Bonnie T100 Tappet Shims

I checked mine @ 12,000 and all were within specification. I checked them again @ 20,000 (due to forum induced paranoia) and found shims 2 & 6 were out of specification and in need of replacement.

Doing the job yourself gives you the advantage of being able to (correctly) measure shim clearance when the engine is stone cold. Once you've got the cam cover removed you only need feeler gauges to check the clearance.

There is a Triumph peg tool for when it comes to changing out the shims but it's also easy enough to do without it using a workaround.

 

Yes confident enough to check the clearances. Stripping down the camshafts is another matter. Hope mine are within spec.

 

Ok then, my exhaust valves are all on the .30mm limit though two are .30+ but can't get .35mm feelers in.
Three inlets are on .20 limit but one is .25mm.

So only one valve is actually out of spec, I am inclined to leave it now till next years service, when it will be worth the effort/expense to bring them all back into spec. (I only did 3000 miles this year.)

There is an independent triumph specialist near me so it might be an idea to get a quote as I don't have the special tools required. Also the necessary shims?

Anyone know the likely cost of this job?

 

Better to have a slightly loose tappet than a slightly tight One (the old saying 'a slapped tappet is a happy tappet)

 

I see the shims are £6.26 - £7.83 depending on thickness. (x8?)
Oil feed pipe o-ring £2.06, Crush washers £1.06 x 2, Cam cover gasket and bolt sealing washers x 4?
An expensive job potentially!

 

Thanks for the tip. They are in Hereford just up the road from me!

 

If it was my bike I would leave it (and ive done a fair few). The tolerance will close up rather than get bigger. It is not an excessive amount over neither. Check in another 12k miles. Everything now should have bedded into themselves nicely. Why upset the apple cart, It has obviously been fine till now.

 

Yes, only one out of eight valves out of spec, but the other seven are borderline. If I wait till next service It should be more worthwhile stripping down the camshafts. I would have thought it would get noisier, rattle wise as the gaps increase? Thanks for your interest.

 

Typically overhead cam engine valve clearances reduce over time, and can cause starting and running problems along with the possibility of burnt valves and expensive head work.

 

Thanks so much, I didn't realise that the gaps decrease over time So they should be all into spec next year?

 

That is what happens with screw and locknut type. The opposite is true of bucket and shim, they reduce in clearance.

 

Relieved that I don't have to touch the camshafts and that I have plenty of clearance. Intrigued to know what they are initially set at from the factory though? Peace of mind through this forum, thanks all!

 

So, thought I was at peace with this subject, and I am in a way, as I am waiting another year now, but??? Surely as shims wear, the valve springs close the gaps. I'm sticking with that theory!

 

In my opinion. All the spring does is keep the valve closed, unless compressed by something mechanical, in this case the camshaft.The distance between the top of the spring & the cylinder head remains constant.The gap you are talking about is between the shim (in the bucket) & the lobe of the camshaft. So if the shim wears (will happen)or the cam lobe wears (shouldn't happen) The only way the gap can decrease is if the valve heads & seats wear.

 

Indeed it is valve to head contact which causes the gap to reduce. some early models the valve would go very concave requiring new valves. Usually the valve seats were fine only requiring a very quick lap.

 

Shims very rarely wear, if they do you have a major problem re the lubrication system or what you use. The valves don't close gaps,. They are retained by collets, there only purpose is to close the valve as the camshaft turns.