Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

I upgraded the Mag II (2speed) by adding a Polini 64 cc reed valve kit w/ 15 mm Bing carb and 88 jet. Got me a motomatic pipe, and downsized the front sprocket from an 18 stock to a 15! (did re-gearing after the problem described below, and it worked great by the way, but engine still had a metallic knock so I had to take it apart) During breakin around the neighborhood, the bike had low end power, and at about 28 mph, it felt like the bike grew a 3rd gear?!@?! I never topped it out b/c of the breakin period, but this was easy a 40+mph combo. Fastest I took it was about 32/33 mpg. On Day 2, I was approaching a stop sign at about 15 mph, and the bike went into a high wine and then rolled to a gradual stall. Thot I seized it, but I kicked it over and started right up?? But, then it had a metallic ting-ting-ting when running. Took apart the cylinder, and found black patch at 6 and 12 o'clock with some minor longitudinal scratches, I sanded down the cylinder and piston black markings with 800 and 1000 grit (a minor amount of sanding sanded very little but until cylinder felt smooth), popped in a new ring (chrome coated), and put it all back together

NOW...

It now idles out of control, bogs to a stall under startup load, and the metallic knock is still there. The idle is scary way too fast, and not adjustable with the mix screw on the bing carb! Totally different than it ran before. Does sanding mess up the compression? I left in the 15 mm bing with 88 jet and motomatic in place because it worked so nice when i first got the kit. using 50cc high compression head treats recommended. Engine temp under idle was clear in the 300 degree F plus range at idle when giving it some gas after I put it back together.

I think rather than the kit failing, it probably was some debris pulled into the cylinder. We found the intake manifold had lots of metal flakes from the cast process, could have sucked a flake into cylinder causing this pain? Before I put it back together, I filed out the flakes and cleaned the mani all good so there is now no chance of additional metal into cylinder.

What to do? Trash the cylinder? Re-jet? WHat jet? Needle position? Could it be transmission? I know you know! Do you know? I don't KNow. ugh. thanks

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

Soft seized and when put back together you ended up with an airleak

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

Salsa Salsa /

Chrome ring? Is that smart with a nikasil coated bore?

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

also you went from an 18 to a 15? you should have done the opposite 18 to 20 or 21 at 15x40 which is your gear ratio that za was doomed from the start. polinis like rpms so in theory your gear change was correct, but za50s unlike e50s don't like to rev high so the engine is going to blow or has already begun to, some of the noises your hearing may be your crank dieing

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

you may want to take the cover off your trans to see if there is any internal damage.

from what you described, its probably a seizure and if you're lucky the first gear drive didn't get damaged. but you should definitely check to make sure. take your trans cover off, look for metal pieces and chipped / sheared teeth.

anyway with a kitted ZA you should at least change your shift dampeners if you haven't done so already. I'd do other stuff too, but its up to what you are willing to invest...some people are ok with blowing up engines.

Like Andrew said, you want a bigger front sprocket. not smaller. ZAs already have plenty of torque.

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

Adam Klags MPG /

get a new kit. its done. no sense in wasting time. I agree with the gearing statement. If I were you next time I'd go with an 18 stock gear instead. And yeah the bike sort of does have a 3rd gear feeling I know exactly what you mean. better luck on your rebuild, and make sure to check the ports and all for flakes/metal. it also could simply have leaked and it seized from an air leak.

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

Overpriced Parts /

Ya run no less then 20x35 gears. I have polini bikes geared 21x35 been runnin good for 3 summers.

Make sure your timed 16-16.5 mm or degrees on flywheel Cause hi timing = boom.

Prep kit good/ gap ring.

Case match good especially the top boost ports.

Jet around 90 main 1clip rich .

Break in/ run in for 300 miles/500 km per polini pamphlet that comes with the kit.

Of course shut it down when even close to 400 degrees.

