That Montjuic of mine

I’m just binge reading this thread which I’d been meaning to do for ages.

Slow but good progress Andy. I’d heard the Laverda ownership can be painful, in more ways than one. I’m loving the hand holding and advice from different quarters, which I suppose is a real benefit of posting a step by step rebuild.

Good luck with the house too

Andy,
Put a pick up of a shim.
I have an idea which might work for you

NeilDD said:

Andy,
Put a pick up of a shim.
I have an idea which might work for you

Click to expand...

I can do that later this morning.

Bucket and shim


and the other way up


Those marks on top of the shim are nothing to do with me but some of them look as if they’ve had a grinder on them.

The dimensions of the cap/bucket are
25mm outside diameter
21.5mm inside diameter
Overall length 26mm
Depth of bore 24mm

The shims are 10mm diameter, 6mm bore, 5mm long.

I previously looked at punching out some hard shim and putting it in the bottom of the bucket part because while there’s a radius in the corner it’s undercut so a shim would stay where I put it but I’d always be worrying about something going wrong so abandoned the idea.

I’ve only checked two shims so far and they’re right bottom of the size range so things are looking good up to now

New bearings now ordered for delivery tomorrow. Because I’m part of the “I want it now!” generation I happily paid extra for next day delivery

Bugger,
I was hoping they were flat shims.
When I was running the Kawasaki funny bike we used to make our own shims out of silver steel, which was then heated and quenched in oil.
We could make them to within a thou' accuracy

NeilDD said:

Bugger,
I was hoping they were flat shims.
When I was running the Kawasaki funny bike we used to make our own shims out of silver steel, which was then heated and quenched in oil.
We could make them to within a thou' accuracy

Click to expand...

If I end up struggling I’ll make some 20mm diameter flat shims but it’d be a last resort because I’d worry about them wobbling at high speed and wearing the shim caps because they’re not particularly hard. You have to pull them out using an Allen key in a 2mm hole close to the top and I put tiny little burrs on them which stoned off remarkably easily.

Right now I’m halfway through removing the valves and using a 25mm Scotchbrite flapper in a pencil grinder to ease the caps in the bores because they were bastards to get out and I don’t want that if the engine is in the frame and I need to re-shim it. They were minimum clearance (0.015mm) originally so I’m going out to 0.04mm clearance which is still less than the maximum permissible.

That’s me done until the bearings and some 8mm studding arrive so I can at least do a preliminary check of the valve clearances.

Those pesky Italians like to make life difficult don’t they? I’ve been looking at the destruction manual regarding setting the clearances and they say check with everything bolted down and the cam chain adjusted then remove the cam chain tensioner completely, split the cam chain, slacken the head bolts between the ports both sides, slacken the head studs, remove the bearing caps, remove the cams, change the shims then reverse the procedure and check again.

I can understand slackening the head bolts because there’s a chance of distorting the head if it’s only pulled down on half the bolts but it’s not going to be a quick job so I’ll take a major chance and give myself plenty of clearance when I order shims. I’m not sure what the previous owner had done with the shim that was originally fitted to the valve that had been seated deeper than the others but it’s 0.6mm thinner than anything Laverda ever supplied

I know I ordered next day delivery for the camshaft bearings but 7:30am when TNT knocked at the door I hadn’t even got out of bed.

None of that cheap shit stuff from Amazon when it comes to engine work so SKF bearings were ordered and they’re silky smooth unlike the clunky things that came out.



After that it was just a case of tabulate the shim sizes for each valve then put the head on and fit the cams.



I’ll check the clearances tomorrow because I’ve got other things to do this afternoon but I’ll be ordering a supply of M9 nuts to replace the originals which were obviously previously tightened with either an open ended spanner of a cheap and nasty socket. Why M9? It’s a non-preferred size and if M8 wasn’t going to be strong enough I’d have gone to M10 but those Italians like to be difficult.

My wife thought it was hilarious when I made a spreadsheet for the shim sizes, clearances etc then printed and laminated it so I could use a sharpie pen to write on it with oily fingers but I’ve lost so many scraps of oil stained paper over the years that I don’t take the chance now.

AndyB_11 said:

I know I ordered next day delivery for the camshaft bearings but 7:30am when TNT knocked at the door I hadn’t even got out of bed.

None of that cheap shit stuff from Amazon when it comes to engine work so SKF bearings were ordered and they’re silky smooth unlike the clunky things that came out.

After that it was just a case of tabulate the shim sizes for each valve then put the head on and fit the cams.

I’ll check the clearances tomorrow because I’ve got other things to do this afternoon but I’ll be ordering a supply of M9 nuts to replace the originals which were obviously previously tightened with either an open ended spanner of a cheap and nasty socket. Why M9? It’s a non-preferred size and if M8 wasn’t going to be strong enough I’d have gone to M10 but those Italians like to be difficult.

