Over the weekend my son was flying his Hotts with a Webra Bully 35 that’s on gas. The engine only has about 6 tanks on it, when it started surging in the air. He landed and I cleaned out the carb but did not find anything. I put the carb back on and it starts but when you go full throttle it surges real bad and will start to run backwards and die??? I thought it was a carb / air leak problem until the engine wanting to run backwards and now I am thinking it may be the Webra ignition giving me a problem?? Anyone have anything like this happen to them???

anything happened to the sensor position? Check timing before anything else.

The sensor on the Webra screws into the back of the engine case and can not move. I have not taken the engine apart but figure the timing is set and is why I am thinking the Webra ignition may be bad.

I was thinking along those lines too, the Webra being a "passing metal sensor" pickup type.
But it still won't hurt to check pickup position, depending on the fastening method you used.

I think it's too lean on the high speed needle.

The symptom you describe is a CLASSIC indication of too lean on the high end.

Needles are fine, but found the problem,

The ignition battery was almost dead when I thought to check it tonight. Now I need to find out how a 1500mah battery with a full charge could ony last less then 3flights of less then 10 min,.

I may think fuel adjustment, if it were not for the 6 fine previous runs. I agree with looking at ignition components closely. Seems something is failing, loose, or has moved. These symptoms are often misread as fuel issues on ignition engines. I have made this mistake myself.

The 6 previous runs may have caused the battery to be to low for good ignition operation. My guess. Capt,n

He said it only had 6 tanks on it, but I was thinking they weren't all on the same outing. He didn't say. I assumed the battery had been recharged. Perhaps not. I fly all week on my Duralite ignition batteries without a recharge, but he didn't say what kind either.

The first 3 flights were on one day the the next 3 flights were a week later. The battery was taken off my Sirius charger the morning of the last 3 flights.

Been flying nothing but gas for the last 9yrs and everything from a G-23 to 3w-150 and first time with a problem like this.

And the battery is a 1500mah JR nicad that was new.

If you can check the MAH on that JR battery....I have had my share of bad JR packs. I to use a Cirus charger....I still think stock charger does a better job. Capt,n

I have the pack on my Pro Tester to see what the pack is holding.

I have used nothing but my Serius charger to charge my RX packs for the past 8yrs and have never had a problem. Even with my 3000mah packs I had in my 40% Carden Giles and Extra it always charged the packs to a full charge. But then it may be time to send it in for a check up with as much use it has had over the years.

Cycle the battery three times. I bet it will be fine. But you might consider going to a larger pack.

Well the 1500mah pack just tested 437mah after a full charge. I now have it on a wall charger to see what I get. May be time to send the Serius in for a check up

Could be the battery itself when it is new. Slow charge at c/10 rate is recommended for the 1st few cycles. The same thing happend to my A123 cells as well.

Hello Charles I have had 4 problems that you describe, over the last 30 years, with battery packs being the problem. The trying to run backwards symptom, was always part of the problem. Have learned to use a new battery pack, of high quality, on the ignition of my engines.

Did you FORM charge the batteries when new as that could be your problem, one of reduced capacity.

Karol

Thanks,

It's looking like a charger problem as ALL my batteries are not getting a full charge when I started checking yesterday.

Boy, you lucked out this time! Could have been a receiver battery that got you.

Yes, very lucky[8D]