Triumphrat

Tom Herold

Alright all you engine experts, I need some advice!
I'm restoring a 96 T-Bird and have reached the point of getting the valve seals and shims in place. The service manual has a graph showing the required shim size based on clearance and current shim measured size. Unfortunately the manual only shows measured shim sizes in increments of 5 (ex. 270, 275, 280 285, etc.), so what am I supposed to do when the measured size is 272, 273? So I round up or down to get the proper shim size indicated in the graph?

Thanks in advance for any help and advice!

Tom

KitNYC

Hey Tom,

Seems strange, but maybe Triumph shims only come in multiples of 5 & someone before you used a Yamaha shim? The shims are a standard size diameter, so you can use shims from some Japanese bikes.

I'm not really up for doing any heavy-duty math right now, but you should either add or subtract the difference from the measured clearance. Make sense?

Cheers, good luck!
-Kit

Tone in't Fens

I'm about to do my Tiger (955i) tomorrow. I'm sure you double checked the measurement of the shim; it's so easy to apply too much pressure to the mic. and get a reading slightly low, especially as you're talking about a couple of hundredths of a mm. If the shims really are somewhere between the standard increments then ere on the high side of the tolerance.

e.g. On the Tiger the exhaust valve should be 0.15 - 0.02mm, so aim for that 0.02 rather than the 0.15

__________________

jwolf

The shims are only available in thicknesses in multiples of 5, i.e. 260, 265, etc.
Since the tolerances are .10-.15 or .15 -.20 for my Legend, just find a new shim size that will fall within the recommended tolerance range. It might be good to remember that when checking gaps with a feeler guage, the gap will likely be somewhere between the size of the feeler that slides thru and the next size up that won't slide thru.
A site that was helpful to me was the following:
http://www.webbikeworld.com/t2/valves/

KitNYC

+1 on the WBW article. Also, if you need to replace any shims they're 25mm diameter and interchange with certain Honda & Yamaha applications.

Cheers,
-Kit

Tom Herold

Excellent advice, thanks. The shims must have been replaced at one time or another, they're printed in the odd sizes (282, 273, etc).
The Honda CR250 dirt bike engine uses the same shims as the Triumph T-Bird I'm working on, so I'll head over to one of the two shops I have close by and see what they have available.
The WBW article helped out a lot, great reference and good info.

Tom