Topic: 1971 K0 CB500

[RAFster122s]

If the piston is that chewed up I would wager the combustion chamber is as well, beyond hope.
Are you taking it to 550 size or keeping it a 500?

[Shtonecb500]

The original head is smoked and retired. I have my original 73' cb500 motor and the head is already stripped and degreased for rebuild, new pistons are 0.25 over.

[Stev-o]

WOW, sorry to see that catastrophic failure damage, been there.

So was it spring failure, I dont quite understand how it happened?

[Shtonecb500]

WOW, sorry to see that catastrophic failure damage, been there.

So was it spring failure, I dont quite understand how it happened?

if you are asking how the spring failed then my only guess would be from the heavy pitting in the springs and think that happened because the bike was stored with the pipes off of it for 30 years. The other springs are pitting the same way. If you are asking hhy the damage is so extensivead then thats cause I continued to run the motor even after I heard a noise.

[HondaMan]

Wow, this is a heartbreaker.
Sorry about that top end!
On an upswing note, though: you will pick up about 20%-25% more power for the bore job, and it will stay there in the future, not sap away like the original top end always does.

Can you tell if the pitting just caused spring failure, or was it debris jamming the valve movement?

[Shtonecb500]

Wow, this is a heartbreaker.
Sorry about that top end!
On an upswing note, though: you will pick up about 20%-25% more power for the bore job, and it will stay there in the future, not sap away like the original top end always does.

Can you tell if the pitting just caused spring failure, or was it debris jamming the valve movement?

based on what i remember about what i heard when it was all happening, I imagine the spring cracked but it all stayed in place. after another 14 miles maybe the keepers finally moved and the pieces of springs jumped around?

Im not sure, im not very familiar with the internal engine components, this is going to really be my first major deep dive into motor repair and understanding. Phil (mechanic) has not yet laid out what he thinks may have happened...so i can only paint the picture based on the noises i heard before it went south.

[grcamna2]

Wow, this is a heartbreaker.
Sorry about that top end!
On an upswing note, though: you will pick up about 20%-25% more power for the bore job, and it will stay there in the future, not sap away like the original top end always does.

Can you tell if the pitting just caused spring failure, or was it debris jamming the valve movement?

based on what i remember about what i heard when it was all happening, I imagine the spring cracked but it all stayed in place. after another 14 miles maybe the keepers finally moved and the pieces of springs jumped around?

Im not sure, im not very familiar with the internal engine components, this is going to really be my first major deep dive into motor repair and understanding. Phil (mechanic) has not yet laid out what he thinks may have happened...so i can only paint the picture based on the noises i heard before it went south.

I'm interested to hear what Phil tells you about what might have initially caused this.

[Shtonecb500]

stripped and degreased.

[grcamna2]

Looking good. 
I hope you're able to wash the parts out multiple times and blow them out;that sand can really hang-on in unseen passages.

[Shtonecb500]

I did wash it and hit it with compressed air a bunch of times, Phil does that again before he puts stuff back together.

Motor should be rebuilt before he goes to Florida in Jan....So i should have it all back together around then.

[grcamna2]

Did Phil decide to get this bike from you ?

[Shtonecb500]

Did Phil decide to get this bike from you ?

you mean did he buy it off me? no he did not but he is doing the motor rebuild for me.

[grcamna2]

Did Phil decide to get this bike from you ?

you mean did he buy it off me? no he did not but he is doing the motor rebuild for me.

Ah ok,
I thought maybe he bought it from you and taking down to FL. with him.

[Shtonecb500]

Bottom end is complete and together, used all 4 rods from donor motor, all the bearings checked out ok so didn't have to replace any. Everything has been decked, head was rebuilt last week or so and all thats left is the bore job on cylinders. Should have the bike back together and running no later than end of the month.

Phil said its prolly gonna cost me 1k for everything, I can manage that.

[Shtonecb500]

I was stripping the original damaged head and found the smaller inner spring was shattered as we

[grcamna2]

Bottom end is complete and together, used all 4 rods from donor motor, all the bearings checked out ok so didn't have to replace any. Everything has been decked, head was rebuilt last week or so and all thats left is the bore job on cylinders. Should have the bike back together and running no later than end of the month.

Phil said its prolly gonna cost me 1k for everything, I can manage that.

That's a good deal.

[Shtonecb500]

Bottom end is complete and together, used all 4 rods from donor motor, all the bearings checked out ok so didn't have to replace any. Everything has been decked, head was rebuilt last week or so and all thats left is the bore job on cylinders. Should have the bike back together and running no later than end of the month.

Phil said its prolly gonna cost me 1k for everything, I can manage that.

That's a good deal.

Ya he is for sure hooking me up. Had to order new set of rings as one broke, otherwise it would have been back together today.

Very very close. On another note, I finished taking the original head that sustained damage apart. Number 3 intake inner valve spring was shattered just like number one  intake, the main valve spring had not broken yet…..so so and three would have both been destroyed.

[Shtonecb500]

MOTOR IS COMPLETE. Im too busy with work to get to the shop today so Ill have it all back together on Monday.

[BenelliSEI]

Just read about the broken ring. Frustrating, but you reminded me to change my order for my current build. I order 5 sets of rings. Guaranteed if I have an extra set on the bench, none will break!

[Shtonecb500]

 they were the single piece oil ring and he wanted to replace with the three piece anyway. My baby s back together and made whole. I’m gonna wait until Monday to throw it all back in the frame and should have it tuned by Tuesday.

[BenelliSEI]

Congrats. All look great.

[grcamna2]

Nice work. 

That's Phil's place ? Great looking shop !

[MauiK3]

Very jealous of the shop space!!
Nice bikes

[Shtonecb500]

Nice work. 

That's Phil's place ? Great looking shop !

this gives a better idea of the space, still lots more.

[Shtonecb500]

https://bringatrailer.com/listing/1972-honda-cb500-four-7/#comments-anchor
 original gold 72 just listed on bat

this is only the 3rd stock cb500 on BAT,  TOTAL..all others are modified.

this one is a transition model, has small gauges and large reflectors, large rear tail light.

it was originally a candy jade green before restoration, original odometer looks like it had around 7-8k original miles on the motor but faces were cracked, looks like they sourced oem nicer gauges with 80 miles on them. Body kit repainted, looks to have sourced an oem exhaust with rot in some spots on the underside, some coin size holes... I see some red gasket goop or something under the exhaust valve inspection cap..number 3 or 4.