Do I have an engine ghost?

Z

Zippster

New Member
Two days ago my dad took my bike out for a spin - and crashed it. It was your classic case of turning too sharply too fast, and the street hit back. He's okay albeit a bit beat up, although the bike hasn't been the same since. The homemade rack needed fixing, the handlebars and the mirror needed realignment, but that was obvious. When I tried to ride the darn thing, however, the engine ran for about 10 seconds then crapped out and died. It hasn't ran since.

The beauty of these little engines is their simplicity and (general) straightforwardness. Typically when something goes awry there's a defined list of possibilities of what could have gone wrong, and its not easy to eliminate the variables. Given the sudden an unexpected death of the thing, I first checked the wiring. As is the blue and black wires connect with their similar colored counterparts, and the wouthite wire is capped. The aftermarket plug wire was snapped soundly on the plug and I hacked a bit more off the end of it to guarantee a connection with the little black box (w/e you call it). There are no obvious breaks or deformations in the wiring. I've been running an NGK B7HS which has worked well for me in the past, but just to be sure I replace the dirty and oily plug with a shiny new one earlier today to no avail. I think the carb and fuel system are working because whenever I park the bike after a failed run a delicious black substance leaks out the muffler - I can only assume that the black stuff is what the gas looks like when it passes unburned through the engine, which is seemingly confirmed when the puddle grows large enough for some blue gas-oil to separate out.

:-||

I'm stumped. The engine ran, dammit, so why did it just suddenly die on me? I've dropped the bike a few times before, and every other time it sprang back to life without a hitch. My only thought is that its not sparking for some reason, or that something else is preventing ignition. The money questions is, what?

Please, help a brother out - I ride my bike to school, and to a lot of other places too, and I want my relative freedom back.

Who ya gonna call?
 
Zip,
Have you checked to see if the plug is firing? Remove it, ground it to the cylinder head and move the bike forward with the clutch engaged. You should see a spark at the plug's electrode. How hard and where did the bike hit the ground? Could it have damaged the kill switch or associated wiring? It souds as if the carb is getting fuel and could the engine just be so flooded that it can"t start? The impact might have changed your float level and you're getting way too much fuel. Unlikely but possible. Give these things a look and get back to us. We're here to help.
Tom
 
Wow that was fast - works for me!

I don't use a killswitch, so that's not it. My dad's leg broke the fall so there wasn't much of any damage to the bike itself - which is why his leg ain't feeling so good right now. I tried checking for a spark but I wasn't sure where/how to ground the plug so unsurprisingly I didn't see one. Assuming the cylinder head is flooded, how would I go about checking for and remedying it? I'll check the float however unlikely it may be, might as well mark it off the list.

Thanks
 
Zip,
If you suspect flooding, shut off the fuel petcock and pedal with the clutch engaged like the devil is chasing you for a few feet. Any access fuel remaining should be gone. Did the engine try to start with no fuel? Have you confirmed you have ignition (spark)?
Could the crash have loosed or moved the carburetor which might cause an air leak in or around the intake manifold or carb? Keep checking and get back to us.
Tom
 
I've tried my darnedest with my old new and old plugs and plugwires, and I even tried swapping the blue and black plugs to no avail. No sparks.

At least that narrows it down a bit.

I double checked the wiring, and its all connected blue to blue and black to black. There are no faults in the wires, however the wires coming out of the CDI (I think that's what its called) have a kink in them, although its unlikely to mean anything.

Which leaves me just as perplexed as before. Could the CDI or the magneto have been damaged? If so, why did it start up for a moment in the first place?

Thoughts anyone?
 
The CDI is a pretty tough little component but it is an electronic (solid state) device and susceptable to damage through shock or impact. If you're certain the wiring is not at fault then replace the CDI. They're cheap. Check here. Page Title he will have one and fast shipping too. I doubt there is a problem with the magneto. Have you removed the left side cover and inspected it and the wiring connections inside? There's always the possibility that the a wire got pulled loose. 2 are soldered connections to the mag and one, the black one is a screw connection. Make sure there is no damage there before ordering new parts. An ohmmeter will help to determin continuity if you have access to one.
Tom
 
I think I may have found the problem.

After a long and hard struggle with a stripped allen-head bolt I had replaced the kit screws with ironically so that it wouldn't strip, I was finally able to pry open the magneto cover and take a peek inside.

