Jett QM Questions
 

The Engine has lost 5K RPM WHY?

I ran it in on a bench with an FAQ prop. 3 cycles. to break in.

Put a 7.4 X 7.6 prop on and flew it 4 times real rich blowing smoke never on the pipe.

Put after run oil in it and took it home.

Following weekend (yesterday)
Used the same fuel and couldn't get peak over 18K.

Engine when cold still sqeaks at TDC.

Any suggestions on getting the 22K back?

RE: Jett QM Questions
 

I just had the same thing happen to me last night.. Changed the plug and all was good.. The plug looked good and seemed to glow fine but obviously it was short on heat..

RE: Jett QM Questions
 

Thanks Lee..

RE: Jett QM Questions
 

I'm thinking one or your issues is your selected prop. We run a 7.4 x 7.5 Prop, 7.6 may be just a smidge to heavy?

Should peak 24 to 25 but most likely 25+ for a good motor. Launch around 22.5 to 23 with a 7.5 prop.

BTW, I am speaking in context of the QM2

Mike D;)

RE: Jett QM Questions
 

The 7.6 should spin up to 22K no problem.. Still think it's the plug..

RE: Jett QM Questions
 

take the muffler off and see if the sleeve has turned in the case. check the headbolts and retorque them. try a new plug, double check the prop and make sure its not a 8 pitch.

RE: Jett QM Questions
 

When do you take the glo leads off the plug...........the JETT is a cold engine and needs, I believe the leads on the plug until after you've needled it to full rpm- then take them off the plug.what plug are you running?Makes a difference.....suspect you're plug is the problem though.
regards trevor h:)nz

RE: Jett QM Questions
 

Trevor what do you mean by the jett is a cold Engine?

RE: Jett QM Questions
 

Dave.....takes a little while to warm up. Thats why you cannot treat/tune like a nelson, big t;)nz

RE: Jett QM Questions
 

Trevor I thought that would apply to any engine ? Warm up before needling.

RE: Jett QM Questions
 

yes Dave, but the JETT is different, TH,

RE: Jett QM Questions
 

Trevor can you please explain what is the difference of the Jett engine starting proceedure, compared to the Profi & the Nelson Engines?

RE: Jett QM Questions
 

yes, I'll show you sometime, the three engines behave very differently at the warmup stage, TH