1980 Maxi struggling up hills

I purchased a 1980 maxi a few days ago and just got it running. It runs great in the flats and down hills but as soon as I climb even a small hill it it loses all power and has even almost died. Does anyone know some possible explanations for this? Living in Cincinnati and not being able to climb hills is killing my mobility.

Thanks for the help.

Re: 1980 Maxi struggling up hills

do me a favor and count the number of teeth your rear sprocket has and the number your front sprocket has, the rear could be in the vicinity of about 35-45 the front maybe 12-22 possibly, also what carb are you running?

Re: 1980 Maxi struggling up hills

It looks like the rear has 45 and the front has 14 give or take due to poor counting skills. The only thing I can tell from the outside of the carb is that it is a bing, as far as I know it is the stock carb.

After reading up a little I did some tests earlier, and it seems like it bogs out the worst at full throttle, if I ease up a bit I can hold a little bit more speed. Does this tell you anything?

Re: 1980 Maxi struggling up hills

Don't forget, when you give the bike throttle, you're not modulating how much gas it gets, so much as how much air you let in. So, if it's bogging at WOT, I would say the air/fuel ratio is too lean (too much air in ratio to gas), and that you would benefit from cleaning your main jet or maybe moving up one jet size. I could be wrong, but this is just something I've done in the past.

Re: 1980 Maxi struggling up hills

The thing is when I am in the flats or downhill having it wide open doesnt cause any bogging as far as I can tell. If it was running too lean wouldnt it run semi-shitty all the time at full throttle?

Re: 1980 Maxi struggling up hills

As far as I know, the main jet size dictates how much fuel the bike gets at WOT. There isn't any difference between say a 56 and a 60 jet in a half-throttle situation. I may be wrong, someone please correct me if so.

Re: 1980 Maxi struggling up hills

I'm sorry, I misread your last message, so my reply is pretty dumb. I have a feeling the motor is just working hard to pull the hills and is running out of fuel and falling flat on its face. A lot of mopeds struggle with hills. I'd suggest re-gearing or some basic performance mods to give it some more balls.

Re: 1980 Maxi struggling up hills

Steamboat Aka J. R. Stevens /

Hmmm I have always heard if your bike bogs at WOT and picks up when you let off the throttle, you were 4-stroking which means you are running rich.Jim.

Fred's Guide


"Four stroking" means your air to fuel ratio is too rich.

Four stroking is this >>.. when you near top speed the engine goes from a smooth high pitched ziiiiiiiiinnnggggg tone... to a lower pitch rougher tone... and the engine acts like it is choking, like it would like to go faster... and sometimes it WILL go faster if you close the throttle a little bit.

IF your engine is doing this... and the air filter is clean... remove the filter and test ride it again... if it goes faster and "four-strokes" less.. then you need to lean it out with a smaller main jet.

Re: 1980 Maxi struggling up hills

Alright I will try pulling the airbox today and see what that does for me. If it is the case would it be a viable option to leave the same jet in but replace the exhaust with a biturbo, which recommends an increase in jet size? I was already planning on doing this and it seems like a waste to buy a smaller jet just to need a larger one in a week or two.

Re: 1980 Maxi struggling up hills

Dont get a bi turbo for hills, its a top speed pipe. Id get an MF power pipe if you want lowend.

Re: 1980 Maxi struggling up hills

where can I find one of those pipes. I just checked 1977mopeds and didnt see it.

Re: 1980 Maxi struggling up hills

Alright so I did some tests today. For one the bike is running far worse now than it was the other day. Now if I twist the throttle on more than a quarter way the motor bogs down and dies giving me a top speed of 5-8 mph. I tried pulling the air cleaning and saw no change in performance. Does anyone know what could be causing this?

Re: 1980 Maxi struggling up hills

maybe your carb is clogged and your gearing is designed for low end actually, id make sure every passage way is clean. and yea jets are only for WOT

Re: 1980 Maxi struggling up hills

Nvm, they dont sell it for Puch's/

Re: 1980 Maxi struggling up hills

if you just got the moped I would be temped to go thru and check everything (pretend it has never had any matnice done) change tranny fluid, clean the fuel filter (Bing has it in the bajo bolt on the carb) clean the carb, make sure front and rear wheels sping frealy and don't wobble, clean your air filter, clean your exuast, install in a new spark plug.

Look at the choke plate...

Ben Van Zoest /

in maybe disengaged from the shaft. Remove the airfilter box and look into the intake, the plate should almost uncover the intake pipe. You will have to remove the carb top if you can't move the plate with the pushrod.

Re: Look at the choke plate...

NB0tt aholetechbro /

check the points gap/timing too.....I have so many problems with my points coming out of adjustment it's depressing....but makes all the difference.

Re: 1980 Maxi struggling up hills

Alright status report. Took the carb completely apart and cleaned it today. Put it back together and now the bike wont start. We could get it to run but only with the choke in so I feel like it is getting too much air.

Could someone tell me the correct settings of the two rings that clip onto the needle in the slide of the carburetor, We experimented with changing them and I think that is why she won't start.

Re: 1980 Maxi struggling up hills

the needle is not gonna prevent starting.. The clip can go into any groove. Pick one near the middle and tune from there. (a higher grove lowers needle and leans the air:fuel mixture)

Try a squirt of Starting Fluid. If it starts there's a fuel restriction. If so, clean the carb again.

it doesn't sound like too much air.. it sounds like not enough fuel is being allowed in.

Choking cuts off some air and forces the air:fuel ratio to be richer and more nearly correct.

Re: 1980 Maxi struggling up hills

Interesting, fuel flow. We did have a lot of trouble aligning the banjo bolt within the fuel nipple, could that be causing this fuel restriction?

What are some tips for doing that right? We had the hardest time getting the bolt tight while keeping the nipple in the right position.

This whole thing is killing me, I am itching to take that thing out on the road.

Re: 1980 Maxi struggling up hills

If there's a trick, it's to be patient and take the time to become intimately familiar with how and why the thing works.. and so to understand how it's supposed to go together.

Someone once told me ya gotta be smarter than the thing you're trying to fix..

Re: 1980 Maxi struggling up hills

Have you checked out your throttle cable and assembly? Also just follow the flow of fuel.... Petock, line, carb, just watch it go.

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