80 Puch Maxi compression?

Got the bike a few weeks ago and it ran. I replaced some carb parts, changed the trany fluid and cleaned and checked the piston and cylinder. I get a great spark when i take the plug out and ground it to the cylinder head while i petal. If i cover the spark plug hole with my finger while the spark plug is grounded to the cylinderhead nothing happens...no spark no turn over. If i take my finger completely off the hole then it turns over and i get sparks. and if i just barely cover the hole and i get sparks and the engine turns over awesome. Any ideas?

Re: 80 Puch Maxi compression?

Steamboat Aka J. R. Stevens /

I'm guessing your starting clutch is bad. Maybe someone with more experience with mopeds will answer you. Jim.

Re: 80 Puch Maxi compression?

Peter Piper /

The clutch seems to function fine. The engine turns over, just not when the spark plug is in...anyone got any ideas?

Re: 80 Puch Maxi compression?

if i get this right, the finger being in firm contact with the engine prevents spark, as if your finger were grounding the ignition.. but a light touch allows spark.

And the comment about _no spark no turn over_ is kinda weird. What exactly do you mean by "no turn over"?

i'm gonna wait till you affirm or clear this up before suggesting anything..

Re: 80 Puch Maxi compression?

_The engine turns over, just not when the spark plug is in_

If you mean by "turn over" simple crankshaft and piston movement, this seems to suggest the spark plug is too long for the engine ..

When the piston reaches the top of the stroke it hits the plug and gets jammed.

Re: 80 Puch Maxi compression?

Peter Piper /

ok. By turn over I mean that the flywheel turns and the engine is turning-it literally sounds like the engine is running but the sparkplug isnt in. I don't think its the sparkplug because I put the old one in and still had the same problem. The maxi just has a starting lever that you pull back and then petal your ass off. My finger isn't grounding the ignition, or I would feel it believe me, because i have the base of the spark plug grounded to the cylinder head as it says in freds guide. When I leave the sparkplug hole uncovered, and ground the base of the sparkplug to the cylinderhead, then try and start it I get plenty of spark and the engine turns and sounds like it really wants ro run. but if i do the same thing except plug the spark plug hole with my finger, i could petal all day and night and not get a spark or get the flywheel/engine to turn. freds guide says that if you plug the spark plug hole with your finger then try and start it the pressure from the piston should have more that enough power to force your finger from the hole. So im thinking that its a compression issue because its not blowing my finger out of the hole

Re: 80 Puch Maxi compression?

ok.. first off it seems you are trying to detect compression while simultaneously trying to detect spark. Why, i dunno. They are separate, unrelated functions and can be checked independently.

_Got the bike a few weeks ago and it ran_

Seems that the bike was OK before:

_I replaced some carb parts changed the trany fluid and cleaned and checked the piston and cylinder_

Now there's no compression? Did you reinstall the piston rings? Are the the head bolts tightened down? Whatever is causing zero-compression should become obvious. There's a huge leak somewhere.

Double check everything.. disassemble - reassemble whatever you did previously.

_I get a great spark when i take the plug out and ground it to the cylinder head while i petal. If i cover the spark plug hole with my finger while the spark plug is grounded to the cylinderhead nothing happens_

Your finger in the spark plug hole prevents spark. Why? If your body is not grounding the ignition, what could it be?

Are you simply failing to ground the plug securely while trying pedal, hold some lever, stick a finger in the plug hole while trying to ground the plug?

_If i take my finger completely off the hole then it turns over and i get sparks. and if i just barely cover the hole and i get sparks and the engine turns over awesome_ <-- turns over awesome.. If the engine turns over it turns over.. how it could be better or worse is somewhat of a mystery to me.

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Forget about trying to detect spark and compression at the same time.

Install the plug. Spray some Starter Fluid into the carburetor. Attempt to start. If the engine runs for a moment, you've got a fuel delivery problem.

If the engine doesn't start, the trouble could be either no compression or no spark.

Zero-compression is somehow related to the work you did previously.

