Problem - exhaust valve rapid recede into head

[The Buddha]

Dgyver has been able to pull the head with the motor in the frame (if I recall).

I've done it too. It's tedious work, but do-able. Probably a lot easier than putting a heavy new engine in as well. Your pistons and everything else is probably fine.

Well ry_guy, you dont think yours started out like this and then you lost a chunk of it ?
I suspect it can mushroom and start to break bits off. I dunno ... but I just think with a defect like this it can, as well as the extra heat when its burning can well get it heated to the point where its like cheese ... maybe I am imagining it. But a valve isn't supposed to run red hot right.
Cool.
Srinath.

[intergalactic]

If you are serious for $500, then I can do it.

Well, I want to see a pic of the bike first, but you are riding it to work, right?

And depending on the year, I'd need a title and/or registration/ bill of sale, etc.

I have a friend who wants one.

Are you serious on that offer? I rode it to Indy last year for MotoGp...Boston is closer 

I am with gsJack. Add some more valve clearance. If your measurement method results in things on the tight side, then at .002-.003" there is little margin left. Limit the revs. Jet a little rich to reduce available oxygen in the exhaust, in doing so, you are less likely to erode the seat. Don't add oil to the gas. That lowers the octane equivalence rating. You might start pinging. A "instead of lead" additive is a possibility.



Then in the winter pull the head and put a new valve in it. Or have it done.

Edit:  Or drive it up here and I'll buy it for $500 plus train fare home on the Amtrak Acela.

[HPP8140]

Yes, I rode it to work today and have the title.

If you are serious for $500, then I can do it.

Well, I want to see a pic of the bike first, but you are riding it to work, right?

And depending on the year, I'd need a title and/or registration/ bill of sale, etc.

I have a friend who wants one.

Are you serious on that offer? I rode it to Indy last year for MotoGp...Boston is closer 

I am with gsJack. Add some more valve clearance. If your measurement method results in things on the tight side, then at .002-.003" there is little margin left. Limit the revs. Jet a little rich to reduce available oxygen in the exhaust, in doing so, you are less likely to erode the seat. Don't add oil to the gas. That lowers the octane equivalence rating. You might start pinging. A "instead of lead" additive is a possibility.



Then in the winter pull the head and put a new valve in it. Or have it done.

Edit:  Or drive it up here and I'll buy it for $500 plus train fare home on the Amtrak Acela.

[HPP8140]

Wow, didn't mean for this to turn into a sale thread but...

To eveyone that expressed interest...

Please give me a week to see what dealerships in my area will take it for and to see what's out there for a replacement.

In the meantime I'll work on sending pics to those who requested.

Thanks!

[The Buddha]

Do not tell them you have any problem with it. That way they cant shaft you and shaft someone on the resale.

If you dont tell them, they shaft you less, and the person that buys it from them will be shafted the same, so its not going to make any difference.

Cool.
Buddha.

[intergalactic]

With everyone jumping to buy it, you can figure that maybe this is not such a  bad problem to have?

Wow, didn't mean for this to turn into a sale thread but...

To eveyone that expressed interest...

Please give me a week to see what dealerships in my area will take it for and to see what's out there for a replacement.

In the meantime I'll work on sending pics to those who requested.

Thanks!

[HPP8140]

Yes, maybe to someone that has the knowledge of these bikes and expertise to repair it. I'm mechanically inclined and perform other maintenance, but don't really have the desire or knowledge to tear into the engine. I figure it's easier to sell/repair something that still runs well before I run out of clearance and possibly destroy the engine. I'm not sure if the clearance problem will stop at some point or not.

With everyone jumping to buy it, you can figure that maybe this is not such a  bad problem to have?

Wow, didn't mean for this to turn into a sale thread but...

To eveyone that expressed interest...

Please give me a week to see what dealerships in my area will take it for and to see what's out there for a replacement.

In the meantime I'll work on sending pics to those who requested.

Thanks!

[The Buddha]

No you lose the first few 1000's and its could go like butter. Figure that you have one very uneven surface seating against an uneven surface. The clearance you set to could well be a peak against peak clearance, as it burns, that peak can get obliterated ... and further valves rotate so in a few cycles it can be peak to a different spot. It will burn even if you set the clearance as loose as a DDD cup bra on a AAA- chick.

