Measuring valve clearances.
 

I'm in the process of stripping the bike down because ive got a very loud tick tick tick coming from the engine.

I have had a mechanic check the tensioners and replace them and he is sure they are fine.

He said to measure the shims, how exactly do i achieve this? I have got a feeler guage here all I need to know is what I'm meant to do with it .

Cheers

Re: measuring shims
 

Use the feeler gauges to measure the gap between the cam and the bucket (lobe facing directly away from the bucket, or up towards you).

From memory the clearances would be:
inlet 0.10mm - 0.20mm
Exhaust 0.20mm - 0.30mm

The shim is a small metal disc that sits under the bucket and on top of the valve stem. This would need to be measured with a micrometer and changed only if the gaps checked with the feeler gauges are wrong. The Haynes manual has a step by step that you may want to follow.

Jambo

Re: measuring shims
 

Ok I'm not sure if i have done this right but judging by the haynes manual there is a good chance I have. I have got the front cylinder at tdc, and I have measured with the feeler guage the distance between the valve thing and the round thing underneath it. The front exhaust valves have measured in at 0.40 on both and the inlet valves have both measured in just over 0.25, a 0.30 wont go in and a 0.25 is just a little bit loose so i would say its around0.26 or 0.27.

Does this sound right?

Re: measuring shims
 

Then the front exhaust valves are out of service limit and should be checked, and the inlet valves are also out o.o :)

Re: measuring shims
 

ok ive now tried to measure the rear valves but i cant get any of the feeler guage in because when you stick it at tdc on the rear cylinder the valves dont point away like they do on the front. they point downwards and only slightly off center pointing towards the outer side on the head.


If you spin it again like it says to do in the manual they point upwards. The front valves pointed outwards perfectly but these just dont.

Any ideas?

Re: measuring shims
 

I'm quite sure that 0.25-0.27 on inlet is outside the 0.10 - 0.20 inlet limit, As is the 0.40 outside the 0.20 - 0.30 exhaust limit.

Pretty please with sugar on top, if you're going to offer assurances on technical matters, read the post first.

sv_rory: For this check don't worry so much about TDC, just turn the engine by hand (anti-clockwise from the LHS of the engine using the appropriate socket as I'm sure you are). Turn it until the cam lobes are pointing directly up and away from the bucket (that shiney thing the cam pushes down on), and measure one cam at a time. I.e, adjust the engine position until the rear inlet cam lobes face up, check clearance, turn engine until rear exhaust cams point up, check clearance etc.

The markings for TDC Front are essential if you are taking your cams out to make sure the timing's correct, as you're just checking at the moment it's OK to do this bit by eye.

If you are going to attempt to change the clearances, get a better set of feeler gauges before you buy shims, a 0.25 - 0.29 (all of which will take a 0.25 but not a 0.30), may change the shim size you want to put in.

HTH

Jambo

Re: measuring shims
 

I thought I did?

My bad, at least I was half right. (:

Re: measuring shims
 

Thanks for the advice, Il go and od it now and il post in a few mins what the reaings are off the rear cylinder.

cheers

Re: measuring shims
 

Ok,

Doing what you have just told me to do I've managed to get some readings.

The rear exhaust valves have measured in at 0.40 on both.

The rear inlet valves have measured in 0.25 on one and 0.24 on another.

what do i have to do now?

Re: measuring shims
 

Short answer: The clearances are all out of tollerance and should be rectified.

You've got options. You've got this far, If you can get hold of a micrometer and are a patient logical person there's no reason you can't re-shim the engine yourself. It'll take you a while the first time you do it, but it's just measuring. If you have a Haynes manual it's pretty straight forward.

Essentially you line the timing markers up correctly, remove the cam chain tensioner, and remove each cam shaft. Under the bucket is that metal shim we discussed at the start of the thread. You remove the little disc, measure it carefully and repace it with one of a thickness that brings your clearance back in. In your case, a thicker one will close the gap up. Then you put it all back together, double check your timing markers and turn the engine over a few times by hand and measure again.

Alternatively you can phone a local garage and say "I've measured the shims, they're out, how much to just re-shim the bike?" Gets rid of some hassle.

If you're methodical about this there's no reason you can't do it, but remember the potential is there to put it back together wrong and have a piston-valve interface, and that's expensive and a touch upsetting.


Jambo