Do I have the carb?!

Know I posted another topic here about the carb in my 79 Puch Magnum XK and not getting enough speed ...

I recently asked a dealer what type of jet I needed in my carb. I told him it was a 1/12/316 carb and he looked it up and said I needed a 64 JET. I put the new jet in and it ran even slower , sluggish , poopy. I looked back at the carb and it actually say's 1/12/306 not 316! Does this mean I should have gotten a different JET? The main jet that was already in the carb was a 54 I think which works better than the 64 but something tells me the 54 might not even be right.

Second , I don't know if this is the original carb on this moped , someone might have changed it. On a 79 Puch Magnum XK is the carb supposed to be a 12MM 1/12/306 .. or do I have the wrong king of carb on this?

Re: Do I have the carb?!

when you come right down to it, it really doesn't matter what some manual says.. That manual refers to a brand new bike in factory tune.. everything is new.

you got an old bike.. and yeah, someone may have dicked with it.. with more than just the mainjet.

You can determine what mainjet is best for that bike with the stuff it now has on there (exhaust, air filter, tuining condition etc. by doing a plug chop.

Buy a few brand new plugs. WArm the engine up. Drive over to a long straight flat road. Install the new plug, get to top speed for about 1/2 mile and kill the engine.. "chop" the engine's electrical while at top speed to kill it.

coast to a stop, remove the new plug, install the old plug and drive home.

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Examine the new test plug under good light and magnification. If there is any carbon duston the plug the jet is probably too big. Carbon is unburned fuel. The insulator should come out clean and white like it went in (not grey .. overheated). The electrodes' edges should be sharp under magnification (not melted round)

I say probably because not enough air intake (clogged air filter) could falsely show the same thing. a rich mixture.. so will ignition timing that's way off.

So, tune the bike as best you can.. no air or fuel leaks, no nothin, before doing the plug chop. Get it in best tune possible. Use only a new plug and only when the bike is thoroughly warmed up .. and dont let the engine idle or run below top speed... chop it off.

Re: Do I have the carb?!

See Ya Moped Army /

If you have a 2.0 hp 1979 XK, it originally came stock with a 1/12/316 carb, #64 main jet, #2.12A needle jet, #51 throttle slide and a jet needle with two lines scribed on it.

If you have a 1.5 or 1.0 hp XK, the specs are completely different.

Re: Do I have the carb?!

Patrick Keaton /

I think what you have is a 1.5 model and that model came with the 50 jet,so try a 50 and/or 52 jet and if that is not good enough try a 56 jet and see if the 56 jet is worse then then the 54.Keep increasing size until it worsens.

1/12/306 came on Puch Magnum XK mopeds.

Re: Do I have the carb?!

I sure hope he's figured it out after nine years.

Re: Do I have the carb?!

simon thokaar /

Saabsonettguy . Wrote:

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> I sure hope he's figured it out after nine years.

Ah, that explains the useful replies he got.

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