Just bought a used 50cc brison. It's on a 80 inch cap total weight 16 pounds, am I incorrect or should this plane rocket with this motor power seem's low and misses??? Any suggestion's on what I can do to fix I am new to this.

I had one on my first gasser, a Wild Hare Edge 540 that I over built it was the 1st gen. so it was heavy. My 540 with the Brison had good power not great because of the heavy plane it was in but it would hover and climb out of a hover .. So in your smaller Cap it should pull it good..If missing could be runing rich will the motor clean out on a up line?? If so it's rich..I hope this can help ...

The Brison 3.2 (52cc) will pull any 16 pound plane straight up all day. It will hover a 21 pound plane and still manage some vertical pull out, but is will be slow in the doing.

If your engine is missing and lacks power there are three places to look. First will be the propeller where power is concerned. Many that bought Brison engines never bothered to learn about performance props and continued using Zinger and master Airscrew products. Big mistake.

Next will be the carb tuning and carb condition. A carb rebuild kit only costs $10.00 or less and investing in one and using it is a good idea. I'll venture that carb tuning and condition is the missing problem before any other

The last place will be the spark plug and ignition. You should use a resistor plug (Champion RCJ7Y) to minimize RFI. Gap it to .025". Check you battery condition and wiring connectors.

I had one that missed and carried on. The carb adjustments didn't help

I checked the timing and it was 36 degrees toatal.

It had auto advance CH ignition.

36 is wrong, 28 is right...
Been doing ignitions for 22 years every day...NO one uses 36 unless they don't check it...Some A&Ms were 45 or more....

I reset the timing to 28 degrees

How many years again?

Since the '80's engine specific. Aerospace machinist prior.

Funny thing about that timing. depending on how you intended to run our timing curves pretty much suck. Especially since they really aren't "curves" They start from 5 degrees or so at zero and sharply ramp up at about 3,000 rpm to 28 and stay there. There is no alteration in the advance after it ramps up, just steady at 28 to 30* depending on how accurate the chip is. The only true "curve" on cdi ignitions was with the mechanical advance, which was why they had a so much smoother mid range.

For those that desire to debate the point and rpm values previously noted, I was deliberately noting values that were not completely accurate. I'm prohibited from noting the specifics.

Assuming the timing and ignition is fine,,

Also check,
The smoke tap is 100% plugged,
Carburetor screen is clean (this is a 1-2 gallon run time maintenance)
Use only 91-93 octane gas, they'll detonate on the cheap stuff

You'll love the Brison if you take care of it,,
Mine is currently in the 5th airframe over 12 years,, 80" extra 300
I'd guess well over 20 gallons of fuel though it

Good luck, and Welcome to RCU

I wonder where the lumberjacks out in the wilderness get high octane gas for their Makita chainsaws that use the EXACT same cylinders..Think they know something we don't ?
Try sending a whole chainsaw back to civilization for warranty
ANY gasser timed CORRECTLY will not detonate with 87 octane fuel.....

Same place they'd get low octane I'd imagine, I'd guess they have to bring it out from a gas station just like anyone else,
I don't know everything,, you'll have to ask a lumberjack to know for sure I guess

I'm just relaying my experience
I've never changed mine from the factory tune, it runs great on 91 or better, crappy on 87,
Brison recommends 91-93 in the owners manual also,, I'm guessing they are tuned for that fuel

Wisdom from TOC and Top Gun caliber fliers
The TOC guys like auto advance, because above 4000 rpm all that is varying is the throttle and they fell that the engine has a better throttle response.
The scale guys like the throttle coupled because of the smoother mid range, that's where most of the scale ships are flown
99% of the modelers can't tell the difference. Me included

When an engine has to provide consistent performance at all useable rpm bands with minimum instabiity the need for a different type of advance curve becomes evident. The most apparent for the average person is in heat generation. Of couse this presumes an individual documented run results with at least rudimentary instrumentation. Run a 35 degree advance at high rpm and note the temperature delta between that and a 26 or less degree advance at rpm above 7,000. Tuned pipes would also benefit from a different curve since pipes typically generate more heat when set up correctly. More rpm=more work=more heat. There are other considerations but I have to save those for work only discussions.