Should I Do Shim Replacement/Valve Adjustment ? - Honda CBR250R Forum : Honda CBR 250 Forums
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post #1 of 8 Old 12-07-2018, 03:43 PM Thread Starter
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Should I Do Shim Replacement/Valve Adjustment ?

Hai.

So my bike mileage is around 26k miles right now. And i notice ticking needle like sound when the bike run hot (3 bar temp on dash). Not the rattling kind of sound that produce by the timing chain. Since i replaced the chain and the tensioner a while ago.

Is that needle like ticking sound produced by the valve ? If that so, should i do shim replacement or valve adjustment ?

Thank you.
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post #2 of 8 Old 12-07-2018, 06:17 PM
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One of the "joys" of buying a used bike is changing the fluids, checking brakes, chain and sprockets, and valve adjustment.

I thought that the 2012 bikes had an initial 600 mile check of valve adjustment, but, that might have been the previous year. At 16K miles another check and adjustment is on the maintenance schedule. If you didn't do it at 16K miles (or a previous owner and you have receipts) then you definitely should check the valve adjustment. You need tapered gauges if any of the shims fail to rise above the top of the spring retainer that they are seated in. See the image below (best if clicked on to get the full sized image).


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post #3 of 8 Old 12-07-2018, 07:22 PM Thread Starter
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One of the "joys" of buying a used bike is changing the fluids, checking brakes, chain and sprockets, and valve adjustment.

I thought that the 2012 bikes had an initial 600 mile check of valve adjustment, but, that might have been the previous year. At 16K miles another check and adjustment is on the maintenance schedule. If you didn't do it at 16K miles (or a previous owner and you have receipts) then you definitely should check the valve adjustment. You need tapered gauges if any of the shims fail to rise above the top of the spring retainer that they are seated in. See the image below (best if clicked on to get the full sized image).

Should i replace the shim if it's out of spec ?
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post #4 of 8 Old 12-08-2018, 08:14 AM
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Should i replace the shim if it's out of spec ?
Yes and no; you replace the shim to get the VALVE CLEARANCE in spec. The shim isn't what goes out of spec; it's simply a spacer between the rocker and the valve stem and doesn't wear down.

I would recommend a couple things: 1. Definitely get a service manual as it describes the calculation for your current measured valve clearance, current shim thickness, and the new shim thickness you need to get the correct adjusted clearance. It's worth it to have in your library for any service your bike needs, and all the torque specs in one spot.

And 2: Do not rule out your cam tensioner. I replaced mine after 28k miles on the factory tensioner, and the new one went out less than 1000 miles later. They all suck, and they all give too much slop as they age. It seems most noises 90% of the time are attributed to this.

I have a thread here that details how to convert to a manual tensioner; you have to set the tension yourself, but it will never break and hardly ever needs adjustment. The photo links are broken, but I've included a link to the album in the thread. https://www.cbr250.net/forum/cbr250-...nual-%244.html

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post #5 of 8 Old 12-08-2018, 12:54 PM
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Your valves are opened by the camshaft/rocker arm and closed by valve springs. The parts pound against each other and the valve deforms a tad getting deeper into the valve seat. That means that the end of the valve stem is closer to the camshaft and rocker arm, so the thickness of the shim has to be reduced.

Clear as mud, eh?


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post #6 of 8 Old 12-09-2018, 03:29 AM Thread Starter
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Alright. Thanks guys. I just want to make sure that if the mechanic suggesting that the shims needs to be replaced, it's because it needs to. Not because he/she gonna rip me off.

Also, do i need to replace oil just like when the oil need to be drained when you replace the clutch pad.

Last edited by cibaru; 12-09-2018 at 04:05 AM.
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post #7 of 8 Old 12-09-2018, 01:31 PM
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Quote:
Originally Posted by cibaru View Post
Alright. Thanks guys. I just want to make sure that if the mechanic suggesting that the shims needs to be replaced, it's because it needs to. Not because he/she gonna rip me off.

Also, do i need to replace oil just like when the oil need to be drained when you replace the clutch pad.
No, the engine oil does not need to be drained & replaced in order to do a valve clearance inspection/adjustment.

Former Factory Test Rider/Technician
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post #8 of 8 Old 12-09-2018, 07:36 PM
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Considering that you have considerable labor getting to measure the valve clearance, putting in a new spark plug and getting fresh oil and a new filter seem quite sensible.

Conversely, you can get the service manual and do the work yourself if you enjoy tinkering.

John '14CB500XA (Daily Rider), '09CRF230L (Li'l Red Piglet), '89NX250 (sold)
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