Question......why not an aluminum block?

dgsoles · Post by **dgsoles** » Sun Feb 15, 2009 12:37 pm

I hear of everyone talking about how you can only make as much power (heat) as you can shed. I know these bikes have an aluminum cylinder head on them, but has anyone made an aluminum block? I know it has a lower melting point, but, doesn't aluminum dissipate heat so much faster than iron does? I don't know....just a thought....

Kenny_McCormic · Post by **Kenny_McCormic** » Sun Feb 15, 2009 12:41 pm

AL bores cost a lot more to rebuild.

dwsracing · Post by **dwsracing** » Sun Feb 15, 2009 1:17 pm

Don't they re-sleeve them ??? Seems that what they did on the dirt bikes.
DW

scooterwerx · Post by **scooterwerx** » Sun Feb 15, 2009 2:37 pm

Al cyliders dont make that much more power to warrant their cost and disposable nature. once an Al cylinder gets wasted, the only thing you can do to salvage it is sleeving. cast iron is easy, rebore and hone with an O/S piston and its good to go! that said, my brothers zuma is running the athena kit, which includes an Al cylinder. it has almost 1500 miles on it, i pulled it apart to inspect and decarbonize, it was weird how new it looked! the piston had no scuffing, the bore was smooth and shiny. so, i guess if you feel like spending more, Al works just fine! my aero still pulls him up to top speed though! then his gets 75mph!!!

dgsoles · Post by **dgsoles** » Sun Feb 15, 2009 3:43 pm

The only reason I brought this up is from people saying that overheating was the limiting factor on power on these engines, I was merely trying to point out there are other ways to help dissipate that heat (other than water cooling, which might actually be more expensive than an Al block). Oh, and then a ceramic piston would be nice to prevent burn through....now I'm just dreaming

dgsoles · Post by **dgsoles** » Sun Feb 15, 2009 3:52 pm

actually...I'm seeing quite a few ceramic coating operations out there, for quite reasonable prices.....we could benefit from the top of the pitons being coated. for instance....maybe even the cylinder walls...

Kenny_McCormic · Post by **Kenny_McCormic** » Sun Feb 15, 2009 6:07 pm

dwsracing wrote:Don't they re-sleeve them ??? Seems that what they did on the dirt bikes.
DW

If its cast iron lined yes you can resleeve after you bored it a few times. Nikasil bores have to be replated. Alumisil/plain aluminum(briggs made quite a few motors like this and sold em for cheaper than solid iron/iron lined) doesnt need to be plated as it has no plating to begin with. Do keep in mind you must run a chromed piston in a AL bore, Al on AL will scuff.

keithw · Post by **keithw** » Mon Feb 16, 2009 11:35 pm

Cast iron cylinders are cheap, easy, and good enough for the HP these were intended to make. The perfect choice for Honda when they made them. An aluminum cylinder with a cast sleeve will shed a lot more heat but cost more to make. With all the fancy CNC stuff it seems like it wouldn't be horribly expensive to have some billit aluminum cylinders made up with cast iron sleeves.

The old British Bantam class of motorcycle racing kept the racing even by insisting that you use the stock iron cylinder. The trick was to make the most power you could without overheating. The bikes had been used by the post office by the thousands and were very common and quite cheap.

keithw