Stripping Down The Motor

[Adrian]

Hi once again - I'm still in the middle of a rebuild of the whole bike. Still no shed but I'm tinkering in my kitchen slowly. I intend to build a wooden bench to it one side of my kitchen to be able to do heavier work. Okay end of catchup.
I have the skills to completely dis assemble the motor I believe. I want to clean up all the casings fully so I need it stripped down. I'm thinking hydro blasting. I do however intend to give the whole thing in pieces to a local BMW workshop that's has a good reputation. My only concern - small as it is - is the retiming of the motor including a brand new Ignition trigger Unit on the timing chain cover. The old unit is definitely shot as before the bike was taken off the road I had sprayed it with WD40 just to keep it running for a while before it became a problem.
So the question is this. Should I make any kind of markings on the old unit and the casing - like a deep scratch across both surfaces as a guide for the new one or is it okay to just hand over the whole motor for reassembly - and some new parts of course - and let the shop work out the timing settings. A new unit I feel will probably need slightly different settings.
Also will the new unit only be properly timed once the bike is in one piece again an the timing can be sorted with a running engine. I haven't spoken to the workshop yet because his work is a few months away and I'm just interested in what might be best for the motor.
Thanks in advance for any advice - Adrian ......

[Warbucks]

You will need to mark the tooth on the camshaft where it mates before you remove it. Scratch it with a screwdriver or a scriber. Or leave it intact and let your mechanic sort it out.

You can do it without marking it, but you'll get a headache and waste a lot of time trying to figure out where the camshaft is supposed to be positioned when you put it back together. Get it wrong by just one or two teeth and she won't start. Worst case scenario is that if it's out too much the valves could smash into the pistons due to opening and closing in the wrong place.

Also note when you reassemble the engine that there should be arrows stamped on the pistons. They point to the front. Put them in backwards and the pistons will disintegrate after about 10 minutes running. Don't panic! You'll find what's left of them in the sump. LOL

[montmil]

Couple of points for you, Adrian:

The completed engine, properly reassembled, will fire and run with your new bean can ITC positioned in the middle of its range of adjustment. No damage will occur while you run through the ignition timing drill.

As far as piston install, the valve pockets on the piston domes should be matched up with the valve sizes in the cylinder heads. That's an easy confirmation should the 'barely there' arrows be difficult to see.

Rather than paying your mechanic extra labor charges as he/she figures out assembly alignments, permanently mark areas that could be assembled incorrectly. Be sure to point out these locations to your mechanic. Do not assume they will be understood.

Glad to hear you're getting back to your R65 project. Continue in good health, old friend.

[Tony Smith]

So the question is this. Should I make any kind of markings on the old unit and the casing - like a deep scratch across both surfaces as a guide for the new one or is it okay to just hand over the whole motor for reassembly - and some new parts of course - and let the shop work out the timing settings. A new unit I feel will probably need slightly different settings.

I wouldn't bother. Given you will be replacing the timing chain (and most probably the crank sprocket at least), the timing will be very different when you put it back together.

My relatively recent experience suggests that it takes about 2 minutes of trial and error to put the beancan in a position that will let the engine start and run so that you can then wave a timing light at it.  If you wanted to, for the price of an LED, a 9v battery, a bit of wire and some alligator clips (or even a "proper" JPT socket) you could make a combination beancan tester and initial timing setter.

I'm kind of against scribing lines were they will only cause confusion at a later time.

[Tony Smith]

You can do it without marking it, but you'll get a headache and waste a lot of time trying to figure out where the camshaft is supposed to be positioned when you put it back together. Get it wrong by just one or two teeth and she won't start. Worst case scenario is that if it's out too much the valves could smash into the pistons due to opening and closing in the wrong place.

I do not enjoy being the one to tell you this, but if you put a new timing chain on a crank sprocket that had worn sufficiently for the timing mark to be obliterated - you wasted your nice new chain and will be doing that job again real soon.

Oh, and thank BMW whilst you do it because the older duplex chain is near a "life of bike" part.

[Warbucks]

Thanks Tony. I'm well aware of how quickly a worn sprocket will trash a timing chain. I've never pulled a camshaft out of a boxer engine before, however I did it once on a Briggs and Stratton engine without checking for the mark. I just assumed that it would be clearly marked. When I reassembled the engine I realised there was no mark, so I had to use the common sense method to get it into the correct position while cranking it by hand. It took many hours and a lot of swearing and cursing before getting it right.

[Adrian]

Okay thanks guys - that's all really helpful - I hadn't considered a new rank sprocket so I'm glad that was mentioned. I'll do some research with Sno bum and my Clymer and Haynes also. With care everything should be fine. Some of the blogs I've read are always about caution but also say that with common sense and care its not so difficult cos these motors are fundamentally quite simple