Conrod

cloudbusters
what fuel and glow plug are you running?

Turk1

Gentlemen,I have found that the problem(if there is)is mostly not engine itself but carb faults.If a new or used engine is having running problems then the carb is the problem and you should remove all parts,cleaning, o ring fixing and carefully reinstalling all parts generally solving the problem.I have discovered that on a classic 2 needle carb,mostly fuel leaks (not air) at low throttles around the spray bar unit instead of spray bar only.This is misleading to wrong low speed needle adjustments and faulty running.So that system must be fixed carefully.

bigedmustafa

My Feedback: (2)

I tried to take the plunge and try an Aviastar .46 engine, but I'll have to try again later.

A buddy called me up and asked about buying one of my old engines for a SPAD he was building. I told him that, if he wanted a good engine on the cheap, Sig had new Aviastar .46 ABC dual ball bearing twin needle 2-strokes for $49.99. I also mentioned that we could get free shipping if we bought three or more ($150 minimum) directly from Sig. He said to order them up and he'd take one and another buddy of his would take the other.

I ordered up three Aviastar engines on Tuesday, and Sig had them on my doorstep on Thursday. I called Darren and Chris to tell them their engines showed up and I'd take them out to the field with me on training night if they wanted to stop out and get them. I set the engines out on the table and several other pilots came over to check out what I had in the cool-looking black boxes. Naturally, one of the other pilots wanted one too, so I sold him mine.

Maybe I'll get to keep one next time.

NM2K

My Feedback: (14)

I should buy an Aviastar and give it a whirl.


Ed Cregger

James c harrell

My Feedback: (18)

Well, since I started this thread I have had carb problems with my 53. I had the engine on my SR-71 by fly-boy models. I finally found a MDS carb that fit correctly and that did not have the spray-bar with the slit in the bottom like the Aviastar did. What I ended up with was a fantastic running engine. More speed and power than I have ever seen on this plane and, as it turned out,more than the plane could take. The last low pass was more than the elevator could take and it bellied in at better than 100 MPH. Didn't hurt the engine though. Think I'll stay away from pushers for a while. Time to find a new toy. Still think these engines are power-houses just need to find a plane that will take it.

jag215

I recently replaced an old FP 40 with an Aviastar 53 on my LT-40. Today I finally flew it. Wow! What a difference in power. The LT-40 took off in about 1/3 of our runway when it use to take almost all the runway area with the fp40. The fp40 would fly the plane,but this .53 made a big difference in the LT's capabilities. Couple of problems I need address on the engine. I had to add a lot of nose down trim to the airplane (all I did was swap the engine from a good trimed plane and it seems to balance O.K.) and the engine did not seem to transition well from low power to full throttle. It seemed to hesitate or "Burp" abit before the rpm's came up. Didn't quit on me which was obviously a good thing,even though I though it was going to dead stick a couple of times when I changed throttle positions. Any suggestions. Thanks jag

bigedmustafa

My Feedback: (2)

I got a chance to help one of my buddies break in and fly one of the Aviastar .46 engines I ordered last week from Sig. The engine turned an APC 11x5 prop at 12,600 rpm right out of the box and idled well. We ran one tank through the engine on the ground and then put his plane in the air.

Unfortunately, the new Buhor SPAD trainer that he mounted the engine to suffered from elevator flutter on its maiden flight. The plane went in fairly hard and the carburetor was busted up pretty badly in the crash.

This engine looks like a winner; the $49.99 sale price is simply icing on the cake.

ProBroJoe

Well, ummmm, Duh! ;-) I love the .40 FP for it's handling, but it's no powerhouse by a long shot! Hopefully you're not propping that '53 the same as the ole .40... The '53 will happily swing a 11x7 or 12x6 with authority while rewarding you with an engine that's almost as quiet as the FPs....

Assuming you've done all you can to tune the low end, it sounds like the classic Aviastar carb problem. Sig has been really good about honoring the warranty on these things, so give 'em a call and they'll hook you up with a good carb. If you can't wait, the "forty size" Super Tigre, Perry and other carbs work really well.

Hope this helps,

-Joe

jag215

I have been flying for many years now, all trainers with .40 size engines, so the jump up to the .53 was an experience for me. I have a 11x6 on the .53 now. Would the 11x7 be a better choice for my engine/Aircraft combination.

ProBroJoe

An 11 x 7 would be nice if you want a bit more speed, but a 12 x 5 or 12 x 6 would be the ticket if you have the ground clearance. You'll give up a little top end, but it'll yank that plane off the ground even quicker, but slow down nicely in the dives and on landing...

I'm told the Aviastar .46 & .53s are designed to swing a bigger prop (at a lower RPM) than typical sport engine in an effort to keep noise down. As long as you're propping for around mid 10's to mid 12s, that engine should be happy - the rest is all up to your personal taste and flying style.

Obviously your plane flew well with the .40 FP, so why not have some fun with your newly found extra power?

