Who Likes Fast?!

[**RP**]

Bikes can be set up to run blown motors reliably with forged pistons of the correct alloy with proper ring end gaps and skirt to cylinder clearances. 

Not in AMA Production Engine classes if the bike was manufactured with cast pistons.

[racer]

Ray,
You're really quite the optimist looking forward to the year "2105". 
In another 91 years there will probably be a hovercraft class.
Until then we will get our excitement from blown 4 cycle internal combustion. 

 
Drew

Thanks ....A tad overly optimistic ... quite possible ....fat fingers over and out ...

[wobblywalrus]

RP, I am not familiar with AMA rules.  I was once then I forgot them when I stopped racing under AMA classifications.  A previous post mentions 45 seconds of WOT boost.  Boost means blower or nitrous?  That is too long of a time to use standard pistons.  Racing pistons and proper setup are very important.

[**RP**]

RP, I am not familiar with AMA rules.  I was once then I forgot them when I stopped racing under AMA classifications.  A previous post mentions 45 seconds of WOT boost.  Boost means blower or nitrous?  That is too long of a time to use standard pistons.  Racing pistons and proper setup are very important.

Boost means a turbo, I ran a 1015cc 1978 Kawasaki Z1R TC.  At home at the top of 3rd gear the boost was set for only 4 pounds, but as a rookie on the salt I was too focused on watching where I was going to see what the boost gauge read going though the speed traps. 

[wobblywalrus]

Do you have a picture showing the undersides of the piston crowns?

[**RP**]

Do you have a picture showing the undersides of the piston crowns?

What are we looking for on the undersides? 

[wobblywalrus]

The brown is from oxidized oil.  The oxidation is from heat.  Comparing the color between the pistons will tell you if a cylinder is running hot.  Darker deposits indicate more heat.

The oxidation around the corners like seen is not uncommon for cast pistons.  Heat is concentrated there.  Is the ring land failure on the outside in the same place where there is dark color on the inside?   

[**RP**]

The ring lands are pinched on the centerline of the intake valve notch where it is not so dark.  First I need to work on jetting, and maybe take a couple more degrees of timing out of it, and it might live.

[nrhs sales]

you are correct. Pinched ring lands is a sign of detonation.  Definately need to take out a few degrees of timing.

[wobblywalrus]

The lack of cylinder wall to piston seizure marks at the corners, combined with the not very brown of black undersides, says heat might not be the problem. 

[firemanjim]

Funny,I thought in Production class anything goes internally just exterior needs to appear stock and same bore/stroke.

[wobblywalrus]

How could the AMA reasonably enforce their rules unless they do like Fireman says?