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Valve issue help (video)

C

chris.poole

New member
Valve issue help (video) UPDATE

Hi guys,

I took my R90/6 out for about 60mi this morning for the first time in a month or so and it ran/sounded great. When I got back home, I had it idling in the garage and heard a loud SNAP and then clank clank clank clank, as the engine continued to run for another 10 seconds or so, before I was able to shut it off.

Just to make sure I was hearing things right, I started it back up for another 6 or 7 seconds. It seemed to be running okay but there was a noticeable clank clank clanking from the left side head. I pulled the valve cover off and noticed there was a good 1/8” of play on the intake valve.

I’ll get around to pulling the head this week hopefully, but just curious if anyone had any ideas before I get going? Thanks!

 
Last edited:
That's kinda weird. Before pulling the head completely off, see what you can do to just pull the pushrod out. Maybe pull both intake and exhaust. See if they're the same length. I'm wondering if the end has fractured, the end with the ball on it to fit into the cam follower.
 
Might be a stuck valve. If you’re lucky, it hasn’t hit the piston yet. You have to pull the rockers to remove the head, so you’ll have that opportunity to inspect the pushrod and rocker. But before you disassemble things, pull the rocker cover on the other side and compare the exposed valve spring length at TDC on compression stroke to what you see on the loose side. Probably best to first fully loosen the adjuster on the loose valve.

Best,
DeVern
 
Check the compression first, it will help let you know your next step. Zero, or very low compression? Pull the head, stuck valve. Decent compression? Push rod or cam follower.
 
You could also pull the spark plug and shine a light down the hole to see if the valve is stuck open, or for anything else.
 
I wouldn't run the motor or do a compression test!

You have a "clank clank" noise when its running so that would indicate there is some sort of failure or malfunction, if you run it more or turn it over for the compression test you may end up causing more damage than you already have. Disconnect and isolate the negative battery lead first off. I would then pull both spark plugs and the other valve cover, take the front cover off and slowly turn the motor over by hand with the a ratchet and correct socket (I think its a 6mm allen). Check and compare one side with the other and look for a broken valve spring, sticking valve or even loose rocker arm assemblies or worse case a pulled cylinder stud. If you don't see anything obvious outside try looking into the combustion chamber through the spark plug hole, chances are you won't be able to see much.

Regardless of what you can see on the outside I would plan on pulling the cylinder head off for a real good inspection for loose or broken parts.
 
69zeff65 said:
You have a "clank clank" noise when its running so that would indicate there is some sort of failure or malfunction, if you run it more or turn it over for the compression test you may end up causing more damage than you already have. Disconnect and isolate the negative battery lead first off. I would then pull both spark plugs and the other valve cover, take the front cover off and slowly turn the motor over by hand with the a ratchet and correct socket (I think its a 6mm allen). Check and compare one side with the other and look for a broken valve spring, sticking valve or even loose rocker arm assemblies or worse case a pulled cylinder stud. If you don't see anything obvious outside try looking into the combustion chamber through the spark plug hole, chances are you won't be able to see much.

Regardless of what you can see on the outside I would plan on pulling the cylinder head off for a real good inspection for loose or broken parts.
Click to expand...

Absolutely +1 :thumb
 
As above posts. I wouldn't even rotate the engine to get that cylinder on TDC, just go ahead and take that head off and see what's going on.

Just curious but did you do any valve adjusts or anything on the bike that could have caused your issue. If you hadn't made sure that intake pushrod was in the ball of the rocker and then went and adjust the valves, once the pushrod worked its way into its proper spot it would create too much slack on the intake and it would clack as you describe.
 
I see no issues doing a compression test. The damage is done, if any. Read his post, he started and ran it again after the failure. 3-4 more revolutions on the starter isn't going to hurt.
 
Maybe a leakdown test first? No turning of the engine except manually to get the cylinders at TDC.
 
After u get the left head off and see what's going on; pull the right head off for inspection to make sure the same thing ain't happening there.
 
Clank Clank

If I had a clank clank sound in my bike, I would NOT fire it up to run any compression test. Besides, what is a compression test going to tell? Something is obviously broken inside the engine. Even if you have perfect compression, you still have to take things apart to find what is making the noise.

You could cause a whole lot more damage than you have now. For example, a wedged piece of something could possibly break a con rod causing damage to the crank shaft.

I could go on and on with horror stories.

To take the heads off, the engine does not have to be at top dead center. For the most part, the only time you need to be at top dead center is when adjusting the valves or timing.

If it were my bike, I would start going bit by bit taking things apart to find out what is broken. St.
 
If there is good compression there is no reason to pull the head, at least not yet. Diagnosis the problem before you just start tearing things a part.
 
You fail to see the point

I will say it again, if there is a loud clanking noise, something is broken. Running the engine to do a compression test might result in worse damage.

There are other things mentioned in the posts which make more sense than running an engine with something broken.

I would do a compression test ONLY if there was no noise and there might be something leading to a loss of power. St.
 
Time

It does not take a lot of time or effort if one knows what one is doing and has the proper tools to pull off the valve rockers, or even the head to see what is wrong. Could be something simple, might not be.

Takes a lot more time to repair a broken con rod or crank, pistons and such are expensive things to knock holes in if loose bits are in the combustion chamber or a stuck open valve.

I would rather spend an hour and the cost of a new head gasket than running an engine and perhaps causing more damage. St.
 
A dislodged valve seat maybe?

Just a thought and a clear reason why you really don't want to run it or turn it over for a compression check or even bother with a leak down both of which could come back fairly normal. The valve seat migration would explain the additional clearance, the rocker arm slapping the top of the valve as it travels to open the valve all the while the bike idles pretty good and doesn't have any serious oil leakage. You run that motor or turn it over for a compression test and you very well could knock the valve seat out enough to cause the piston to hit the valve on the compression stroke. You would be lucky to get away with a dented piston dome and a bent valve but may go as far as bending a rod, or some other more serious damage.

If your on the fence with this just do the math.
 
My bet is also a stuck valve. I’ve had this on an English car (AH Sprite) where the shop that did my head work did not open up the new guides enough. There was no damage, but there could have been. My compression gauge has a regular Schrader/pressure release valve that I can connect a pump to. I used it to do a simple leak down test by threading the gauge into the spark plug hole and used a bike pump to apply pressure. If the valve is open you will not be able to build up any pressure. From the video it appears the other valve is closed.

Or, just remove the head to access the damage. I agree with the others, don’t spin the engine over further until you find out the cause of the loose rocker.
 
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