Originally Posted by badedge540

check the back plate on the spinner and see if it is warped. mine started to anyways still cant figure out how it got that way but did

Is it a CF backplate? If so watch out. The engine heat can soften the CF and then all the prop bolts get loose and shear.

Yes t is the CF back plate.. I do pull the cone and check them often.

Ooh, sorry i was directing that towards Badedge lol. My bad.

I agree with the idea of taking the spinner and plate off and running it and seeing what you think.

It's the large heavy prop causing the thumping at idle. A better every day prop would be a 27x12 Beila. Or wood NX/Xoar 28x10. A lighter prop requires less energy to speed back up after the compression cycle.

Try a higher idle. It's only at very low idle that mine shakes. I'd never sell it. Hasn't hurt my 110" Yak air frame one bit. Fire wall is solid. Love the engine. As recommended make it lean as you can but it will still shake at low idle. Doubt it's the prop or spinner out of balance. I think a heavier spinner and prop would actually smooth it out. The inertia of the extra weight helps. Like a fly wheel.

Maybe it would improve with a different ignition that retarded the timing to around 5 degrees BTDC at idle? You might try an RCXCL ignition.

DA timing is already at about 5 BTDC at idle...

Originally Posted by Huckin Chuck

Is it a CF backplate? If so watch out. The engine heat can soften the CF and then all the prop bolts get loose and shear.

Thanks for the info. I think im going to just buy one that has the aluminum back plate with carbon fiber spinner.

http://www.mejzlik.eu/spinners/?page=2
http://www.krill.cz/shop.php?category=15&k=161

Originally Posted by Huckin Chuck

Is it a CF backplate? If so watch out. The engine heat can soften the CF and then all the prop bolts get loose and shear.

I haven't had that problem on mine after 90 flights. I think this was a problem on another engine?

Originally Posted by rick dazzler

I understand.. IMHO I feel they tried BME's approach to have the lightest most powerful engine in its class.. I have ran a few BME with the shakes as well.. I would love to have the pound back they shave off these things if it makes my airframe glue joints hold up...

This is exaclty the reason I went with a DA150 on standard muffs vs. a DA120 on pipes; close to the same power and weight, but the DA150 is much smoother.

I learned my lesson back in the day from a BME 5.8; light compact engine, but shook like Katheren Hepburn on a paint mixer!

The melting backplates are on the 150 class engines with carbon props. They heat up, and then the screws loosen up. Been running carbon spinners and carbon props on 100 class engines all year. No issues. Also been using carbon spinner and wood props on my 150 cc engine for the past 3 years. Never had 1 loose bolt.

Originally Posted by antique

DA timing is already at about 5 BTDC at idle...

I believe you Ralph, but someone on one of these forums from Australia checked the DA timing with a timing light. They reported that the DA ignition only has a very limited electronic advance. I was thinking that if the full advance at high speed was set near 28 degrees, the ignition would still be fairly advanced at idle. What have you measured for idle and full advance with a DA ignition?

Originally Posted by antique

DA timing is already at about 5 BTDC at idle...

Do you know what the norm is?

Originally Posted by Altavillan

It's the large heavy prop causing the thumping at idle. A better every day prop would be a 27x12 Beila. Or wood NX/Xoar 28x10. A lighter prop requires less energy to speed back up after the compression cycle.

You might as well put a paint stick on the front, it would be just as efficient as those. just sayin. If you can spare the money got with a Vess Stealth Series Carbon, I garuantee you will like it.