RE: SK ENGINES

RE: SK ENGINES
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RE: SK ENGINES - 1/14/2007 4:28:55 AM

rustypep

Posts: 342
Joined: 9/12/2004
From: Powell, OH, USA
Status: online

I will have to give that plug a shot next time. The No. 8 has been perfect in regular weather. I really don't think castor was a factor that day. The "friend" that helped me that day had an SK 50 before me and was what led to me buying one and I am happy he did. I didn't find this thread until later. I did change plugs to eliminate that possibility but with no change. He indicated similar problems on colder days and there are three of us now running SK 50's at my club. My friend had two SK 50's in a Dual Ace and it was a sweet sound. They don't run castor so the more I think about it the less I think it was a major factor. I am kind of eager now to get another cold day so I can figure out the problem or if I was doing something wrong that day. I got desperate enough that I did a pressure check on the tank to make sure there wasn't a leak and that wasn't it either and it worked fine a week later.

quote:

ORIGINAL: Ed Cregger

Slap an OS Type F in that rascal. I'll bet it stops all of that finicky behavior in chilly weather after that. <G>

Ed Cregger

_____________________________

Club Saito Member 354

(in reply to Ed Cregger)

Post #: 151

RE: SK ENGINES - 1/14/2007 9:02:15 PM

Turk1

Posts: 645
Joined: 10/8/2004
From: Istanbul, TURKEY
Status: offline

Hi, today 2 SK 50 were on field , mine and friend s I mentioned before.He used a commercial fuel today with nitro and full synthetic and mine was still with old full castor,self mixed.Bingo, his SK didnt show any issue and was flawless this time with his 3 d type plane.Very sharp maneouvers and no problem at all.Mine was great too (with revised low speed needle). Good high speed needle adjustment and good
idling.He uses OS 8 plug, 12-6 prop.I think this showed my theory is true.Unfortunately such contemporary engines has a carb design based on contemporary,synthetic oil based fuels.So, what I can see that SK50 owners should be careful on low speed needle adjustment that possibly could be the reason of leaning or even stopping on air during a certain partial throttling position and this problem sometimes can be missed on ground run test.Simply some more richening of low speed needle would solve the problem.

(in reply to rustypep)

Post #: 152

RE: SK ENGINES - 2/6/2007 5:18:32 PM

Team_Monkey

Posts: 63
Joined: 11/15/2005
From: Northeast, OH, USA
Status: offline

Hey folks,
long time lurker here. I bought an SK 50 last fall with excellent input from Turk1 here and some folks over on spadworld.net. There's a gent over on our board that has (4) SK 50's and an 80. He loves 'em.

Can't wait to get my 50 broken in, darn weather

The manual suggests an 8 oz tank for the 50 but I usually run a 10 ounce for my .46 size birds.
Do you think the smaller size was recommended off of a fuel consumption calculation? I really have a hard time believing the 50 might have a lean condition using a 10oz tank.

I've subscribed to the thread and will probably be buying a 70 in the spring for a new 60" bird I'm working on.

(in reply to Turk1)

Post #: 153

RE: SK ENGINES - 2/6/2007 5:26:30 PM

Turk1

Posts: 645
Joined: 10/8/2004
From: Istanbul, TURKEY
Status: offline

Hi,Teammonkey, welcome to community.Im sure you will love your SK.Choose your prop to load your engine about 11000-11500 RPM s on ground.Thats important.And be careful about your low speed needle not too much in before getting used to your engine.Then very reliable,very easy starting great engine you will have.I am using 10 Oz tank and even cant meet the center-carb regulation,no problem if you make your adjustments accordingly.

(in reply to Team_Monkey)

Post #: 154

RE: SK ENGINES - 2/6/2007 11:11:54 PM

Cambo

Posts: 1516
Joined: 6/20/2005
From: Phoenix, AZ, USA
Status: offline

I have got the sk 90 and I love it. It is super easy on fuel, i am getting 15+ minute flights easily with an 11oz tank, flying 3d though. It will swing a 15-6, 15-8, APC 16-4W, and soon to be tried 16-6 non wide blade.

(in reply to Turk1)

Post #: 155

RE: SK ENGINES - 2/20/2007 9:29:16 PM

Team_Monkey

Posts: 63
Joined: 11/15/2005
From: Northeast, OH, USA
Status: offline

Hey gents, question for you...

I'll be buying a .70-.75 sized engine in the coming weeks and I've narrowed it down to the SK 70 and the Tower Hobbies .75. I've 'talked' with folks who have had the Tower and we've discussed the merits of the SK engine line here. Both come very highly recommended.

