My crank or rod broke on mine today, it only had at the most ten gallons of fuel through it. It is still under warranty so I am going to call Brison tomorrow. Anyone else had this problem before. Thanks James

I called brison to day and they were very nice and said send the engine in and the would check it out. I guess I will see where it goes from here.

Gary at brison will bend over backwards to take care of you. i have over 30 gallons on my edges brison 3.2 and she still peers like a tiger. i think they will end of fixing your motor for free or very close to it.

I agree with Krayzc, unless you did something to cause the problem, Gary stands behind his engines. Even sometimes when the warranty has expired

Well that makes me feel some better. I don't think I have done nothing to hurt the engine I ran Bell-ray MC-1 at 50-1 and ran a Mejzlik 20/10 prop. I like their engines I also have a new 5.8.

Hey Walton,

What RPM are you getting on the Mejzlik 20X10? I run the same prop on my Brison 2.4 and I am getting only about 6800. Does that seem right? Thanks.

i got around that same # on a zdz 40 so i think those are some good numbers...

I was getting around 6900 to 7000

Thanks Walton/Krayzc,

At least I know that my Brison is not too far off the mark. I bolted on a Menz Ultra 20X10 today and got a 100 RPM increase. The 100 RPM made some noticable difference but I am still left wanting. Guess I need a slighty larger engine for my plane. (Dave Patrick Extra 330L) Maybe a 44 or 50 cc.

can you run a 20-8 prop on this? What would that turn? maybe gain a little rpm and thrust?????

I run an APC 20x10 on my Giles 202 and I get 7300 rpm with mine. I have another 2.4 on a PW Extra but I have not measured the RPM yet. I am running a 21x8NX prop on that engine/plane

What muffler are you using.
The BCM seems to do better than the slimline or the stock muffler.

I was running the stock muffler. What is BCM I haven't heard of them?

BCM stands for Bisson Custom Mufflers.
http://bissonmufflers.com/en/index.html

Take their standard muffler and remove the tips of the pipes.
Ugly but good!

I ran a top flight 20/8 wood and ran around 7200 rpm. I don't know if it gives you more torque with less pitch tho.

I talked to Harvey at Brison this evening he took the engine apart and said the crank shaft was broke, and he looked it all over and could not find a obvious cause. The good news is that he is going to fix it for free, and all I am going to have to pay for is shipping. I think this is a good company to deal with.

What will removing the tips of the BCM do for my ZDZ 40 RVL and my brison 2.4. Jerry.L

WHen I removed my tips, I got 200 more rpm (7200 to 7400). I am assuming it has something to do with the tips being rounded in. It did make it a little louder but quieter than the standard muffler.

from post 3 i may can use that on my resume for a tela card reading job:

congrats on buying a brison and Harry tells it like it he he crakes me up.

Wood,

I tried three different 20X8 sized props. All were wood props.

Menz-S : Didn't get to measure the RPM on this prop but it pulled pretty good. Broke it on the first flight when I ran out of fuel and the plane didn't quite make it back. (the vent line got bent down. What I thought was a full tank turned out to be only a quarter tank)

Top-Flight Powertip : I got only 6600 on this prop. Performance was pretty dismal. Anyone wants to buy two cheap? They have been balanced too!

MasterAirscrew Simitar : 7600 rpm on this prop. Performance was good but decided to take it off as I consider that over revved for this engine.

I would not consider 7600 rpm as overrev.
If I am not mistaken the Mach .6 rpm for a 20 inch propeller is something like 8000 rpm.
I would say use it and enjoy!

I got 7900+ from a Zinger Pro 20-8,and this would cause a
over -rev in level flight,but it is great on up-lines and for engine
,or .prop,braking on down lines or landings...

I just wanted to stay within Brison's reccommendation. According to Brison's owner manual, (Third page under 'Propeller') they stated that engine RPM should be kept between 6500 and 7500 RPM (Static) for best torque.

But you are right, 7600 RPM for the MA Simitar is probably still fine to use.

I don't understand why we worry so about over reving these gas engines.... are they really that close to flying apart and overheating at the max torque rpm?? Why do we need max torque right at the max rpm?? Seems to me max torque would be more usefull down in the middle to 2/3rds of the power band where the throttle gets used more. as long as were getting the thrust we need, and are not overheating the engine, what are we hurting?

Kevin

My Brison 2.4 would turn a Mejzlik 20x10 @ 7100 rpm - that's open exhaust (no muffler). A ZDZ-40 (rotary valve) with a B&B muffler (?) turns the same prop @ 7600 rpm. The point is that there is free power available if you can put a less restrictive muffler on these engines. Check your rpm open exhaust and compare to your muffler - you may be surprised.