Slow Puch

I got this 1hp Puch Maxi recently, and it's running strong - just really slow!

The carb was really corroded and stuff - so for testing purposes I put a brand new 15mm carb on it, and it's still going like 20mph. It's somewhat loud, kinda rackety, and it knocks a little. There doesn't seem to be an air leak anywhere (anymore at least). I tested compression on it, and got 120 - is that good?

Is this timing / points do you think?

So far:

Fixed air leak issue

Cleaned cylinder and checked rings

New carb

New spark plug

I hope this thing isn't supposed to be going 20. I measured the rear sprocket, and it's the same size as my Newport (which does not go 20)



Re: Slow Puch

Hey Beamer

I don't think there should be much difference on the top end between the 1hp and the 1.5hp the smaller engine will just take longer to achieve the same top speed.

That compression sounds fine but I'm not expert so you may want to ask Brett...

When I had my stock exhaust on my 1.5 clogging was a constant issue untill I loosened the nut at the end of the pipe and slid the baffle back to open it up a bit... if it has a muffled vacuum cleaner sound then it's not right... check the gasket between the header pipe and the back part of the exhaust and makesure it is tight...

Good luck with it!

Re: Slow Puch

Yeah I forgot to mention that I loosened the exhaust a lot, and nothing happened. I also put new oil in it.

It feels like off the line it's really good, but as it accellerates it bogs.

Yargh, this is so annoying.

Re: Slow Puch

what size jet are you running in the 15mm carb... and I'm assuming you are using the 12mm intake which shouldnt be a problem.. and are you using the stock airbox with the plug in or out??

Re: Slow Puch

I've tried all different jets - I can't remember what's in the 15 now to tell you the truth. I put the 15 manifold on it as well.

I've tried it with stock airbox, without plug, and no airbox.


Re: Slow Puch

i think that they made the 1, 1.5 and 2 horsepower models to go 20, 25 and 30 mph. this was to meet requirments for different states. you probably have the 20 mph puch.


Re: Slow Puch


are you kidding??

The guy I'm selling it to was going to throw a 70cc kit on it - would that bypass the whole hp nonsense?

Re: Slow Puch

ok.. the 15mm manifold is too big for that engine... it dumps too much fuel into the piston... I found that when I went from the 15 down the 14 or even the 12 it has alot more pull and power! Save the 15 for your kit! The 15mm carb is fine though! you need the airbox.. with or without the right jet... Those engines dont like unrestricted air-flow to the carb I tried the K&L filter too and the stock airbox will give you more power!

Re: Slow Puch

Yeah, I tried both manifolds with no luck.

Do you think Dave is right? That this is actually a 20mph model? I didn't think Puch was that lame. Leave that to Honda.

Re: Slow Puch

1 hp = 20 mph?

i wouldn't be terribly surprised. You could always replace the engine with a 1.5 (possibly a 2) those engine are pretty easy to find

Re: Slow Puch

What's the difference between the engines? Just cylinder/piston?

Re: Slow Puch

I cant beleive that the different Puchs cant all be made to get up to the same top end speed... there can't be that much difference..

Re: Slow Puch

Smitty Smith /

There are a few differences, mostly in the "top-end"...such as the ports sizes and shapes, head gasket thicknesses, intake manifold, carb, and even the baffles inside of the exhaust.

Changing the sprocket gearing can also help.

Re: Slow Puch

Okay, well I ordered a 70cc kit for it. I'll post the results.

Yeah I put a bigger front sprocket on it. It had a weiner one when I got it.

Re: Slow Puch

check the exhaust - the 2hp editions have two holes going all the way through the baffle (10mm) , the 1 hp and 1.5hp models have 1 hole at the end of the baffle before it turns into that long rod with the threads on the end. Your front sprocket is probably an 11, 13 or 14 too, which you need to switch to a 16 if you're at 45 on the back. this will get you back to stock 1 speed gearing. There's lots of other subtle differences, including round vs. square intake ports on some...and they even made a 17mph maxi too, yikes, with 11x45 gearing.

Re: Slow Puch

there is no reason why you couldnt take a 1hp engine and make it go 30+, its the same engine as the rest of them, just built with primarily different cylinder set ups

simple things like replacing the head gasket with a thinner one and opening up the air flow and matching the jet, and removing the small baffle from the pipe all should make it hit close to 30 if not more,

plus there is no reason why the bike shouldnt run without an air filter, you just need to compensate the jet

it sounds to me like its more of an air leak or points issue, like earlier mentioned, if the points arent set properly it wont start but could still yield spark, 120 psi is enough to most likely run, but nowhere near as much as you need to run WELL, spray some soapy water pon the cylinder and pedal it over, if you see bubbles you probably have an air leak

putting a speed kit on anything completely negates HP

Re: Slow Puch

Dude, the 1hp cylinder intake port has a restriction plug in it to make the intake port super small... Even if you take it out, it's not as large as the intake port on a stock 1.5 or 2hp, which means as much gas isn't getting sucked in... 20ish is about all a 1 hp will do stock... That is how they designed it. Take off your carb and intake and check it out... It's real easy to see what they did when looking at it up close. My first ped was a 1hp Puch Maxi Luxe... Here's what I did: Get a new or used 1.5 or 2hp top end, along with that 15mm carb and intake. You might have to do some airbox derestricting possibly... Of course figure out the correct jetting... I believe i was running a 66 or 68 main jet in my Puch Maxi with a biturbo 15mm carb and intake manifold and a stock airbox... I'm not posotive about that jet size though... Dan or Dave at 1977 Mopeds can hook you up with a brand new replacement cylinder for your puch that would work awesome... Ike from Ikes Bikes may also still have some NOS Puch cylinders... Also you should check ebay. Hope this helps.

Re: Slow Puch

hmmm, i have come across some 1hp bikes that didnt have that small of a port, however i know of the small ones your talking about, i pulled one on monday night that you couldnt fit a #2 pencil through

Re: Slow Puch

Michael Nesson /

I have a 1978 Puch Max-Lux that is all stock and easily tops 35mph. It's a one speed. also have a 1980 MaxiSport 1,5 that is stock and it only tops out at 24-25mph. The sport is quicker to accelerate from a stop.

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