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

wow, thanks all. i now know what u know, kind a.

with respect to the gearing. the seiz symptom happened before me play with gearing. it happened with the stock 18 front, so after the seiz symptom, it would start back up just fine, run normal, so i decided to try the lower gear on the front. putting on the 15 actually made a huge low end difference. does that make sense?

with respect to the cylinder condition post-sanding. it starts up and idles without stalling, but it idles crazy like i have it at half throttle. maybe i should try down-jetting? when i get on bike and give it any type of gas, it stalls out immediately

not sure what an 'air seize' is, but it sounds cool, and i wanna know what you know of course

should I throw out this kit????? man, what a waste of $200 + bucks! and i'm a fan of bing carb's traditionalist, so this kit is the only one with reed valve and intake mani that fits nice.

anyone wanna come over to the garage to play fix it with me and the boys? we gotta a 4 man crew down here in kingston, ny. would love more to hang ....

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

don't throw out kit. double-check the easy stuff first: fuel mixture, slide going all the way down in carb, etc. then spray for air leaks around the intake and cylinder w/ carb cleaner.

it really sounds like you got an air leak while running and it got worse after you rebuilt the cylinder. find it and fix it. also carefully chamfer the edges in your polini

my $0.02

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

Overpriced Parts /

Ya I got two polini 15 mm combos both running fine for 4 summers now

So it is possible to have a 15mm bing polini bike that lasts. The carb works fine with a polini. In fact polini kits were designed to use a 15mm bing.

Again stock 18x40 za50 gearing is too low and the higher the rpm you run the hotter you run unless your ignition has a curve. Points ignition does not have a curve

Timing, Jetting, gearing, head squish, head temp and break in is so important to keep a kitted za50 alive

You got to do it all not just one thing.

Like a car engine rebuild with solid lifters. you can't do everything right and not break in the cam at 2,000 rpm whatever. You can spend 15-20 thousand dollars at this point and you will wipe out your cam/ lifters if you don't break in the cam right.

So research everything and do everything right

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

What head you running? Hope its not one of those hi hi heads.

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

mike boyd= thx for the tip, i did do a thorough air leak check and i keep it tight on reinstall. no leaks, it appears.

Michael Thomas= using a 50 cc high comp head with the 67 cc polini reed setup. recommended by treats. during initial testing, it rode promising.

Ken Roff= Can you recommend a realistic break-in procedure? Prolly not gonna be sophisticatd plug chop.. thx for the tips, whats a head squish?

Casserollers= chrome plated ring comes with the kit. i guess chrome has a higher melting point than base ring steel, so its more resistant to running at higher temps.

I'm gonna research the gearing, and prolly take yer'all advice.. actooly, fer sure i will.

I'm a gonna throw the stock setup back on just to check trans. last i rode it b4 the tear apart, it shifted like a dream.

I'll play with the jets too.

This is a 1981 with only a few hundred miles on it. One owner, he had it in a shed pristine for all those years. Bought it, and put it away, and i stumbled upon her.. fun...

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

OK all. so the high idle/ stall out symptom was an air leak. at carb/intake, found a leak. sooooper rookie, i know. it was worth checkin out.

went back to the 18 front sprocket, and bike runs fine.

metal knock is still there, but really basically when it idles. when i ride it, knock not really noticable. just worried that small chance its the trans and not the engine!?!? wow. that would b bad.

anyway, i got a trailtech all rigged up, going to post some pix of the set up. having digi speed and engine temp is pretty sweet.

d

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

KEN-shut up ........timing man.

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

Overpriced Parts /

Please post your head temps after riding full throttle for a few mile blast

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

i only pushed it to low 300's ysterday after about a 1 mile constant 33 mph. had a lot more unused throttle. top spd will probably be in the mid 40's, but paranoid at this point. i put the 18 tooth back on front, so low end suffered...

my crew just ordered springs/tools to experiment with clutch engage on a 1 spd. timing is a bit out of our ability, especially for a 2 spd. do u have a resource that describes how to check timing and generally tune the 2 spds?? i have 2 of em.

my other ride is a Newport w/ a 70cc athena and bi-turbo pipe. that also has a 15 mm bing. its been running sweet for 3 seasons. really realy peppy low end (accidentally pulled a wheely once and nearly crashed!?!?), tops out at 37 mph tho. still a fun throaty bike.

Re: Puch Mag Disaster HELP!!! U can do it, u know stuff, I need to know what u know!?

timing... how do i??

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