Will it affect my 1.20 four stroke if I remove the baffle? It is to quiet.

I like to hear a engine run, but a lot of flying fields are lost due to noise.

Yes you may change how the engine runs, good or bad I don't know.

sticks

Best answer is it might. Back pressure in the muffler acts as a fuel pump to the tank. 4 strokes also use the back pressure to help them run their best. Another consideration is noise. You said it's quiet, but if you fly anywhere near a house this may be just enough excuse for someone to complain. Just don't mess it up for everyone else by causing a problem that wouldn't have happened if you just left the muffler intact. Not everyone has the same passion for flying as we do. They look at it as an intrusion and any excuse to whine - they will take it.

My 2 cents.
Mike

Our club is out in the middle of the woods. No houses for atleast a mile.

I have never bought a four stroke that had a baffle. I have also made up my own header systems and just run straight pipes with them. No performance difference at all. Even with a straight pipe a four banger is very quiet, the sound does change but not any louder, just different.

[quote]ORIGINAL: Gray Beard

I have never bought a four stroke that had a baffle.
I stand corrected!! By myself no less. I just started thinking about that and I kinda remember removing the baffle out of the YS mufflers?? I went out and looked and sure enough, they have four screws in the back. Senior moment!!![&o] None of my older OS engines have baffles, they are one piece mufflers and just cans with a taper. I think I may be behind the time or something. Anyway, no problem removing them.

Sounds like a Harley rider getting into the hobby.

What 4 stroke? If it is a pumped 4 stroke, you can run a straight pipe and get away with it. If not you will need the backpressure created by the muffler.

It is a magnum 1.20.

I have the same engine and it is pretty noisy with the stock muffler. Even that it is noisy, the sound is soft, removing the baffle will create a different type of sound (regardless of the efficiency and fuel pump needs) it will become a metallic louder sound (more like a two stroker) and maybe will disappoint you.

I drilled out the stock muffler to no avail. I guess I am just use to gassers. This is my first 4 stroke.

Drilled it out?? What are you drilling??

There is a baffle in the stock magnum muffler.

OK, here is the deal. I'm a NYSC Small Engine Tech and studied under AMI for Yamaha when I lived in Florida.

On a 2-Stroke and this includes Glow the less back pressure the better. It improves power and a bit louder... the only downside is fuel consumption is increased.

On a 4-Stroke it needs the proper back pressure to run properly. Without it it weakens the horsepower by 10-20 % and damages the valves after a while from unheated air hitting the hot exaust valves. Also the 4-stroke will run on the rich side and it takes a bit to get it somewhat lean without custom jetting.

Sure it sounds great but but in the end it damages the engine. If you want to go straight pipe, you have to change the Jetting in the Carb. If it's fuel injected the computer has to be manipulated or switched. If you don't believe me ask anyone who straight pipes a Harley Davidson, they usually pay for a Top End much sooner than someone who keeps the baffels in.

I like loud glow engines and I'm not a Harely Davidson fan. The best answer I can give is call the engine manufacture or get after market mufflers that are designed for your engine to help increase preformance and loudness.

Hope you got the answer you're looking for.

I have an old satio 120 with a straight pipe and a pressure tap runs fine o. s. pipes do not have a pressure tap Why is this? ALso the flex pipesfrom o.s. breaks of right at the head I have tried to stop this inculdeding anchoging it right at thehead but nothing worked Any tips?? BOB

The pressure tap on an OS is on the muffler itself, if you have one without a tap it is because it is off of a pumped engine that does not require one. The flex pipes weak point is right at the junction of the header and flex pipe joint and with a sharp bend and not enough soft mounted anchoring points it vibrates and breaks off right at that junction, just the nature of the beast.
If you can find the January issue of RC Report read The Oily Hand by Brian Winch, he talks about headers and tuned pipes for glow engines with some good photos of some pipe/header/muffler systems.
Luft, your saying the headers on my dragster gave me less horse power?? I did always jamb a tennis ball into the pipes after running it to keep the cold air from being sucked back into the hot valves. None of my racing bikes ever had baffles either, four strokes had open straight pipes and two strokes had tuned pipes or stingers. My choppers all had straight pipes too. No valve problems. Just wondering.

OS recently updated their 4-strokes, but before the new ones came out, we rarely ran a muffler at all - just a straight pipe with no pressure.

The newer ones require pressure - they don't run worth a damn without it.

Now, I'm not familiar with the Magnum 120, but I would say that if it were me, I would at least TRY running the engine with no pressure (You'll need to richen the mixture a bit, but that's all).

If it works well with no pressure, then you can do whatever you like with the muffler baffle