NB50 resurrection

Trying to get your Spree/Elite to run, or run better? Post your questions here.

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NB50 resurrection

Post by nateberrier » Mon Jul 22, 2019 10:02 am

All, I posted a few days back looking for an air screw on my 85 aero "barn find".

The previous owners were riding it around the back yard with no air screw and the needle clipped at the bottom. Actually ran pretty good!

I moved the needle up a clip and was able to get the scew i found at a salvage shop (they had a ton of spree and elite stuff NOS in a box in the back corner hehe) to work with a couple turns out. I never quite felt like it was perfect, but it seemed to run pretty well and on the initial plug chop it seemed to be running healthy.

It had a crappy piece of old foam in the air box, so i ordered an oem filter that fit 100%. After doing that it was bogging a little bit till it got to high RPM, I assume because it was a little too rich, but im definitely not an expert. We rode all around for ~50 miles, a full tank and then some basically. Could tell theres a bit more in the bike, but running the speedo out past the 40 mark on flats.

Anyway, the next day I get the bike out to get ice cream with the wife and I can tell its not running quite as well. Its dropped off a few mph from top. We're about 4-5 miles into the ride and it starts to bog hard and lose power. I backed off and coasted into a drive way, but shes still idling great. Take off again. Then about 2 miles later it shuts down and there is some smoke coming from under the faring, presumably up by the motor. Wouldnt start any longer, occasionally would get a "poot" from the exhaust.

The insulator on the plug has some black blisters and it looked like some shiny flecks on the outer ring of the plug. At first I thought it had seized, but after talking to some friends and further thinking. Im guessing it was overheating or detonating or both. Id imagine ill find a melted piston.

Ill accept responsibility for the sad state of the beast, but I thought it was worth mentioning that it was probably still 94 degrees out when we were riding.

Now that the novel is done, I wanted to ask about a rebuild and preventing this in the future. I have a spare engine from teh same barn find people, but they noted that the scoot stopped running and they started treating it as a "parts bike". Its been sitting with the carb off for who knows how long and i dunno if its worth trying to swap motors.

My options at this point seem like buy compression tester and test dead engine knowing its probably toast, swap over motor then test again (these are 85s so idk if ill get a good reading w. starter and no kick????) and hope there isnt dirt or water inside. (maybe the reeds kept s*** out?)

OR, just buy a bore kit and rebuild the dead motor. If I do this, Id like to get a CHT and tach (accepting recommendations), figure out a new fan shroud, and also figure out if i need to get a different pilot jet/ carb that has removable pilot jets, or if im good just changing main jet.

I will gladly paypal you the price of a decent beer for reading this * pile, I just wanna get my scoot up and going before summer is over so i can ride with the wife. Also curious if anyone has added additional cooling via computer fans or something to their bikes?
1986 Aero White -- Stock With Keli Var
1985 Aero Red -- Af05 Malossi BBK + Keli Var
1985 Aero Red -- Af16 Corsa / Fabrizi Pipe / Polini 24 PWK / Athena Stuffer Crank

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