I'm going for a little more speed on the next plane and I'm wondering if the SK would 'rev' like the Tower and be able to produce the same speed. The SK would fly it fine for sure but I think I'll be running a deep pitch rather than a long shallow prop.

The RPM range can't be taken literally, but the Tower is listed up to 16,000RPM and the SK is listed up to 11,650RPM. They both have the same listed horsepower, which again can't be taken literally.

So, if I'm going for speed, would the Tower be a better choice or can the SK use a deeper pitch prop at less RPM and give me the same result?

(in reply to Cambo)

Post #: 156

RE: SK ENGINES - 2/20/2007 9:38:04 PM

ckangaroo70

Posts: 2084
Joined: 10/3/2003
From: London Mills, IL, USA
Status: offline

For speed applications, your Tower 75 would probally be the best choice. For power and 3D, the SK would probally be the better choice. The SK engines really like big props, and are more comparable to how you would set up a 4 stroke of similar size. The SK would really be fine in all applications, but if speed is your thing, then the Tower 75 is probally your best bet. If someone asked me an opinion between the Tower 46 and the SK 50, then I would say SK 50 all the way! I wouldn't take another Tower 46 engine as a Free gift, but the 75's seem to be less troublesome.

_____________________________

Visit Mikes Ultra Sport info page! http://www.tesla-2.dyndns.org/~mhammer/us60

(in reply to Team_Monkey)

Post #: 157

RE: SK ENGINES - 2/20/2007 11:59:42 PM

Ed_Moorman

Posts: 3684
Joined: 1/5/2002
From: Shalimar, FL, USA
Status: offline

Think sports car (Tower) and tractor (SK). For speed, go for the Tower. For a big prop go SK.

Actually, the 3 SKs, 70, 80, 90, and their displacements are .75, .80 & .91, all weigh about the same, so for a big scale or 3D plane, get the SK 90. I have 2 of them and the 50 (actually a .525) and they have all been excellent engines for me. The .91 needs a 15-6 prop. My 2 are on an Ultra Stick 60 and a Twist 60. I could not be more pleased with them. I have only flown the Twist a few times, but the Ultra Stick is my favorite and the SK hauls it around great. That being said, I would absolutely not put it on a speed plane.

_____________________________

Ed Moorman, AMA 553, KD4QBM, Revver Bro #156
R/C Report Magazine, Fun Aerobatics Column

(in reply to ckangaroo70)

Post #: 158

RE: SK ENGINES - 2/21/2007 1:12:49 AM

PointMagu

Posts: 609
Joined: 1/29/2005
From: Cumberland, MD, USA
Status: offline

Ed,

I read RC Reports frequently and have come to respect yours as well as the other contributing editors columns. Always great info there...kinda like a "hard-copy" RC Universe, lol...

I've flown the SK50 for just over 2 years on a number of airframes but none seem to respond to it's virtues quite like the now-defunct Falcon Trading, Aerobat.

I actually had two of these, one with the TT Pro 46 and the other running the SK. The SK hauled the better of the two and appeared to be faster as well. APC 11x7 props on both.

I flattened the dihedral brace a tad and ditched the nose gear, (drag). With flaperons, the airplane flies like a rocket and lands like a feather.

I plowed the one into a dirtpile,(Pro 46) but the other flies on, and on and on. Interestingly enough, my SK50 has the serial# "0000" stamped on the port side mounting flange. It came with an exhaust extension which I'm told, is no longer available (from Kangke), nor does it have a remote needle assembly.

Everytime I fly it, my buddies laugh and tell me it's the best $49. I ever spent in the hobby!

Regards,
PM

_____________________________

Ah yes, snakes in the cockpit....

(in reply to Ed_Moorman)

Post #: 159

RE: SK ENGINES - 2/21/2007 7:25:40 AM

Team_Monkey

Posts: 63
Joined: 11/15/2005
From: Northeast, OH, USA
Status: offline

Thanks gents, that was my take on it. I've got to do a little more soul searching on the future models mission but I think little speed is in order.

I have an SK 50 now. Have yet to break it in due to the weather but here's the thread for the biplane of my design. I call it the Fun 46 Bipe. http://spadworld.net/forum/viewtopic.php?t=13180

(in reply to PointMagu)

Post #: 160

RE: SK ENGINES - 2/23/2007 2:03:26 AM

prgonzalez

Posts: 352
Joined: 6/7/2004
From: KATY, TX, USA
Status: offline

All,

I have been considering what engine to put on a GP Giles 202 of 59.5 in wingspan. I flown this plane with an OS 61-FX and this engine is not enough for IMAC. I had a TH 75 in mind before reading about SK engines. GP recommends OS FS-91-II w/pump as modelers choice. The snag is that I prefer 2-stokers for their simplicity and cost.