The moment the screw came out (it was the bottom one), some icky smelling brown water began to leak out. When the cover was off the water damage was clear - some appetizing brown stuff here and a mysterious white substance there, and plenty of rust to boot. The most obvious answer is that rainwater (it got caught outside during a thunderstorm at school (damn seniors only off-campus rules)) and the crash either coincided completely or the bike being on its side albeit momentarily was enough for whatever water had hidden somewhere within to find the sweet spot.

Whatever the cause, I think it'd be wise to go ahead and order meself a new magneto coil off of thatsdax - unless there's anything else I should nab while I'm at it.
 
Doesn't your motor have a small drain hole at the edge of the cover ?

I used to see the same thing happen with those ol' VW tail lights and some other cars too
as they would ride down the rorad at night and in the car behind them you could see the
rain water that had leaked in them sloshing around. It's nice to have them sealed, but like
anything else if water gets in it will likely not get out. Murphy's law.

The auto supply stores should have some spray's you can shoot into a wet area like an
ignition that will help migrate the water out of it and perhaps slow down the rusting and
damage.

But it's good to see this thread here so those who are new to these Chinese motors will
realize it's something to keep an eye out for.
 
Zip,
Glad you have it nailed down. eDJ is right; you might get away with simply cleaning up everything around the mag and spraying some WD-40 on things. If you have access to compressed air that will help too. If there is any sign of an oily residu inside the magneto cover there is a possibility that the crankshaft seal is bad. This will cause a lean running condition and the associated problems it brings. After cleaning things up and you're ready to put the mag cover back on, use a good grade of silicone gasket sealer, such as 'Permatex Black'. Make a gasket with it to seal the mag cover to the crankcase. Also squeeze some of the silicone into the opening around the ignition wires where they exit the case. If the crankshaft seal is leaking this will get you going, at least for a few more miles. Maybe someone here can offer some advice on replacing that seal and where to find them. I was told they are something not readily available but I have not researched this myself. Good luck and get back to us with your results.
Tom
 
When I first took off the cover the water was an appetizing dark brownish-whitish color, and there was this white crap on the side of the cover that looked like bird poo. My personal concern was that the water shorted out the copper coil, but I'm not sure. I already ordered a new mag among other things, so when that gets in I'll slap it on and see if it works.

Why would I need WD-40 to clean out the mag cover? Can I not just reuse the same gasket? I kinda got screwed when it rained 'cuz when I parked the sky gave no indication of its future mood-swing, and when it did start to pour I was stuck in class. Does the mag cover really do anything other than keep the mag safe - ie its not part of the crankcase seal or anything is it?
 
all the cover does is keep the mag dry and if moisture gets in there,theres a drain hole.
wd-40 is to dry out the mag and get rid of moisture.
without the mag you have no start or running engine.
if youre lucky,after drying it,it might start.or you will have to replace it.
seal it with your gasket and some sealer like gasket maker(dont seal drain hole at bottom) or it will happen again.
 
Zip,
The reason I suggested sealing the mag is because it is a possibility that your crankshaft seal is bad. You described a white gooey substance and that is indictative of water and oil mixing. If there is oil inside the mag cover that is a good indication that the crank seal is leaking. Sealing the magneto cover, and any openings into that area, is to keep the engine from sucking air at the defective crank seal and causing a bad/lean running condition. Keep in mind that this is a temporary repair and at some point you'll need to think about getting the crank seal replaced. The original gasket will not be sufficient to seal and that's why I said use silicone on the gasket surface and the opening where the ignition wires exit the case. If the crankshaft seal is not bad then the silicone will assure that water cannot get in there again.
Tom
 
Just now on another of my running tests using the stock magneto I had a breakthrough - a spark! One, lonely power stroke, but at least it verifies my electrical connections. I'll post again once I've tried out the en route mag.

On a tragic side note, my dad just got a call from the doctor saying that he had broken his 4th metacarpal in his hand. The fall didn't even look that bad to begin with - its frightening how easy it is to get yourself hurt on these things.
 
What would be the point in removing the muffler and letting crap gush out? Unless I shutoff the fuel supply it'll just spew crap continuously, and what would be the point?

I'll take another shot at fixing the mag - there's no loss even if I do end up screwing it up somehow.
 
I got the new mag in earlier today, slapped it on, and the bike rode like a dream. Easy fix - not so easy diagnosis. Thanks everyone for the help fixing this; it turns out it just needed that one part.
.shft.dance1
 
You must log in or register to reply here.
Back
Top