The outside of a motorbike engine seen up close near the exhaust

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CB500X Tappet Time Again

Job Date 4-8 March 2023

Urgh. No. Anything but. It's not CB500X tappet time again surely? Don't call me Shirley. 

Actually it's only about 12,000 miles since I last checked them, they're "due" every 16,000 miles so I'm doing them early. Why? I have plans for Spain in September, there might be a trip to Scotland this summer and hopefully lots of weekend camping trips over the spring, summer and autumn. This means I'd have the bike in bits when I want to be riding. I've no trips upcoming presently and it's still winter, although I can feel spring in the air. Let's get them done NOW so I don't need to worry about them when I want to be riding.

Majestic grand scenery of hills and mountains in Scotland
I'd rather be riding here...
A tangled mess of wires, pipes, components and connectors under the tank of the 500
...than dealing with this little lot.

It's a miserable job. The actual checking and replacing of shims is remarkably easy for an overhead cam engine, the camshafts do NOT need to be removed. It's GETTING to the shims that's the freaking nightmare. 4 plastic panels need to be removed, 2 of them are majorly fiddly. Tank off, being a modern bike this involves electrical connections, high pressure fuel pipe, and several breather/emissions pipes as well. 

Then there's the "tray" under the tank. Wires, pipes, emissions, all specifically designed to be efficiently assembled in a factory in Thailand and incredibly inefficiently disassembled in a shed in Bolton. Oh, and the rocker cover can be removed but only in one very very specific way that includes a twist to the left, a triple backflip summersault, incantations to the god of the 4th dimension, and a doctorate in Hondaology.

I have learned NOT to try and do the tappets all in one block of continuous work. I get tired and confused, I get frustrated and angry. I panic, I'm very good at panicking. I have informed Sharon I plan to use the car this weekend coming, and I psyche myself up. On Monday I simply remove the 4 panels. I want to continue but I tell myself no, I go and watch YouTube and TV. 

Tuesday evening tank off and get the godawful under tank tray off to one side. Start cleaning (I don't want to fill the cylinder head with road dirt). Wednesday more cleaning, coolant pipe off, more cleaning, remove rocker cover, first check of tappets. All inlets are 0.16mm, spot on. Exhaust should be 0.27mm, I have 0.35, 0.32, 0.33 and 0.26. It's unusual for tappets to be loose these days.

The valve train of the CB500X
I suppose I gotta be here...
Ren's CB500X loaded with camping luggage
...before I can be here.

Wednesday recheck and adjust. At the exhaust I end up with 0.30, 0.28, 0.31 and 0.26, that'll do me. Rocker cover back on. Watch YouTube.

Thursday rebuild back to getting the tank back on. Start the bike for 5 seconds as I don't want another heat cycle on the engine and I don't want to put the panels back on only to find I've missed connecting a wire under the tank or something. It starts immediately.

Friday panels back on, push the bike out ready for a shakedown ride. Kft kft kft kft... Poop. Kft kft kft kft kft kft kft. Oh holy double poop and testicles. Kft kft kft kft brum kft kft kft kft brum brum kft brum brum brum. It did not want to start. Once running it runs perfectly. I take a 55 minute ride and it behaves exactly as I'd expect it to. What was all that about?

I've arranged to use the car this weekend, but I want to use the bike now. However Sharon's side stand on the Z400 has been shortened but it's still not quite short enough. As such I'm taking my welder to hers to shorten the stand a little more and I can't get the welder on the back of the bike. I'm in the car. I spend the weekend stressing, fretting and worrying about why my 500 is not starting quickly.

Sunday I check the battery voltage - 12.89 volts after resting the whole weekend. That's good. Can batteries give good voltage but poor amperage? Google confirms this and the suggestion is to crank the engine and see what the voltage drops to. I can't disconnect the spark plugs without removing the panels, the tank, and the godawful tray. I'll just crank it anyway and measure the voltage.

Kft-brum brum brum, not a moment's hesitancy. Swine. 

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Reader's Comments

nab301 said :-
Ren , glad to hear with advancing years you're not stressing quite as much about valve clearances ... as for the hiccough I would hazard a guess that it was to do with the quick 5s start . My BMW is prone to that sort of thing, basically flooded, cold start full rich switch off. Maybe I'll try and replicate it for you with my CBR 500...
14/03/2024 15:45:56 UTC
Upt'North ¹ said :-
Well done Ed.
Maybe a bit of air in the fuel system the first time but now primed out.
Ride it.
14/03/2024 16:41:25 UTC
Ren - The Ed¹ said :-
Will you do the tappets yourself nab301? Please don't risk your own bike not starting on an experiment to see if you can do what I've done. Anyhow I'da thought with 24 hours between startups any fuel in the motor would have evaporated by then? I don't know this as a fact though so I can't be sure.

I can imagine Upt' that there was a smidge of fuel left in the injectors, enough to run the bike for 5 seconds, then I reached the air in the pipe from removing it from the tank. I'll see what happens this weekend.

As for worrying - I have a feeling in about a year I'll be having to learn how to do the tappets on a Z400. That is a far more terrifying prospect because no only will I have to answer to myself, but to "The Scary One" as well if it all goes wrong. Even worse I can't find any details online yet on how it's done. I hope someone does a guide soon.
15/03/2024 07:50:16 UTC
ROD¹ said :-
I believe the Z400 is the same procedure as the Z650, but the clearances may be different.
15/03/2024 10:29:37 UTC
nab301 said :-

Ren , yes I'll probably check the clearances myself, sometime ... Did you do the 5 second start up without the tank connected? I may have misinterpreted what you did , as UPT says , just ride it .
I'm with you on the Z400 valve clearances and having to answer to Sharon especially after her comments on bike theft.. Good luck !

"Quote Sharon said :-"
"I fear however that I would grab my axe and chop off their arms in a fit of rage.
I am rather possessive of my possessions."

16/03/2024 13:10:02 UTC
Ren - The Ed¹ said :-
nab301 - the tank was on and connected when I did the 5 second start - but - the high pressure fuel pipe was empty and this would not fill up with gravity. When you disconnect the high pressure pipe there are a few small drips from the fuel in the pipe but the tank does not self drain. As such when the pipe is reconnected it won't self fill until the ignition is on and the fuel pump runs. I can easily imagine a temporary air blockage.
18/03/2024 07:59:17 UTC

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