1986 Honda Spree Bogging Under Throttle

[MrChimpo]

I have a 1986 Honda Spree NQ50 (and I have an 85 Spree NQ50) and until yesterday the 86 ran great (despite the 3mm crescent gap between the cylinder & the exhaust flange). It is pushing a lot of the fuel charge out of that gap. There is white ashy scorch marks around that opening, and I am unsure what this is doing to the engine temps, compression, etc... Also the scoot has just the straight downpipe cutoff from where it met the original OEM muffler.
I was able to get up to 30 strong and smooth until yesterday when I took the {reed valve, intake manifold, Carburetor}, and CDI off of the known-runner 86. I got the 85 to fire up, after having to fill the carb and prime the combustion chamber. It smokes like crazy and has a delay in throttle accel & hangs on decel. There was a small leak at the case-reed valve-intake manifold mating surfaces that would whistle/bubble at idle and cause it to die. This setup on the 85 would run strong up until 28-29 mph but would then cut out periodically and hang on decel for like 5-6 seconds before the RPMS would fall. It smoked white trails of smoke like a stunt plane everywhere I rode on it. I topped off the OEM honda mix oil reservoir with new syn oil (it was about half full), and topped off the 1/2 tank of OLD gasoline with shell 92 + Gunk Carburetor Treatment 2oz in the tank.

I would like to think that the reason my 85 isnt running like it should is because of improper carburetor adjustment / bad gas(oil?). The 85 has 2518 miles on it and the body is in great condition (springs, brakes, tires, plastics). The 86 has some gouges in the cylinder wall and the leak at the flange for the exhaust where it meets to the cylinder. The 86 is on mix fuel 32:1 and seems to run WAAAY better like that. The 85 is Oiled...

So after reinstalling the reedvalve-intake-carburetor and snugging everything down the scoot finally started. I believe that there is small vacuum leak there.

Any insight, advice, or encouragement would be greatly appreciated =). Thank You in Advance.

[devenex]

My vino was having similar problems with temporarily cutting out at full throttle, turned out to be the muffler clogging. One camp fire and a coat of rustoleum bbq paint later and it was good to go.

The beater 86 is probably running lean considering the exhaust issue, which improves performance at the cost of durability.