Pictures of a few BBK's

[theo547]

Just installed the Autotech355 Aluminum kit today... let me tell you, just looking at it all i could think was that this thing is beast. i took out my Athena 70cc and my Iron Autotech 70cc kit.

Took a few pictures... not sure if they are of any use to anyone, but here goes


IMAG0590 by theo547, on Flickr
From left to right: Autotech Aluminum, Autotech Iron, Athena 70

IMAG0593 by theo547, on Flickr
Aluminum Head

IMAG0592 by theo547, on Flickr
Beat to crap Iron head - you will notice its the same head down to the blank stamp on it.

IMAG0591 by theo547, on Flickr
Athena Head

IMAG0597 by theo547, on Flickr
Aluminum Inside shot

IMAG0598 by theo547, on Flickr
Iron inside shot

IMAG0599 by theo547, on Flickr
Athena Inside shot

IMAG0600 by theo547, on Flickr
Aluminum Exhaust

IMAG0601 by theo547, on Flickr
Iron Exhaust

IMAG0602 by theo547, on Flickr
Athena Exhaust

Just thought someone might find them interesting. I installed the Aluminum kit tonight but for my neighborhoods sake i didnt tune it. it sounds pretty awesome from just the few quick revs i gave it.

[theo547]

side note - if you install either the Aluminum kit or the Athena kit on a standard Minarelli Horz engine you will need to remove the oil pump. the kit will not fit because it has heat fins (?!?) that go very low on the base and will hit the pump before going in.

I only make this point because i dont remember ever reading that...

[theo547]

Another thing i noticed: The piston that comes with the Aluminum kit is a single ring, but a double ring should be very close in size. now obviously very close is not exact and could cause issues, but just eyeing them up it seemed like it would work.

So this kit could possibly have a little less power, but last a whole lot longer....

[jmkjr72]

something isnt right if you have to remove the oil pump i have yet to have to remove an oil pump with any of the kits
as the oil pump is under the flywheel

dont forget to drill some cooling dimples on the piston for th eal kit with the split exhaust port

[theo547]

dont know man - i have a Minarelli Long Case and large 21mm stroker stock. i was bumping into the oil pump a good 1\8 inch onto one of the fins. no way that was fitting without taking it off. guess i should have taken pictures

[theo547]

aww man! i need to drill out some dimples on that piston...
Something like this huh?
i30.tinypic.com/2sbjtxv.jpg
Wonder why id never read that before.

[jmkjr72]

or you could have done like we do on the stellas or the vespas with ele start
and thats just grind the fin so it fits

[theo547]

thought about doing that.. no grinder and i premix anyways.

[90GTVert]

Thanks for the comparison pics and info. We have talked about drilling/dimpling the piston a little. I did it to one of my engines near the single exhaust port. I drilled all the way through though. I've been told it's a good idea and been told it's wrong. That engine has pulled a 300lb rider over 70MPH so I figure I didn't mess it up too bad. ;D

[jmkjr72]

i was always taught that you had to dimple or drill a bridged exhaust port otherwise you run the risk of a hot spot

[theo547]

i read a few articles last night that that were pretty helpful with that. they said the main reason you put the dimple is for cooling because sometimes the piston will get hot and the ring can actually get caught in the bridge and not only blow up the ring but drag and take the bridge with it.
Another one said that people used to have to do that because any slight manufacture defect could cause the above issue, but most modern cylinders wouldnt need it anymore....

So... ill be putting those dimples in tonight - no reason not to.

[2strokd]

The little bridge gets hot and swells into the cylinder. The dimples hold more oil, cooling the bridge and keeping it in the port.

Just letting the engine warm proper before WOT blasts does wonders too