Hi,

I've just cleaned out my CCT and am now reinstalling everything. I have the manual, as well as Naga Thai's writeup, and have been following carefully. Which makes the fact that I can't seem to figure out how to set timing even more annoying. On top of it, I'm now worried I could have bent a valve.
- After installing the CCT, I set the ignition pulse generator to "T". While turning, however, I found I suddenly couldn't turn anymore. I was turning gently, in small increments. I applied a little bit more pressure and when it wouldn't move, I stopped. I looked at the top end, and because the cam chain had come off the exhaust sprocket (and the intake camshaft/sprocket was off), the exhaust cam had not been turning. I immediately unbolted the exhaust cam and then of course everything started moving again. I never banged or wailed on the pulse generator - am I still likely to have bent valves?

- Anyhow, after lining up the "T" index mark, I put in the intake and exhaust cam shafts back as shown here:


The cam sprockets are NOT bolted to the camshafts at this point. They can turn independently of each other. I now install and bolt thes cam cover. Now the cams can no longer be turned by hand.

Next up: make sure the pulse generator is still on "T", and line up the IN and EX on the cam sprockets to the top edge of the engine. The cam lobes are still the way they were in the picture above.

And now here is the issue: If I thrown the cam chain over the sprockets, and now want to attach the sprockets to the camshafts, how do that? The manual says:

But...I can't actually turn the cam shaft. It doesn't turn at all. I could just rotate the crankshaft to make the holes in the sprocket and the cam flange line up. But there are two possible ways to attach the sprocket to the cam flange: you can turn the sprocket 180 degrees, and it still bolts on. But presumably only one orientation can be right.

What am I failing to understand here?

Thanks in advance!

 

It is unlikely that you done any damage if you were only cranking slowly by hand. Although the valves are slender, they are made of tough stuff to survive the repetitive pounding at the valve seat at high temperature.

Just be careful when you install the camshaft holders. The camshafts are “floating” in the horizontal direction, and they are located by a slot in the left side holders that fits over a guide on the camshaft. When you install the holders, just make sure you don’t pinch the camshaft at this slot by giving the it a wiggle as you install.

The cam sprockets are generic, that is, they fit both front and rear camshafts. They are stamped with an UP mark so you know which way up they should be when the camshafts are installed as you indicated in your picture. Obviously, the stamping needs to be to the left so you can see it.

Your procedure of rotating the crankshaft a few degrees to line up the holes in the sprockets with the camshafts is fine. There is some degree of latitude to rotate the crankshaft with the cams installed without fouling the pistons. As an alternative, in his video rebuild series here:

https://cbrforum.com/forum/how-tos-8...r1000f-156490/

tentacleslap uses a drift to rotate the camshafts to the correct location. I am no fan of impact methods where aluminium is concerned, so if you use this method, proceed with only just enough tapping to move the camshafts.

 

While you have the lid off, I wonder if you could measure something for me? I'd like to know how deep inside the cylinder head is the mounting face of the CCT. A good measure would be the distance from the cam cover face (which is at half the depth of the camshafts) to the mounting face where the CCT bolts to the cylinder head. Thanks.

 

Thanks for that very detailed reply! That clears it up. I think I should only have to rotate the crank clockwise by a few degrees to make the cam and sprocket line up - as you say, hopefully this isn't enough to cause any damage. I supposed I could also give the crank nearly a full counterclockwise revolution to achieve the same thing, but I'm worried I'd run into the valves again because the cams won't be turning when I spin the crank.

As to the measurement you asked for - I've already reinstalled the CCT. Would it be of any help if I get you the cam cover face - top of the CCT measurement? If not, I can pull the CCT and get the one you want.

 

Stop. Don't rotate the crank any more than a few degrees with the cams in and the chain/sprockets not connected. If you want to make more than a few degrees, take the cams out so they can't action the valves.
I know for sure a few degrees either side of T are OK as this is how I did mine.

Yes a measurement to the top of the CCT would also be great - don't pull the CCT just for me. I know the thickness of the mounting flange on the CCT, so this would be great.

 

Had a chance to pop in the garage and take a measurement, and got 35.17 mm from the cam cover face to the top face of the CCT.
I'm not sure how much accuracy you need, so I'll tell you how I got it:
Laid a pencil across two of the cam cover faces. I have assumed assumed all cam cover faces are on a single plane, parallel to the top face of the CCT.

42.23 mm.

I then subtracted the thickness of the pencil:


I realize this isn't a perfect method. The pencil isn't going to be perfectly flat, for one thing, but it is all I could find that fits in there.

If you have a suggestion for a way to take a more accurate measurement, let me know. The engine is likely to be open for at least another day before I can find time to finish the job.

 

Splendid. This is perfect, thanks.

 

Alright, everything is back together. I was a touch worried that the timing wasn't exactly perfect, but moving it another tooth in either direction would be far too much. The method I proposed above didn't actually work for me, so I wound up using @tentacleslap 's method of lightly tapping the camshaft to get it to rotate just a touch and line up.
I checked valve clearances while I was in there - I set them just 5k miles ago, but it seemed silly not to check them while I was in there. A few of the intakes were actually tight - 0.0025", and one of them was VERY tight (less than 0.0015", which is the thinnest feeler I have). I adjusted them, and swung the crank around a few times manually (CCW, of course). Everything seemed fine, so I fired it up...and all seems good! It idles smoothly and revs to about 3k smoothly (don't like reving it while stationary, so that's as far as I went). It rattled horribly for a few seconds, but I knew to expect that. It stopped after that, and I fancy the rattle is quieter than before (likely because I threw some 20W50 oil into the CCT). Will adjust the carbs and take it on a test ride and report back to close the loop on this.

Thanks for your help @andy_williams !