26k valve check

[Constant Mesh]

I'd think the clearances would have to be pretty far out of range before it'd affect starting, etc.

I'd say it's a bit easier to work on an '06+ than the earlier models. More coolant system hardware above the engine on the earlier models.

 

[v65]

Time will tell I guess.

A picture of a shim under bucket valvetrain similar to the one in our FJR's

The FJR is a four stroke motor: intake, compression, ignition, exhaust. Those four strokes are accomplished in two revolutions of the crank. The intake when the piston is moving down, compression when the piston comes back up - one revolution of the crank, ignition and exhaust are the second revolution. The opening and closing of the valves during this cycle is controlled by the camshaft. The intake valves are open during the intake stroke, the exhaust valves during the exhaust stroke (a bit simplified, but close enough). That means that the camshaft only has to open the intake and exhaust valves once per every two strokes of the crank.

In other words if your tach reads 4,000 RPM the cams are turning 2,000 RPMs, tach reads 8k rpms, cams are at 4k rpms. Now picture that cam lobe above turning at 2k rpms as you cruise down the highway at 75mph. That means that the tappet is riding up and then back down the lobe of the cam in the picture roughly 33 times a second! Engineers spend a great deal of time getting the profile of that lobe correct so that at the velocities we are talking about the valve is not slamming into that ramp (or the valve seat on the other side), but rather riding on it nice and smoothly. The tappet sits on top of the valve we are trying to open and close to spread the forces out along the cam lobe.

Well sort of, you see the tappet does not actually ride on the lobe of the cam. The tappet actually rides on a thin film of oil, not directly on the cam - metal to metal at those speeds = BAD! How thin a film of oil you ask? See the shim under the tappet? The shim is between the tappet and the valve and is used to control the valve clearance, or the thickness of the oil film, or in the diagram it is called the tappet clearance, different names for the same thing. Get that tolerance too tight and the valve actually never closes. So on the ignition stroke when the valves are supposed to be closed they are open a little bit. Not only do you lose some performance, you also will burn the valve. Get the tolerance too lose and the valve will close OK, but it is so far off from the ramp that all of the hard work done by the engineer goes out the window and the tappet slams into your cam lobe 33 times per second. That is not healthy either.

Now the terminology seems backwards, why would too tight mean the valve never closes? You measure the tappet clearance with a feeler gauge of the right thickness. Too tight means you cannot get the feeler gauge in that clearance, in other words the tappet is too close to the cam at all times, the valve never closes.

Personally, I would check those clearances before the motor doesn't start well. Either of the above clearance problems, lose or tight, are expensive.

 

[charismaticmegafauna]

Fear Monger....! :blink:

And...., what's an Alfa Romeo? Is it something like an 'Alpha Dog'? Or, a 'Don Juan'/gigolo? :huh:

Seriously, nice description (that 33 times a second, tho, is still pretty scarey.....)

 

[mcatrophy]

...what's an Alfa Romeo? ...

Beautiful Italian sporty car maker. "Every motorhead should own an Alfa at least once in his life." Unfortunately has a reputation for unreliability.

 

[Karl]

I just had mine checked/adjusted at 40K for the first time. All the intakes were fine, but all the exhaust were a little tight. If I keep the bike, I'll check it again in 40K. If you're constantly redlining the thing, then maybe every 26K. But typical ST mode should not require adjustment that often IMO.

 

[v65]

I just had mine checked/adjusted at 40K for the first time. All the intakes were fine, but all the exhaust were a little tight. If I keep the bike, I'll check it again in 40K. If you're constantly redlining the thing, then maybe every 26K. But typical ST mode should not require adjustment that often IMO.

Every year someone will ask if the 26k check is necessary. You will see numerous posts from folks that did the check and had no shims out of spec, and then one or two of us that had a shim out. So statistically ...

 

[mtnhigh]

I'd think the clearances would have to be pretty far out of range before it'd affect starting, etc.

I guess I should have mentioned, I'm taking that with a grain of salt.

I watch the fuel economy as a general rule for engine health. The performance should change a little before the starting issues, and I am thinking I will notice by feel, or sound, when it needs a little more tlc. Worked on Ferrari's a few years back, and i think that they were pretty much 8,12 cylinder motorcycles. They definitely tell you when they needed something, when you hit the gas you could feel that they were a lttle "off" when the valves needed adjusting. Similar setup.

 

[user 213]

What V65 said.

I'll add that at 26k, and 61k, my valves were still in spec. At 88k they needed re-shimming.

However, I will also add that you should pull the tank and check everything yourself after they are done. Specifically, check your TB connections to the head and the air box. No, these don't need to be touched to do the service. But if you have a tech reading the shop manual they will pull more off than they need to, including the air box. My connections to the air box were left loose at the 61k point. Long story short, it cost me early ring wear and an engine replacement on my dime. I screwed up and didn't do what I'm suggesting you do. It cost me.

You should also check all the coolant hose connections. At 61k a couple of my hoses were getting a little crunchy at the ends and I replaced them. The smaller ones were still ok, but I would have replaced them all if they were not back ordered at the time. Shouldn't be a problem at 26k, it's mostly heat cycles that do hoses in.

 

[SkooterG]

You should also check all the coolant hose connections. At 61k a couple of my hoses were getting a little crunchy at the ends and I replaced them. The smaller ones were still ok, but I would have replaced them all if they were not back ordered at the time. Shouldn't be a problem at 26k, it's mostly heat cycles that do hoses in.

Baaaah! Fear monger!

164k, LOTS of heat cycles, and still have the orginal hoses.

Folks, you gonna listen to the little school bus guy that installed a car tire on his FJR?

 

[Bugnatr]

Little??

Sorry Eric couldn't resist, I'm the kettle calling the pot black

 

[user 213]

Baaaah! Fear monger!
164k, LOTS of heat cycles, and still have the orginal hoses.

It's not like I said you're gonna die a flaming death if you don't check your hoses.

Sometimes you get lucky, sometimes you don't. Judging from the number of crashes you've had, you're a very lucky guy to still be walking around and riding the same bike SkooterG. :lol:

Sure, I've seen hoses last longer than 60k, and ones that didn't last that long. Depends on how the vehicle is stored, the overall time and the heat cycles. I'm simply suggesting people check out their hoses for signs of cracking or hardening at the service intervals.

Give 'em a squeeze and see if they still fell flexible, as opposed to hard as a rock, or worse, crunchy. They deteriorate from the inside out, so it's not going to be obvious just looking at them. You will sometimes see the ends showing deterioration though, and that can be a tip as to how the rest of the hose is doing.

 

[zorkler]

Had my 05 checked at 25k right on the mark .Check you owners manual i am pretty sure theres alot more to do to the bike .Or hit the links section and look under maintance .