Puch Moped Head on HT 67cc bicycle engine- thanks Foureasy!

H

huckersteve

New Member
I decided to start a new thread real quick so as not to hijack Foureasy's thread on Hybrid Moped/Chinagirl engines any more than necessary. On reading about Foureasy's experimentation with Moped parts, I decided to try installing a Puch moped cylinder head on my bike to see what it would do. I asked a buddy of mine who has a few Puch's if I could borrow a head to try out. If this works out I will buy one of his spare heads from him and try to run it moving forward.

Well, I got the cylinder head, but I decided to slap it on last night without a head gasket bc I thought it would be awesome to run high compression, ('Cause I'm just so hardcore, LOL) and it turns out that the Puch head has SO much more comp stock than our heads, that I literally couldn't kick the bike over to start it! WOW. I actually had to pop it back off for the night and go back to my stock head so my friend and I could go out to meet our wives for dinner. I am going to try again today with a head gasket in there and see if it lowers the compression just enough that I can still start my bike, LOL. If it does work with one single head gasket, then I have a feeling the head is going to be a huge improvement over stock. The size of it alone is incredible compared to a chinagirl. There's no doubt in my mind that the cooling alone will be a boon to the bike's performance, especially on big days on the bike running wide open.

Side note: Yesterday I cleaned my carb and intake, and re sealed my intake on the jug with some red RTV stuff, and while I had my air filter off for cleaning, I decided to see how the bike ran without it. Now mind you i already had a high flow air filter, but I realized I hadn't cleaned it once since I built the bike up two summers ago. Well, when I put it all back together sans filter and ran the bike, it ran really good, and I decided to leave it off for the day. Upon having to revert my head back to stock after failing to be manly enough to start it with the moped head, I was toying with the idea of trying to run it anyway last night and had found a head gasket, and almost put it right back on, but decided better safe than sorry, and slapped the stocker back on there. NOW- I've mentioned elsewhere that my bike really didn't like the Head gasket with the new SCSW pipe, and was a little boggy like that. Where I'm going with this is, I forgot to pull the head gasket again and ended up running around town all night with the head gasket ON, and my near stock head, and NO AIR FILTER. The bike was singing. It was smooth, and it was operating at full power. I'm convinced that the air filter was a lot dirtier than I realized and that it was in fact restricting airflow significantly enough that now that it's off there, the bike is getting a heck of a lot more air than it was. I find this fascinating, though in no way surprising.

The moral of the story boys and girls, is that small changes make a BIG difference in these little machines! What an exciting and engaging hobby we have!

I'll get that Puch head back on there today and see if I can't get it to work. Sometimes I wish I could roll start my bike, but that's impossible with the shift kit.. Oh well, small price to pay!

PuchHead.jpg
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

Looks good! BTW, I think you have a miniature sperm whale hiding behind your bike! :p
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

That's one of those parasites like tags along with the sharks:p
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

That head looks bad to the bone . I would love to see a pict of the squish band.
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

Funny you should post this. Yesterday I was looking at moped heads and carbs with the same thought in mind! So...YOU be the test monkey!

Terry
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

Pretty cool...I just might try this if My engine kit ever gets here. Any links on where to get one of those heads?? Will they fit the zoom cycles 80 ??
Cheers
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

So far, I haven't got it to fire for me. I put the head back on just now, and pedaled it around with the plug out, trying to make sure the piston cleared (two head gaskets). Well, Tyreslider happened to be on the phone with me at the time and asked "Hey how did you ground the plug out? Or did you just let it dangle?" and I'm like "No Dude, I just removed the plug and let the cap dangle" and he's all "Dude, I hope you didn't torch your CDI like that" and I was like "Shut up dude! You mean that can happen?" and so he's like "Yeah Dude, you aren't supposed to crank the motor without a plug in the cap, it will totally burn out your CDI." And I'm like "You're annoying." then he says "Well it sounds funny over the phone but your bike sounds kinda weird, are you sure you arent smashing the piston into the head?" I says "No, I'm not sure at all, it sounds kind of 'pingy' to me too. Maybe what I should do is put the plug in and try to start it anyway". So he says "That's a really great idea, NOT!" But by now I was like "Well, tough noogies 'cause that's what I'm gonna do, it's gonna work GREAT." So's I do that and try to start the bike- it was really hard to pedal but I got it to cycle over a few times, but still it won't fire up. So I pick the phone back up and hes like "Dude, it didn't start" and I'm like "No kidding." and he's like "Well, that's 'cause now you got no spark 'cause you burned out your CDI, genius."

So long story short, he's on his way over here now with another CDI since I already used up my spare on another bike. We'll do some more testing but apparently this "Bolt on" upgrade is a little more involved than I first supposed..
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

Uh, oh- you guys found Treatland! What a great store. I've got a bunch of stuff from them!

