I am having a hard time setting up the needles I have the H speed at 4 turns out for it to run I get 6100 rpm with a Menz 24 10 Low speed set at 2 turns out. The problem is when I hold the throttle at 50% it wants to quit.I try to lean both needle and it gets worse I richen it and it stays the same. I am using the oil that it came with at 32 to 1. At first I had a bisson pitts muffler then I swithched to a slimeline modified da 50 pitts . I have tried the factory settings and it would not run. I have in a wildhare 28% 540 edge.I have replaced fuel,fuel tank,fuel lines fuel filters I tried amsoil at 32to 1. I don't know what else to try.Thanks in advance
Joe

Hi Joe Just wondering what you had to do to make the Slimline muffler fit the MVVS 58? Thanks.

Joe,
Is there a difference in running between the Slimline and the Bisson? How do the two compare volume wise?
Switching oil while running in the engine is a bad idea. MVVS supplies Mobil 1 2t Racing just to make sure you use the right oil for the process. When changing oils, it takes a long time before the previous oil is washed away completely. As the two may not be compatible very well, during that period the engine is jeopardized.

Your setting up problem: I take it the carb is clean, so make sure of that first. Also make sure the carb is secured well.

Regardless of factory settings, get the engine to run well at WOT, then little by little reduce throttle, whilst keeping the engine running well using the idle needle only. In between open the throttle again, and adjust to best speed with the H needle only. Then proceed as before.
Continue, until you can very slowly reduce the engine speed to near idle without problems.
Now check throlle response, and adjust with idle needle only, all the time keeping best WOT power using the H needle.
Make a note of the needle settings. They belong to your particular carb-engine combo.

If using this method, you cannot get the engine to run well:
Keep using the same fuel, and check plug gap ( 0.6mm = 0.024" ), replace plug. Also check out the mufflers for difference. These pitts type mufflers choke the engine quite a lot.
If all fails, check for damaged carbon reeds, and replace as required.

Edited:
It helps to realize that the H needle is active only from 30% throttle upwards. The idle needle however is active over the complete range from idle to WOT. That is why I suspect a lean idle needle setting.

When I had the bisson muffler I could only get 5700 rpm. The slimeline gave me more rpm at the same settings. I had the vent and pulse tube crossed on the first start up. I had fixed that problem and the motor ran good at home. I will clean the carb and make sure it is secured. I have already changed plug NGK BM6F . I will also check the reeds .

Some times after 5 to 8 flips it does not start I would switch the ignition switch ON and OFF and it would pop as if it backfired without turning the prop.
I will go back to MT2 oil . I have used ams oil saber mixed at 32 to 1 for about 1/2 a tank.

Thanks Joe

Always be careful when turning on the ignition. That will produce a single spark. Backfiring into the crankcase may damage the reeds.
Also, do not run the new engine long at WOT. It is not run in yet. At the first sign of sagging or laboring, immediately close the throttle.

I removed the motor from the plane for inspection and found a possible problem 1 the nipple on the back plate was lose (it unscrewed by hand by only twisting the hose) 2 inspecting the reeds I found them not sealing the cage is that normal there was a 2mm gap. everything else seemed normal.

If your engine starts well, and has reliable idle, leave the reeds alone. They will close as soon as gas flow wants to reverse. Being fibre reinforced plastic they will set, So if you adjust them, after a while they will be slightly open again.

We've tried the Bisson Pitts exhaust and found it to be a poor performer on the 58.