linkadrip

Well i have a GMS 120 and it has a pitts muffler on it and i'm looking for a stock type muffler and apparently the stock mufflers for these engines cant be bought at this time Tower hobbies has had theres on late may july and will probably got into august i dont think they will ever get them in stock. So i'm considering buying a tuned header from MACS but have looked at some other mufflers and there is a solid one for a WEBRA 120 on there site says currently in testing but has a price. I'm just wondering what other muffler would be comp[atiable with the GMS 120??
THere must be someone outthere that has done some experimenting in trying different nufflers for this engine. i cant figure out why a manufature would sell an engine without one anyway. but GMS does heres a link to two pages from MACS. they sell a header for the GMS 120 but not a solid muffler and think that going withthe solid muffler would be a better way to go as far as cost effectivness.

http://www.macspro.com/onepiece.asp

Webra 1.20 7130
in testing
http://www.macspro.com/headers_side.asp

Webra 120
Bully 1.2 PR
GMS 120
Mark 135
MVVS 215
UAV 120
part numbers for diffrent length headers #4130 4131 4132

Reason i'm thinking the Solid muffler will work is the partnumbers for the header fit several engines in the list.

So should i take the risk of getting a solid webra 120 muffler for my GMS 120 or would i just be shipping it back in disapointment that it doesnt work.?

linkadrip

I guess no one knows what mufflers are compatible with a gms 120. Must be someone out there that has put a different muffler on this engine. I called MAc mufflers and left a message and they never called me back that s the only reason i pose this question here. I'm wondering out of all the 120 size engines out there there must be at least one muffler that is compatiable.

these an os 120 AX,ASP 120,magnum XL 120,webra 120, and i'm sure there are others that i dont know about. One of these engine's must have a muffler that will fit. Guess i'll try calling macs mufflers again..

linkadrip

Ok i called MAcs mufflers again and got a hold of them and the muffler that fits the webra 120 will fit the GMS 120 but its currently in testing and that is why it is not listed. but i'm having one made for it so that should solve my pressure problem that i'm having with the pitts muffler that is currently on the the engine. Macs mufflers wanted me to make sure i understood that this is not a tuned pipe just a muffler. According to them there are several people testing the muffler on other engines and i guess i will be the first to put one on a GMS 120 and any feedback i cangive them on its performance will be appriciated.

anuthabubba

My Feedback: (102)

Now that you've mentioned a specific problem you are having with the Pitts style muffler it might be that there is a fix. Not about what muffler fits a GMS but what to do about not having enough back pressure. Usually this problem can be fixed by reducing the exit area of the pipe or pipes on the Pitts muffler by plugging one off or crimping them to make the holes smaller.

Terry in LP

earlwb

It is a little late now, but I have a GMS 120 and the Webra 120 mufflers and tuned pipe headers fit Ok.
I was bench running the GMS engine for a few tanks to work out the kinks and I used the Webra 120 muffler on it no problem.

I got the GMS 120 from a guy really cheap as he couldn't get it to run OK. When i bench ran the engine, I saw that the remote needle valve was sucking a lot of air, thus causing erratic running and false needle settings. I corrected the problem by using a different Perry remote needle valve and the engine ran fine after that. I saw that when MECOA was selling the engines, they were replacing the carb with a Kavan carb. I also tried a large Perry carb and the engine ran good with it too. But the Perry carb has a plastic body, so you need to be careful using the pinch bolt and not overtighten it. i suggest using some blue locktite on the bolt.
Another method would be to remove the needle valve and grease just the threads and O ring, if it has one, and then fit on a short piece of XL silicon fuel tubing and reinstall the needle valve. That should cut down on the air sucking problem too.

Hobbsy

My Feedback: (102)

http://bissonmufflers.com/en/muffler...mageField.y=14

Here are a couple of options, these are high quality mufflers and no muffler pressure issues.