Hello! Rotax 503 help!

by George Gallagher in 2 Stroke Technical Questions 13 years ago

Hey everyone, I am new to the forum, tyring to learn about my Rotax engine. I have a 1986 SCAT hovercraft with a twin cyinder Rotax 503. It has no battery, it is the newer style engine with the external mounted coil, and CDI box. Well my issue is no spark! I tried new plugs nothing. I tested with an ohm meter the coil, plug wires, light coil, magneto? (piece in the engine, with three wires coming out, and a plug that goes to the CDI box. Everything seems to be fine, only thing I do not know how to test is the black CDI box itself. thoughts? Help? info? Wiring diagram would be great also. Best place to get cheap parts?

Hope someone can help.

Thanks so much.
George

Re: Hello! Rotax 503 help!

by bill martin » 13 years ago

bill martin

10 757 0

George,

You can download the engine manuals, which will include the wiring diagram, on this site. Go to the SUPPORT tab at the top of the page and click manuals.

Parts are plentiful from many sources such as Lockwood Aviation, LEAF, California power systems, to name a few.

If you are trying to hand crank the engine, you may not be able to see the spark unless it is dark or in a darkened room. When cranking, the spark is not bright like an automobile spark, and you have to hand crank vigorously (200-300rpm) to get any spark at all.

If you go to the California Power Systems 1-800 airwolf website and look under the tech info tab for tech articles, there is one article titled "troubleshooting the CDI ignition" (or something like that). It will give you the resistance values for checking the black box.

One other thing you might check is to make sure the ignition system is not grounded somewhere. The grounding circuit is the only quick way to stop the engine and if the circuit is grounded you will definitely get no spark.

Bill.

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Re: Hello! Rotax 503 help!

by George Gallagher » 13 years ago

George Gallagher

1 2 0

Well actually I figured out the problem, it was the CDI box was not working. Now I need a replacement. The numbers on it are Nippondenso, 070000-0770

Best place to get one?

Thanks
George

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Re: Hello! Rotax 503 help!

by Geoff Storey » 13 years ago

Geoff Storey

7 33 0

Hi George you can look here for a replacement http://www.ebay.com/itm/CDI-Module-for-Rotax-with-Nipon-Denso-ignition-fits-582-503-447-277-others-/261085688234?pt=Motors_Aviation_Parts_Gear&h.
hope this helps.
cheers Geoff.

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Re: Hello! Rotax 503 help!

by George Gallagher » 13 years ago

George Gallagher

1 2 0

I actually was able to use the CDI box off the 277 motor. New problem now, getting the motor to actually run, it kicks and wants to, but won't run. Weird thing is I unhook both fuel lines to each carb, and that is when the engine tried, and seemed to try and start the best? I do not get it.

I guess my next step is pull carbs, clean real well, and take apart the fuel pump and clean that up, and see if that helps.

thanks george

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