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1995 Thunderbird valve check

3K views 21 replies 10 participants last post by  NEALR 
#1 ·
With the bike rapidly approaching 12,000 miles i need to check her valve clearance. Suffered severe shock when i saw the price for the tool,to remove the shims if this proof necessary. How can they charge that much for a bit o bar with holes in it?
I intend to knock one up in the garage. Does anyone have a drawing with dimensions for the tool. Otherwise i have to size it off photos . If i have to change lots i will pull thr cams. Thanks in advance.
 
#2 ·
Exact dimensioned drawings have been posted on here before, but I don't have the links saved... have you tried using the Search function?

You can of course just remove the camshafts to replace the shims, or even lift/tilt them enough (carefully) by loosening the bearing caps.
 
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#9 ·
I'm trying to recall exactly what I did on #3. I may have not needed to change any shims there, but pretty sure I did at least 1. IIRC, I had to remove the cam bearing caps on the #3 end entirely (and very loose on #2) and then GENTLY (I used the rear wheel with the bike in 3rd or 4th) turn the engine so that the valve springs on #2 push the cam up enough to clear the shim "buckets" on #3.

This will, of course, put more tension on the cam chain, causing the tensioner to move, so here is one of the main places where it is important to move carefully so that the chain and sprockets do not slip a tooth and alter your cam timing.

I'm making it sound more scary and dangerous than it really is.
 
#11 ·
This will, of course, put more tension on the cam chain, causing the tensioner to move, so here is one of the main places where it is important to move carefully so that the chain and sprockets do not slip a tooth and alter your cam timing.
Well, no, more tension on the chain cannot cause the tensioner to move because the plunger is held by a one-way ratchet mechanism.

The risk with this method is the opposite - loosening of the chain, which potentially could allow the spring behind the ratchet to push it further outward against the tensioner blade. This would then cause an over tension on the chain when the components are re-tightened.

However, you could easily prevent this possibility by removing the tensioner bolt and spring from the tensioner body (19mm socket or spanner) before loosening any cam caps. (But still being careful not to slip a tooth with the chain.)
 
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#10 ·
Had a go today despite the cold. It worked very well. I loosened all the cam cap bolts, but left those on 3 loose by a few threads only. It was quite easy to slip out the shims on 3. I just need to buy 5 new shims as all the inlet gaps were too tight. 2 exhaust gaps were also too tight. Why are the cam cap bolt so tight. Haynes shows them as 10 nm and mine were way above that - about 25 nm. Taking the water pipe elbow off makes life much nicer. Thank you all.
 
#12 ·
Ideally, you could release the ratchet without removing the tension...

Haynes shows them as 10 nm and mine were way above that - about 25 nm.
Torque to loosen a fastener is not a reliable determinate of the torque used to tighten it, and is always higher, unless the fastener has worked loose.

Yeah, the water pipe has to come off. I couldn't feel confident about the valve cover gasket if I tried to put it back without doing so.
 
#14 ·
Valve Shims
Some Honda shims are the same.
The models are: 1979 thru 1983 CB 750 K,F&C
CB 900 F&C
CB 1000 C
CB 1100 F
CB 750 SC

Kawasaki KZ 900, 1000
Yamaha Royal Star and Vmax
Suzuki has also used them but I do not have any specific models
Honda autos also use them in some engines.
They are 25 mm diameter valve shims.
I've found that many parts guys will not know what you are talking about if you go to a dealership, Talk to the Service manager.
 
#15 ·
Those shims are very common. Just about any shop will have them. Finding exactly the right one might be an issue, though. I needed one and ended up getting it from the Triumph dealer as the local shop didn't have the one I needed.

A lot of times they'll just swap the one you have for the one you need. If it's used make sure the surface that contacts the cam is not pitted.
 
#16 ·
I asked the parts guy at Donnelson's if he'd swap shims with me, and he looked at me like I was nuts!
 
#18 ·
I just had this conversation with a guy I met this weekend. He was doing Valves on a Kawi and the local dealer had to order shims for him. Took a week to get.

I find it hard to believe that if a bike comes in for an adjustment they tear it apart and leave it half assembled on the bench waiting a week for shims. I think the key is getting to a service guy and having a relationship with them to maybe ask.
 
#19 ·
The UK Triumph tech Clive Wood explained to us about shims...

All the bikes come from the factory with a fairly narrow range of shim sizes fitted. The clearances always tighten up over time (miles). So all the sizes bigger than that range are of virtually zero interest to anybody.

As the bikes age, we're all looking for much the same sizes, and the larger sizes in the range become less and less sought after.

I have probably 2 dozen shims, but near all are too big to be of use to anybody. Which backs up Clive's explanation of why mechanics aren't interested in swaps. It's a bad deal for them mostly, as they get shims they'll never use in return for useful sizes.

I guess if there were enough of those other, older bike models, around, the demand range for sizes might be different? But those models with 25mm shims have long disappeared. I'm not surprised really, since they are a sizeable chunk of metal for an engine to be chucking about at 10k rpm (ok, 5k on the camshaft, but still, shedloads of inertial mass!).
 
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#20 ·
Clive's explanation of why mechanics aren't interested in swaps. It's a bad deal for them mostly, as they get shims they'll never use in return for useful sizes.
Interesting! I was thinking from my automotive days. We did a lot of valve jobs and would grind the valve stems to fit whatever shims we had a lot of. It is true, though that from there they only get tighter, so only thinner shims are of value.
 
#21 ·
I'd hazard a guess that modern high rpm valve trains are far more stressed and finely tuned, for materials and tolerances than older general automotive stuff?

There's still some old push rod motors around (just) in ageing cars here. A friend of mine was driving round a Ford Fiesta where you could hear the valve clatter a mile away. The valve train was seriously worn and had a major fault causing one valve to disconnect occasionally from the push rod/rocker. But the engine would continue on 3 cylinders, and he ran it like this for near a year, occasionally popping the valve cover to pop the valve rocker back in and return to 4 cylinder operation. :O
 
#22 ·
Couple of tricks here.

1 learned from the old air cool Kwacker 4s - Take one sprocket bolt out of each cam sprocket AFTER you've measured (2 or 3 times) each of the valve clearances and noted them all clearly. Replace that bolt with a cable (zip) tie, nice and snug. Remove tensioner, reset ready for insertion. Carefully unbolt cams in turn (ie all inlets, then replace cam and do all exhausts), you can lift the cam clear with no stress on the system, do the shims, then replace cam, guaranteed the camchain to sprocket position is the same. If you're paranoid you can also take the timing cover off and wedge the chain against the crank sprocket to make sure nothing moves but I have never needed to and it wasn't an option on the Kawas due to a central chain. Just remember to cut the tie off and correctly torque the sprocket bolt when reassembling!

2. You can also use shims from a Toyota range or 2 - I think it was the oldish 6 cylinder Supra and a mid range 1600 (4Ga or GE something?). I did that and got 4 new shims for under £8 outright a few years back from a motor factors, rather than the £2.50 exchange rate at my local all make bike shop.... I did have a link to a document that had the cross references but I can't track it down right now, I'll upload it later if I can find it.
 
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