What do you guys think is a better choice: the TH 75, the SK 70, the SK 80, or the SK 90.

Pedro

(in reply to Team_Monkey)

Post #: 161

RE: SK ENGINES - 2/24/2007 1:05:29 AM

Ed_Moorman

Posts: 3684
Joined: 1/5/2002
From: Shalimar, FL, USA
Status: offline

Pedro,

The SK 70, 80, & 90 all weigh the same. I see no reason for buying either the lower two displacements. Really, then, we are looking at the SK 90 and the Tower 75. Both engines are about the same price, right at $100. The SK is going to turn a big prop. The smallest size prop you can use is a 15-6. A 15-4W might work for 3D. You could also try the 16-4W. Don't let your buddies or the local experts tell you they can make a smaller prop work. You can check the SK threads here-it won't work and your engine will lean out and quit. I love my 2. They are great torquer engines. One is on an Ultra Stick 60 and the other is on a Twist 60.

The Tower 75 turns a slightly larger prop than a .61. It is also noted for being pretty fast. Check in the Extreme Speed Prop Planes forum for mentions of the Tower 75. Tower has a .75 & Patriot combo I have been eyeing.

_____________________________

Ed Moorman, AMA 553, KD4QBM, Revver Bro #156
R/C Report Magazine, Fun Aerobatics Column

(in reply to prgonzalez)

Post #: 162

RE: SK ENGINES - 2/24/2007 2:53:06 AM

Ed Cregger

Posts: 7744
Joined: 1/31/2002
From: Ringgold, GA, USA
Status: offline

quote:

ORIGINAL: rustypep

I will have to give that plug a shot next time. The No. 8 has been perfect in regular weather. I really don't think castor was a factor that day. The "friend" that helped me that day had an SK 50 before me and was what led to me buying one and I am happy he did. I didn't find this thread until later. I did change plugs to eliminate that possibility but with no change. He indicated similar problems on colder days and there are three of us now running SK 50's at my club. My friend had two SK 50's in a Dual Ace and it was a sweet sound. They don't run castor so the more I think about it the less I think it was a major factor. I am kind of eager now to get another cold day so I can figure out the problem or if I was doing something wrong that day. I got desperate enough that I did a pressure check on the tank to make sure there wasn't a leak and that wasn't it either and it worked fine a week later.

quote:

ORIGINAL: Ed Cregger

Slap an OS Type F in that rascal. I'll bet it stops all of that finicky behavior in chilly weather after that. <G>

Ed Cregger

----------------------

Now that I think of it, I have had several engines that didn't want to start in cold weather. My Enya 80-4C four-stroke was a bear to start once the temp dropped below 45 degrees, believe it or not. My OS.61VF was a bear to start when cold too.

Ed Cregger

_____________________________

Artisan

"Flying models since the Fifties - I'll get the hang of this yet!!!"

(in reply to rustypep)

Post #: 163

RE: SK ENGINES - 2/24/2007 11:31:58 PM

kbear

Posts: 295
Joined: 9/11/2004
From: Denton, TX, USA
Status: offline

I'm still reading through the posts here to see if any of you guys have run into this, but I will ask as well.

I have broken in two engines in my time in this hobby. Both gave no problems. I am trying to brake in my SK 50 at the moment. The procedure says to start it at a high needle setting of 1 3/4 turns. No problem here, primed her and she started on the first flick. Next the instructions say to open to full throttle, and then open the needle until I get to a 4 stroke. I know what that means and have been able to accomplish it on the other engines I have broken in. The SK will not get there no matter how far out the needle goes. I even backed it completely out of the carb body and the engine ran for about 4 or 5 seconds before it quit. I don't want to run it too lean as the instructions say to bring it back just out of a 4 stroke to a 2 stroke. When it quit after removing the needle, it ran strong and then just stopped. It didn't speed up like engines do when they lean out and stop as when you pinch the fuel line to stop it. The fact that needle movement over 3 or 4 turns makes no difference bothers me. Any idea what would cause this? Is there a problem, or have I just been bless with easy engines to brake in till now? I check the low needle and it was set at 1 1/2 turns as the instructions say it should be. The engine runs strong and sounds great, but I don't want to ruin a nice new engine by assuming all is ok.

(in reply to Ed Cregger)