Magnum .40 2stroke issues...
 

I've got a magnum 40 2 stroke that screams at wide open throttle and the idle is reasonably good too. PRoblem is the transition sucks bad. I don't have the instructions but I'll be looking for them on the net here real soon so I'm not sure what they say.

Any suggestions?

I'm running 10% in it at the moment and I know a little more nitro will help but I don't think that's a real "fix" I'm sure it's a mixture problem on the low end but I'm not sure what the setting for that little screw should be. I'll likely take the carb apart on that side to make sure it's all clear before I go flying with it again.

Like I said - screams like a banshee at WOT though. Can't complain there - take my ugly stick verticle for ever.

RE: Magnum .40 2stroke issues...
 

submikester....

....Turn the small screw in (clockwise) 1/8 of a turn at a time, until the
transition (mid range) clears up. With the stock setting (too rich) the engine
will spit and sputter....and sometimes die out, trying to go from idle to
full throttle. Every time you reset the idle screw, go back and recheck the
high speed needle as well. Turn it "in" until the engine is screaming as fast as
it will go....then open the needle until you hear the engine slow down just a bit.

You must always make sure the full speed setting is just a little on the rich
side, so the engine will not over-heat. ;)

I have two of those engines, and they are jewels. :D

FBD. :D

RE: Magnum .40 2stroke issues...
 

What is the stock setting? This engine is second hand to me so I don't have any documentation.

Thanks man.

RE: Magnum .40 2stroke issues...
 

There really is no stock setting you can rely on, because there are a bunch
of variables....:eek:....

....that being said....use 3/4 turn as a guess-timate. ;)
(that's 3/4 out from a lightly seated position)

RE: Magnum .40 2stroke issues...
 

3/4 turn out from seated....

Well....when I turned the thing in today it seemed to go in a loooooong way and I never really felt like it seated.

I'll give it a shot tonight.

I need to go get a good glow plug for it and a new prop from the LHS.

RE: Magnum .40 2stroke issues...
 

Well, I turned it all the way in and then 3/4 turn out. That sound about right? That screw is waaaaay in there...

RE: Magnum .40 2stroke issues...
 

OK, ....here's the way mine are set on the TwinStar....

....the one looks like about a half a turn out from flush, the other about
flush. I would guess....split the difference, and adjust it about 1/4 turn
out from flush. That should at least get you into the ball park. ;)

Every engine is slightly different. The last time I ran this plane....it sounded
like only one engine was running....the synchro was perfect down to the
last rpm. :D

FBD. ;)

RE: Magnum .40 2stroke issues...
 

I'm using K&B 1L plugs, PowerMaster 15% sport fuel, and (I think)
10-8 Master Airscrew props.

RE: Magnum .40 2stroke issues...
 

Thanks Dave.

RE: Magnum .40 2stroke issues...
 

Here's another way to set the idle screw, if it gets out of whack. :D

http://www.rcuniverse.com/forum/m_16...tm.htm#1715072

RE: Magnum .40 2stroke issues...
 

Oh yeah...worked on it for about an hour today and it just would not run right at all. NEW glow plug (OS #8) and tried 15% fuel. There was literally no change. The top end is great but the transition sucks - the fuel just spits out the carb and the thing dies unless you really transition slowly. If it's been idling for more than 20 seconds or so - forget it.

I'll take it apart maybe to see if there is anything really wrong with it on the inside. It had been running acceptable a few weeks ago and nothing really has changed that I know of except how it runs. We'll see - I don't feel much like pursuing this to death - it's a club engine and not mine. I'll give it back to the fellas at the club and let them figure it out.
It is very frustrating...I even changed the tank at the field...

RE: Magnum .40 2stroke issues...
 

If fuel is spitting out the carb on transition, it's still too rich. Turn the idle
screw in about 1/4 turn, and see if it gets better. [:o]

Dave. ;)

RE: Magnum .40 2stroke issues...
 

I just acquired a Magnum SP .40 and had to totally clean before using. It has the older style carb which has an low end air mixture screw similar to the idle stop screw. Should the begginning setting on the idle airscrew be set at 3/4 turns from fully seated?