One for the 250cc folk

[generatorshovel]

Instead of looking at the fuel is it prudent to wonder if that 1 cylinder sitting off by itself will run a little hotter than the others, just enough that it goes over the edge first!

I hear ya there gearheadeh, #4 needs an excuse for getting itself into trouble all the time
Tiny

[generatorshovel]

Working on this baby is like working on a ladies wristwatch









Pistons appear to be made of unobtanium 
Tiny

[55chevr]

Looks like you need a magnifying glass to install rings ... miniature components.   

Joe

[Stainless1]

I was just thinking "man that guy had big hands"
Cute motor.

[DND]

Hi Tiny

Did they run the engine in the road race bike blown , or did you add the blower?

The #4 hole chamber & valves looks a bit wet, did it oil in there because of a bad stem seal or oil ring?

Looks like a bore size of about 2.500 dia ?

Don

[generatorshovel]

Hi Tiny

Did they run the engine in the road race bike blown , or did you add the blower?

The #4 hole chamber & valves looks a bit wet, did it oil in there because of a bad stem seal or oil ring?

Looks like a bore size of about 2.500 dia ?

Don

Honda never planned on some nutter fitting a blower Don, they left that job to me
After it holed the piston,,it idled until I made it off the track, there's just a little hole in the piston that let the oil into the chamber until I killed the ign.
Bore size 48.5 mm stroke about 34m ? from memory.
This is an opportunity to lower the static comp. ratio, and get rid of the stock valve overlap I guess, the cost of which scares me. seeing as it was just a "stocking filler" project.
Tiny

[Jon]

Running the standard compression with boost on Methanol shouldn't be a problem I recon.

When you get the fuelling right and stay out of detonation the standard pistons should be ok?

 I'll ask Dave if he knows where to find some pistons, he used to ride one and has mates that have trashed a few.
Have you tried the cbr250.com forum?

jon

[maj]

coating the pistons will help too, instead of doing that to a piston you will get a little further down the track before hurting the head
 

[generatorshovel]

Running the standard compression with boost on Methanol shouldn't be a problem I recon.

When you get the fuelling right and stay out of detonation the standard pistons should be ok?

 I'll ask Dave if he knows where to find some pistons, he used to ride one and has mates that have trashed a few.
Have you tried the cbr250.com forum?

jon

Thanks Jon

coating the pistons will help too, instead of doing that to a piston you will get a little further down the track before hurting the head
 

Yeah Greg, ceramic coating was the plan, maybe some advice on water injection later down the track ? depending on the EGT readings once I get it to the test stage again ?
Tiny

[wobblywalrus]

Arias makes custom pistons.  There is a data sheet you can fill out and send in.  They did the ones for my bike on a special order basis through Triumph Performance.  Maybe Woessner?  Forged pistons are better at dissipating crown heat.

My experience is the bottoms of the pistons will be brown and sometimes black in the centers on the undersides when they get really hot.  It is burned and oxidized oil.  Your pistons do not show that.  It seems the problem that killed your piston happened pretty quick and before everything got hot. 

[Grandpa Jones]

Hi Tiny,

Anyway to tell if all the cylinders are getting the same mixture? The old
draw-thru bikes used an intake manifold that looked like it wouldn't flow
worth a damn, but the design helped equalize the flow to all the cylinders.

I've been trying to find a picture of an example of those manifolds, but
haven't had any luck yet.

Cheers,

Dave

[stay`tee]

 oil + methanol + compression = detonation,  ,

[JimL]

How far up are the plug threads showing color?  Just curious.

[generatorshovel]

Arias makes custom pistons..    Maybe Woessner? -------- I emailed JN @ woesner, awaiting a reply---------  Forged pistons are better at dissipating crown heat.

My experience is the bottoms of the pistons will be brown and sometimes black in the centers on the undersides when they get really hot.  It is burned and oxidized oil.  Your pistons do not show that.  It seems the problem that killed your piston happened pretty quick and before everything got hot.  

[generatorshovel]

Hi Tiny,

Anyway to tell if all the cylinders are getting the same mixture?

#4 seems to be missing out, here's the setup (not the carb I use)