GX270 Kickback

[jshep1102]

Now I do just one question in reference to your image of the coil aglinment. Did you verified the piston was at TDC when you took the picture? I never seen a flywheel that far off at TDC.

Yes, the spark plug was out and I verified that the piston was at TDC. It really has me stumped. Do you think a new coil can compensate for the flywheel being off that much? I didn't measure it but it looks about 30 degrees off to me.

 

[StarTech]

I just wish someone would take the time to look at one their GX270 for us. I don't have one in the shop right now nor does the service manual show an image of the flywheel to coil timing but 30 degree a lot to be off by in my opinion.

 

[jshep1102]

I took a screenshot of a youtube video by Autotech (thanks Autotech) of him removing the flywheel from a GX390. It shows the magnet at about the 12 o'clock position and the piston down about 1" in the bore. With my GX270 magnet at the 12 o'clock position, the piston is at TDC. If I put the magnet even with the coil, the piston is about 1" down in the bore. Not the same engines but something is definitely different (i.e. wrong) with mine it seems.

 

[jshep1102]

Thanks to all for weighing in and giving me some things to try. Still stumped though. Looks like I need to tuck my tail between my legs and tell my friend I got my butt kicked with this one. Unless you guys can reach a little deeper into your bag of tricks one more time, I'll admit defeat.

 

[bertsmobile1]

Remember that the spark has ADVANCE so happens BEFORE the piston is at TDC
Typical advances are 25 to 35 degrees of crankshaft rotation

 

[jshep1102]

Thanks Bert. Looks like mine is advanced about that much but I still haven't figured out why it's kicking back. I put it all back together today and it started twice with one pull. Woohoo!!!
On the 3rd start, it snatched the cord out of my hand again. It's just teasing me now. Dang it!

 

[bertsmobile1]

Increase the air gap between the magneto & flywheel
This will ****** the spark
You can keep on making it wider till it stops snatching provided that it runs fine WFO blades on.
Start with double and see how you go.
The amount of ****** will depend upon the sensitivity of the coil & the strength of the magnets
It could just be you lucked in a very sensitive coil + a stronger magnet

 

[ILENGINE]

Just a wayward thought. Could the compression release return spring on the camshaft be weak and give the appearance of working when turned over by hand but be kicking out too early when cranked by starter rope .leading to kickback.

 

[jshep1102]

Increase the air gap between the magneto & flywheel...

That's a great idea! I'll try that today after my bloodmobile donation appointment. Thanks!!

Could the compression release return spring on the camshaft be weak

I wondered that myself but if I disconnect the spark plug, I can pull it over all day without any kickback. As soon as I reconnect the plug, it kicks back when I try to start it. That points me back to a timing issue.

 

[ILENGINE]

Has compression been checked on this engine. More for excessive compression not low compression Normal is 85-121 with decompress without decompress is 114-170 Also the other choice is a ignition module with a faulty spark advance.