Puch Maxi - how to start?

Hi,

I've just bought a Puch Maxi, its a UK 2-speed automatic and it had been stored for 11 years.

I don't understanbd the starting procedure. I had to thoroughly clean out the carb and petrol tap but it doesn't start - I have a good spark and petrol at the plug.

I have a string lever on the handlebars, the cable from this splits into two at a plastic Y lever. It seems to operate the decompressor and starting mechanism.

If I pedal off and pull in the lever the engine turns but sounds as though it has feeble compresssion (presumably because the decompressor is on) and doesn't fire. When I release the lever the moped just reverts to freewheeling.

How the hell do I get it started? I can see that it will ever start with the decompressor lever pulled in and yet as soon as I release it the the engine stops turning over and I just coast........... Frustrating.

I'm loathe to adjust anything since I assume it was put away, 11 years ago, in working order.

Also I don't seem to have a RUN ande KILL switch, just one big black switch which appears to control lights and horn, I think!

Any advice?

Thanks

Allan

Re: Puch Maxi - how to start?

What you're describing sounds weird...pictures might help.

There shouldn't be a decompression valve on a Puch. There should be a single cable running from the large black lever to your gearbox. That engages the clutch and lets the pedals turn the engine over. Turn the run switch (there should be one) to run, turn the fuel valve on, pull the clutch lever and pedal. If everything is working properly, the engine should start (might take some choke). If it doesn't, you have a problem(s) somewhere that you need to fix. Check out Fred's Guide in the Resources->Articles section.

Re: Puch Maxi - how to start?

Hi Matt,

Thanks for your reply.

I can't find the exact manual for this model, its a 1979 Puch Maxi 2-speed automatic, but any standard Maxi manual mentions the decompressor.

I have the standard black starting lever with one cable, this goes down to a plastic Y device which branches into two cables, one to the decompressor and a short one to the top of the gearbox. When the starting lever is pulled the Y piece operates both cables simulataneously although they can be adjusted independently.

The manual actually states that the starting lever operates a decompressor and that it should come into action before the starting device (clutch?).

Since I have spark and petrol then I gues its either compression or timing. The mileage is only 4679 so I wouldn't expect massive wear but operating the decompressor would of course mean low compression. I'm reluctant o alter the timimg yet since it belonged to one old lady and I'd probably make it worse.

No apparent run/kill switch, I guess its left down to the decompressor.

Just one large black switch moilding. It has three switches one large one with two positive positions plus a push position, one red button which operates the horn and then a small pointed switch on the inderside of the moulding which has two positive positions plus it can be pushed in. Again I can't find a picture of a Maxi with a similar switch but everything seems original and untouched.

It seems to be quite a common problem with the Maxi and one guy is selling his on ebay cos he just can't cure it, there have also been post in the forum with the same problem.

Hopefully all will be revealed in the fullness of time.

Cheers

Allan

Re: Puch Maxi - how to start?

Try adjusting the part of the cable that pulls the decompression so that it does not pull it. The bike will be harder to start but it's the easiest way to figure out if that's the problem.

Re: Puch Maxi - how to start?

Hi Matt,

That's a good point.

The other thing which occurs to me is that>

You pedal off with the starting lever pulled, this eases the compression making it easier to pedal and operates the starting clutch then maybe when you've reached a couple of mile an hour the centrifugal clutch should come into operation so that the rear wheel is turning over the engine and you can release the starting lever therby allowing maximum compression. Mine just goes back to freewheel.

This seems the logical method and as I remember is how some of the simple mopeds work, including my Velosolex. So I wonder if somehow the centrifugal clutch is stuck, perhaps through standing.

Any Maxi owners out there who can confirm this point?

Regards

Allan

Re: Puch Maxi - how to start?

i know that ped! pull the starting handle, then pedal while holding it until it starts....

--cb-

Re: Puch Maxi - how to start?

i have a 1 spd 1.5 hp... i would need to see this ped though so i can see the problem and help.. he should only have to pull that lever then pedal forward...

--cb-

Re: Puch Maxi - how to start?

Gregory Mcintire /

Your reasoning is logical but this is not how the 2-speed Puch works. The first gear centrifugal clutch can only come into play when the crank shaft has reached an RPM which equates to several MPH. The second gear centrifugal clutch weights are actuated when the rear wheel reaches a speed of around 15 MPH (depending on the sprocket sizes you have) BUT, the second gear clutch requires that the first gear clutch be engaged in order for it (2nd gear clutch) to engage the wheel to the crank. It is kind of complex but actually a very clever way to deal with the problem of keeping the transmission from shifting back and forth between 1st and 2nd at a certain engine speed.

Some Puch engines have a decompression valve but most don't. It is not necessary, and can cause problems. I would suggest disconnecting the cable going to it. Mine starts fine without a decompressor and I have even raised the compression ratio quite significantly (11.1:1).

Re: Puch Maxi - how to start?

Thanks Greg,

Well, that's two votes for disconnecting the decompressor.

I'll probably leave it until tomorrow cos I'm whacked from pedalling today!