No spark is also likely due to the work you did previously.

This bike ran fine until you worked on the carb and cylinder and piston. Go back and double check all your work.

Re: 80 Puch Maxi compression?

Peter Piper /

thxz joew. you are simultaneously helpful and hurtful.

Re: 80 Puch Maxi compression?

i try :)

actually i tried to tailor my response to my estimate of your skill level. Since you seem to have no fear of diving into that engine, i think it's pretty high. And the odd nature of some things in your questions can be attributed to just plain old difficulty with the typed word..

but if you're new to all this engine/mechanicals stuff and i came on too strong, im sorry about that.

Anyway, the bike ran ok before you messed with it and thats a very positive sign. It means that whatever is wrong will have a simple fix if you can just back-track and find it.

continue to post about any progress or setbacks. i, for one, would like to know what's up with that bike.

Re: 80 Puch Maxi compression?

peter, i live really close to you. about 30 sum miles north of you. i know a moped shop just 30mi south of you. i am goin there this weekend. if you would like to come, ike and i could DEFINATLY find the problem. get directions from his website. or im me. check my profile.

<www.ikesbikes.com>

Re: 80 Puch Maxi compression?

Jason Luther /

it sounds to me that the problem _is_ your starting clutch. without the plug or your thumb covering the hole, the air can escape easily and there is no resistance on the clutch. now when the hole is plugged, the clutch cannot grab hard enough to over-come the compression and it slips. try adjusting the cable tighter.

Re: 80 Puch Maxi compression?

agreed. and peter...ike probably has/can get any part you need for your puch. let me know if you will come down...it's worth the drive to meet some ncie people. ike is the best...awesome guy. he would bend over backwards to help ya.

Re: 80 Puch Maxi compression?

Peter Piper /

Mr. Jason, you were absolutely right. In my haste to reassemble the bike, the starter clutch cable was slightly slackened. My problem now is that I'm getting a bunch of white smoke and the engine is running rough and loud. Any ideas??

pete

Re: 80 Puch Maxi compression?

Jason Luther /

thats great news (and not only because i was right). louder than before? or just louder than you think it should be? when was the last time it was run for any length of time? old crap in the exhaust will smoke for a bit until it burnt out.

Re: 80 Puch Maxi compression?

yes.. that is good news .. my brain's clutch has been slipping a little ever since the MA server crashed a few days ago.. this place has been hard to access ever since.. and i'm annoyed.. :/

The smoke is probably just accumulated junk in the exhaust as jason suggests. As far as the sound goes, check the exhaust connection for a leak. Since the bike is a new aquisition examine the whole exhaust system for holes, cracks, looseness, an installed baffle (if it is supposed to have one) etc. People try to "modify" exhausts in all sorts of ways and end up just making a lot of noise.

Also, intake roar can be substantial unless the stock intake air-box/filter/silencer is installed.

The roughness could mean it's misfiring and needs a tuneup. Check ignition timing and get a new spark plug if you havent already.

Re: 80 Puch Maxi compression?

how old is the gas? old gas and oil smokes bad.

Re: 80 Puch Maxi compression?

Peter Piper /

the exhaust seems fine, no holes or leaks at gasket points. but the engine itself seems to be running rough(like i can hear the parts turning inside), maybe because it hasnt been run ina while or maybe not enough transmission fluid?(i changed it and added the told ammount of 170mL) It also could just be that im used to my old 1hp tomos and this is a 1.5 or 2 hp puch. Also I barely get any power at low speeds but it takes off like a cheetah on coke once i get to about 10mph-maybe a throttle issue? It is a 1 speed so maybe thats just the nature of it, (also used to 2 speed tomos) Also i have to mess with my idle screw. anyone know how it works?

Re: 80 Puch Maxi compression?

1spd do take off slow untill the clutch get's ahold on the clutch drum real nice and off ya go! you should consider going to ikes this weekend. ike can get ya parts, and you could have a good time just riding with some peoples! let me know. im me on aol.

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