jett 60
 

Got DD up yesterday. Jett 60 just wont run well. Tried several props and had the needle all over the place. Ran very hot and cracked head button. Top speed only 115 and that was for the first lap. Seemed to have good power on two takeoffs only to richen or lean up once up in the air. Everyone at field scratching their heads. My scat cat with a direct connection 40 and 9x7 prop beat my dust hands down. Very dissappointing.
Just got my whiplash. Was going to put nelson in it but now i am just going with a ys 45 so i know it will fly without spending hours tuning.

jett 60
 

What props, pipe, fuel & rpm were you running? Did you run the engine on a test stand before the flight? You must launch rich with the DD or you will lean the engine. Also, a Dust will turn so fast it will starve the engine of fuel, a bladder tank will help here or wider turns.

Mark M.

jett 60
 

Prop size was 9x10 down to 8.5x7.5, fuel 15% wildcat with 20% oil, rpms varied so much it was hard to get reliable readings. With pinching the line rpms would come way up and get on pipe then sag back down. With leaning the engine it would come on pipe all at once and rpms went way up but then it would lean out and fall back down. Could not get a good setting where it would run at right rpms for it to unload in the air. The pipe was made by jett and supposedly tuned for a 9x10 apc.
The head bolts kept coming loose also. I have sent them back and will see if he can help. My feeling is it wasnt broken in with the bigger props and the smaller props turned too fast

jett 60
 

I think you are right about the break in. The head bolts shouldn't be coming loose. Although the loose head bolts would cause the symptoms. Balance at high RPM's becomes critical, you might want to get the balanced spinner for this engine while it is at the shop.

Mark M.

balanced spinner
 

I had ordered the balanced spinner but dub jett said it wasnt neccessary. Maybe i should do it anyway.

jett 60
 

It will help to eliminate one possible problem. I agree, not necessary, but helpful for longevity when you are running high RPM.


Mark M.

problem solved
 

Put ys45 in place of jett fire 60. Hooking up fuel lines found tank stopper almost completely out. Couldn't tell with tuned pipe in place and it was wedged in place so it didn't appear to be loose until i was bending brass lines to fit the new engine. Could not have been holding much pressure at all, engine starving for fuel. I have never had a stopper come loose and didn't even think to check the screw. I had inspected the cap several times and it appeared to be ok and felt tight. Another lesson learned the hard way.
BTW with the ys 45 i had to add six ounces tail weight to balance. Brings it up to 3 lb 9 oz. I have a 9x7.5 prop. Will fire up tomorrow.

problem not solved
 

got email from jett about 60. They say the 60 should not be used in this application. Not designed for high rpm. It is more for pattern usage not speed. It is trashed from the few runs i put on it. Stick with the 50 or go with q500/qm40 for the dusts.