Anyone running the OS.91SZ-H PS-Hyper Engine ?

[titanlee]

Appreciate any tips.

Out of the box, ran it on 16% fuel. Lots of vibration for the first few tanks then smoothened out. On someone's advice, changed from the supplied OS glowplug to an Enya No.3 - certainly idles far nicer. But then the damn thing cut in flight, cue my first auto (n00b !!), luckily only a cracked skid strut....

kinda wish the HZ-H had been around when I bought my bits. Read some articles online from guys who couldn't get the SZ tuned right day to day and ended up ditching them :sob: thats a £190 motor !

any advice welcome :D

[titanlee]

See attached. Guess thats why it cut ;)

was producing plenty smoke and the needles are as factory settings. So must have leaned out in flight due to fuel starvation. Another motor with a pump issue ?

[GenReaper]

Looks to me like your head wasnt tight looking at the fuel stains and colour of the bottom of the head.

[mapleleafs]

CARBSMART....it would have helped....

[HeliSmith]

You need to start practicing surprise autos in the sim. If you have the function have the flight error be motor. Gotta get use to tiliting the disk to take that forward momentium into headspeed so you can sit it down nice and easy.

Nitros have a way of building your trust then flaming out, or simply running out of fuel. Go for months without one then all of a sudden zzzzzzzzzzzt "silence"


Really sorry about your motor that's a bummer.

[Mike Fortin]

You ran the motor to lean, it's not a matter of tuning at that point. You can rebuild the entire motor but it would probably be chaeper to simply buy a new one.

Get some help tuning your motor so that doesn't happen again.

The SZ pumped motor always had some issues with the pump, most of us went to the OMI Cline Carb.

[Ernie]

Time to invest in that HZ now!

[titanlee]

Looks to me like your head wasnt tight looking at the fuel stains and colour of the bottom of the head.

after I posted last night I went over the "evidence". You are correct in that the black staining on the head *outside* the seal is where the piston edge has melted. The bolts securing the head were loose to undo. Not falling out, but certainly not as I would expect.

I have read that a detting engine will loosen the head so I wonder if it was generally lean, the head loosened on that edge, leading to piston meltdown.


I can auto just fine in the sims and with a bit of height I'd be fine. Unfortunately for me on this day there were tonnes of flyers at the field so the noise from the pits and the fact the heli was the far side of the field meant I couldn't hear the motor, thus didn't hear the cut.

Ah well :)