k_sonn

My Feedback: (32)

I posted the following question in the RCShowcase Support forum a couple of days ago and did not receive a response so I am going to post it in the general forum.

Here goes: "I have a RCS 1.8 installed in a Hanger 9 cap. The engine has about a 1/2 gallon run through it. I am having a sputtering problem at throttle settings greater than half when the plane is flying level or in a turn. The sputtering problem does not occur when the plane is going vertical at full throttle or on the ground. I have checked the fuel lines and the fuel tank clunck and found no problems there. I am not using a muffler. Any clue to what may cause the sputtering problem? Thanks in advance for any help."

NM2K

My Feedback: (14)

It is hard to diagnose via the internet, but I'll bet you are running a prop that is not quite enough load for the engine. Try something with a little more pitch or diameter and see what happens. I'll bet your problem goes away. Don't forget to retweak the high and low speed needles. Good luck.

GeraldRosebery

My Feedback: (14)

I am curious as to why you are not using a muffler? Most two stroke engines run better with some back pressure. Without a muffler installed that is missing. It will be especially a problem in the mid-range as you report. Early two stroke engines in the uncivilized times before mufflers often had a rotating baffle in the exhaust port to provide back presure at lower throttle settings. Installing a recommended muffler will most likely cure your run problems and help you keep your flying field a a second benefit.

NM2K

My Feedback: (14)

I did not notice that you were not using a muffler until the other posted pointed it out.

Two-strokes burble and talk to themselves quite a bit when under anything less than full load. What you are hearing may be normal and "unfixable", so to speak, since nothing is really wrong anyway.

A little back pressure isn't necessary, but don't expect the two-stroke not to make two-stroke sounds...

k_sonn

My Feedback: (32)

Gentleman, thanks for the feedback. The prop is the recommend size for engine break in. The reason a muffler was not used is the pitts muffler I have for the engine will not fit without major firewall surgery. I found an old Super Tiger 3000 pitts muffler that fit. It has been installed and tomorrow, weathering permitting, I will try it out. Where I fly a muffler is not required. The nearest house is several miles away. Once again, thanks for the info.

Antique

My Feedback: (4)

Somne engines idle funny without a muffler, otherwise no back pressure usually results in more rpm..Except for tuned pipes...
Dave Johnson told me today that a quiet tuned pipe on a DA 50 turns it into an animal, and it's already very good...

BUCKETOBOLTS

My Feedback: (1)

Curious? What prop and rpm do you get? I use a 20x6 Pro Zinger and get 8000 with a modified G38 muffler. Test flew mine for the first time Monday evening and was getting some gurgling when at a low speed. I leaned the low needle about a 1/8-1/4 turn and cleared it up. I'm still a little rich on the high side and have close to a gallon of fuel run threw it. Mostly on the ground (just like to hear it run I guess).

BUCKETOBOLTS

My Feedback: (1)

Here is a pic of the muffler set up on my engine. I was getting 8000-8100 with the muffler and a Bambula 18x8 before I added the extention to the muffler. It will turn the 18x8 8400 now and the 20x6 at 8000.