I have to admit it goes against the grain to do away with something that presumably worked when it was new and I won't rest easy until I get to the bottom of it, but for the moment I'll settle for just hearing a splutter from the engine.

I'll let you know the result...............

Thanks Allan

Re: Puch Maxi - how to start?

Pause for thought...........

I then have to fit a kill switch cos should it fire up I've no decompressor to stop it!

Flaming mopeds, I have a Cyclemaster with a duff HT coil, a Trojan minimotor, early model without a decompressor or clutch, which makes riding unpredictable and a Velosolex which is fully operational but wouldn't pull the skin off a rice pudding! these are actually cyclemotors but very similar.

Allan

Re: Puch Maxi - how to start?

Jason Luther /

i would get a new spark plug (gap it at .018"), and just pull the lever like you normally would. its a puch, itll fire. do you have the air cleaner on?-jason

Re: Puch Maxi - how to start?

I don't know if your model has the same wiring as the Puch models that were imported into the U.S. but check to make sure the two wires that go into the back of the horn are connected. It was (is) a common problem on old Puchs that the horn would buzz when starting and running. Make sure these wires have not been disconnected.

Also use an Automotive Electrical contact spray to clean the ground wires (brown?) anywhere they fasten to the frame. Also check the terminal wiring block by the engine area to make sure there are no loose or disconnected wires.

If I remember correctly either the Kreidler or Sachs Prima moped has a similar setup with a combination clutch/decompression cable. If you disconnect the decompression cable, it will be much more difficult to pedal start.

Re: Puch Maxi - how to start?

Gregory Mcintire /

To stop it without a kill switch all you have to do is pull in the clutch lever, with the wheel on the ground and you sitting on the bike or with the rear brake applied.

Re: Puch Maxi - how to start?

Hi,

Got so fed up last week of being soaked in petroil and pedalling to no end that I haven't done anything further.

Yes, tried new plug and air filter on and off.

How it manages to start still baffles me. Let me put it forward again in case I worded it badly.

I mount the moped, petrol on, choke on, etc I pull in the start lever which engages the decompressor and engages the starter clutch and I pedal off, the engine is turning over and the back wheel is being driven. I then also open the throttle. Engine doesn't fire. I release the starter lever, the engine stops turning over and the back wheel freewheels!

It defies me at what point the engine is supposed to fire. If I have the starter lever and hence the decompressor open it will never fire due to lack of compression. And yet if I loose the starter lever everything stops turning over so again the engine can't fire - am I missing something? I just can't see at what point the engine has the opportunity to fire? Can anyone tell me how its supposed to start up cos I'm baffled?

I'm not sure either about the quality of construction of the Puch, far too much plastic for my liking even a plastic throttle grip. Any other moped I've owned has always had a sturdy metal twistgrip. Poor paint finish, doesn't seem to be any primer coat. Indifferent chrome plating. Perhaps I'll feel differently once its fired!

Back to the Cyclemaster for a change..........

Regards

Allan

Re: Puch Maxi - how to start?

It's supposed to fire up exactly like you thought. Now, as for the decompression being engaged at the same time as the clutch: if you pull the starter lever in and pedal hard, then let go, the engine should continue turning over for a period of time. Since you've let go of the decompression cable at this point, it should have compression and still be turning over. If it's still not starting, go back to basics: spark, fuel, compression, etc...

Re: Puch Maxi - how to start?

Cheers Matt,

It seems a bit hit and miss since there is only a short period of time for it to, hopefully, fire then.

All my other machines continue to turn over as you're pedalling and sometimes they require up to 12 feet, I guess, which represents quite a few revolutions.

Maybe I need to pay a bit more attention to the plug and points gaps. I tend to think that two-strokes are fairly tolerant but perhaps I need a bit more precision on this one.

Thanks

Allan

Re: Puch Maxi - how to start?

Jason Luther /

i dont think the decomp lever is the problem at all. if your peddleing forever and its not firing, youre just soaking the plug, and itll never spark.-jason

Re: Puch Maxi - how to start?

Hi all,

LOL, LOL,

Guess what, yes, I've had it firing.

Simple really, only spark, petrol and compression to consider!

A trick I read somewhere, could have been on this forum, put a teaspoonful of petrol into the plug hole. Terriffic, fired virtually instantly! but only for a few seconds, of course.

So now we know where the trouble lies. When I bought it the petcock (petrol tap) was blocked solid and the carb was bad as well. I though I'd cleaned them but it look as though there is still some blockage somewhere. I think probably a new petcock wouldn;t go amiss. Any advice on removing it. It doesn't want to come out. I can see that there is a thin tube going inside the tank, presumably the reserve pipe but there also seems to be a plastic washer or tube which stops me from pulling the petcock right out of the tank. Can I force this plastic tube out? I think this will release the head of the reserve pipe.

Great news though?

Many thanks

Allan

Re: Puch Maxi - how to start?

Allan,

This is what the petcock looks like for your Puch. It should come out pretty easily just a little twist at the end. When I pulled my petcock out there was a bit of remanence of a seal. When you put the valve back on use some lock-tight around the threads. When you have the petcock out get a small screw driver out and check the bottom of your tank I found about a 1/4 inch of rust flakes in my tank that had been clogging up my filter. Also I found that the threads on the nut that connect to the petcock thread backwards.