James c harrell

My Feedback: (18)

If you are still having carb problems talk to Bob at Sig. Alot of the time he can help on line and they are excellant at taking care of their customers. Sent my carb to him and had it back in less than a week and a half. He said it was fixed . Now just got to find a plane to put it on cause The ground ate my other.Ground said it tasted like chiken. Can't remember the address for Sig but it's on this tread somewhere.

jeffie8696

SIG Manufacturing Co., Inc.
P.O. Box 520
401-7 South Front Street
Montezuma, IA 50171-0520
641-623-5154

wyo69cowboy

My Feedback: (2)

Well, it looks like I got one of the ones with a bad carb; started trying to tune in the low speed on about the third tank on the test stand, and ended up getting the low speed needle turned all the way in. Still won't hold an idle for more than about 15 seconds before it loads up and dies. Transition was getting better; using an OS 8 plug, and 15% Morgan fuel that is the castor/syn blend. Put in a call to Bob at Sig today; hope to hear back. Would like to just exchange the carb if that's all it really takes. Motor seems good otherwise; running an 11x6 APC for breakin, and by the fourth tank, had leaned it down and was getting 12,600-12,800, which seemed pretty good for my elevation (5000')

ScottMcM

My Feedback: (66)

I got two of the 46's to put on a Top Flite Cessna 310 that I got on a trade. Broke them in this morning, and I'm happy to say that they are both running great...top end, bottom end, and transition! I'm running a Master Airscrew 11x7 prop, 5% Omega, and a Fox R/C long plug with idle bar. Next, I think i'll fly them on a "more forgiving" plane for a while before i commit them to the Cessna. If they do well, then they'll go on the Cessna. I almost didn't buy them because of the carb problems that I've read about. I e-mailed Sig, and Bob assured me that only about 5% were causing all the problems. I'm glad I took a chance.....heck, I might even buy a couple more...hard to go wrong with a deal like that

ScottMcM

My Feedback: (66)

Looks like I spoke too soon. I mounted one of the engines on the Sig SSE, took it to the field and could not get it to run right. The low end screw is nearly all the way in, and it still floods out after about 15 seconds at idle. Transition is horrible, if at all. It mostly just quits when the throttle is advanced. Strange....the only difference was that on the test stand, it was laying on it's side, and on the plane, it was upright. Everything else was the same....fuel glow plug, etc. I'm gonna put the carb from the other engine on it and try again.....

ProBroJoe

These ongoing carb problems are going to be the death of the Aviastars... shame too, with a good carb they are sweet running engines. Can't blame Sig, as I know they've been bustin' their hump in an effort to get this problem taken care of...

-Joe

ScottMcM

My Feedback: (66)

I wonder....will any other carb fit, say a Perry, or an OS, or..........? Carb throat OD looks to be 17/32, measured best I can with a ruler[]

ScottMcM

My Feedback: (66)

Looks like a Perry 1600 might fit.....

wyo69cowboy

My Feedback: (2)

I did receive another carb for my Aviastar .53 from Bob at Sig; definitely much better than the first carb, though I was still having some trouble with the transition. Got it idling pretty good; just a little rough in transition. Had about 8 or 9 flights on it in my Phoenix Decathlon, so about another 1/2 gallon thru it with the new carb. Unfortunately, dirted that one in 2 weeks ago on a hot 85 degree day when a slow pass into a vertical for a stall turn turned into a spin. Bye bye Decathlon []. I need to check the crank, cuz it hit straight in, but overall, not a bad engine for the money. I may try the carb off my old OS .50FSR when I get it going again for giggles.

ScottMcM

My Feedback: (66)

I think maybe I'll just get a couple of Saito 82's.....would rather not have an engine out on the 310[X(]

jeffie8696

If Ican not get a carb to work Iwill replace it with a Thunder Tiger carb from a Pro 39 that Ihave a few of. Ihave helped out a few members that had engines out of warranty and needed a good carb cheap. You loose a little off the top end but the idle and transition are so much improved everyone says it is a great trade off. As long as you are propping to use the torque of the engine instead of the rpms you will probably never notice.
Often people do not understand how to adjust a carb and did not even read the manual, not to say anyone here is doing so but it has come up before. These engines are also a chrome bore high quality number and take several tanks to break in properly. I would not even bother to try and adjust the low end until you have a good 20 oz (or more) of fuel run through it.

NM2K

My Feedback: (14)

No, increasing pitch on the 11" prop mounted on your Aviastar 53 is going to cause even more aggravation with your model's pitch trim, as you described when switching from the OS .40FP to the Aviastar .53. The Aviastar can handle the extra pitch with ease, the problem is your type of trainer (flat bottomed airfoil, IIRC) cannot.

Remember the old Bridi/Great Planes Trainer 40 & 60 kits with the fully symmetrical airfoils? They would absorb the extra power easily without you requiring ongoing flight trimming sessions every time you take off.


Ed Cregger

MetallicaJunkie

I say yay, i put a carb from 55ax that i had lying around and it runs incredibly good

faulknej

My Feedback: (9)

After trying the 46 and 53, I have to say NAY. The 46 has never landed running, dead stick on every flight. Ido most of my flying around 1/2 throttle, and every time I increased it after flying at half, it would quit. That's after getting a new carb back from Bob.

The 53 is a total dissapointment. During the breakin, on the second tank, the rod bearing let go, poked a hole in the bottom of the case. I've had enough, I'm not even going to send it in for warranty.

MetallicaJunkie

the stock carb is crap.....it is the worst carb i have ever dealt with...no matter what , i could never get it adjusted right..... i remembered i had a carb from an OSX55, and it ran like magic.... Good motor bad carb