I have a converted 26cc stihl on my edge 540. It dead sticked on me everytime i flew today. It seemed to be fine running full throttle but if i backed it off in a dive it would start missing and dead stick. its a gas/glow setup with 13.5mm walbro, free flowing exhaust and on the regular 2:1 gas:glow, OS 4 stroke plug vented diaphram plate.
Any ideas?
thanks

Does it do this all the time?
When tank is full.1/2 full,empty?-If mostly after a 5 minute run Check your clunk.
Is this a new conversion?If it is use another glow plug.When breaking in an engine the first one will go bad.
Retune maybe.Could be a little rich?
The pump membrame could be going bad as some carbs cant take the nitro.You only need 10 percent nitro.I thnk av8tor has had problems with zama especially.Check on the gas/glow threads.Just the newest one will work.

Yesterday were the maiden flights
all 4 flights were deadstick landings
The tank was more than 1/2 everytime, i will check the clunk today
Its not a new conversion but I had a new glow plug in it
I am running 20% glow cut down with methanol
Its a walbro wt-540

Hey, it's chain saw engine. In a dive, it sense that it is falling and shuts itself down to prevent damage to the chain. <grin>

You indicated that it's not a new conversion. Has it always been run with the 13.5 carb? That may be a touch large for the 26, leaving the engine vulnerable to some transition issues.

Jack - still working on my first conversion, so I am speaking with book experience only.

I dont run over a 10-11 mm carb on my 26 and 28cc.Might be toomuch like jib said.Check the new gas/glow thred.There might be a few of your questions answered.I dont know about adding the methanol.All ive used is 10/10 glow and gas.
Check on the gas/glow thread and look at your membrame.

My best guesses would be that either the clunk tube in the tank is getting uncovered and not sucking fuel, or that your metering diaphragm is getting a blast of air in that attitude and is screwing up your mixture. I have never encountered this particular problem, but I am sure normal trouble shooting procedures can solve it. It is not a problem related to using Gas/Glow.

AV8TOR

Fixed. I rerouted the vent line on the diaphram and completely sealed the fuse from the cowl. 2 flights today with no deadsticks.
Thanks once again for the help.