seagull extra

My Feedback: (12)

Thanx for posting your prop no's Bob. I am planing on using the 20x8 xroar as well. I just recieved mine a couple af days ago and it looks great. I comapred it to a new DL 20 and DL 50 that I have and it is very easy to see that the OS is made to a much higher standard just by looking at them. I will be putting mine in a Great Planes Patty Wagstaff so I will probably be on the upper limit for good performance with the 33cc. I have another Patty with a 50cc that I did a lot to keep the weight down to 15.0lbs. I should come in at 13.5 to 14 lbs with this one. Do you know how much your Yak weighs Bob?

coronabob

My Feedback: (10)

I'll weigh it tomorrow when I get to the field. Received Falcon props 19x10 and 20x8. Will try them tomorrow also.

coronabob

My Feedback: (10)

Flew a few more flights today. My GT33 has put all of my gassers to shame. That includes DA, DLE, MVVS, Zenoah, BME, Brison, etc. It's smooth, powerful, starts in less than 3 flips, idles LOW, super quiet, accelerates very well, very little shake/vibration. What more can I say?

My GP Yak AUW is 13lbs 6oz. Tweaked the needles some today. Xoar 20x8 was 1550 idle, 6400 steady, 6500 peak. Falcon 20x8 was 1550 idle, 6700 steady, 6850 peak. The Falcon pulled like a tractor, revved like a Ferrari, and outperformed the Xoar. Got my Falcon from justmodelprops dot com.

john josey

I have my 33 in a 70" yak and it's superb, huge 400" loops, unlimited vertical rolls, just a pleasure to fly. It's great not needing tolug a flightbox with heavy starter around, just the model, TX and a can of fuel. It fires on the third flick with the choke on and runs on the third flick with it off. Because it's OS, it will outlast the other chinese engines by probably two or three.

seagull extra

My Feedback: (12)

Great prop info Bob. Looks like the xroar 20x8 is a little too much for it. I like the looks of the xroar sword props so I might try a 19x8 or a 20x8 carbon falcon. In Canada the same guy sells xroar and falcon props. It looks like the 33cc Patty will weigh about 1/2 to 1lb more than your Yak so vertical performance should be close to your Yak. I am looking forward to my next Patty build and using some of the new tech today to keep the weight down that was not available when I built my 50cc Patty.

MTK

Give the new engine a chance to break in. The 20x8 xoar shouldn't be a problem. Let me also suggest you try the APC's. You'll need a stick to turn it by hand but that's no biggie (trailing edge istoo sharp for finger work). If I recall, the Falcon carbon in this size range are APC copies, so performance should be similar to the APCs. Except APC's are 20$ and are very quiet. Get their PN type....

BTW- the engine takes around 50 flights to fully loosen up. You'll be able to tell when you turn it over; bearings and ring will give practically no resistance. You should pick up another 100-150 rpm give or take. But even tight, the engine is a stump puller; I really don't think you will have any issue hauling a 15 pounder around with this engine.....

coronabob

My Feedback: (10)

A couple of shots our club's instructor/safety officer, James Lemon, took of my GT33 powered GP Yak. The back drop is some of the facility at the Johnson Space Center in Houston.

john josey

Now ! that is a lovely colour scheme for a yak !!!

I disliked the colours my own yak came in that much i peeled it all off and re-covered. the first pic is my yak next to a friends which has the original colours.

wyo69cowboy

My Feedback: (2)

How's the vertical/hover performance? I'll bet that makes a nicer setup on that plane than the 50/55's most guys used to stuff in them...

MTK

Just realized that you are in Friendswood.30 years ago I lived next door in League City. I know the JSC well....

ameyam

So how does this engine compare usability wise against the dle30?

Ameyam

coronabob

My Feedback: (10)

Copied and pasted from my previous post:

Flew a few more flights today. My GT33 has put all of my gassers to shame. That includes DA, DLE, MVVS, Zenoah, 3W, BME, Brison, etc. It's smooth, powerful, starts in less than 3 flips, idles LOW, super quiet, accelerates very well, very little shake/vibration. What more can I say?