GH- I usually run 100LL Avgas in my bikes.
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

UPDATE:

I was grounding out on my frame! Yay! We wrapped the wires up better and she started right up! After Evan gets a new shifter mounted up on his Worksman 4cycle shifter bike we'll take them for a good little spin and I'll try to get some video up!

Initial indications are for a nice smooth feeling power, maybe not too much faster than stock but let me wind it out and see. I rode it about a mile through the hood around the block and up and down some side streets. I'm going to go inspect the head and piston and maybe put it all back together with a single HG instead of the two and if I can kick that alright try to run it that way.
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

SO I decided not to take the bike apart again since I've had the head off about four times in the last 24 hours, and it was time to ride. The test ride was maybe 20 miles round trip across the 'Hood and down to Georgetown. We were having too much fun to take video the whole time, but here's a bit of riding going South on Airport Way past Boeing Field. Steve is riding his Puch Maxi one speed bike, with a 65cc Metra kit, Biturbo pipe, and a 19mm Dellorto PHBG carb. At one point he holds up his hand and indicated 40mph indicated on his speedo. We were on a dead flat road going into a headwind of maybe 12-15mph. Anyone who rides this area knows the valley floor there gets directional winds there that go either North or South but can either add 10mph as a tailwind, or hamper you by the same amount easily if you encounter them head on.. All in all the Puch head works awesome, and the bike felt like it was a little bit less buzzy somehow, don't ask me why. I know we were pushing higher speeds than here at some other points of the ride, but we won't get caught up in speed numbers and suffice to say that the bike is running great, the exhaust note sounds good, and I'm happy with this experiment.

 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

Very cool thanks for sharing! Its always a blast trying something new on these. That head with all those fins sure looks purty on that china.

I have gave some thought to port timing on these china's with the added compression raising the jug just a scotche higher might give it another whole personality. Ive gotten the impression that the ports are a little low. Just a thought can't say I know that much about it. Really nice to see it running!(^)
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

That's nice. Check out this radial head:MopedShop.com that thing is massive!

Click on pics and check the squish...cheers!
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

It sounds good!
Why was your buddy riding with his kickstand down? Does it have a habit of deploying itself?
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

Yeah we removed that kickstand about a mile later after the clip. I think it's a little heavy, it's extended because of the big front fork He's running I think..
 
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

Goat Herder said:
Very cool thanks for sharing! Its always a blast trying something new on these. That head with all those fins sure looks purty on that china.

I have gave some thought to port timing on these china's with the added compression raising the jug just a scotche higher might give it another whole personality. Ive gotten the impression that the ports are a little low. Just a thought can't say I know that much about it. Really nice to see it running!(^)
Click to expand...

GH- Thanks for the suggestion. I will look in to this and as I think I have one or two spare base gaskets, maybe I can try it by using double base gaskets, at least it's easily reversible if I don't like what it does.

UPDATE: I rode last night with the moped kids and the bike performed better than it ever has. I chased down a head leak (I hadn't tightened things down as hard as I needed to initially) and stopped that, and the bike was running SO good. Also I decided I am running too much oil (like 4oz/Gal) and I'm going to start leaning that mix out a little and see how the bike likes that.

I don't have hard numbers on speeds but the bike was in 5th, 6th and 7th gear all night long. I had no trouble getting through 6th and clicking into 7th on several points in the ride, and all I know is with my original configuration on this bike, I was living in 1st through 5th gear and rarely saw 6th, let alone 7th. It is pulling and pulling like never before. I can only assume that the SCSW pipe and somehow this cylinder head are improving performance significantly. It's really really fun.

I'll let you guys know when I get an accurate GPS speed on this thing, and if I decide to fiddle with the port timing I'll def. update then too.

PS- I was riding most of the way home with my bare leg laying on the SCSW pipe. It was only pleasantly WARM not hot! Only when going up the last hill or two to my house did the pipe ever get so hot that I eased my leg off it but even then it was nowhere near scorching. It was like 90 degrees during the day yesterday but last night cooled down a lot, so on my 25 mile solo route home from the moped kids party I was freezing in my shorts and t shirts. I was practically hugging that pipe to stay warm lol! I just thought you guys would like to know that the high pipe is not a threat to your health!

Thanks for watching this thread guys
 
Last edited:
Re: Puch Moped Head on HT 67cc motor- thanks Foureasy!

You know I kinda wish we had varying thicknesses of base gaskets available in aluminum like we do for the head gasket. I was gonna use a piece of sheet metal semi liken to the amount of piston skirt that remains in the intake port at TDC. Naturally window the piston skirt to split the difference. [Advance the timing by trimming the piston skirt] Two suddle differences done together.

I have to build another weld a bike together project before my next China. Anyway that's what I was gonna try. Got one of MM's billet heads here.
 
You must log in or register to reply here.
Back
Top