rich or lean gas?
 

I have a Brison 3.2 New with 22 x 8 on it , RPM. 2200-6700 I have way way to much power , 26lb thrust on 18lb/ but how do I know if it is too rich or lean? do I hold the nose up and pinch the line like I do with a nitro?

jason

RE: rich or lean gas?
 

Jason,

Gas engines do not work like that so pinching the line will not work because they use so little fuel you may have to hold that line for several minutes. On the Brison 3.2 do not make the adjustments while it is running, you will be way too close to the prop. Once you get the needles set unless the weather really changes allot, you will not need to touch them again. It may tke 20 minutes but its well worth it. If you bought this engine new, Gary usually has a tag on it that tells you what prop he tested it with and what rpm he got. The needles will most likely be set already.

If it's used then you may have to adjust it yourself. It's really not hard. Remeber one thing, you will be making very small adjustments. 1/8th fown to 1/16th turns at a time where most nitro engines you make 1/4 turn or more adjustments.

Here is something I found that will help you.

Open both needles 2 turns
Start engine
Lean out high speed needle for max rpm, then back off about 200 rpm
Slowly lean low needle and try transition
Do it until no transition
Open low slightly until transition is good
Re set high, leave slightly rich
FLY............................
Applies to ALL gassers, Walbro, Tillotson, Zama, Del Orto, Bing, etc.....................


If the ‘H’ needle is too lean, it may cause the following three symptoms.
1. Engine stops at full throttle.
2. Engine hesitates when accelerated rapidly.
3. The engine will not come up to full RPM at full throttle.

If the ‘H’ needle is too rich, it may cause insufficient RPM at full throttle. This
causes carbon buildup on the spark plug.

If the ‘L’ needle is too lean, it may cause the following three symptoms:
1. The engine hesitates when accelerated rapidly.
2. The RPM increases at idling.
3. The engine stops when the throttle is moved from high to low.

If the ‘L’ needle is too rich, the idle may be unstable.
The position of the ‘H’ needle will vary according to air temperature and
field elevation.

These are generic instructions but they have served me very well for my Brison, Zenoah and DA engines

You also have one of the better 50cc engines around

RE: rich or lean gas?
 

Use a tach to set it at the richest possible setting for maximum rpm at full throttle. The carb has a diaphragm pump, so it doesn't go lean when the plane goes nose high.

RE: rich or lean gas?
 

Also,, after flying for a while pull the plug and see what it looks like. Black=rich, brownish/tan=good, white=lean

RE: rich or lean gas?
 

I have a Quadra 50 and can't get the thing to run right. It always sounds too rich on the high end but will idle great for ever. I have it on a Midwest Exra 300 which is 18 lbs and it won't even hold a knife edge. This engine should be trying to pull the firewall off this thing. Any ideas will be most helpfull.

RE: rich or lean gas?
 

I can't help you with the engine but I can tell you I had a Midwest 300 with a Brison 2.4 @ 16.5 lbs. and there is no way in the world that I could get it to hold a KE. I tried everything, props, balance, servos, everything, I finally got so upset one day I stripped her down and throw it in the garbage. Others have no problems - don't know why - never did figure it out.

I had a Quadra 42 in a 1/3, 16 lb. Pitts Special and it would KE all day at about 1/2 rudder stick.

RE: rich or lean gas?
 

The 2.4 on the 300 was a simple problem. Too small an engine on too heavy a plane. The wing area on the Midwest was a little on the short side, too.

That brings up another subject that's so often overlooked. Wing areas. A lot of people see a new plane hit the market and the go "OOh, a new Extra, Yak, or Edge. That should fly great." But they often fail to take the wing area for the suggested plane weight into consideration. A heavy plane with too little area will fly like a powered brick, even worse with a larger engine. A heavy plane with a plentiful wing area can fly very well with a smaller engine than the plane with less area. That's why so many heavy robotic aircraft fly so well and so long with relatively tiny engines. Combine weight with large wing area along with clean airframes and smaller engines can be used.

RE: rich or lean gas?
 

What propeller are you using?
You may be able to go with a lower pitch to increase the RPM and get more pull.
You can also go with a thinner blade propeller to get more RPM.
You could also not have enough rudder or strong enough servo on the rudder and getting blowback.

RE: rich or lean gas?
 

this is regarding the DA50 that I'm trying to break-in. it's on it's 3rd tank, the "H" and "L" needle are set at DA's recommended settings, 17/8 and 1 5/8 respectively.
on the ground the engine seems to run well, both low and the high seem good and the transition between them. but once in the air, the engine sputters throughout the whole throttle range. any idea on what's going on?
thanks

RE: rich or lean gas?
 

hello tiktock Have had this problem several times over the last 25 yrs, flying giant scale planes. This problem happens in the air because, when airborn. the air pressure around the carb fuel metering diaphram is not letting it do the metering job correctly. to solve this problem, I suggest soldering a length of 1/8 inch brass, or copper tubing to the center hole on the dia. cover. Then run a piece of fuel line to the rear of the carb. I usually run the tubing back of the firewall into neutral air. This has cured the problem every time. Also, if there are any holes around the metering plate, just solder them shut. If there is no hole in the center of the plate, drill one to fit the 1/8 tubing. Hope this helps, please let me know. Regards jack

RE: rich or lean gas?
 

tiktock, I don't have a DA but my FPE had the same symptoms when I first got it. It ran good on the ground but airborne it sputtered and went rich. The velocity stack was in the airstream and the mfg suggested it might be creating a vacuum causing the engine to go rich. He suggested I remove the velocity stack, which I did so the carb would be inside the cowl, and the problem went away.

It worked for me.

Larry