OK so I rewatched Kerry's valve video again for fun last night.   But one thing I am confused on....  why do we do valve adjustments?  I realize that there is an accepted range, but what happens if you're out of range?  Do you over heat?   Backfire?  Engine seize? Too much vacuum pressure generated?    I kind of understand how carbs work, I guess I'm just kind of confused on the next section of the engine.

Quote from: JCHOK so I rewatched Kerry's valve video again for fun last night.   But one thing I am confused on....  why do we do valve adjustments?  I realize that there is an accepted range, but what happens if you're out of range?  Do you over heat?   Backfire?  Engine seize? Too much vacuum pressure generated?    I kind of understand how carbs work, I guess I'm just kind of confused on the next section of the engine.

If the intake valve does not open at the right time, by the right amount , for the right length of time the mixture cannot get in and your bike will run like crap - after a certain varience from standard, not at all.  Given that the valves on this bike tend to get "tighter" meaning  that the cam ends up not letting the valve close all the way, or at the right time and it opens too far when it does open - that means that the intake charge can get blown back out the valve as the piston rises on compression -  and,  on the exhaust side, the only way the valve has to reject heat to the environment is through contact with the valve seat - if it is not incontact long enough, it overheats and burns.

This is one of the reasons for the delay of the "final" version of the video - I want to add a section about "what goes on" in there, and why valves need to be in adjustment.  I took some footage using drawings on a white board, but it's all kinda hokey.  Sigh.

Anyway, to answer your question:

* If an intake valve is too loose it will open too late and close too soon.  So the cylinder gets an insufficient "charge" of air/fel mixture to burn.

* If an intake valve is too tight then it opens too soon and closes too late (stays open too long).  That can result in backfires through the carbs as well as "burned" valves where hot exploding gases whoosh around the rim of the valve and expose it to excess heat.

* If an exhaust valve is loose the valve won't stay open as long as it should, so you'll have "leftover" exhaust in the cylinder when it's time to suck in a fresh charge of air/fuel.

* If an exhaust valve is tight the valve will be open too long.  Again, possibile burned valve AND loss of power because the exhaust is allowed to start exiting the cylinder before all of the "oomph" from the combustion has been used to push on the piston.[/list:u]Does that help any?

For more background info on how the whole thing works, see this post.

hey Kerry...
I have a few questions for you

Does the bike have to be unwinterized before I do a valve adjustment?
What's the worst case scenario that can happen if i mess up?
What special tools do I need?

Quote from: FrostDoes the bike have to be unwinterized before I do a valve adjustment?

I guess that depends on whether winterizing the bike involved any drastic measures.  But in general, NO.

Quote from: FrostWhat's the worst case scenario that can happen if i mess up?

The possible bad things that I can think of are:

* You strip or break something when taking things apart and putting them back together.  If you're a careful kinda guy this shouldn't be a big concern.

* You might tear the valve cover gasket (again, if you're careful....) or reinstall it slightly out-of-place and develop a (fixable) oil leak.

* You might drop a tool or a shim down the camchain well.  Stuff a rag or two in there after removing the valve cover and you'll be OK.

* Other than that, the only thing you can really do is put the wrong-sized shim in.  It would have to be several sizes off to hurt the engine, and then only after quite a few miles.  Again, if you're careful with the measuring and calculations (or

table lookup) you should be fine.[/list:u]

Quote from: FrostWhat special tools do I need?

You'll need:

* 10mm and 12mm sockets and pliers to remove the fuel tank

* 10mm or 12mm socket to remove a couple bolts on the breather cover

* 6mm Allen wrench to remove the valve cover bolts

* Feeler gauges to check the valve clearances.  (And a large 21mm? wrench or socket to rotate the engine if you decide to do it "by the book".  And a 7mm? socket to remove the right-side engine cover so you can get at the end of the crankshaft with that large wrench.  Alternately, leave the right-side cover on, put the bike in 6th gear - on the centerstand - and turn the rear wheel to rotate the engine.)

* If any clearances are off you'll need something like the Motion Pro valve tool, and a tiny screwdriver (or knife blade) to pry the shim up out of place, and tweezers or a magnet to pull the shim all the way OUT of the bucket.

* Micrometer or dial calipers to measure the thickness of the shim.

* The correctly-sized shim to put back IN the bucket.[/list:u]
Here is my version of the valve adjustment toolkit that is circulating around the country.  The sockets, pliers and Allen wrench are not included.  The gasket sealant is optional, to make it easier to get the valve cover on and off in the future.  Not shown are the "How To" video CD and the valve clearance chart:

Did I forget anything?

