for 15 to 20 seconds at a stretch, and yet not have enough to power the proimary side of an ignition coil.



Jungnitsch's has observed what I mean about the spark...good to know that I'm not the only one!

 

[jbfla]

TW_in_BC,



Thanks for the update and pictures.



Glad you got your TW running again.



And tracing the side case gasket is a great idea.



jb

 

[arrowsmith]

I don't think the battery is the problem as it is NEW (June) and I have done a load-test on it and it passed. I can't see how a battery would have enough juice to crank it over for 15 to 20 seconds at a stretch, and yet not have enough to power the proimary side of an ignition coil.



Jungnitsch's has observed what I mean about the spark...good to know that I'm not the only one!

In the picture where you checked the ignition coils says that the battery has nothing to do with the spark. Two seperate systems.

If the battery is weak it will not crank fast enough to start. Also both of mine start better if upright off the stand and my 03 starts better in neutral with kickstand up.

 

[peruano]

In the picture where you checked the ignition coils says that the battery has nothing to do with the spark. Two seperate systems.

If the battery is weak it will not crank fast enough to start. Also both of mine start better if upright off the stand and my 03 starts better in neutral with kickstand up.



I agree. My 2002 seems more inclined to start in neutral than with the clutch in (if its in gear). I've always assumed there was that much drag from a disengaged clutch relative to neutral. Ditto, I tend to jump to the kickstart if it doesn't fire right away on the electric. Hey I need the exercise and I'd rather not run down my battery if its just needing to get a bit more gas in the cylinder before it goes. 95% of time its off and running with the electric start, but I do use the kicker when it hesitates. Tom

 

[TW-87]

Even tough the battery is not connected to the ignition system, a weak battery may not turn over the engine fast enough to produce a strong spark. At low RPMs the magneto output voltage will be proportional to the engine speed. ( or time rate of change of the flux linkage of the coils - if you want to get technical ) At higher RPM other factors will come into play.



I have read that when charging a lead acid battery from a trickle charger, the current distribution through the electrolyte is not uniform. As a result, only a part of the volume of the battery is fully charged. This explains why the open circuit voltage may be up, but may sag excessively under load. It is better to use a higher charging current for less time in order to stir up the electrolyte (with the gases produced by electrolysis). The stirring ensures that all of the electrolyte is involved in the chemical reaction that occurs.



Even though the battery is new, two weeks at rest in a warm or damp environment may have allowed it to discharge significantly. As others have noted, the TDub does not have a lot of margin in it's design when it comes to starting.



If my theory is correct, the problem will go away with regular use of the bike.

 

[aktw200]

Fantastic, 1-Nanaimo Bar for you.

 

[SirSmighty]

Hi, I also have a firing problem on a 99 TW200 No spark from the spark plug what so ever i got the bike from a friend that said he ran the bike without a battery (huge mistake i know) so i am thinking it is the stator that has blown. I have no idea where to even start checking this bike should i start with the stator, ignition coil, CDI box? Any help would be great!