gms 76 problem
 

I am having problems getting the engine to prime by hand. When I flip the prop over the engine sucks the fuel just alittle bit but it never makes it more than 2 inchs up the line from the tank. I think on the up stroke of the engine is when the suction occurs but after that the fuel just goes back to the tank. I have it set at full throttle and I have my thumb over the carb. It will prime with the electric starteronly when i have my my finger over the carb.
The manual says the engine will feel like it doesnt have compression due to the dykes ring. It says this only works when its running.

I had the tank slightly over the engine and about level with it and it still didnt draw.
Is there somthing wrong with the engine?

The engine runs really well though, it idles real good and transotions good, considering I have only run about 10 ounces of fuel through it.

could you give me some tips on breaking it in? I have been just varying the throttle with it fairly rich. The manual didnt tell me really how to run it in.
Thanks,
Grant

gms 76 problem
 

You are doing OK with your engine.

Don't know about your priming though. Generally when your fuel level is higher than the needle valve, the fuel will stay at the needle valve when primed.

Good luck,

Jim

gms 76 problem
 

You'll end up flooding the engine and breaking the conrod doing it thid way with the starter.

Hold throttle wide open, flip,flip, flip --three or more times while the fuel in the line hits the carb. Close the throttle, flip,flip, flip, open 1/4 throttle and hit it with the throttle.

Break it in the way the manual says. If not do a search on "break-in and ringed and engine" and you'll find loads of info. General concencis is to break them in rich:
http://www.rcuniverse.com/showthread...ged+and+engine

It'll be a good strong engine, just be patient..

GMS 76
 

I have the same engine on a four*60 that i purchased in July 02 and have just purchased an O.S. 60FX to replace it.It has never run right and the muffler comes loose regardless of how much thread lock is used.If you can, spare your self and send it back.Even pilots with 10+ years can not get it to run right.

gms 76 problem
 

The GMS 76 runs great in my 4*60. You have to adjust the low-end needle to get a reliable since it dosen't come from the factory set. When I got mine, the low-end needle was all the way in.

gms 76 problem
 

I had a GMS76 and it was one of the better engines I've owned. No problems what so ever... Being that it is a ringed engine I would use an electric starter to start it simply because it won't suck the fuel up as easy as an ABC engine.

As for break-in I ran about half a tank through it on the ground then went flying... I never had a single dead stick with this engine.

As for props it likes the APC 13x6. :)

gms 76 problem
 

Though the GMS 76 and Tower 76 are twins, they are not identical. One has a remote needle valve. The Tower is ABC and the GMS has a Dykes ring (I'm thinking). A Dykes ring has almost no compression when turned over slowly. But the engine will run fine.

Jim

gms 76 problem
 

The way a Dykes ring is designed when the engine fires the explosion inside the cylinder presses the ring against the cylinder wall. This is why you feel little or no compression when turning by hand, you simple can't turn it over fast enough for the ring to expand to the wall creating the compression.

Priming GMS 76
 

Try covering the muffler outlet instead of the carb venturi when trying to prime it. I prime all of my engines this way.