Hi all,need some help,I've not familiar with this engine.Polaris Hawkeye 300 quad,single cylinder 4 T,starting good,but extreme detonations in exhaust when trying to accelerate.Customer says,problem came from one day to next,everything is stock,no modifications.I have negative ???12volt pickup signal,first spark occuring at 90deg BTDC!!!,2nd 12deg BTDC(it's ok)3.rd 246deg ATDC and 4.at 305 deg ATDC.I'ts constant,not seems to be the flywheel is moving,Maybe it's not the problem,but if yes,I can't figure out why good for this engine one spark 90 degrees before TDC,when the piston is moving upwards and valves are closed :o :o :o

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Put the photo you had on Facebook showing the 720 degree markers.

Clearly the problem is wrong breed of dog

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timing specs

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Here it is. Not sure how it will look on here as its from Facebook. It looks like the exhaust cam is advanced to me.

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Can you post up the data file so I can have a play? I personally would not put too much on the cam timing as of yet. In my experience its pretty hard to go by the phase ruler markings on a single cyl engine due to the variance in crankshaft speed when cranking.

What is used as a trigger such as a crankshaft sensor?

It seems whatever is on ChB has a defect.

Spence wrote on Aug 11^th, 2018 at 6:45pm:

What is used as a trigger such as a crankshaft sensor?

+1`

But it sure looks like a physical problem to me.

I would suggest it has a single point trigger wheel to know the position once per revolution which triggers the spark once per revolution where the timing is controlled by the ignition module.

Thus the waste spark

Something is physically causing a second trigger on the wheel, damage metal debris or the like I would think.

The pickup waveform looks wrong. It is a VRS sensor so should be a sine wave.

James H wrote on Aug 12^th, 2018 at 8:06am:

The pickup waveform looks wrong.

It sure does but I am not familiar with this vehicle. If the original poster does this for a living then taking a capture from a know good would put this thought to rest.

If not then looking at what triggers this sensor as well as the sensor, wiring and anything that could induce a signal into the circuit would be my next thought.

Does this engine have a mechanical compression release that is malfunctioning.

StitchB wrote on Aug 13^th, 2018 at 4:31am:

Does this engine have a mechanical compression release that is malfunctioning.

Always thinking Larry!   [smiley=thumbsup.gif]

Logic wrote on Aug 11^th, 2018 at 3:26am:

Clearly the problem is wrong breed of dog

Off the Subject, but found this from ancient history. A picture of myself with this scout dog in VN, I was thin and had more hair. You and Spence should find this to be the right dog as I have heard.

Spence, have Mick bark if he approves.

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StitchB wrote on Aug 13^th, 2018 at 4:37am:

Logic wrote on Aug 11th, 2018 at 3:26am: Clearly the problem is wrong breed of dog Off the Subject, but found this from ancient history. A picture of myself with this scout dog in VN, I was thin and had more hair. You and Spence should find this to be the right dog as I have heard. Spence, have Mick bark if he approves.

I hope they supplied you with mags!

Like the dog! What was its name?

Mick says hi.   8-)

Yeah, no webb belt in the picture. I used an old claymore bag to carry mine in, usually about 30 mags if I could get them.