Iflyglow

My Feedback: (79)

You can get a Magnum .46XLA for $59.00, or a Magnum .52XLS for $69.00, and not have to mess with carbs to make them run. They run just as good, if not better than the $139.00 engines. Whhy take a crap shoot on a $10.00 savings?

jeffie8696

My Magnum XL46A ran no better,carb was just as bad.

Conrod

What is squeezing the spray bar down to decrease the slop doing for the carb?
Geoff

Iflyglow

My Feedback: (79)

Are you talking about the older magnum. The XLS's that have been out for years run awesome.

jeffie8696

Ibelieve decreasing the size of the bored hole through the spraybar causes the fuel flow to be stemmed properly, it seems there is too much fuel getting past the needle. And the notch mod drops the vacuum signal on the spraybar so less fuel is sucked into the engine. The only down side is sometimes the engine doesnt want to shut down by the throttle.

Motorman my point is that not every manufacturer makes every engine perfect and (in my opinion) Aviatronics is being bum rushed because of the carb issue.
I have never seen the plating peel in any of my Aviastar engines and they have been abused I assure you. Despite the torture testing my original dyno mule still has excellent pinch!

Dont know if any of you have worked in manufacturing but there is the way the engineering department wants something done, then there is the way the manufacturing department wants it done, and then there is the way the machine operator does it. They dont always agree.
Quality Control usually gets in the middle of everything and in my experience, comes up with a solution.

Conrod

Hi
Interested in how you reduced the spray bar outside diameter and therefore internal bore diameter?

jeffie8696

Ijust sqeeze it down very carefully with a jacobs chuck.

MetallicaJunkie

if you use it stock it is....i had to take a carb off my 55ax for it to run good

Jav409

Ok After a little mesuring I found the OD of the .46 carb to be .550 and the IN to be .330 Perry makes 2 carbs that may work. ( I luv perry carbs have them on three engine ,easy to adjust and instant transition.) the model 1401 which has a .312 Id and the hi po model
4400 which has a .340 Id. Which do you think would give the best performance. Understand I am not having any problems at this time with the factory carb. I am just partial to perry's.

gmccord1970

Jeffie, I just ordered my Aviastar .46 and I hope it is as trouble free and powerful as you say. Didn't these engines have problems with their carbs at one point?? I also heard the needle valve point was rather blunt. Do you know if Sig fixed these problems???

What do you suggest for break-in?

-Geoff

jeffie8696

These engines have a very heavy pinch so heating it up with a covering gun will do it a lot of good. The carb problems persist , it is just luck of the draw if you get one that wont lean enough at idle. If you do it is no big deal you just call SIG and they will have you send the carb to them for repair. The carb you get back will be fully tested too. No other major problems have been reported, Ithink you will find it a really stout engine.

gmccord1970

Hi David,

Sorry to hear about your Aviastar problem. I'm waiting for mine to get shipped . This is just my opinion, it sounds that 15% nitro may be too much for a #3 plug. Jeffie mentioned that Aviastar's like hot plugs but as a rule of thumb, the higher percentage nitro you use, the "colder" the plug should be generally speaking. If your engine is overheating you may want to drop your nitro percentage to perhaps 10% or 5% or use a #6 or #8 plug. I have found that my magnum engine runs best on a #8 plug with 15% nitro. BUT....(and that's a big BUT) Aviastars are not the same as Magnums and comparing the two is like comparing apples to oranges. Good luck! Let me know how it turns out.

-Geoff

gmccord1970

Hi Jeffie,

Well, I ran 2/3rd of a gallon of 10% castor/synthetic blend Byron fuel through my Aviastar .46 and I think it is STILL breaking in. However, I was able to turn an 11x7 prop and crank out 11,000 rpm. Definitely a powerhouse engine! But....still having problems with idling and transition I have to fly my bird with a high idle because a lower idle just causes the engine to get bogged down and then when I throttle up it just quits. Hesitation in the transition to WOT makes me think I need to adjust my lower end needle more lean. Anyways, I'll wait a few more tank fulls before I start messing around with the LEN.

-Geoff

HangarRash

Geoff,

I had the same issue with my Aviastar .46 out of the box, but now it's a great throttling and very powerful engine, and
one of my favorites in it's class. I filed a little groove in the carb barrel just like Jeffie shows in post # 10 in the following thread:
http://www.rcuniverse.com/forum/m_86...tm.htm#8607023
If you have that magazine, it goes into a little more detail - and it only took five minutes to really transform the engine!

jeffie8696

GMC
Have you adjusted the low speed needle from the factory setting?

gmccord1970

Nope, not yet.

jeffie8696

Well, there ya go.