Valves being loose actually are going to have to be very very lose before they'd affect performance ... they make a racket ... one so bad you can hear anyhting else long before it starts to affect performance. Now being tight ... even a little will create misery very very quickly ... first symptom is a bike that sorta misfires when warming up. The valves are tightish, but when cold they are not at negative clearance, when hot they aren't negative clearance, just at some point as the pieces begin to heat up, and they all heat up at uneven rates ... they go negative before becoming positive again. Negative clearance is where you have a shim that's too thick to even let you spin the bucket. Valve is held open. It will soon turn into a negative clearance when cold as well ... and startups and warm up's will be pathetic. Misfiring, dying, slow warm up's you name it ... of course if you ignore it even at this point or made some carb adjustments to help you past that stage, it will be negative even when hot ... loss of power and gas mileage in addition to the other symptoms. Of course eventually you'd burn that valve and possibly the carbs with it if its intake.
Cool.
Srinath.

heres a pretty pic of the process....
SUCK...SQUEEZE...BANG...BLOW
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/otto.html

What - you don't like the HowStuffWorks animation that I linked to?    

Just kidding - thanks for that link and the "adiabatic" details.  

i'm sorry.....    
i didn't look    

.... and when they are too tight with cut pipes you shoot flames  :mrgreen:

Wow, thanks for all the great information..... I'm beginning to wonder if valves aren't the source of my current problem (bike dying after being at high speed for extended times).  After about 30 mins on the freeway at 85mph the bike died.    It started again but once I got it back up to 55mph it backfired and died a second time.

Looks like I may need that valve adjustment ASAP.

if it does it again open and close the fuel tank, sometimes they get a vaccum lock in the tank and that will do it

Quote from: davipuif it does it again open and close the fuel tank, sometimes they get a vaccum lock in the tank and that will do it

been there done that....oh mine was due to completely covering the cap assy with rubber from tank bag and sucking the tank in....

our beloved webmaster figured out that problem !!!!!!

Quote from: JCHWow, thanks for all the great information..... I'm beginning to wonder if valves aren't the source of my current problem (bike dying after being at high speed for extended times).  After about 30 mins on the freeway at 85mph the bike died.    It started again but once I got it back up to 55mph it backfired and died a second time.

Looks like I may need that valve adjustment ASAP.

Nope not at all ... of course the vacuum thing that Davipu mentioned could be one and the second possibilty is that the fuel flow is somehoe getting killed. Crap in the tank choking off the flow or tank petcock set not fully open or somehting.
Oh wait CA bikes have a Tank vent setup. if that hose the right side hose on the under side of the tank is blocked or pinched it may cut your fuel flow just enough to do this.
Cool.
Srinath.

There is no hose there, its been removed.   I doubt its pressure as the first time this happened the first thing I did was check the fuel.  And it still had problems after I opened the cap.

Apparently the fuel flow has been checked...  if it is a fuel problem, why would this problem only appear after a certain amount of time, even if speed was relatively constant?   Is it because it needs a certain heat level to build up?  It didnt have a problem when I road at slower speeds the same amount of time, so I'm thinking it has to be somehow heat related right?

When the bike died the first time I waited 30 minutes then drove the bike a quarter mile to a parking lot. I checked the spark plugs and the appears to have a light to medium tan shading.   Would that be indicitive at all of the problem?  Or did the quarter mile change how they might appear?

Anyone want to buy a gs500? lol

Quote from: davipu.... and when they are too tight with cut pipes you shoot flames  :mrgreen:

ohhhh really..... would that happen to the same set o pipes i got from you?.....  

this could be fun :mrgreen:

Quote from: JCHThere is no hose there, its been removed.   I doubt its pressure as the first time this happened the first thing I did was check the fuel.  And it still had problems after I opened the cap.

Apparently the fuel flow has been checked...  if it is a fuel problem, why would this problem only appear after a certain amount of time, even if speed was relatively constant?   Is it because it needs a certain heat level to build up?  It didnt have a problem when I road at slower speeds the same amount of time, so I'm thinking it has to be somehow heat related right?

When the bike died the first time I waited 30 minutes then drove the bike a quarter mile to a parking lot. I checked the spark plugs and the appears to have a light to medium tan shading.   Would that be indicitive at all of the problem?  Or did the quarter mile change how they might appear?

Anyone want to buy a gs500? lol

I dont know why heat would do anyhitng. If the bike was crap when hot due to the valves staying open, then cold and warming up will be hell ...
I cannot help but think its all carb related. BTW is the problem fixed now ... after you got it from the new shop.
Cool.
Srinath.

No.... I rode it Saturday and it ran better than it ever has.  Took it through the Malibu canyons on a 3 hour ride and it went great. What surprised me now was all the power I had between 8-11k that I never had before.

Sunday I had it on the freeway.  30 minutes in as I was traveling 85 mph it died.  I let it sit 30 minutes and got it off the highway. Let it sit an hour more and tried to get back on the freeway.   After one exit It backfired and died (within 2 secs of each other).   I picked it up in my truck and drove it home.

Oh yeah, and loading a bike on a bike ramp by yourself is a horrible idea that almost ended horribly.  

Its not anyhting other than the carbs ... dont know what exactly but clogged up some or other as well as somehting fooked up in the carbs is all I can say.
Cool.
Srinath.