Running Lean (?) on a '78 Maxi

I've tried searching for this issue and didn't find any quite like mine, so apologies if I'm covering old ground here.

I have a '78 Puch Maxi Luxe. Stock E50 engine, stock airbox, 12mm bing carb, and a new BiTurbo pipe. I use a 50:1 gas/oil ratio with an in-line fuel filter. Chains are tightened appropriately and tires are at recommended psi. I live in the northeast at about sea level and it's summertime. I'm new to mopeds and have learned what I know from this site and a couple of nice local folks.

When I added the pipe, I upjetted from the 62 that had been in the carb. I started out high and it bogged down on everything until I put the 62 back in. It runs best (in terms of acceleration and top speed, but also in terms of "sounding right") with that jet and the little plug on the back of the airbox removed. So, duh, stick with that, right?

But when I check my plug with that configuration, it looks like I'm running lean. It darkens up if I cover the airbox hole and crimp the tube that comes out the back, but I lose speed and it feels sluggish.

So what do I do? Stick with the intuitive answer and open up the airbox or go with everything I've read, which says a clean plug means my engine's gonna seize up any second? Thanks a lot for taking a minute to weigh in.

Re: Running Lean (?) on a '78 Maxi


Re: Running Lean (?) on a '78 Maxi

Overpriced Parts /

Richen the needle like he said But just get a metal mesh filter and prolly use a 64-66 jet

Re: Running Lean (?) on a '78 Maxi

Thanks guys. I raised the needle a notch. Ran rich, lost a few mph, so I took the airbox out and shortened the hose and cut a few extra holes in it. The ped started to really rip, but ran super lean. Upjetted to a 66 and started covering some of the holes before time ran out. More work tomorrow, but I think I'm on the right track.

Re: Running Lean (?) on a '78 Maxi

Yeah, A lot of this (from my experience new like you are so limited) is trial and error. I'm still working on my jetting as well. Just try something and blast it, re adjust and blast. I know I'm on needle and jet combination 15 and still need to try more. Trial and error man.

Re: Running Lean (?) on a '78 Maxi

Gromosaurus Rex - Brad Pitt /

Re: Running Lean (?) on a '78 Maxi

"Trial and error" ought to be in every newbie tutorial. I think I learned more about my carb in three days of actually messing with it than in the three previous weeks of reading and watching videos about it.

I still don't know shit about my engine, though!

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