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Home Repair And RestorationCB500X Major Service

Tappets, Shims And Plugs

Job Date 2 Oct 2017

By Ren Withnell

This is the one I've been dreading. Getting and setting the tappets on my little CBF125 is a couple of hours work if I'm doing everything properly. Alas having once checked the tappets before on the big 500 at 8,000 miles (CB500X Adjusting The Tappets) as a precaution I know what is coming. This is going to take much more than a couple of hours. Urgh.

Firstly there's the side panels. Then there's the fairing panels. Then there's the tank. Then...then there's that blasted plastic tray located under the tank. This - this is living proof that motorcycles are designed to be built in a factory without one single flying - erm - damn given to any poor sap cursed with the task of actually servicing the machine.

I'm sure in the factory it goes swimmingly well. I suspect the wiring harness is passed through the plastic tray by an incredibly adept technician before being wired in to the headlights at one end and the rest of the bike at the other. However this traps the plastic tray unless you are willing to entirely de-wire the whole harness. And I'm not. It takes a considerable amount of patience to remove the tray.

THe nest of wires, parts, connectors, pipes and clips under the tank of the CB500X
Yeah, just pop this little lot off and away ya go. 

Aha! So that's it, we're at the rocker cover. Oh, no, I forgot to mention the peculiar rubber mat that requires the radiator top bolt to be removed before it can be removed. Oh, no, I forgot to mention the top radiator hose that needs to be removed otherwise the rocker cover can be loosened but not removed. Oh yeah.

At last Ren has access to the rocker cover on the CB500X
It needs a jolly good clean before it take it all off.

The whole ethos of this service is to take my time. I'm tired, it's raining outside the shed and I've had enough excitement for one day. I am happy to be at the stage where I can finally do the job at hand.

2 days later and I'm back in the shed, feeling refreshed and ready with spanners and feeler gauges. Inlet - 0.16mm +/- 0.03 and Exhaust 0.27mm +/- 0.03 

The inlets  - 0.20, 0.13, 0.15, 0.15. Hmmmmm. the 0.20 is just over tolerance but then a slack tappet is a happy tappet. The 0.13 is within the +/- 0.03 but it's on the cusp. By ridiculous luck the 0.20 has a 1.95 shim in and the 0.13 has a 2.00 shim. By swapping them I get 0.15 and 0.18 gaps, all good.

The exhausts - 0.21, 0.23, 0.28, 0.28. My shim collection comes in 0.05 steps. I get the 0.21 up to 0.26 and the 0.23 up to 0.28, all within tolerances. 

A J cloth is stuffed into the cylinder head to stop shims dropping into the engine
DO NOT lose any shims into the cam chain tunnel. Nightmare.

I'd be a blasted fool not to change the spark plugs now as I'm already looking at them. The old plugs have a perfect colour to them, I'd expect nothing less from a fuel injected computerised self monitoring system. The new plugs are pre-gapped but I check them anyhow, 0.8-0.9mm. I wind them in and nip them up.

The spark plugs from the Honda look a tan colour, just right
The old plugs look spot on colour-wise.

All I have to do now is put it all back together. 

Again having time on my side I'm cleaning as I'm going. Clean the rubber sheet that covers the rocker cover. Clean the plastic tray that holds the electrics. Clean the top of the radiator while I can. Wipe down the EGR valve (consider removing it - not yet). Clean the spark plug caps. I'm hoping I won't see these things for at least another 16,000 miles so now's the best time to clean them.

So that's that bit of the service done. I'm glad it's over, it bothers me that it actually all went rather well, it's unnerving. 

If you'd like to sponsor a page then contact

Why And How Ren is explaining (or justifying) why and how he's going to (attempt) to service the 500X himself. I see trouble ahead.
What Parts Do I Need Fearful for his wallet Ren takes the plunge and purchases genuine Honda parts from a genuine Honda shop. Brave fool
Change The Oil And Filter It's the first and probably one of the most important jobs of the service. Luckily it's quite simple too - change the oil and filter.
Change The Air Filter (Cleaner) Ren's changed the air filter this time, or as Honda like to call it - the air cleaner. Luckily this one's not rocket science either.
Tappets, Shims And Plugs It's the big job, the tough task, the one Ren's been dreading. It's time to take the top off the CB500X and do the tappets and plugs. Wish him luck, he'll need it.
The Other Service Items Just like painting a room it's the fiddly little tasks that are often neglected. In the interest of being thorough (for once) Ren goes through the oft forgotten service items on the CB500X
Home Repair And RestorationCB500X Major Service Random Link

Reader's Comments

Pocketpete said :-
Sounds easy but it obviously isn't. I can't wait to see you do mine.