The low revs may delay it, the better oil, the stay out of traffic etc etc etc can all delay it. but you dont have 2 solid mating surfaces, you will have combustion behind the valve you'd lose less heat, and you'd definetly run hotter and hotter and hotter.

Now the right fix - fix it now and you get away with 1 valve and a head surface job if you're in a $ tight spot. You break off that valve or a significant part of it and you lose the piston, cylinder and more. You lose the con rod, the game is up.

Can anyone tell me that this is incorrect I have only seen the final result of a broken valve, not seen it get there.

BTW how does it run. 5 seconds after startup to 5 mins after start up. As it gets worse, it will want to stall right after starting. It also will blow into the exhaust, though that may be hard to spot.

Cool.
Buddha.

[HPP8140]

Well, this morning after getting clearance by popping in the 255 shim, it idled after roughly 1min on choke. It hesitated a little at low revs when I took off, by 5 mins its all warmed up.

BTW how does it run. 5 seconds after startup to 5 mins after start up. As it gets worse, it will want to stall right after starting. It also will blow into the exhaust, though that may be hard to spot.

Cool.
Buddha.

[intergalactic]

stock jets? or do you have 40 pilots?

[HPP8140]

Stock jets.

Ok I'm about to ride it home.

stock jets? or do you have 40 pilots?

[gsJack]

From my post above:

Increased exhaust valve clearance allowing the valve more cooling time on the seat seems to be very effective in extending GS valve life.  I had one exhaust valve on my 97 GS down to a 215 minimum shim at 76k miles.  It started it's fast regression at about 40k miles after running at a minimum clearance for over 30k miles before that.

My 02 GS had an exhaust valve starting to receed at 30k miles after running at minumum clearance for many miles.  I increased the clearance to .005" (.012 mm approx) at about 40k miles and it still had .004" clearance at about 60k miles and now at almost 70k miles it stills idles smooth cold indicating it still has clearance 30k miles later.  It's time for my annual valve check so I'll be measuring this soon.
http://img.photobucket.com/albums/v443/jcp8832/valveclearances.jpg

Did my annual valve check yesterday with approx 70k miles on my 02 GS now.  No changes in shims or valve clearances.  Last exhaust valve shim change was 3 years ago at approx 40k miles.  The minimum shim is still a 250 in this engine.  This is becoming a contest between me and the 02 GS, which will live longer?   

[The Buddha]

OK GSJack - you need to definetly out last that GS ... it was born this century ... score one for the 19's ...

And I had shims getting fatter all the time, so y'all doing something weird.
The one instance of my fat shim was when I put in a shim that was a bit fetter than ideal.
Cool.
Buddha.

[HPP8140]

So I finally found a replacement...another 95 with less than 5000 miles 
The choke on the this one doesn't work the same as my old bike. With my old bike I would start it by using full choke, it would rev to 3-4k, then I would back off the choke until warm. When I start this new bike on full choke, it doesn't rev up. The tach stays at 1.5k. What's the problem?

[HPP8140]

Any ideas? Does the choke have another adjustment besides at the handlebar?

[joshr08]

try 3/4 choke my bike doesnt rev on full choke

[The Buddha]

Yea 3/4 choke, 1/2 choke, in fact some bikes have a 1/2 choke setting, vulcan 500 from my recent memory has a 1/2 setting.
Cool.
Buddha.

[HPP8140]

Hmm...I've tried different positions on the choke and I it still doesn't rev up? Rpm just stays around 1.5K and it smells rich. Is this an issue? Don't want to have problems staring in the colder months. Was trying to avoid this, but maybe I should just go with what I know and spend the time swapping carbs with my old bike.

[HPP8140]

bump

[HPP8140]

Well, for peace of mind, I decided to go with what I know and swap the carbs from my old bike.  I noticed the brass caps on the new bike's carb had been drilled out. The previous owner told me it was stock. I'm sure it's just a matter of adjusting the mixture screws, but don't want to mess with it. They work great despite this choke issue, if it even is an issue. I've got two good running bikes...now I can put the old one up for sale.