New Slant Heads for 80cc's: Compression Boost!?

I was on zoombicycles forum today while ordering another motor kit for my new moondog/(shorewood) and i found a thread about the new heads they sell for $12.95.
New Slant Head: Zoombicycles Motor Bicycle Engine Kits 80cc Slant Head Cylinder Cover (A-2B) | 14-Addons | 6-Parts and Accessories | RuiHong Enterprises Ltd..

Thread: zoom 80cc slant head upgrade evaluation - Zoombicycles Motorized Bicycle Engine Kit Forum.

I ended up ordering one of their new engine kits with this head already installed and ordered an extra head for my other motor. Ill let you guys know if it helps -Justin



UPDATE:
Purchase the following for successful installation*****:
(1) Slant Cylinder Head: Zoombicycles Motor Bicycle Gas Engine Kits 80cc Slant Head Cylinder Cover (A-2B) | 14-Addons | 6-Parts and Accessories | RuiHong Enterprises Ltd.
(1* or 2*/****) Head gasket(s): Zoombicycles Motor Bicycle Gas Engine Kits 80cc Head Gasket (A-3) | 10-Gaskets | 6-Parts and Accessories | RuiHong Enterprises Ltd.
OR Sick Bike Parts
(1*/**** or 2*/** or 3*/**/***) Cylinder Base Gasket(s): Zoombicycles Motor Bicycle Gas Engine Kits 80cc Cylinder Bottom End Gasket (A-7) | 10-Gaskets | 6-Parts and Accessories | RuiHong Enterprises Ltd.

*Most 69cc/80cc engines utilize m8 head studs, but the gaskets pictured show m6 diameter holes. The gasket holes may need enlarged for the larger studs...
**The reason for 2 or 3 cylinder base gaskets is some engines need the extra space to prevent the piston from hitting the head... Use only one gasket if you can get away with it!
***If you have modded your motor to reach extreme rpm (boost porting & other porting), I noticed my connecting rod is stretching enough to allow the piston to hit the head (power drops and slapping noise...) either add another base gasket (total of 3) or dont rev so high (10,000+rpm when it occurs for me). I didnt have any damage and it has happened a couple times (not intentionally), but i dont recommend it. BUT if concerned add another gasket or head gasket to make up the space...
****Jet silver motors currently sold by zoombicycles have the slant cylinder head preinstalled and they use 2 head gaskets and 1 base gasket to prevent the piston from hitting the head. I think that this raises the chance for a head gasket leak especially with the higher compression but so far i havent had any leaks on my stock jet silver motor so maybe this is another viable solution to the clearance issue, especially since this leaves the port timing unchanged.
*****Try at your own risk!! I cannot guarantee that it will work on absolutely every application (differences in manufacturing & tolerances etc.), I'm merely stating what worked for me and others. Have Fun!!!

I thought the exact same thing when i read the thread and saw the picture but then I looked a little closer and although the fins are shorter there are 13 fins on the slant head versus 11 on by BGF. I figure that the extra fins will atleast equal the surface area of the original. I guess ill just have to be the test subject on this one -Justin

(slanthead on left, standard on right)

well i dont have access to a dyno but if i notice any difference ill let you know. Im surprised no one else has compared the old motors to the new slant head ones (80cc). Im curious to find out what happens cause i read somewhere (besides the thread above) about the compression bump in the newer slant head motors and the only place i found the 80cc version of the cyl head is zoombicycles We shall see... -Justin

Found these reviews on zoombicycles site (one is the same guy that started that thread...):

Customer Reviews:
fenderhole (Sunday, 08 March 2009)
Rating:

freakin awesome! engine now has gobs of torque and gained 7mph on top end... best US $13.00 (Convert) i ever spent!


farmboy72 (Saturday, 31 January 2009)
Rating:

The slant head adds some bottom end torque due to the smaller combustion area which adds compression. the head is not painted so if you dont paint it
it stands out like a sore thumb. Overall the slant head is well worth the 12 dollars.


I hate waiting for the brown truck to show up!! -Justin

Last time I ordered from ZoomBicycles it took 7 days for my parts to come so it will probably be here on tuesday... -Justin

No package yet. the tracking number says its still in washington state. Maybe they sent it back to china for a final quality control check. Justin

Now im real excited for this new head!! Im out of town today and the package is sitting at my house, Ill probably install it tomorrow. Glad it worked out for you donuts!! BTW did your BGF have 6mm head studs? Does the new slant head have larger holes for 8mm studs (80cc PK motors typically have 8mm studs where as BGF have 6mm studs)? How does the surface area of the old head compare to the slant one? I guess i could answer all these questions tomorrow myself when i get home... (I also have a shifter kit with a 34t mega range its great for standing starts .)
-Justin