Oh poop

[chuck hahn]

ed i would love to learn every inch of these bikes.. The next thing i know i will be a certified pro like you!!! LOL ARE YOU READY TO RUMBLEEEEEEEEE?????

[rustybronco]

Ed, not a half bad idea.

Chuck might be coming by in the next few days to work on/upgrade his '750's charging system, then we can kill two things at the same time.

[chuck hahn]

first day i am not working with Scot i will be there.. All my spare parts are up north in my storage unit.. Yes we can install the unit you have but what if the stator is junked??? and yup we will pull that head as well i am curious to learn all i can about the bike and the engine.. will be a cool experience.

[rustybronco]

UPDATE... I built a re-purposed DIY leak down tester (thread soon to follow).

cylinders 1 and 4 less than 5% leakage
cylinder#2 12% leakage out the intake valve.
cylinder#3 100% leakage.

time to remove the head and investigate.

Bummer and very strange. Sounds like something is holding one of the valves open.

I finally got back to working on the '80 this evening after "quite a few" non M/C related projects.
I haven't ripped it down any further than just taking the one exhaust valve out.

all I can say is... PLEASE check your valve clearances!!!!!!!!!!!!!!!!!!

http://img130.imageshack.us/img130/9782/img2168q.jpg

http://img97.imageshack.us/img97/1411/img2167kd.jpg

[Guest]

Holy cow!! That's one nasty valve...

well, at least now you know what the problem was.

[Guest]

Sucks!...

May be a dumb question but any thoughts on what coulda caused this?
Looks like a plain old burnt valve to me.

[tkent02]

Usually from the clearance adjustment being neglected far too long as he said.
The clearance gets too small, the valves can't close, they can't transfer heat away through the seat, they get hotter and hotter, stem expands from the heat and gets longer, valve can't touch the seat at all, pretty soon flames are leaking through and then it looks like this.
Could be a carburetion thing but that's not really very likely.

[rustybronco]

A plain old valve held off it's seat because of little or no valve clearance. when it's held off the seat it can't transfer heat to the head. remember metal expands when you heat it and that's the reason you need clearance. if you start with no clearance and the valve is heated by burning exhaust gases, the heat transfers to the stem, the stem lengthens, the valve is lifted off its seat and you see the results.

<edit> sorry Tkent02 I was interrupted while composing this... carry on.

[Guest]

RRRRuffles have RRRidges

[Matchless]

Well, at least its repairable!

[Nessism]

Well, at least its repairable!

Wow Dale,

That bike wins (or looses) the prize for worst maintenance. People that refuse the adjust their valves are just plain idiots.

The next question is whether the seat is salvageable? Hope so. Let me know if you want to borrow my Neway cutters.

[rustybronco]

Wow Dale,

That bike wins (or looses) the prize for worst maintenance. People that refuse the adjust their valves are just plain idiots.

The next question is whether the seat is salvageable? Hope so. Let me know if you want to borrow my Neway cutters.

Ed, the bike had 34k miles on it and all the shims in it were 2.75 and 2.80's. it's no wonder why the valve burnt. I think the seat will survive but the stem on the valve is pretty dark. didn't notice any galling so hopefully the guide is ok. I'll tear it down and inspect it, then make the decision whether to find a valve or two and rebuild this head, or just go ahead and use the one that's on the spare engine I have. (with new seals and inspection of course)

thanks for the offer to use the cutters. I "may" need to take you up on it.

[Flyboy]

Am I missing something here, I see the burnt valve and hense no compression on that cylinder, but how did that cause the motor to lock up, when trying to turn it???

[rustybronco]

You're missing nothing.

I bought the o-rings for it and ordered valve stem seals from Z1 yesterday. when I go to re-assemble it, I "may" find what could have been the cause of it not rotating fully. I suspect it's chain timing related.

[Flyboy]

Ok, gotcha.