Piston and lower end pics

Exnav · Post by **Exnav** » December 2nd, 2007, 5:11 pm

Take a look at these. The piston has 25 on the crown showing overbore. Comments on the piston and cylinder wall if you can see anything. Calling Glen in the morning to get it fixed up.

Crummy pic of the bore.

My real question is about the apparent spider cracks in the next 2 pics around I am guessing crankcase ventilation holes? Ideas and thoughts?

britincali · Post by **britincali** » December 2nd, 2007, 5:16 pm

Those "cracks" are casting flaws nothing to worry about.

The piston/bore just looks worn and having blowby, glen will fix you all up

Ported&Polished · Post by **Ported&Polished** » December 2nd, 2007, 5:18 pm

If that is an original 85 cr500 on it's second bore and piston, I'd say it looks very good. Show me any other 23 year old dirt bike that looks that good, gota love the Hondas.

Exnav · Post by **Exnav** » December 2nd, 2007, 5:30 pm

The engine is from a 96' model.

Exnav · Post by **Exnav** » December 2nd, 2007, 5:33 pm

britincali wrote:Those "cracks" are casting flaws nothing to worry about.

The piston/bore just looks worn and having blowby, glen will fix you all up

I was assuming a casting flaw, but wasn't for sure. thanks!

Rosco-Peeko · Post by **Rosco-Peeko** » December 2nd, 2007, 5:59 pm

You will not be able to see the bottom of a crack. A test I use in the Jet Engine world to see if something is a stress or a crack:

Use alcohol
Apply liberally to surrounding area and suspected crack
Blow lightly, the alcohol will evaporate quickly
If it is a crack, the alcohol will seep into it keeping it from evaporating. "The crack will stay wet." If everything dries..its a flaw in the metal.

sabreguy · Post by **sabreguy** » December 2nd, 2007, 7:45 pm

Rosco-Peeko wrote:You will not be able to see the bottom of a crack. A test I use in the Jet Engine world to see if something is a stress or a crack:

Use alcohol
Apply liberally to surrounding area and suspected crack
Blow lightly, the alcohol will evaporate quickly
If it is a crack, the alcohol will seep into it keeping it from evaporating. "The crack will stay wet." If everything dries..its a flaw in the metal.

Hey that's a damn good tip right there!!

Spyder · Post by **Spyder** » December 3rd, 2007, 8:24 am

Exnav wrote: My real question is about the apparent spider cracks in the next 2 pics around I am guessing crankcase ventilation holes? Ideas and thoughts?

I think those holes are there to direct any gathering oil down to the main bearings.

OR maybe they direct some premix mist up to the piston pin bearing.

Anybody know for sure?

dannygraves · Post by **dannygraves** » December 3rd, 2007, 8:46 am

oil to the out side of the bearings. Yeah, it looks like time for a .5mm bore, you got lucky that it was only at .25.

ou812 · Post by **ou812** » December 3rd, 2007, 10:22 am

Why does the exhaust bridge look funny?

Exnav · Post by **Exnav** » December 3rd, 2007, 10:59 am

ou812 wrote:Why does the exhaust bridge look funny?

I think it just blow by buildup, but need to go out and look at it again to see.

There is some evidence of someone getting happy with a die grinder on the exhaust side.

Hell who knows, it's buyer beware off of Ebay.

Exnav · Post by **Exnav** » December 3rd, 2007, 11:24 am

I cleaned the bridge with some Brakleen and it feels smooth to the touch, but the wear pattern is irregular. There are shiny metallic areas and parts that are brownish in color, but definitely smooth. There is a corresponding wear pattern on the piston.

Exnav · Post by **Exnav** » December 3rd, 2007, 2:41 pm

Shipped via UPS today to GSS.

britincali · Post by **britincali** » December 3rd, 2007, 3:04 pm

Exnav wrote:Shipped via UPS today to GSS.

Exnav · Post by **Exnav** » December 3rd, 2007, 4:07 pm

Yep...getting it punched, head cleaned up, new wrist pin bearing, piston and rings, and gaskets.

Glen was cracking me up on the phone today. Next year at Sema, I am going to have go and meet him at his booth at the AAPEX show. He's a character for sure.

britincali · Post by **britincali** » December 3rd, 2007, 4:08 pm

Exnav wrote:
Glen was cracking me on the phone today. . He's a character for sure.

Yes he is!!!!

iggys-amsoil · Post by **iggys-amsoil** » December 3rd, 2007, 10:49 pm

The shiny places on the bridge are whats touching the piston.

It may fell smooth but its not.

Exnav · Post by **Exnav** » December 4th, 2007, 5:31 am

iggys-amsoil wrote:The shiny places on the bridge are whats touching the piston.

It may fell smooth but its not.

No doubt; the inside micrometer would tell the story fo' sho'.

MICK · Post by **MICK** » December 21st, 2007, 4:09 pm

Have you got it all put back together yet? I'm anxious to hear how it runs now. Does Glen do a general clean up on all the ports, like match the exhaust port to the manfold and touch up the rough transfers?

Exnav · Post by **Exnav** » December 26th, 2007, 3:00 pm

Not all back together yet....haven't the time to work on it. Call Glen and discuss what you want done and I'm sure he can help steer you the right way. In the short time I have spoken to him, it is quite apparent that he has forgotten more than I will ever know about the CR500 engine. His number is in the approved vendors section.

BannedCR500Riders.com

Piston and lower end pics

Piston and lower end pics

Re: Piston and lower end pics