Puch head on a 66cc HT bicycle engine with 6mm studs

Re: Puch head on a 66cc HT with 6mm studs

Please help me be less confused...
I would like to order a Puch head for a current style Grubee 66cc motor.

Which head is the right one to order? I am looking at treatland.tv btw. I see the possible options:
puch 70cc hi hi comp head
puch 50cc hi comp head old style fins
puch 50cc hi hi comp head
puch 70cc hi hi comp head type 2
puch 70 hi comp head old style fins

Which would be the most correct for this application? Are there any others to consider?

Aside from possibly having to re-drill for larger head studs and using smaller diameter nuts, what else is required? I see descriptions of people using extra gaskets to raise the jug, as well as stacks of head gaskets to raise the head. And would I use Grubee head gaskets, or Puch head gaskets? None of this is really concerns me. I just want to make sure that I have the neccessary parts on hand before I begin.

Is there any benefit to polishing the combustion chamber? Is there a reason to unshroud the spark plug? Sand the head and jug to flatten the mating surface? Any other prep work to consider?

So, in short:
What is the right head to purchase?
What gaskets/shims should I order for installation?
 
Re: Puch head on a 66cc HT with 6mm studs

I have a PK 68.5/80cc engine I bought the Puch 70cc High High comp head form Treatland.tv, you will have to drill out the mounting hole but other then that it's all good with fit, other might have different opinions on 50cc or 7occ so listen to the advice and then make your dicision, Maurtis seems to be well educated in this field.
 
Re: Puch head on a 66cc HT with 6mm studs

PAracer said:
Please help me be less confused...
I would like to order a Puch head for a current style Grubee 66cc motor.

Which head is the right one to order? I am looking at treatland.tv btw. I see the possible options:
puch 70cc hi hi comp head
puch 50cc hi comp head old style fins
puch 50cc hi hi comp head
puch 70cc hi hi comp head type 2
puch 70 hi comp head old style fins

Which would be the most correct for this application? Are there any others to consider?

Aside from possibly having to re-drill for larger head studs and using smaller diameter nuts, what else is required? I see descriptions of people using extra gaskets to raise the jug, as well as stacks of head gaskets to raise the head. And would I use Grubee head gaskets, or Puch head gaskets? None of this is really concerns me. I just want to make sure that I have the neccessary parts on hand before I begin.

Is there any benefit to polishing the combustion chamber? Is there a reason to unshroud the spark plug? Sand the head and jug to flatten the mating surface? Any other prep work to consider?

So, in short:
What is the right head to purchase?
What gaskets/shims should I order for installation?
Click to expand...

I use this puch head to https://www.treatland.tv/ProductDetails.asp?ProductCode=puch-hi-comp-head-70cc-maxi work very well, uses 2x cylinder base gaskets, has a squisch measure approximately 2mm, a bit too much, but do not want too high compression want the engine hold together
 
Re: Puch head on a 66cc HT with 6mm studs

Neat.

It sounds like all of the options will work with varying degrees of modification. Being adventurous, I went with the 50cc hi hi head. We'll see how it goes. :)
 
Re: Puch head on a 66cc HT with 6mm studs

...not good. Your compression ration will be in the area of 16:1, dang near deisel level of compression. When you consider the stock is around 6-7:1 I'd just about bet you won't even get the wheel to turn over and when you release the clutch all you will do is skid.

Or as the saying goes these days; good luck with that :p
 
Re: Puch head on a 66cc HT with 6mm studs

... and when I make it work you'll be all like... Daaaaaaaaaaang!

xct2

You'll see! You'll all see!
 
Re: Puch head on a 66cc HT with 6mm studs

Actually, I based my purchase on the recommendation by culvercityclassic. And also the experience of Maurtis.

I feel pretty confident that it will work. :)
 
Re: Puch head on a 66cc HT with 6mm studs

PAracer said:
Actually, I based my purchase on the recommendation by culvercityclassic. And also the experience of Maurtis.

I feel pretty confident that it will work. :)
Click to expand...

I think CCC does use the 50cc head, but I used the 70cc head with one head gasket. And make sure your clutch spring tension is tiiiiight. I had to tighten mine so much that I had to buy a clutch roller in order to comfortably pull the clutch lever. And even then, I still got clutch slippage on startup sometimes.

