Never heard of a Pacer
With modern 2-stroke oils you should probably pre-mix between 3 oz.( 43 to 1) or 4 oz.(32 to 1) of oil per gallon of gas.....and mopeds are designed to run on the lowest octane of gas you can buy (87 oct.) because they are afraid that somebody who doesn't know better will put the cheap stuff in..... and higher octane will not make it run better or faster or make more power.
Clogged or dirty carburetors (on the inside) are the most common reason for poor performance... the carburetor must be removed..... then you take off the float bowl.... then you remove the brass "main jet" in the middle of the carb.... hold it up to the light and look thru it.... it must be clean and clear..... if it is not clear you must poke a piece of fine wire thru it.... a wire plucked from a wire brush works good.... or some soft multistrand copper wire like from speaker wire or lampcord wire... don't use a drill bit !!.... next you should screw the idle mixture screw in while counting how many turns out it was set at..... then remove it and all other screws...... now you must clean out all passages in the carb with aerosol carb cleaner and compressed air (like 100 psi) with a blow nozzle... squirt the cleaner in all orifices one by one followed by a blast of compressed air.... while you are blowing air thru the holes feel with your fingers to feel where the air is coming out of and blow the other way too...... then reassemble all the parts (remember to turn the idle mixture screw out to its original setting... usually between 1 and 2 full turns out from all the way in) and reinstall the carb.
The next most likely cause of bad running are dirty or mis-adjusted ignition points..... to clean them you need some fine grit sand paper (like 400 grit), a piece of clean paper, some scissors, and some aerosol brake cleaner or carb cleaner and some compressed air with a blow nozzle....... remove the ignition cover and look for the points in one of the holes in the flywheel.... lay the bike over on its side and sit on a milk crate or something to get comfortable... then cut some thin strips of sandpaper.... pry the points open with a small screwdriver and stick the piece of sandpaper in between the points and let them close.... then pull the sandpaper out.... do this several times to each side.... now pry the points open and blow them off with compressed air... then spray them with the cleaner.... then cut a strip of the clean paper and pry the points open again and drag the paper thru a few times.... blow them off again with air while open.... now they should be good..... next find the timing mark on the flywheel and see if the points open when the mark on the flywheel passes by the mark on the engine case.... that is the timing and to set it accurately you would need special tools or take it to a shop to have it set.... if it looks like it opens when the marks line up you are probably OK.
I am going to save these instructions and post them when people need them.