Rotax won't start and no spark issue

Chad Landers

During one of my races last year my Rotax wouldn't start whilte in the pits. Hit the button and nothing. Unplugged the battery, button, switch on/ off connectors and then it started. During the race the motor started I took off and it sounded like a lean pop and then died. Got the motor re-started a little while later and the kart ran great.

Fastforward to this week. I bought a new starter button thinking this was the cause of my no starting issue. I had one go bad before and it was like it was stuck on on the time.

Put the new button on hit the button and the startedrengaged, Hit the botton twice and thought it was going to be good.

Came back a few hours later after running some errends and getting some gas to get the motor running. Press the botton and nothing. Checked the volatage with a meter and it reads 12.7. I also have a lawn tractor tester that shows how full the battery is. This tester says the battery is full.

Checked the connectors at the button and on/off switch and they read 12.5. I grabbed the external starter and tried starting the kart and it wouldn't fire up. Pulled the plug out and it isn't getting spark.

I thought the on/off switch might have been bad so I made a jumper wire and also bought another switch at the hardware store just to try. Hit the button and nothing. Try the external starter it won't start or show spark.

So it looks like I'm not getting spark and the starter won't engage. Battery shows it is ok.

Any ideas? I will try a good known battery at the track. Being a zero loss
system I know you can't get spark with a bad battery. Only other thing I can think of is the wiring harness might be bad somewhere.

No spartk might be coil related. But if I had a bad coil wouldn't the starter at least try and engage?

Stumpt on this for now.
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Scott Grenier · Joined: 23 Nov 2002 Posts: 69

Chad, I would check the batter with a load tester. Batteries can show well static but sometimes when you load them they go to poop! If the battery is good loaded then I would replace the wiring harness...engine should still turn over even if the coil is bad.

Chris McGinley · Posted: Sat May 11, 2013 4:33 am Post subject:

Also check the starter's connector. Sometimes that gets dirty and doesn't make a good connection. Put your meter there also and see if you get voltage when you push the starter button.

Also, you won't get spark if the motor isn't turning. Not sure if you were checking it when turning it over with the external starter Question

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Chris McGinley
Monster Raceworks
Rotax Masters
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Chris Bany · Posted: Sat May 11, 2013 5:37 am Post subject:

Chad, for what its worth I chased a similar problem and once I was able to swap my wiring harness for a known working wiring harness ...everything worked great.

If possible, I would try with a known working wiring harness to at least eliminate that variable.

Good luck.

Chris

Marshall Martin · Posted: Sat May 11, 2013 4:28 pm Post subject:

Could also be a problem internal in the starter.
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Marshall Martin
LSR Motorsports
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Chad Landers · Posted: Sun May 12, 2013 8:18 pm Post subject:

Well after checking that I was getting power to the button and switch. Then getting power down to the starter with the button pressed. I ended up borrowing another wiring harness and new battery. This still didn't fix the problem.

Just as i was getting ready to take the starter off to check if the brushes were possibly causing a short a fellow Rotax racer stopped over after I was explaining my problem to him earlier in the morning. He said he had a similar problem once and told me to move this ground wire (I think it was the lower one next to the grey timing clip) to the other side of the pro speed coil bracket. Moved the ground wire and it fired right up.

Just seems odd that the kart previously ran a full weekend with the ground wire on the other side and it started up fine earlier in the day.

Thanks everybody for the help getting this thing fixed. Ended up getting a 1st and 3rd place for the weekend after getting things sorted out.
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Joe Ricard · Posted: Mon May 13, 2013 12:11 pm Post subject:

One woould think that a ground wire is the most simple thing in the world. But in reality it will kick a smart guys butt all day. Probably would have worked if you just scrubbed the contacts better. But eventually it would have resurfaced again at a bad time.

Glad you got it working. nice day of racing BTW
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Chad Landers · Posted: Mon May 13, 2013 7:40 pm Post subject:

Funny thing is I cleaned the connector and sanded the bracket and it still didn't work. But moving it to the opposite side fixed the problem.
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John Savage · Posted: Tue May 14, 2013 7:09 am Post subject: