My Brison 2.4 has never tuned well, always has run well on the ground but on roll out for take off it starts to miss and pop. Land it and it runs well again. I have cleaned out the jets and carb and it is doing the same thing still. Just wondering if maybe I should go to the bigger gas lines through out the system?? Anyone else had the problem and what was the fix??

I do not have such an engine, but I do know engines pretty well. It sounds like it is leaning out, either intermittently or evenly during T/O roll. Therefore, there are two factors involved: 1. Vibration, and 2. Airspeed. Try running the model and then holding it inverted. If it starts misfiring again, then you probably have a loose fuel line fitting or a cracked fuel line that allows air entry when it is shaken. Take a look at the carb position and see if there is the possibility of an air pressure change or restriction. Next, if the RPM increases significantly during takeoff roll, it may be that a fuel line restriction is causing the problem, either because of overall small flow capacity, or some other restriction. The only way I can think of to check that is to ground run it with a prop of less pitch or diameter to run at a higher RPM to see if that induces the misfire. If it does, then an increased fuel flow is required. Be sure and check all the fittings, including the needle and main jet for foreign objects. I hope this will be helpful.

'Jet-Eye' Don

I'm sure you do not bigger fuel lines. These things just sip gas ( I have one ). I did have the same problem with another brand of engine and tracked it down to the battery. It would supply enough voltage when running static but as soon as the prop unloaded it started backfiring & missing. I was running an 1100 mah nimh and switched to a 1400 mah nicad - end of problem. This may or maynot help.

Hey Don,thats a great piece of advice,i'll try it on my 2.4 also! Right now the only cure i've found is to use a 17/6 zinger prop and really let her turn up the rev's. Got that info on the 17/6 use from Bubba Spivey, Mr Lanier himself!

Good Lord man a 17 - 6 [X(] Mine turns an MSC 18 -10 @ 8000 some guys are running 20 - 10.

Thanks guys. I have tried different sizes of props at different RPMs so that wasn't it. I have the 1700 amp NIM and they call for A NI-CAD so there could be something going on there?? I had already gone through the carb. I will go through the gas tank one more time and check all the lines and make sure the gas isn't foaming. I want to check the ignition pick up and make sure that isn't loose and just for grins I will change the battery over to A NI-CAD. I'm also going to pull the needels and roll the engine over and try to flush out the carb just in case I missed something??
I'm open to any other ideas that haven't been brought up. This is getting to be A pain in the mule.

If you get disgusted I'm looking for another one Mine gave me a lot of grief at first but I sorted it out and now it's like the Energizer Bunny. On & on & on.

Actually I sorted mine out by sending it to C & H Ignitions. They replaced the ignition module and told me that Brison should never have installed the sensor that far away from the magnet. They made a new bracket and moved it closer . That was 5 years ago and it hasn't missed a beat since.

GUYS
i have the b2.4 for some time now.
i had them both..the old verstion with the MECH ADV IGI, and the new one with the FIX pickup sensor.

both had problems!

1. prop: the minimum size is 20x8!!!!!!!!!!!!!! and this is by the manufacturer him self GARRY.
2. set is an issue, needs a lot of time...for myself and other guys more exprienced than me!
3. chk the fule system-> tank, make sure the tube is not twisted-> holes in fuel line-> for some reason the B2.4 dont like a "T" line for fueling???->try to add a ventury knob to the carb, like the ones that come on the Zenoah's...u can get one from BONZI

moreover, when this engine is tunedup and working..it is pure fun but it take time to get there.

enjoy

To each his own but I've had a "T" fitting on my 2.4 for years and never a problem. Just replace the fuel if it gets too brittle.

lucky guy

HOORAYYYYYYYYY thank you don! the battery change did the trick! My 2.4 is swinging a 20/8 at 7600rpm! I LOVE IT!!!!!!!!!!!!!!!

abacro, What brand 20/8 prop are you getting 7600rpm with?

Well I finally was right about something. Maybe 2007 is going to be a good year

I turned that with an APC 20x8 propeller.

My 2.4 was a PITA to start yesterday, thought I had flooded it. Finally get it running and the transition seems a tad sluggish so I leaned the low needle a hair. (Just got it back from a full service - was thinking that needles might need a mild tweak to compensate for the difference in locales.) I have 3 flights on it since the service with no issues. Once in the air the engine was pulling my 15lb CG Yak like always - nice strong performance on a 20 x 8 Xoar prop. I flew for 6-8 mins and all was fine, good throttle response coming out of downlines and all. Then I put it into an inverted flatspin and about 3 rotations in the engine bogs. I roll out and fly wings level for a bit and the engine finally cleaned up (after 15-25 seconds). I come around to land and it won't idle down low enough to land, so I go around and drop my throttle trim several clicks (5-6). I put the yak on the ground and then the engine is just about dying the idle comes down so low, and has trouble coming back up to taxi in to the pits.

