Without sounding non technicaly inclined what are Shims? I have a slight tapping sound from the engine on my CBR600F4, 18K miles on the clock. I'm sure I've heard something about engines need top end setting every so often! Thanks! :o
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Without sounding non technicaly inclined what are Shims? I have a slight tapping sound from the engine on my CBR600F4, 18K miles on the clock. I'm sure I've heard something about engines need top end setting every so often! Thanks! :o
without being too technical,i am no mechanic the shim sits on the end of the valve & under the valve lifter on the camshaft end.
when the valve clearance has exceeded range then they need replacing....
As you need to measure the gap then order shims which then maybe the wrong size best left to the pro,s who should have various sizes in stock.
Yes this will be a light rattle especially when cold coming from the top end
This is what i am led to believe i may stand corrected
Theres a possibility that it could be your camchain tensioner which is causing chain to rattle slightly not sure how yours works on your bike but that might go as the tensioner moves inwards on its ratchet (if its got a ratchet system)
Shims usally need doing every 25-30k miles cause they dont wear out so fast as adjustable manual(lock nut and screw) do which usally are every 4k.
As the shims wear then the gap gets narrower so infact it tightens up which in extreme cases if left to long you end up with burnt valves cause they are not sealing properly.
But phone up dealer to find out what mileage the shims have to be checked/replaced
Alan, thanks for that info mate. Never thought about the cam tensioner as a possibility. Sometimes the noise is louder then quietens other times. Im no expert. :-/
I keep thinking about this statement since I read it last night and I'm struggling to understand it. If the shims sit on top of buckets which sit on top of the valves and are directly under the cam shaft as they would be in any OHC engine... then as they wear the gap between the cam and the shim is going to get wider/bigger.Quote:
Originally Posted by alanTDM
What am I missing?
Thanks,
I keep thinking about this statement since I read it last night and I'm struggling to understand it. If the shims sit on top of buckets which sit on top of the valves and are directly under the cam shaft as they would be in any OHC engine... then as they wear the gap between the cam and the shim is going to get wider/bigger.Quote:
Originally Posted by hotdog
What am I missing?
Thanks,[/quote]
Your right about that i miss read the second post that would be the case they would widen, if the shims were underneath the buckets then it would tighten up I dont know how long he has had the bike but at 18k i would not of thought they would need doing yet for at least another 10k usually there checked at say a first service and if they have to have new shims not all but some its done then till the next major service eg 28k then every 28k depending on manufacture.If he has got to take it to a dealer to be done every 28k or whatever it will cost a lot in labour(fairing and watercoolant taken out etc) I done my own and the Yammy ones are about £2.50 each so not sure about Honda ones.The cost of dealer doing my TDM was £140 but have known peeps to pay £200 for shims to be replaced its the labour charges that hit your pocket.
If the camchain is on the outer side of engine and not in the middle he could use a big screwdriver to listen to it to see if it is rattling by placing next to ear and other end on casing so it acts as a stethoscope
But it just still could be the tensioner/camchain
:D You lads have lost me with this tech talk!lol . I'm down sallys' Thursday so if you're around have a listen to my bike and see what you think! Like I said before I'm not an expert on bike engines yet so apreciate comments given so far.
I cant make this thursdayQuote:
Originally Posted by Iceman
No worries Alan.thanks anyway!
I don't think it is possible just by listening to an engine wether the shims need doing. You may notice if the tensioner is worn, but I dont really know what to listen for. I did listen to your bike the last time I was at the Sally, and to be honest I thought it was perfectly fine.
My CBR's shims are where due at 16000 miles and were done on the last service. 5 out of the 16 where changed cos the gap had changed. It was still runing great before it went in, but it was better once I picked it up. If you want peace of mind, like I did then get them done. It has been known for valves to burn out as has been said, but thats in extreme cases. Just don't do what I did, and that is spend a fortune on a service and a few other bits, then buy another bike :)
Fair point there nickw. Thanks for the vote of confidence!
;)
right then, valve clearances can tighten, by the valve regressing/wearing into the seat ( this happens when gears are missed) or they can open up due to wear in components.
the buckets that contain the shims, or cover the shims are ofset from the centre of the camshaft and rotate, although sometimes they get a bit stuck and wear in a funny pattern, causing noise, when the bucket rotates the clearance is not so large and the noise is not apparent.
only way to check is to lift the rocker cover and check clearances.
take the cams out, and check if the tops of the buckets are square. measure the shims and minus this from the clearance. then work out the correct size you will require for the correct clearance.....simple :-)
ive done loads before, if you get stuck gizza shout.
jd.
Burger , its not so much the shims wearing , its the valve seats in the head m8 as mentioned above , , hence the valve moves closer to the cam , making the gap tighter ,
also , the shims are not adjustable , if the gap is incorrect , you will need to remove old and order the correct sizes from honda , but keep the old ones you remove,
Finally if you do this check , ensure the engine is cold !!!!
Oh and wind the CCT in , this will enable easier removal of the cams !!
;)
That all makes sense... thanks for clearing up my confusion :)