You won't have oversized shims - the 7.48mm dia is a snug fit in the recess on top of the valve.

It could be true about the shims getting hammered, they seem to measure ok but I had a .29 clearance, I fitted a .05mm larger shim & ended up with a .22 clearance. This happened on several valves.....
They are shim under bucked types but can't see that'd make any difference.

If you have a borderline clearance, again I did yesterday on the 750 @ .13mm by a pure stroke of luck they both had 202 shims fitted, 2.00 shims put them perfect
Like I say, you could go on forever trying to get them spot on, especially if quite a few need doing!

Phil

Of course, if you have lots that need changing, you might be lucky to find that some can be swapped around. The first time I had my 35 done at a motorcycle shop they adjusted 13 valves, and charged for a new shim for each. you can bet your life they all came out a box full of old shims, and the ones from my bike went back into it. Seem to recall that was about £80 just for them!

Aye - that was the plan Speedy - I'm off to Screwfix to pick myself up a micrometer on the way home, I have 4 or 5 valves at 0.13 clearance, so I think I'll pull them, measure and put back as and where fit best - with a bit of luck I may only have to get one changed.

At least this way I'll have knowledge of exactly what is in the engine, for a good portion of the valves. I dont fancy pulling the shims from the front Vee unless I have to - the exhaust shims look like an absolute pain in the arse to remove / replace with the engine in place.

deequeue wrote:Aye - that was the plan Speedy - I'm off to Screwfix to pick myself up a micrometer on the way home, I have 4 or 5 valves at 0.13 clearance, so I think I'll pull them, measure and put back as and where fit best - with a bit of luck I may only have to get one changed.

At least this way I'll have knowledge of exactly what is in the engine, for a good portion of the valves. I dont fancy pulling the shims from the front Vee unless I have to - the exhaust shims look like an absolute pain in the arse to remove / replace with the engine in place.

On my 1st '30 just about all of the front ahims needed changing - I ended up stripping the front wheel/forks off for better access - I wanted to check head bearings/change fork oil anyway.
I also ended up stripping the rocker gear off for simplicity!

Phil

I guess you could heave the top rad off for a bit of extra working space. I plan to find out exactly what size shims are on all the valves regardless of needing changing or not so I can get some spares that are a similar size for when they do. Don't see much point in buying a box of a zillion when most will be miles out of what could ever be needed, although I suppose there's scope for swaps with other people...

I've dropped the top and bottom rads, but I didn't really want to empty the system unless I really needed to, I've got just enough room to get to them, I guess I'm fortunate as all but the one inlet are in spec on the front Vee.

I think it would be a great idea to see if we can get a shim box together going forwards - Although I guess I'll end up using Rick O's swap service, as its well priced, none of the local mechanics do shim exchange, and the local honda dealer wants 9 quid a frigging shim.

9 quid is a pisstake, you can order new ones from Honda for under a fiver each!

Ebay you can get new shims for about 3 quid delivered & you get to keep the old ones or put a wtd ad up here

Phil

There are already some valve clearance guides so I wont go into great detail, just cover some of the things I think don't get mentioned enough.

1. Get a good set of feeler gauges / and a micrometer that will measure to 0.01 accuracy.. a lot of the cheap crap will only measure to 0.1 and this isnt good enough.

2. Measure twice, buy once. Some people swear by using two feeler gauges put together to get the gap, others use individual gauges (this will depend on how many you have available.) But always take two readings, I generally do them all then do them all again (not do the same one twice in a row) and compare the results.

3. Measure all the clerances and existing shims, then make a list of what you need, you can see from the shims you are replacing if any of them will fit in places you need to buy shims for. My worst case was I had to buy 14 shims, all 16 needed replacing but I could swap two over.

4. Recheck after replacing shims, dont assume that your measurements were right. Its easy enough to put the wrong shim in the wrong place.

Is the rocker pressed hard against the cam when everything is in the right place for measuring? There's no scope for inadvertently lifting the rocker slightly away from the shim when putting the gauge in?