I am trying to decide between these two engines for my GP Patty Extra 300. Please give some advice on which engine would be better. Thanks

I would have to say the BME although the Brison may be a hair more powerful. The Brison has a mechanical timing advance that I'm not too fond of.
I just test hopped a GP Patty with a BME-50 and it was a great combo! More power than you need. I personally favor the DA-50!

I have a brison 3.2 in my GP patty and it is great. I have never had any trouble out of the mechanical advance on the Brisons I have owned. I don't think you can go wrong with either one. I like Brison and their service after the sale.

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There are several microprocessor controlled timing units on the market. These units fix the timing ring at a specific setting, while changing the timing based on the engines current rpm. These units work very well, but are limited to a 24 degree advance or retard in the timing.
The Brison engines are optimized beyond the capabilities of the electronic timing for ease of starting and maximum power output. This is achieved via a mechanical connection to the timing ring. Using the mechanical timing ring in conjunction with the electronic module, allows for a broader Advance / Retard range, and more effective performance.

I happen to be in the market for a 50cc gasser also and was wondering how the ZDZ 50 compares with the aforementioned engines? I intend on putting a 50cc gas engine on a 16-18lb Kangke/Superkraft 87" Laser 2000. Any advice or suggestions will be welcomed. Thank you.

...The Syncro Spark processor has a range of either 20 or 26 degrees and full advance at either 4000 or 6000 rpm..Almost ALL engines use the 4000 rpm, 26 degree setting...
FPE made some engines fixed at 18 degrees..They run MUCH better when retimed at 28 degrees..
Mechanical advance systems can be set for whatever the manufacturer want to use, but setting up an engine retarded would be not in their best interest..
It's REALLY easy to lock the mechanical advance units at 28 degrees and put a Syncro Spark processor in series with the Hall sensor, just takes a male and female Dean's plug and about 5 minutes soldering time....
Can't be done on the FPE engines with 18 degree fixed timing, the hub is in the wrong place on the crank....Either re locate the sensor or the hub....

RCIGN1

Did you read that review on the ZDZ50 in RCM? He said the compression ratio was less than 6:1 and the timing was 20 degrees to 36 degrees? I find that our engines wont run well at much more than 28 degrees and that 87 octane fuel is fine. I have always been a fan of Mr. Lee but that review was a bit lacking.



Keith
BME

I'm with you...Wonder how he checked the timing...20 would seem to be high for starting, and 36 a little high for running......28 degrees seems to be the best timing for any engine, except for a 289 Herbrandson twin in one of our race planes..We got the same results from 22 degrees, so that's where it stayed...Most of these engines were originally designed to be used all day long in the woods cutting trees down and any old gas and oil could be used...One of my customers is a logger, using Husky saws..They go for 2 or 3 years without any problems other than dirty air cleaners and spark plugs..Airplane engines are pampered by contrast

Kind of puts an end to the high compression/high octane theory for model airplane two cycle engines custom made or not. We run most of ours at 9:1 and have found that 90 plus octane is not necessary. I found this to be true with every engine I have tested BME, 3W, ZDZ, DA, Brison, Zenoah. The compression ratio is probably the main factor in the timing settings. Isn't that Herbranson really high compression? I heard that A.I said the 3w timing is set -10 degree at idle and +20 at max rpm. Have you ever tested one? My 3w runs best at 28 degrees.


Keith
BME

thanks for the info guys Which engine do you think would be smoothest?

depends on which way you rub them!

Yep, I'd be interested. How much time has it seen?

On second thought, maybe I won't be. I see you're having problems with this/a BME 50.

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BME..
A Herbrandson is a big tractor, made to run at 7000 all day long..We use .022 from the piston to the top of the chamber, don't know what the compression ratio is...
Tested many 3w engines...Had to remove the braid from one plug lead to put the inductive lead from the light to make it work...
minus 10 to plus 20 is way more than I have ever seen...At minus 10 it would start backwards, and plus 20 would not be enough..I have two 3w ignitions here, neither shows any advance or retard at all..They're both old, maybe the electronic advance function no longer works...When I set a 3w with the light I use 28 degrees, seems to work best....I have "power timed" some 3Ws, when checked later it was close to 28....

clatsmith, whats wrong with looking at a Taurus 52cc 3.2cu.in most guys are running 24x8 on this engine in a Patty or DP Extra.

i have 2 of the 3.2 brison
a friend has the tarus that baby is very smooth right out of the box.
Da is suppose to have a very smooth 50 as far as powerband goes.

get you a motor in the 50cc range all the boys are kicking butt and taking names right now.

i am also enjoying my zdz 4o, i hear that are bad on a can.