Blown Head Gasket- Please Assess and Advise

[jensen]

Hi,

This hone pattern sure doesn't help the piston, next to that, it's too rough (but it's difficult see it from here). My advice still stands, no matter what the piston to wall clearance is. A cross hone pattern is absolutely necessary for a good running engine.

Jensen

[LOUD MOUSE]

I asked about the cylinders as they have the darndest pattern I've seen.
Almost looks like the engine wasn't run after the hatching was done but I doubt that for sure.
I agree ya need to get them to a shop who knows what to do.
Any luck and ya may be able to just install a new set of rings after a good machine shop hones to fit what with the clearance ya have now. ........lm

Just curious.
Did ya run a Flat Hone in the cylinders after ya pulled it off the pistons> ..........lm

No sir- i simply split the head and cleaned everything up as best I could. They haven't left my basement and I'm not about to try anything of the sort myself!

So here's the latest:
As Teazer instructed, I inserted the piston back in the cylinder and used a feeler gauge at the front of the piston to measure the gap. I'm pleased to report that the .002 wouldn't even work it's way into the gap; if I slid it into the side wall of the cylinder and then moved it around to the front it still would only wedge itself in there rather sungly and resist when I went to pull it out.
The cylinders themselves have etchings going horizontally and vertically, but not a 45 degree crosshatch.
Also attaching a pic of the old head gasket per Teazer's request. It's pretty ragged since it was stuck pretty firmly to the cylinder head in places and it peeled apart in my effort to remove it.

[houseowax]

I asked about the cylinders as they have the darndest pattern I've seen.
Almost looks like the engine wasn't run after the hatching was done but I doubt that for sure.
I agree ya need to get them to a shop who knows what to do.
Any luck and ya may be able to just install a new set of rings after a good machine shop hones to fit what with the clearance ya have now. ........lm

Well, there IS a chance, albeit a slim one. I bought the bike last November and it was not running,. although a carb cleaning was said to be all it would need. The PO was a bit of a fanatic and it came with 2 boxes of parts including a NOS headlight(!) and a bunch of gaskets etc, Including a complete OEM bottom end set. So the guy was into the bike, although his attention to detail was sometimes less than impressive.
I knew nothing about bikes at the time and proceeded to read up on carb adjustment. I tried my best but probably did more harm than good in my attempts. I finally got the bike running- well, starting - when I first heard the head gasket noise. I've since learned a whole lot, but I have never ridden the bike. Ever- not even down the block. So I guess it IS possible that the cylinders were flat honed shortly before the bike was sold.
I'd be thrilled if the cylinders could just be lightly honed and a new set of rings would get me on my way. Both for the cost issues and because I'd like to know what it's like to ride a motorcycle (never really even been on one) before the Winter sets in!

I had no idea how lucky I was when I bought this bike, but ALL the chrome is practically brand new, I got the headlight, new wiring harness, a spare tank (rusted), extra side cover knobs, gaskets, sealed wheel bearings....

[teazer]

That's three out of three of us think the hone pattern is odd. With the odd machining pattern, and loose head nuts, I'd speculate that the barrels were bored to finished size at the PO's place of work and not honed by an engine machine shop.

They are tight enough and teh motor has done basically no miles since a rebuild.

The head gaskets is showing signs of blow by bit no sign of catastrophic failure - good news.

I agree with LM. get the barrels and pistons to your local engine machine shop and see if they can run a hone through them and measure the clearances. If the bores are round and parallel, you might get lucky. if you don't have a place locally, Bill Bune in MN can do that work.

It must be an auto/bike machine shop. Local bike shops are usually no good and die/tooling machine shops are also no use. It needs to be a motor shop. They will be able to check the barrels, hone them and measure them and tell you if they are OK to use. if they are good, wash the bores out with soapy water and wipe with a clean white rag until the bores are spotless. rebuild with new rings.

I would also have them skim the top of the barrels and bottom of the head just to be sure - after you check the valves for leaks. I prefer to use kerosene rather than gasoline and I do all 4 valves at once by screwing the plugs back in and fill the chambers with kero and come back later to see if any is leaking out of a port.

Replace the cam tensioner is possible and check the cam chain and idler wheel.

The whole things is about a two week turnaround and that's all shipping/machining time. Assembly is less than a day.

[houseowax]

That all sounds great and completely within my realm. I live in Brooklyn, NYC, so while I'm sure there's a place locally that can do the job, I'm also pretty sure that they'll be either backed-up or impossibly expensive. That's the way things are around here; if someone can actually do what they claim to do they get swamped and the prices inflate. I'll check with my local vintage motorcycle mail list and see what their thoughts are. Might be wiser to send them out of state.

One question about the valves- I can turn the cam sprocket by hand (with some difficulty) since the chain's disconnected, but how do I know when the valves are as sealed as they can be? Is there a punch mark on the cam sprocket that I can look for?

[teazer]

Yes, There's a mark on the cam sprocket that you will become familiar with when you reassemble the motor.

But why not just loosen off the valve adjusting screws so they are all loose? Just a thought.

[houseowax]

See? That's why I come here. Thanks, Teazer- will do!