flyerdave

My Feedback: (212)

Tried all morning to hit the sweet spot on this one, but everytime i get it to half throttle, it wants to die. I've tried every carb adjustment and only move the needles 1/16 turn at a time. The top of the carb has a small inlet nipple brazed on it and I wonder do I need to attach a piece of fuel line. Could the airflow from the prop be disrupting the pressure? This engine isn't new but is new to me. Thanks for the help.

All Day Dan

My Feedback: (5)

flyer, make sure you are using the right ignition module if it's the one with mechanical advance. Also, make sure the sensor connector is plugged in right. That inlet filter should have no effect if it's on the side with the four screws. On the side with the four screws, you should see the gasket against the body of the carburetor and the diaphram aganst the silver cover. Post an image of the engine. Dan.

flyerdave

My Feedback: (212)

I will get an image posted in a few minutes. Could it have anything to do with the mechanical advance linkages and could they need adjusting? Thanks

w8ye

My Feedback: (16)

The vent tube soldered into the steel cover needs a piece of fuel line on it and trailed behind the engine preferably inside the fuselage.

flyerdave

My Feedback: (212)

Who would have thunk it. An 8 inch piece of fuel tubing from the vent tube solved the entire problem. Runs like a dream. Xoar 22 x 8 wood prop turns 6450 and I still have it just a little rich. Is that pretty close to the number it should be getting? Thanks

All Day Dan

My Feedback: (5)

Good one Moderator. Why would that length of tubing have any effect? All I have on mine is that breather hole in the cover. Dan.

w8ye

My Feedback: (16)

If air blows across the breather hole it will sometimes change your mixture for the little hole is a static air pressure reference for the metering valve diaphragm for the demand regulator in the carburetor.

flyerdave

My Feedback: (212)

Well, I'm at a loss. Went out to fly today and I wondered if someone swapped the engine that I had the other day for another. Fueled up,choke on,cranked and started perfect, ran pretty good but only 6050 rpms on a 22x8 zoar prop, even so plenty of grunt at that speed. Went to take off and 20 seconds into the flight, she started slowing down and almost died so I pulled back on the throttle and was able to milk enough power to get her landed,all it wanted to do was die at anything above half throttle,after that trying to get a good needle setting just wasnt going to happen. I'm going to check the ignition battery and take out the fuel tank and plumbing,then maybe rebuild the carb. If that dosen't solve it, I'm going to take it off and put a DA 50 on the front. Just frustrated right now.

bcchi

Check filter screen in the carb for trash. Check and set timing at 28 to 30 degrees at full throttle.
BCCHI AMA 2500

flyerdave

My Feedback: (212)

Thanks bcchi, I will pull the carb off tonight and probably go ahead and rebuild it before I remount.Help me just a little on how to check or set timing on this one. I know how to check for TDC and use a degree wheel, but not with an engine with mechanical timing advance.I've got to get a little more knowledge of how and when to adjust the mechanical timing linkages. Thanks again.

w8ye

My Feedback: (16)

The ignition module that belongs on this engine does not have electronic advance.

With the throttle wide open,set the ignition advance at 28 degrees. At idle it should be around 4 degrees. Close is good enough

If the truth was to be known, the ignition was possibly set correctly before you changed it?

https://www.youtube.com/watch?v=GBXFpxWg7vY

abacro

To help u out if you don't have a degree wheel. the 3.2's, 4.2's,5.8's and a few other engines I've had with the manual C&H timing ring could be set using a piece of masking tape and ruler. With the piston at TDC and the pickup over the magnet ,place 2 lines on a piece of tape with a measurement od 5/8ths of a inch between the 2 lines. Place the tape on the hub with 1 mark on the magnet center and roll the tape clockwise on the hub. Now all you need to do is open the throttle wide open and adjust the timing ring till the pickup sets on top of the second mark! This places the timing roughly at 29 to 31 degrees.

Hope this helps you out!

Art

All Day Dan

My Feedback: (5)

Dave, Here's an image of a Brison 3.2 with the timing ring fixed at 28 degrees BTC. Dan.

flyerdave

My Feedback: (212)

Thanks guys, but I haven't changed the ignition,nor have I changed the mechanical linkages, this is the way I bought it from the previous owner.I haven't had time yet to try a different battery,check the fuel lines or pull the carb.Maybe there is enough in the picture to tell something about the ignition,later I will get a better description of the make and type ignition. Thanks

All Day Dan

My Feedback: (5)

Are you sure that the metering diaphragm is against the cover with the four screws? Usually the alignment tabs are waving in the breeze. If the gasket is against the cover, they are in the wrong positions. Dan.

av8tor1977

My Feedback: (6)

Good catch!

AV8TOR

KenLambert

My Feedback: (107)

but lok at that plug wire , has a lot of black tape on it

flyerdave

My Feedback: (212)

Looking closely at the ignition and wondering if it might be a good idea to replace the entire ignition. No I'm not just trying to throw money at the problem but at the same time I need an engine that I can trust when pulling an airplane that I have a pretty large investment in.I'm told that this brison engine is one of the most reliable engines out there so I'm not throwing in the towel on it without trying everything.Where can I find these ignitions? I am thinking of just pulling the engine and sending it to BJ's engine service,his website lists the brison as one that he services.Thanks

w8ye

My Feedback: (16)

BJ's will definitely tell you the ignition is bad in order to seem more important and jack up the price.

Someone at BJ's doesn't like the mechanical ignition advance or does not know how to set it?.

The new ignitions advance electronically. You will need to remove the mechanical advance mechanism to use a new ignition.

New ignitions are available from CH ignitions and RC Extreme Power

All Day Dan

My Feedback: (5)

Dave, did you check the position of the diaphragms and gaskets? Dan.

flyerdave

My Feedback: (212)

Been working way too much lately but hope to pull the engine tonight and break apart the carb. I will let you know what I find. Thanks Dan.

flyerdave

My Feedback: (212)

Hey Dan, finally pulled the carb and I think you are exactly right, the gaskat appears to be against the cover. Also the diaphram appears to be streched way out of shape. Going to my local small engine shop tomorrow to see if he has a kit for the WT76a carb and will report after I do the rebuild. Thanks for the help.

All Day Dan

My Feedback: (5)

Thanks for the thanks. It’s a common error. Take a look at the metering needle lever. It may have been bent out of shape just to get the engine running. Be sure to replace it with the one in the kit. Another thing, don’t tighten down on those four screws too much. You’ll crush the gasket at the four corners and distort the cover. Dan.

flyerdave

My Feedback: (212)

Okay heres an update. I finally took the carb apart and put a new kit in it. I am happy to report that so far she is running like a charm. I still have some needle adjustment to do but so far, so good. I am not going to get too carried away until I put this plane in the air,but it appears that the carb might have been the problem all along. I hope to get some flying time tomorrow although the weather forecast isn't looking too good, I know someone who has more control than the weatherman, and I've already put in my request.

All Day Dan

My Feedback: (5)

Dave, I run my Brison 3.2 at 6800rpm. The high speed needle valve is at 7/8 of a turn out to 1 and the low speed is at 1.5 turns. A little four cycle on the first flight is fine. Tune it from there. Dan.