3C first service

Paul Marx

Paul Marx

Hero member
Location
France
I'm doing the first service on my 3C after a complete engine rebuild. 3500 km since start up. I'm not used to these triple thingies so have a few questions.
Work done by Keith Nairn.

Cams are A11, new billet cam blocks, new valves, new valve seats.
I was expecting to have to tighten the new cam chain, but it's okay.

Question: what valve clearances am I looking for? According to sources, it's either, inlet, then exhaust, 0.20 and 0.30 or 0.25 and 0.35.
What I measured surprised me since I wasn't expecting to have to re-shim.
I found, left to right,
Inlet: 0.15 to 0.20 on all 3 valves.
Exhaust: 0.25 to 0.30, a loose 0.25 and on the right, around 0.18 likely. The 0.2 feeler won't go in.
Measure done with the cam pointing straight up perpendicular from the bucket.

So, I need to re-shim don't I?

Paul
 
dude said:
Don't you have the French RMT Paul ? If you want I send it to you by Wetransfer .
Click to expand...
Salut camarade,
I do have it, thanks. It gives 0.25 and 0.35 for the A11 cams, and 0.10 and 0.20 for the A12s.
I also read somewhere 0.25 and 0.35 for 4Cs.
Phil Todd gives 0.20 and 0.25 for all.
The Italian workshop manual gives 0.20 and 0.25 as well.
I was a bit confused.

I'll opt for 0.25 and 0.30 since gap appears to be closing, probably due to new seats bedding in. And bigger is better isn't it?

Paul
 
Hello Paul,
after the revision (including new valves and seats) on my engine the valveplay (after 14tkm mileage) has hardly changed, so far there was no need to correct it.

With your engine it seems that a slight correction is necessary. Keith may have set a little less clearance than it was set up with my head. However, I assume that you wouldn't have to touch the valves for a long time after this correction. The service lives of the materials used today are really good!

Jo
 
Jo said:
Hello Paul,
after the revision (including new valves and seats) on my engine the valveplay (after 14tkm mileage) has hardly changed, so far there was no need to correct it.

With your engine it seems that a slight correction is necessary. Keith may have set a little less clearance than it was set up with my head. However, I assume that you wouldn't have to touch the valves for a long time after this correction. The service lives of the materials used today are really good!

Jo
Click to expand...
I obviously didn't check clearances when I got the engine from Keith. Keith did say somewhere that they wouldn't move, but they seem to have done so. It should settle down afterwards.
The clearances never moved on my 3CL, bought new and put aside after only 50 000 when I bought something lighter to ride daily.

Paul
 
you are using metric gauges aren't you Paul
imperial ones can confuse imperial peoples, but you are not one of them are you, I set mine at .008" and .010"
CLEM
 
In the 2008 post "Valve clearances?" Keith explained which figures he adjusts to:
Outlet 0.254mm - 0.0279mm
Inlet 0.203mm - 0.228mm

No idea, if this is still exact what he's setting them up to today. Kindly enough, Keith tranlated the figures already into metric (continentel) amounts - so you've to be strong Clem ...
:)

Cheers,
Jo
 
Last edited:
CLEMTOG said:
you are using metric gauges aren't you Paul
imperial ones can confuse imperial peoples, but you are not one of them are you, I set mine at .008" and .010"
CLEM
Click to expand...
Don't worry Clem, had I used Farenheit, I would have died of cold a long time ago. Or vice versa?
Paul
 
Preparing to do the shims.
I've ordered some fine feeler gauges so as to be as precise as possible.
I've found a stock of 20 or so shims which should allow me to get the clearances right. But.....there are two different types of shim. On the left, a shim that was on the bike before restoration, on the right a shim given to me by my good friend Eric, alias Dude, previous owner of the bike.
The shim on the left is thicker, wider, heavier than the one on the right.
What gives?
Paulshims.jpg
 
The inner dimensions (good fit on the valve stem) and the hardness of the parts would be important. I think the weight is secondary (given the size of this parts) ...
 
The horrors I've seen!
The shim on the left, in your pic, looks closest to OEM. Make sure it's a snug fit on the valve stem and not too long (see those on the right of the picture below) that it touches the collets.
The ones on left of pic. below, with the lines on, were bought years ago and never used.
The horrors, in the centre, were taken from a bike, being overhauled by its owner. Some valves had the skinny shim inside the conical lump, some had only the conical monstrosity! The thought of all that inertia, moving around in there, still gives me the shivers.Shim Horror.jpg
 
the one on the right Paul is a Jota one (lightened for racing), quick sell it for big bucks!

I have every faith that out of your 20 or so shims in stock none of them will be the right thickness, dont forget to remount and tension the chain before the recheck of clearance once you have calculated and varied your shims
CLEM
 
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