I have an evo 46 that won't hold speed on the high end tryed new os a3 plug cheaked the fuel line and muffeler line for cuts or cloges trasitions good holds nice idel gos to high speed great a minute into it the it gives up. Any advice would be aprciated.

G'day Mate,
It is too LEAN, richen it 1/4 turn, & try it.
It should slow slightly when the nose of the plane is held at 45 Degrees up. if not, richen more, until it does.
Then it should be good enough to fly without stopping.

Try that it did not help just made transition slow and it still died after about a minute.

G'day Mate,
It's still lean, & your low speed mixture is rich.

The A3 may be a good choice for a plug. The OS 8 is too cold. You could also try a Saito SS plug.

Do you know how to tune it by ear?

G'day Mate,
Yeah I know how to tune by ear,
that's why I gave the advise about raising the nose, you can hear it speed up, when it is rich enough.
& I think you will find that the OS #8 is not too cold, it is a medium plug, the A5 is the colder one. I don't like the OS A3, they are cheaper for a reason, they are plated plugs & don't last very long, compared to the #8, using around 10% nitro.

I had the same exact problems you are having with my RTF Alpha. It was a huge PITA to tune. have you checked your fuel lines? i had small pin sized holes on BOTH of my lines going from the tank and i replaced them. Since then i haven't had any problems. I noticed fuel around my motor and on the table where i tuned the engine. I checked everything and noticed some leaking around the tank/muffler so i changed them out. Also, the lines that came with my plane were very long, noticed some improvement by shortening the line going to the muffler.

I will try the low speed again and change the lines.

Allan,

My question about tuning was for kleverprop, but it was not worded well in any case. I should have put it differently. Guess I was interested in typing too quickly.

Over here where I am, the #8 is not a good plug for the .46NT or .455 TPS. I gained a lot of power when I was advised to change to a Towers plug. I'm not sure where that fits in with the 8 and A3. It is hotter than the 8. All of the stumbling, and excess fuel in the crankcase after cranking ended with the Towers plug. The extra power was easily noticed right away. A couple of other people at my club are running Saito SS plugs and they seem to be very good for the Evos.

Changed lines and leaned out the low speed mixture works good took out the baffel in the muffler works great sounds as loud as bisson pitts with 10/6 prop getting 12960 rpm and i backed off 500 rpm from peak think this will be a winner. I think i will later go to 11/5 or 10/8, thanks for all the help every one.

Check for air leaks at the back plate and the carb throat. Tighten up the back plate bolts/screws and loosen up the carb retention bolt and then press very hard on the carb pushing it downward while retightening the carb retainer bolt.

Sounds to me like it is sucking in air from somewhere and is going lean. That will result in a hot run and quick shut down.

After leak checks, retune as all the other tuning will be off now that you have closed off all the air leaks.

Good luck,

Chip