Bonneville America Forums Forums Technical Forums General Tech valve adjustment...Help.

Here are my valve gaps and shim measurements.
exhaust 30.5 / 30.5 / 30 / 30
shim 2.67 / 2.57 / 2.63 / 2.80

Intake 20.5 / 22 / 19 / 15
shim 2.82 / 2.77 / 2.82 / 2.90

can someone please,, help a poor math challenged boy determine what shim size i need to get these centerd.

Go to Dinqua's web page and download the shim calculator. click here

I have, and I don't understand the figure it gives me or what to do with it... There in lies my problem.

I should add be sure to use a micrometer to measure the old shims as well as the new ones, not a veneer caliper since they won't be completely flat. Also don't take for granted the size marked on the shim be sure to mic them to be sure. I didn't and ended up with 2 valves not where I wanted them and had to take the cams back out to correct the problem. Also be sure the shims are well seated before you measure at the end of the job. Rotate the engine a few times then measure. DO NOT START IT I pull the plugs and spin it with the starter but only pull the plugs when you are ready to spin the engine and be sure there is no debris that can fall in the plug holes.

By the way there are Yamadog valve shims that work and come in closer increments.

ok decimal was in the wrong place..

Here's what I came up with to get maximum lift but to still stay in spec

If exhaust is: 305 / 305 / 300 / 300
Use shim___300 /300 / 300 /325*



If intake is: 205 / 220 / 190 / 150**
Use shim____325 /325 /300 /perfect as is

* Be careful with this one. 325 is going to get you very close to 250 clearance. A 300 would be safer, but a 325 should fit if the numbers are right. I'd want to turn the engine over a number of times by hand and measure a 325 shim 8 or 10 times before I fire up.

** This one is dead nuts on perfect as is.

Thanks again to Pat for taking the time to write the shim app.

Be sure to shoot for 1/2 way between the 2 extreme tolerances, some valves seem to tighten while others will loosen up some so you want some space on each side.

Never work with kids or dogs

Thanks for the help guys, Bucky, I thought the general rule of thumb was to go to the middle of the tolerances rather than the lower end of the tolerance?

My thought is that a hair to the safe side of 15 & 25 offers the maximum lift, and more air in & air out. A fraction of a cc of air times 1/4 of X,000 RPM of air adds up.

If the final result of the new shim install is within Triumph's spec, as ascertained by rolling over the engine by hand a few dozen times, then painstaking accuracy in measurement and re-measurement of the gap (to include calibrating the feeler gauge blades with a mic or caliper,) prior to winding up the starter, then I don't see the harm in going for maximum lift/air. I did 1 & 1/2 modern Triumphs this way, with no problems.

Will this method put an extra load on the valve train?
Probably.

Is there a risk of crashing the valves into the piston crown?
Definitely.

Would I do it this way again?
You betcha.

Should everyone do it this way?
If you met me live & in person you'd probably scream - NO!

Air in & Air out - a naturally aspirated engine's two best friends

That is correct that as long as you are within the spec you should be OK but you should shoot for the middle of that spec. If you don't hit it dead center you should be OK but still want some room on both sides of the spec.

If everything is done correctly as far as putting the cams back in the right way and the shims are correct then there should be no danger of a valve hitting a piston.

Do you think he should shoot for the middle?

i feel groovy getting it anywhere within the tolerances.

+1, particularly after having to re-do the process a second time as a couple were out of spec.

Not sure what I did wrong mind but have a sneaking suspicion my feeler gauge technique needed work or as dog mentions, the shims weren't properly seated to the "ENth" degree.

I do like the idea of running the motor via the starter (got the, ensuring no spark suggestion) too as I only used my wheel in gear to seat them. Maybe they still didn't seat properly - dunno.

Anyway, my valves have been smick now for 16k kilometres and she's still running "BEEEAAAUTIFUL".

One of the many reasons I love my bike, cos if this is virtually the most complicated maintenance requirement then I'm looking pretty especially with the blokes on here to answer any questions.

Shoot for the middle. These aren't race bikes.

I figured since trash is a mechanic, he'd have no trouble at hitting that easy mark of a hair less than maximum factory approved lift, and also be able to attain the longest duty cycle between now & the next shim job, and after initial break in, he wouldn't already be halfway to out of spec with a fresh shim job.


It could well be I'm wrong due to lack of understanding something, perhaps related to wear issues?

It seems some valves tighten while others loosen with wear. If you set them to the tight side and that valve tightens you are already out of spec.

Seems all of mine have loosened sense I last checked them. Not by much but by enough to warrent my troubleing with um. Besides I was bored at the time. Now im busy as crap at work and havnt felt like screwing with it when I get home. So she sits, cams out waiting. Bucky, your points are well taken about performance. But even though I'v done many things to improve performance. Valve adjustment to the thightest setting would not, in my opinion provide enough of a difference to warrent the trouble. Perhaps if I were drag racing and trying to cut et's then it would be worth it. I do apprecitate your imput though, and agree with what you're saying.

Finally got the two shims I needed today. Put her back together,rechecked valves. Darn, I miss calulated on one. Pull the exhuast cam back out switch shim. All back together, recheck valves, all good. Took her out for a short spin and sounds just fine. Thanks again guys for you imput and help. Thanks specially for dinqua's little shim cal. It really makes it easy.

Don't feel bad, I have been working on bikes my whole life and I missed 2 of them. Had to run back to Hermys for the other 2. Seems no shops here carry the 25mm shims I needed. One had some but not what I needed. Hermys was cool and swapped the shims even up at no extra cost to me except the extra gas and time to run over an hr back down there.