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Comment by Shafid Khan on November 6, 2011 at 10:00pm

Thanks Ralph, you have been a big help. Looks like my prop is ok, 64 x 30 from Brent Thompson. I shall have to look into the max throttle position on the carby and the timing. When we had to remove some broken flywheel bolts, the timing may have got out of kilter. It is supposed to be 25° BTDC. The motor starts very good, runs ok but does only 2600 rpm maximum, takes ages to climb with two people. I shall keep you posted with any findings.

Shafid

Comment by Ralph Sanson on November 6, 2011 at 9:04pm

Hi Shafid, I'm not sure if I already posted on this, the standard Jabiru prop is 60 x 38 and a poor prop at that.

I fitted a wood prop 64 x 30 made for the 701 / 2200a  from Brent Thompson in NZ.

Takeoff roll rpm is over 3,000 and climbing is between 3,100 and 3,300

After fitting this prop, Jabiru issued the service bulletin and AVDAL SR050 suggesting that a portion of the 3,000 engines built to that date  may need rework to correct a design defect.

When I replaced the cylinder basenuts, it became possible to run 3,350 on climbout and 3,540 in level flight. this is not a misprint I had to fit a digital tach to be sure.

The idle setting had to be re - calibrated because it became 1,100 and made landings longer. 

 

I had to replace the Jabiru prop because it's pitch was different between each blade. It's not possible to compare one maker's sizing directly with another, and the Thompson prop is lighter and thinner (but harder) than the old. A 64 x 32 might be better if the engine is the [so called] 85 hp solid lifter version, but for a 701 it's not that important.

 

Ralph