I HAVE A WEBRA 4T-80 4 STROKE THAT RAN GREAT 2YEARS AGO ,TOOK IT OUT THIS YEAR-STARTS, RUNS 30 SECONDS AND DIES. I HAVE NOW SCREWED AROUND WITH THE NEEDLES SO MUCH I THINK I LOST THE PROPER ADJUSTMENTS.
SEEMS LIKE I'M GETTING BACK PRESSURE FROM THE MOTOR INTO THE CARB BACK INTO THE THANK[:@]
ANYONE HAVE ONE OF THESE MOTORS HAVE SOME SUGGESTIONS!!

The Valves are either out of adj or could be sticking. Have you tried a naw plug, the seem to die after not being used for that amount of time. Also is the fuel fresh.

Cheers

I has same engine as your.

Are compression good?
All marks at right place when timing belt are at place?
Are the reed valves in crankcase ok, not broken or leak?
Cleaned carburator free for dirt?
Tried with new glowplug?

Jens Eirik

Roggy-

I think this is unlikely since you say it runs for 30 sec., but any chance you took off the intake & exhaust and got them back on in reverse?? I believe the threads are the same for this engine and I've seen eBay photos of engines with them installed backwards. I *think* the exhaust comes out the back of the head and intake is on the right side (facing it from the rear). My T4-40 is that way. If any question, I could call a friend who has an 80 and ask him.

Another question is whether the belt was replaced or removed/reinstalled since it ran well 2 years ago? If so, the timing may be off.

There is no valve "adjustment" possible, other than belt timing, nor "sticking" because this engine has a rotary valve, not poppet valves like most 4-strokes.

Maybe there's some crud in the carb's fuel inlet? Remove the fuel line, back the needle valve way out and blow vigorously into the intake, or blast some fuel into the intake to backflush (first rotate crankshaft so intake valve is closed). Hold some tissue near the inlet to catch the crud so you can see and admire it.

If all else fails, set the high speed needle valve open about 3 turns to begin. Thats probably too rich for proper running. If your carb is similar to the one on my 40 (might not be), back the low speed needle out so that at full throttle, it's backed out and clearing the end of the spraybar. Check that closing off the carb intake with your finger (choking) and turning the prop through at least 2 full turns will draw fuel from the tank.

Remember, persuasive insults must be in German.

-Dave

Roggy-

Jens' post reminds me I believe there were two quite different T4-80 designs. The one I was referring to has both the intake and exhaust connected to the head. I believe there was another (of which Jens' description reminds me) which drew intake through the carb into the crankcase - I forget how it got from the case to the combustion chamber. Then again, maybe I'm all wet.
-Dave

This is the way my T4 15cc is arranged.

There was only one T4-80, Hobbsy's engine is the Webra "T4", and is .87 cubic inches displacement. Its the precurser to the T4-40/60/80 line.

I had two T4-80's - one was flown in my Astro Hog for a few seasons before I sold it. I had the belt skip one tooth on me and it threw off the timing bad enough to know immediately. Perhaps thats what happened? It will still run, but very poorly. I just put it back to the correct position and it was fine again.

AJC

AJ, I guess that you noticed that I didn't call it a .91 like I used to.

See at the marks of timing of Webra T-4 MK.II at pic. same as my engine has the marks alignet with other marks at the engine. I am using 1 dot, not 2 dots at gearwheel to cylinderhead.

Ajcoholic are right about displacement.. not 0.80 or 0.91 cu.in.
Displacement are 14.31 cc or 0.87 cu.in, Bore: 27mm (1.061 in.) , stroke: 25mm (0.9842 in.)

Jens Eirik