Hi all. I really hope you can help me figure this out. I have a 2004 4-stroke DS-90 that I bought from the original owner. It worked fine, until the battery was a bit low from sitting and I jump started it. After that it only worked randomly. I took it to two different "authorized dealers" and told them what I checked and both robbed me and kept the quad for months at a time without fixing anything. They replaced plugs, CDI box, coil and stator, but condition is the same.

Here's what it does:
When I kick start it, there is no spark at all.
When I use the electrical starter, there is no spark, UNTIL, I let off the starter button, then there is a fat spark, but only one. If I push the starter button quickly in and out after letting off the starter, I do get a couple sparks but thats it. I took the switch all apart and cleaned it and nothing looks amiss. This really sounds like its getting grounded or something?

Any thoughts? I'm stumped. Its not been working all year. Even to get rid of it I need to fix the dang thing, and hate having machinery beat me!

 

Does you quad have a tether kill switch at the back? My friends had a problem with his, come to find out that the switch was not full seated properly and the real kicker was that his tether was never used.

 

There's no tether that I'm aware of, but thanks for the tip.

 

I think with a voltmeter and a wiring diagram this should be easy to solve. But try as I might I can't find a wiring diagram for a DS-90 on the internet. Do you (or anyone wlse) by chance have one?

Twice now I read about this exact same problem (one spark when the startor is turned off) on a buggy forum with chinese 150cc engines. Both problems were solved when they went messing about with the trigger pickup coil mounted outside the stator. One person said he fixed it by cleaning rust off the pickup coil and the raised plate on the flywheel that activates it. I don't believe this for a minute, but I do believe it possible that something else got moved while messing about in the area.

I'm trying to think about why you would get one spark with the starter, and no spark with a kick start. The starter draws a lot of current, and when large currents are interrupted (i.e. starter turns off) large transient voltages are generated. I'm wondering if these transients are triggering the CDI to fire once. The only paths I can see for this getting into the CDI is through the trigger input (which comes form the trigger pickup coil in the stator), and ground voltages changing (as in you don't have a good ground somewhere in the ignition circuitry).

I would look very carefully at all ground wires in the ignition wiring, and look very carefully at the trigger pickup coil wiring. If you can adjust the pickup coil so that it mounts closer to the flywheel then try that too, but be remember that there is a raised plate on the flywheel that must clear the pickup coil. On etons the pickup coil is adjustable, and the adjustment spec is 0.025" clearance (just to give you a guidline).

I'm obviously way out of my league here. I've never seen a DS-90, and haven't seen a wiring diagram for one either. But in the absence of others with more experience I thought I would give my best guess.

I'll try to find the links for the similar problems in the buggy forum and send them via private email. No guarantees I will able to find them though. It was quite a while ago, and I'm not exactly what keywords to use in the search engine.

 

Thanks for the help... I can't seem to find a wiring diagram either. The pickup would be a good one to check, but then it does give a fat spark when I let go of the switch though, so the gap couldn't be the issue there could it? I hate this electrical stuff!

 

The thing about trigger inputs is that there is a threshold. If the trigger signal is below a certain threshold you get nothing. If it is above it (even slightly) you get all of it (in this case one good spark). If you narrow that gap between the pickup and the flywheel you will get a higher trigger signal.

Your problem could still be something else entirely. I have no practical experience on this quad. I wonder if you can make the dealers who couldn't fix your quad feel quilty enough that they can give a photcopy of the wiring diagram?

 

i don't know this quad but make sure your plug wire has been replaced. it could be the problem