Believe or not I've never actually seen the inside of an engine.

Mines done 8000miles so a long way to go. Maybe do it at 14000
07/10/2017 06:32:22 UTC
Ren - The Ed said :-
Dead easy mate - not!! The hassle is getting to the engine not particularly being inside it.

We need a vintage bike like Ian's Sunbeam. No plastic fairings to do battle with, no silly undertank tray and no complicated computers or sensors. I daresay our modern digital motorcycles are more reliable though.
08/10/2017 06:53:14 UTC
Ian Soady said :-
.... and the valves are exposed so you can do the tappets without taking anything off at all!

Or even better, with the Arrow there aren't any tappets to adjust.......
08/10/2017 08:58:09 UTC
Ren - The Ed said :-
There are good reasons why valve opening systems became covered and bathed in oil. Something to do with keeping dirt out and lubrication in I think.

And as for that evil 2 stroke Arrow - no tappets no but noisy smelly exhaust, worn out piston rings and bad fuel economy? Give me fiddly tappets any day.

Anyhow all this will be irrelevant when the electric motorcycles take over. No tappets, no piston rings, no shims, no oil and some might say no soul. I'm not sure about the soul thing, I'll wait to see for myself.
09/10/2017 08:13:03 UTC
Liam said :-
You had the pleasure of doing this on the Z250SL yet? Between the Internet and owners manual I can't find any information at all. Not even the clearance values.

Is it just the same as doing the job on a KLX250.
17/10/2017 09:48:30 UTC
Ren - The Ed said :-
Hi Liam. Nope. Sharon's 7,500 mile service with shims was done by the shop as she had a "deal". Once it was done they said to Sharon "£260 Please" Sharon replied "Nope, don't think so, here's my deal done at the point of sale, the service is only £100". She enjoyed saying that a lot.

So no, I haven't done the shims on the Z250SL yet. I have looked into it though. As far as the physical task of doing it I expect it will be the same as the videos and guides I've looked at for the KLX250, as the motor appears to be basically the same.

BUT! I can find the valve clearances for the KLX250 / KMX250 but not for the actual Z250SL. I've seen one forum post from the far east which suggested they're the same as the motocross bikes but I wouldn't put any certainty into that. As the engine is likely to be in a different state of tune to the motocrossers I would not be surprised if the clearances are different too.

My plan is to simply ask the Kawasaki dealers. Experience tells me I ought to ask a few - if they agree then I can be confident they're right. I would not be shocked if they all offer me different values though in which case I'd have to do more research.
17/10/2017 10:00:35 UTC
Liam said :-
I found one post saying they're hydraulic lifters, that's one bike that's not getting its clearances done any time soon!

I'm a few thousand off needing them done yet so I've got a whole to find out. Hopefully be some more concrete info out by that point, or I'll have to start ringing the dealers.
17/10/2017 10:17:26 UTC
Ren - The Ed said :-
I think I must have seen the same post. Hydraulic lifters my arse. If I find anything out I'll let you know.
17/10/2017 11:26:59 UTC
Tom McQ said :-
Tappets & Plugs used to be one of the enjoyable tasks you carried out on a Saturday morning! Now it’s a nightmare that you put off or pay someone a small fortune to do for you. In fact, most jobs are a nightmare these days. My headlight and position lights have stopped working and Honda decided to put the headlamp relay under the fuel tank, which means I have to remove ALL the fairing panels and the tank.

And believe me, those fairings are a royal pain in the a$$! Why don’t manufacturers put all that stuff in one place (ideally under the seat)? This is one of the reasons that I’m still considering the 70’s style CB1100RS. What a joy to work on it must be!

17/10/2017 18:34:48 UTC
Ren - The Ed said :-
Don't you be fooling yourself Mr McQ! While there's no fairings to remove I'm sure it won't be plain sailing. The tank with have a fiddly high pressure hose as opposed to a low pressure rubber pipe. There'll be wires to the tank too for the fuel pump and gauge. There'll be a computer and sensors and environmental control under there too. The cam chain is likely to be in the middle to give it that classic look making camshaft removal almost impossible. The inner spark plugs will be buried under the frame rails requiring a special tool for removal.

If you want simple classic motorcycle mechanics - you'll have to buy a simple classic motorcycle.
18/10/2017 09:46:28 UTC

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