There has been 6 tanks of gas ran through this engine and all the while (it's being broke in in a proper way) running like a top, transition is great and compression is getting very good, starts easy and idles at 1600 RPM, very smooth through out all ranges, then after starting it up (and I always let it warm up some) I set RPM at 4800 and it was running very smooth when it started surging up and down and up down and I droped it down to a smooth idle and then ranped it back up and it started again, tank was full and there was no visable air in lines, I use barbs and pinch clamps behind the barbs. I checked the battery voltage, it was 6.4V ample enough for ignition, reciever also uses 6V. Could ignition module cause this or does it sound more fuel related. I know 2 stroke engines pretty well, just never have had this happen before.

Any experienced engine guys out there that have seen this happen and have any realistic answers, it's a brand new engine and reed box has been resurfaced, carb bolts are tight, need some direction. Thank you.

Leroy

Too lean?

Replace carb with a real Walbro, this is a very common solution.

A couple things to check, one being your ignition battery. Even though you said it was charged, and showing good voltage, it could just be weak cell(s) that are dropping rapidly once the ignition starts drawing power from it. Had a friend have this near exact situation the other day. If you have another battery, swap it out and test run it again.
Check your carb screen for debris.. some crud in your carb screen could be slight enough to run okay, until it really tries to pull a good draw of fuel. Its somewhat a leap to go from good running, to next running such drastic performance drop, calling the carp bad. But not out of the realm.. that would be the final thoughts, once all the typical, more simple problem solving has been exhausted.
May also go over your fuel system, most importantly your clunk, pinched or pierced fuel lines etc..

Good luck

That is a good suggestion too though. The DLE carbs are okay, but the Walbro really does bring the DLE to life.

At this point it's pointing at the carb. Because of warrenty I'm waiting for responce from Valley View, Tom is really sharp on these engines and may want me to send it to him. Every thing is bran new, a tiny hole in diaphragm could produce that throb, I'm pretty sure it's not ignition and I am leaning towards a Walbro, hard to beat that one.

Thanks for trying to help, when I find out whats wrong I'll let you know, could happen to someone else and probably has.

Leroy

How do you know what Walbro carb to get and what kind of price is normal for one?

I hate to keep bringing this up.Sounds like your spark plug cap is not all the way on.Snap ring must be passed the hex on spark plug,really tough to get on with the 45 degree cap installed between the muffler pipes..
BCCHI,AMA 2500 FOG

I just sat out a week of bad weather and finally got it fired up again. I had done nothing to engine and wanted to confirm a couple of things especially the servo serging, yes or no. Well it ran 3 more tanks of gas through it, another hour, and never missed a beat, ran like a top and at this point it's going in the plane.What ever was causing the problem in the first place may never be known at this point. Servo location has been moved in the plane and I'm staying with the analog one for now, I have never had a problem with them in the past. RF noise is picked up in the wireing and I'm keeping engine related wires on one side and all others on the other side. Truth is digital servos are best on gas engine set ups and throttle servo may still get changed. I have 3 DLE engines and they all run perfectly, have been on the same run stand with the same set up.

"Oh" I did charge batteries and may have moved some wires around prior to the last run series and that may have been the problem all along.

Leroy

Glad to see you're running OK now.

Regarding digital vs. analog servos and the difference between them when it comes to RF resistance? Where did you see this info? That's news to me.