My GP Yak AUW is 13lbs 6oz. Tweaked the needles some today. Xoar 20x8 was 1550 idle, 6400 steady, 6500 peak. Falcon 20x8 was 1550 idle, 6700 steady, 6850 peak. The Falcon pulled like a tractor, revved like a Ferrari, and outperformed the Xoar. Got my Falcon from justmodelprops dot com.

The GT33 makes my two DLE30s look bad. I paid $360 for mine with discount from Tower. The muffler alone is worth the extra $50 over the new DLE 35.

wyo69cowboy

My Feedback: (2)

+1 on the muffler!

coronabob

My Feedback: (10)

MTK,

The JSC club boasts a brand new black top runway and it is LONG. Keep us in mind when you come visiting. I can get you a pass onto our field.

MTK

Cool....thanks!!

rstekeur

BarracudaHockey

My Feedback: (11)

Best thing you can do is read through the manual.

Mine ran ok at factory settings. There's also an extensive tuning article as a sticky I believe.

coronabob

My Feedback: (10)

I offer my own experience. First off I did not check the screw on my throttle arm and it vibrated loose on the very first run. Took care of that easily but was surprised how it came from the factory loose. Luckily that was the ONLY thing negative I found about this engine.

It pulled fuel almost immediately. After three flips at full choke, full open throttle, ignition off I turned on the ignition and a couple of fast flips it started backwards. I opened the throttle a little and that helped eliminate most of the backwards starting. I did not change the needles and flew a couple of flights. Started adjusting the needles and got it rich mostly. It still ran ok at rich settings. I leaned out both the low and high after 4 flights.

I am now getting 7100 wide open with excellent throttle response on 20X8 Falcon wood. The handling could not be better and the sound superb. At idle, it sounds like a clean combustible pump that it is. I think it is unique in that the throttle response past idle can be compared to having a large negative expo setting. I have to move the stick quite a bit to get the same speed I would with other gas engines. It might be my linkage, which I do need to check. I might have to dial in some positive expo on my 12FG to see if I can get a linear throttle response.

I plan on buying another one. At $360 at Tower with club member's discount it is a steal in my opinion. Full price is $420 compared with an OS 120 special (glow) at $330.

rstekeur

That's how I got mine with the discount plus there was a $30 rebate that I sent in. That's about where the price should be. I have a dle20 and the OS looks like a nicer quality motor. When I started it up last sunday going to full throttle the rpm would start to drop and it was getting late so I put it off untill this weekend.

MTK

CoronaBob nailed it...

One thing I will add is that low speed needle setting when leaned too far (true with most any gassie eventho the engine idles fine) will cause the engine to die lean when advancing throttle quickly. I found it to be a very reliable check for lean LS needle. When you find that point, it takes a little more than 1/8 turn rich to transition clean

As CoronaBob stated, to start, get the engine set to high idle to minimize reverse starts. It starts by hand fine. Except I use sharp APC props on mine so a Dynatron starter does the job for me. I'm turning the Dynatron with 6S lipo, 2300 ma. One charge lasts about 6 months

WindGap

My Feedback: (3)

Coronabob, many guys are putting dle 55 into that YAK. Does the OS GT33 have enough juice to fly 3d or just sport? Also, did you have to add nose weight with this engine?

BarracudaHockey

My Feedback: (11)

Yea Matt, there's no way I'd be sticking my fingers near an APC, they might as well call them Ginsu props.

Ken Cz

Does anyone have source for prop bushings (metal) to make up the difference between the GT33 8mm dia. prop shaft and the more common 10mm hole in most gas props like Xoar, Mejzlik, etc??

Thanks!

rstekeur

I asked the same thing and was told to wrap a few wraps of tape so it's snug enough. Thats what I did, and it's been fine. If you find any bushings, please post a link.

JoeMamma

Hi Ken,

Give Matt a call at the Prop Shop. He's been able to fix me up with an adapter bushing a number of times.
Where do you fly at ?

Joe M.