Then I blew up my motor ;)
 
Re: Puch head on a 66cc HT with 6mm studs

Very interesting. The clutch feels quite snug. I'm worried that it might be too tight. It takes a good grip to disengage. I also have a couple head gaskets and jug gaskets being sent my way from Dax. If I need to, I might even remove bit of material from the combustion chamber. I think I could smooth out the area where the spark plus threads in. Those ridges create areas of concentrated heat.

Is there any souce out there for grippier clutch friction material?

A blown motor is just a conversation piece for the mantel :)
 
Re: Puch head on a 66cc HT with 6mm studs

please explain did it cool the engine tremendously couse im having the same issues that i go around the block and the engine is on fire i mean extremly hott please telll me what i need to do im desperate its my 3rd engine
 
Re: Puch head on a 66cc HT with 6mm studs

b4guaged...

Yes, and the benefit is two-fold. Cooling, and added compression.

The mass of the head is at least double that of the HT head. I can weigh them both after work today. That added mass directly affects the cooling capacity of the engine.

The compression will boost horsepower at a cost of hard starting. This can be adjusted by using an extra head gaskets and/or jug gaskets.

If you want to do this mod, I would get:
-head from treatland.tv (70cc hi-hi compression. 50cc is possible, but may have too much compression. We shall see. I am trying this configuration)
-two headgaskets (order more than you need, they are cheap)
-two jug gaskets (order more than you need, they are cheap)
-ultra copper RTV
-new spark plug
-new hardware (the puch head has less clearance for hardware.) I am going to use coupling nuts with short socket head screws loctited into the top.
 
Re: Puch head on a 66cc HT with 6mm studs

When talking about head gaskets, what do you by "stock gaskets" ? stock to the Chinee engine kit or stock to the puch head from treatland
My stock Chinee gaskets look like they will interfer the piston up stroke, looks like the piston won't rise as far as it should into the head
 
Re: Puch head on a 66cc HT with 6mm studs

Unless I'm not thinking correctly, I'm not sure how they could interfere. If the same gasket worked with the stock head, then the piston will clear with the Puch head. The piston isn't traveling further up than it was before.

I would use the Chinese gaskets.
 
Re: Puch head on a 66cc HT with 6mm studs

the Id opening /circumference seems to be smaller then both the cylinder and head I'm running a PK69.5/80cc and Puch High High Comp head
 
Re: Puch head on a 66cc HT with 6mm studs

Was it working when you had the stock head? If it worked before, it will still work now. Unless you cut the jug shorter...

I still think that you should use the same head gasket. Are you sure you are using the right gasket for the motor? A 50cc gasket might be smaller.

You should not use a different head gasket just because you are using a different head. Use what worked before and you will be fine. If the headgasket itself was improperly made, or not for that engine, then you might have a problem. Do you have another gasket to compare to?

Mike
 
Re: Puch head on a 66cc HT with 6mm studs

Never ran the engine, when I get my engines I break them down and rebuild them,so I don't know what it ever ran like before? I can tell it has been test fired at the factory but if you can imagine two large circles with a littler circle inside well there you have it I thought the head gasket was supposed to be larger then the head or cylinder and I did order another stock Chinee head gasket for 80cc engine and it is the same size
 
Re: Puch head on a 66cc HT with 6mm studs

Gotcha.

Since I had the head off last night, I gave the rotating assebly a crank to see how high the piston comes up toward the head. On my motor, the piston does not clear the top of the jug. So, the head gasket should work. Since you have confirmed that you have the right Chinese headgasket, you are good to go.
 
Re: Puch head on a 66cc HT with 6mm studs

Soon as I get some Allen head bolts for the head I'm going to start to put this thing back together
Thanks for the info!
 
Re: Puch head on a 66cc HT with 6mm studs

No problem truckd! :) Glad to be of help.

I would still check things out as you put the motor together. Just to eliminate the posibility of an anomoly showing up.

Also, mcmaster has 24mm long coupling nuts and socket head screws that would be great for this application. A drop of red loctite will hold them together. You wouldn't want the socket head to back out while the nut is still tight on the cyclinder head.
 
Re: Puch head on a 66cc HT with 6mm studs

I just received a package of mounting hardware for my M8-1.25 stud Puch head.

Purchased from Mcmaster
p/n
91290A414 M8-1.25 socked head screw 10mm long class 12.9
93020A781 M8 coupling nut 19mm long
98035A105 metric extra thick washer
91458A560 loctite 262 red

I also used anti-seize on the studs.
 
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