I have a OS .46 and i am having a hard time getting it tuned properly. I was wondering if somebody could give me some tips. My 1st plane was an Hangar 9 arrow and that Evolution engine ran great without any adjustment. Therefore i have zero experience with tuning engines

Thanks

Geoff

What part are you having trouble with? High end or idle or both or transition from idle to high?

Take a look here: http://www.masportaviator.com/fh_prifly.asp

Scroll down to the bottom and they have a section for engines. "Engines 101 - Part Two" talks about tuning and break-in. That one is here: http://www.masportaviator.com/ah.asp?CatID=8&ID=47

Hope that helps a little!

The advice here is good. I'm just responding to point out that this is my objection to these engines that have adjustment restrictions : You don't get the tuning experience. Thank you for illustrating my objection.

Best wishes,
Dave Olson

If his OS 46 came perfectly tuned right out of the box, how much experience would he get?

Maybe all mfg should deliberately ship their engines mis-tuned?

So true. The evolution has a roll pin through the high idle adjustment so you can only turn one complete turn they advertise that you can not detuen it to the point where it won't run well. Thanks for the links, and good point Bruce i am going to take some time to play around with the engine. Also as per instructions it is mounted upside down will that have an effect on the engine?

Thanks,
Geoff

You will get arguments from some about inverted installations but with proper tuning and installation you should be fine. Tuning MAY be a little more touchy.

Gracias Amigo!!

Geoff

I also have another question. I dropped my trainer when i was working on it the other day and busted off the the mount where the high idle mounts to the engine(damn cement hands). It also broke the intake fuel nipple off. So i CA the spray bar back on and because the threads are different on the fuel nipples between an OS 46 and the evolution .40 i pilfered the nipple off the Evo muffler for the spraybar and mounted an OS muffler that i had. Now i think that i am building to much pressure in the fuel tank because after removing the rol pin and turning the high idle needle all the way in it still barfs fuel and just bogs when i try to rev it up. Does that make sense or should i be looking for something else.


thanks

Geoff

I'm having trouble with your terminology here.

Are you saying you broke off the hi speed needle valve bracket from the back of the engine?

Are you also saying you broke off the fuel line fitting that goes into the carb?

After that you talk about CA'ing spray bars and I'm lost there.

I don't see any way you are going to over pressurize the tank though, you must have a leak if you have fuel squirting if that is what you are saying.

Which os 46 do you have AX or LA

I beleive he is talking about the bracket. Maybe his LHS may have them.

I also beleive you are correct here Bruce. I'm pretty certain he means he broke of the fuel fitting at the carb. If thats the case, his LHS may also have them if he can get the old one out.

If he means the spraybar inside the carb, that's a bad thing and if it is that and he CA'd it in he will have no low speed adjustment at all if it's the AX or and older FX. I'm thinking new carb and bracket. Funny I actually think have a spare OS46AX needle valve assembly without the bracket because I did the same thing on my 4*40 last year.

sounds like also a fuel line to the tank might be sticking or crimped or even submerged in fuel,also check for a muffler restriction at the exhaust.i have seen people take the baffles completly out...happy flying

How would a fuel line "stick"?

What fuel line might be submerged and what harm would that do?

Soprry about all the confusion. Let me try to explain a bit better. The bracket that mounts the high speed idle adjustment to the back of the engine broke off and the fuel nipple going into the the adjustment peice broke off as well. I was able to get the remaining piece of the fuel nipple out and replaced it with the nipple from the muffler. The reason i did this is that the threads are different from an OS to and Evo. So i glued the broken piece of bracket together and took off the Evo muffler and put on an OS muffler i had so that i had enough nipples for all the hoses that needed to be hooked up. However i am having problems with the engine now as it will idle pretty rough and as soon as i increase throttle it bogs badly even with the high idle adjustment screwed in all the way. is that any better?

Geoff

my local hobby shop does not have any fuel nipples for Evolution engines in stock and it will take several weeks to get one. Also none of the fuel lines are kinked.

Geoff

sorry just some more info.

If the high speed needle is screwed all of the way in, you should be extremely lean at high end and the engine SHOULD die. Open the high speed needle about 1-1/2 to 2 turns and see what happens there. Open the carb slowly at first until you get the tune closer to correct.

BTW - yes, that description make a lot more sense. KLUTZ! Sorry, had to throw that in.

Is it possible that the OS muffler is pushing more air into the fuel tank than the Evo muffler did thus pushing more fuel than needed into the engine causing the bog out? My LHS said that a 46 muffler is a 46 muffler is a 46 muffler (no diff) as far as stock mufflers go.

Geoff

NO! At least not enough to matter. Your problem is in the needle valve area.

If you think the mixture is too rich (too much fuel) do this.

Start the motor and advance the power as far as you can without killing the motor. Careful take a pair of needle nose pliers or similar and pinch the line between the main needle and the carb slightly. If it is too rich it will speed up as you force the mixture to lean out by starving the carb but I am betting you will only kill the motor as it is too lean already. You said in your first post (post #9) that you closed the needle. How do you expect it to run without fuel? You are getting a little fuel because of the idle mixture but it won't run past about 1/3 throttle at best will it

Thanks Bruce i will monkey around with it some more when it get home tonite.

Geoff

I have an O.S. 46 LA engine and I have had the fuel nipple that goes to the carb break off 4 different times. 3 of those times were because of crashes but once it came off when I was putting the fuel line on it. I contacted o.s. engines about it and they gave me one back.

bruce,this is from one of the links here,If the tank has a bubble section, position the muffler pressure/
overflow brass tubing inside the bubble for maximum tank capacity. Most fuel tanks include enough brass tubing to fabricate any three-line system.
Try to reach into the bubble with as straight a brass tubing !QUOT!run!QUOT! as possible. This helps prevent the fuel !QUOT!pickup!QUOT! line from wrapping itself around the vent tubing and getting STUCK in a full forward position, which could cause the engine to quit during the next vertical maneuver,or cause a lean run condition.also run the pressure line or vent line too far into the fuel tank and have your airplane sitting ready for your turn in the box and see how much fuel siphons in the muffler and even engine.sorry for not going into detail that was my meanning.he said fuel was coming out of the carburator like the engine was flooded.

I see what you are saying. I always make my went/pressure lines bend up near the top of the tank and into the bubble if equipped and assumed all others did as that is typically in the directions. To avoid the pickup line doubling back on you is very easy, just add a brass section to the line longer than the with of the tank and then it can not. You could also place a soda straw over the outside of the tube if preferred. I'll see if I can get RCKEN to add a graphic here of this. I don't believe the vent line siphoning would appear as fuel in the carb. The entire engine would have to fill with fuel first IMO.

If anything, due to the inverted installation the tank may be too high in relation to the needle

Bruce,
You're wish is my command!!!

Ken

hey thanks Bruce,i have never seen or thought of using a brass tube between the clunk.thats why i love this place someone has done or has a better idea.thanks again...happy flying

Can't take the credit for that one. I learned it here also. Just repeated it for you. Hope it helps.