Bosch W8AC

I have a rough Puch Maxi 1 speed that I'd like to resurrect over the winter. I have been able to get it to run intermittently, but the spark plug is fouled, so that's the logical place to start... The old plug is a Bosch W8AC, but the threaded area is larger in overall diameter than the W8AC that I just replaced in my Maxi Sport. Can that be right?

I'm looking at them as I type this - same part #, but different diameters.

I just ordered two W8ACs from Moped Junkyard, so I'm really curious to see what I get.

Thanks for any wisdom or advice,

Dave

Re: Bosch W8AC

i don't know if the plug is so old that they changed the make of it, but i do know that all i ever run is bosch w8ac and there isn't a difference between a maxi and a maxi sport, so it should work, further more, why don't you just go to napa or some auto parts store for plugs, instead of waiting for two in the mail, i usually buy a dozen or so from napa for about 1 and change a piece, plus they can look up in their spark plug catalogs there and tell you what plug you would need

Re: Bosch W8AC

I have been purchasing NGK plugs for the Maxi Sport from the local lawnmower repair place - they have the actual plug that's specified by Puch on the left side cover.

It's weird that the old Maxi requires a different diameter threaded area (the W8AC plugs from each bike are clearly different). The cylinder head on the old Maxi has a different color, so it may not be original (but the doesn't explain different threads with the same part #).

Re: Bosch W8AC

I look at the plugs more carefully and it looks like the one with the larger diameter may have a threaded jacket of some sort. Does that makes sense? Has anyone seen anything like this?

Re: Bosch W8AC

I was thinking it sounded like a heli-coil before, and now I bet thats what it is, someone stripped out the threades, then tapped them out to a bigger size, then instaled a heli-coil to make it so the threads were the original size so the plug would fit back in, it is supposed to stay in the head when the plug comes out but it looks like it may be stuck, it should screw right off of the plug.

either that or you striped out the threads from the head pretty good and that is part of your head.

Re: Bosch W8AC

That makes sense. Got out the my caliper: The threads on the 'larger plug' are 18 mm (vs. 14 mm for the 'regular' W8AC) and they are in good shape (i.e., they look like regular threads - no damage, etc.) If I can't remove it, where can I find a heli-coil to fit the replacement plug? I also found a few web sites that sell adaptors that allow 14 mm plugs to fit 'older' (in their words) 18 mm holes. I have found nothing about an 18 mm Bosch W8AC (only 14 mm). Fun mystery...

Thanks!

Dave

Re: Bosch W8AC

W8AC is a aircooled VW Bug spark plug also

Re: Bosch W8AC

NAPA! Go to your local NAPA auto parts store. They have common things for mopeds such as spark plugs, light bulbs, nuts(duh), 2-cycle oil(duh), any old ordinary thing that is "universal." I personally like the Champion L86C spark plug. It is a hotter burning plug that stock, I have had very good luck with them.

Re: Bosch W8AC

i have also been told that a w8ac is a universally moped plug and will work in most bikes fairly well,

i would also suggest buying a new head, as i have heard of people stripping out the threads, re taping them and so forth with those spark plug kits, and then those not holding up much longer, a friend had a plug shoot out of his cylinder, a puch head should be pretty easy to come by, infact i have a few laying about

Re: Bosch W8AC

Thanks for all of the great advice. Buy a new head sounds like the smartest move.

Re: Bosch W8AC

yeah whats the number on the face of the head, its probably a 1,2,3,4,5 however you said its painted, so it could be a 11,22,33, unless someone painted it, i could help you out with a 1,2,3,4,5 i have a few

Re: Bosch W8AC

Jason Luther /

you seem in great spirits throughout this. i probably would have thrown the head through my garage window. look on ebay, heads float through all of the time. -jason

Re: Bosch W8AC

Tyler Jacobson /

ankron moped has a couple of puch heads on ebay right now new and used i just picked u p a new old stock hi comp puch head from them...

Re: Bosch W8AC

>you seem in great spirits throughout this.

This is a project bike (my Maxi Sport runs fine and is driven daily), so I don't get too nuts about it. I suspect that the cylinder head is not original, so I'll have to remove it and look for markings. I'll report back...

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