Good luck

- Chris

1089162138_fuel_valve.jpg

Re: Started but petcock?

Thanks Chris,

I'll have another go at removing it.

When it was unscrewed it would only come out of the tank by about 1". So I could see the small main supply pipe (not the reserve pipe as I called it previously) and I could rotate the tap in the tank but it seemed to be firmly fixed otherwise. Then I saw the edge of a plastic sleeve just peering out of the tank and it seemed to be this which was stopping the tap from coming right out.

I didn't want to force it and risk having the little pipe break off in the tank.

But out its got to come................

Cheers

allan

Re: Just what I didn'y want to happen!

More wasted hours and a bit of petcock broken off in the tank!

I managed to pull more of the petcock and the brass tube out, maybe 2" but there was definitely something preventing the head from coming out.

There was a plastic sleeve which came out but it was almost as though it had broken in two with one half still on the tube but inside the tank and this was holding it back. I pulled, levered tried to break up this plastic tube although I have to admit the bit inside seem like hard fibre.

Eventually the inevitable the brass tube broke leaving the sleeve and top of the brass tube stuck in the outlet. All I could do was tap these back into the tank. Not the end of the world because it will sink to the bottom of the tank but annoying.

Now there must be some washers missing because when I screw it all back together the outlet from the petcock is pointing skywards.

Call it a day for today, yet again..........

Allan

Re: Just what I didn'y want to happen!

I find it really strange that the petcock is somehow attached to your tank. That's new to me. I can help you out with the outlet pointing skywards thought. Mainly you need to loosen the petcock out of the tank threads. Then tighten the nut onto the petcock a half turn. Since the nut connects the petcock to the tank and they share common threads this will allow you to turn the petcock 1/2 turn less when you are screwing back onto the tank.

Ok... This made sense in my head if it dose not make sense to you let me know Ill try try to find my digital camera.

- Chris

Re: Just what I didn'y want to happen!

Gregory Mcintire /

The only way that you can remove the petcock or put it back on is to hold the petcock in its proper position, with respect to up and down, while you turn the nut. The nut is a special nut which has left hand threads on one end and right hand threads on the other. It has to screw onto the petcock at the same time it is screwing onto the tank fitting.

If you turn the entire petcock the brass tube attached to it will be bent all about and destroyed.

And yes, there is a fiber or plastic washer (either will work) between the petcock and the tank fitting.

Re: Just what I didn'y want to happen!

Jason Luther /

im sure it was allens own little moped sedimentary rock formation that kept the petcock from coming out all of the way. the same thing just happened to one of my other peds.-jason

Re: Just what I didn'y want to happen!

Hi guys,

Thanks, yes been through this awkward right/left screw on simultaneously method - a bit of a pig's ear way of doing things!

Looking at a picture of an Italian petcock I see the plastic sleeve and the fibre collar. On mine the fibre seemed to have swollen and just wouldn't make it out.

I've been in touch with mopedwarehouse.com and I'm impressed with their efficiency - I'm still waiting for a reply from a UK company and quite frankly we often get deliveries from the US faster than the UK so I'll be placing an order for a new petcock which mopedwarehouse tell me comes complete with the new seal.

Regards

Allan

Re: Just what I didn'y want to happen!

Well Allan,

While you wait for your new petcock ( I am waiting for a new one too). You can still try to get your engine running without the petcock. Just fill up the fuel line and let it drain into the carb float. With the float full you can get about 2-3 blocks on that fuel. Thus you can diagnose any other issues with the bike.

- Chris

Re: Patience.........

Hi Guys,

Yes, I'll try filling the float chamber. I think there is still blockage in the carburettor so its got to come off again. Anybody know of anything which will remove this old varnish like petroil?

Just posted the Puch page to my website http://freespace.virgin.net/stones.ukp/puch_maxi.htm if anyone wants to see what another mischievous max looks like. You can also access my other pages on my UK Cyclemaster, Trojan Minimotor and other unlikely modes of transportation and caravans!

Cheers

Allan

Re: Patience.........

Edwin Johnson /

hot soapy water

Re: SORTED

While I was waiting for the new petcock I also saw one on ebay for about $5 so I ordered this too.

Fitted the petcock and pedalled anxiously ..........nothing. I still couldn't get any petrol into the carb. Only by feeding petrol into the float chamber manually would it run. Took off the carb to give it another clean (hot soapy water didn't work) and I had to gently scrape some deposits off).

Replaced the carb still no good. I could only get petrol from the petcock if I shook the moped from side to side. Must be a really big blockage in the tank, I thought.

Right, the key is that I had only been putting small amounts of petroil into the tank, mainly because I ended up emptying most of it.

Penny dropped, as soon as I put a decent amount of petrol in the tank the problem was solved.LOL,LOL. Petrol flowed from the petcock, the carb filled. Don't ovelook the obvious!

Now it goes extremely well, much better than I expected!

Thanks for your perseverance guys.

Allan

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