Next flight I fire the engine up - it hits on the 5th flip without having to re-choke, and seems to transition decently on the ground. High end is nice, so I taxi out, blow the motor out and get it into the air - full throttle climb out, and as soon as I get about 15 degrees nose-up, the engine drops RPM again on me, but thankfully is still pulling the plane well enough to avoid a stall. I circle and land it, and the engine dies on rollout when I try advancing the throttle.

I'm thinking that my LSN was lean to begin with, and I made a mistake by leaning it more. Cool 45 degree day (dense air) probably wasn't helping any. I'm going to richen it up a bit and do a lot of ground testing this week see how it runs. Also planning on going through all of my fuel tubing/clunks. Will also pull the cover off the diaphragm and check it for any cracks/tears/pinholes. Anything I'm missing?

Last night was the first time I had A chance to look at it. I found the pick up was loose enough to slide it back and forth and it was sitting about half way over the magnet?? I set that and tightened and will double check the timing sometime today then go through the fuel system. It took some effort to slide the pick up so it isn't like it was bouncing around or anything.
Here is A question for you guys. Why when I get an engine that was test run and all set up from the dealer, I got this one from Garry direct but I have bought from others like RC Showcase, I use the same prop and fuel, they never seem to run well. They have all needed tuning. This one has been A problem from day one. Just wondering?

Not 100% sure what you are meaning, but there are always issues that can make a difference in how an engine runs that are determined by the atmospheric conditions that an engine sees.

If the dealer/manufacturer test runs the engine in a climate controlled room, or even outdoors with very low humidity at 3000 ft ASL, and then ships it to me in Louisiana at 75ft ASL, and I try running the engine at our typical 75% humidity on a 55 degree day - I'm going to expect the engine to respond differently if the needles are set the same. I'm guessing the engine would be running a little lean in my location.

Also the mounting in the cowling can cause some pressure changes that act on the carb differently, and may require some adjustments to make the engine run well in-flight. It's always something.

After reading your first post I was going to suggest looking for a loose wire but I have a feeling you found the answer in the loose pick up.

All engines require tuning after they are purchased. No engine is tuned for best performance out of the box. Believing so will only create a lot of frustration and irritation when the engine fails to perform to the owners satisfaction. You will always have to tune an engine to the enviornmental conditions and the prop selection.

Use a good synthetic oil and use a mix ratio of 70-1 per Gary's recomendations. All Brison engines used to call for a 70 to 80-1 synthetic mix before the company change.

If you have a CH ignition, the minimum battery you should use would be a 4.8 volt, 800 mAh battery. The type does not matter, but the voltage does. An 1,100 mAh, 4.8 volt battery will last you all day.

I changed the battery from A 4.8 2700 amp Nim to A 4.8 1400 Ni-Cad just to see if that makes and dif. I also changed out every line in the fuel system then pulled the needels and turned over the engine flushing out the carb. Also opened up the diaphram plate and checked the pump. Added more foam around the ignition. Everything looks good to go so I will fire it up tomorrow and see what happens. Can't fly it yet but hope to get to the field this week and give it another try.

I haven't read through the thread but a new switch wouldn't hurt matters and is relatively cheap.

I tried the zinger first and only got 6600,then a menz and got 6900,then finaly a mezlik and hit the 7600. I flew it with all three props,and truth be known i prefer the menz better but the zinger sounded more right. Not having to really winde up the motor to 7600rpms or more to me means it should last alot longer

Just A thought but my engine came without A velosity stack, could air flow over the carb have something to do with my little problem?? Still just shooting in the dark here and trying to cover all the bases.

I have flown mine with and without the velocity stack and found 0 difference. That being said have you tried running a vent line from the diaphram cover on your carb into a "static air" location ?

Not yet but I was told to give that A try. Solder on A brass tube and run A line into the fuse or out of the air flow. I think I will just go ahead and do it now because we are getting hit by some storms this weekend with high winds and it looks like I'm grounded until mid week or even next weekend. Thanks for the tip.

Gray Beard is your 2.4 the old style like mine with the mechanical advance or the new style with the Cimmaster ignition ? I am considering a new 2.4 but they now have this type ignition on it and I can't find any pics. or feedback on it.