My wife thought it was hilarious when I made a spreadsheet for the shim sizes, clearances etc then printed and laminated it so I could use a sharpie pen to write on it with oily fingers but I’ve lost so many scraps of oil stained paper over the years that I don’t take the chance now.

Click to expand...

What's with the 1.15 shim.

That’s the one from the valve where the previous owner had ground the seat down miles too far. You won’t be able to read the sheet with your knackered eyesight but that column is for shims fitted now and before I’ve checked clearances and sorted out the new sizes. I’m expecting a maximum of 0.30mm variation because the seats all looked the same as did the valves.

Once I’ve checked the clearances and written down the sizes needed I’ll take the shims out and double check them before ordering the new ones because they’ve got to come out at some point.

I got bored again later this afternoon so fitted the cam chain tensioning slipper and dropped the adjuster mechanism in the tank to clean it up ready for fitting. I even fitted the inlet manifolds and adaptors just to get them out of the way before finding that I need to find some M7 nuts for the exhaust clamps because the old ones are rounded off and the only ones I’ve got have nylon inserts so not a good idea on exhaust headers

There was a few minutes drama when I fished the cam chain adjuster out of the box I stored it in weeks ago and got it in my head there should be a spring between the housing and the plunger because a solid adjuster just doesn’t seem a good idea. I ended up looking through a parts list I’ve got amd there’s no spring in there but then I had a poke at the slipper which is only attached at the top and it dawned on me that it’s a long piece of spring steel with a length of wear material bonded to it so there’s the give in the tensioner that a spring would normally supply.

I’ve also been promised that I can collect the wheels next Tuesday. I’ll have a word with his dad about that boy

Now I’m pissed off. The weather forecast was good for today so I sprayed the exhaust with 2K heat resistant paint then left it outside to dry and it’s just started raining. I might get away with it but if it goes to shit I either buy another can of the same paint or decide I’ve got a good base on there and just fire some normal VHT paint over it as a top coat

I’m waiting for cranked feeler gauges to arrive so I can do the valve checks and thought spraying the exhausts would see them done and stored out of the way ready to fit when the rest of the job is done.

I reckon I’ll need to give the exhausts another coat of paint.

Bugger

There’s no point in messing about so I’ll order another can of 2K heat resistant paint. They should be matt black which also hides some of the surface defects you get with a 40 year old lump of mild steel and now I’ve seen the gloss finish I’m not sure what to go with.

I’ve flashed over the steel plate that holds the carb tops on and operates the chokes but that was with Hammerite because I’m a cowboy and couldn’t be arsed trying to get every bit of rust off first

I’d go with satin black personally, if it’s available. Agree the gloss doesn’t look quite right, but it’s not a bad finish as far as the photo shows.

I wanted satin finish but couldn’t find any high temperature 2K in the finish I wanted by a reputable manufacturer. Part of the problem is that normal high temperature paints need curing at about 150c and while I can do the headers and clamps I’ve got no way of doing the main section.

I’ve got a gas bbq that I can put the lid on and control the temperature for the smaller parts (I daren’t put them in the oven in the kitchen) and using a heat gun isn’t the ideal way to do it. I can get some heat into it with a heat gun and keep gently warming it while it hangs from the ceiling in my workshop because 150c isn’t really that high and I’ve got a heat gun I can use to monitor it but I’ve thrown too much money at the job to fuck it up on something as basic as this.

Minor updates:

Firstly I’ve sourced some 2K heat resistant satin black paint from a company who make the aerosols to order if given 24 hours notice so I’ll be getting a couple of cans.

Secondly I’ve started setting the cam/valve timing with the idea that I can set them then put new dots on the sprockets in the correct positions and having excess clearance at the moment won’t be a bad thing. Sounds good but the standard settings are wrong for the higher lift and longer duration of the S1 cams I’ve got fitted and unless you can get hold of the elusive Montjuic supplement the only way to get it right is to check the position the cams start to open and close by using feelers and that needs the clearances to be correct

At the moment I’ve set the cams so the lobes on the cams are pointing towards each other at TDC which is the suggested base line setting but the timing marks on the sprockets are 3 teeth out of position (the SI cams use standard sprockets) which is about 36 degrees but I was expecting it to be 2 teeth so I’ve put a question up on the Laverda forum.

Thirdly I’ve run out of time because my presence is required by a client starting on Thursday and having not worked since the 23rd March I’m not turning it down. I’m not sure if that’s a good or a bad thing

Sounds like Catch 22- can’t set the timing unless the clearances are correct, and can’t set the clearances without the timing being right. I’m probably missing something

No, that’s essentially how it is.

I moved the cams around a bit so they’re still roughly where the guy on the Laverda forum suggested then turned it over very slowly and carefully and nothing fouled so I can now do the clearances and start again. No two people agree 100% but it seems the general consensus is that it’s a race engine, set the valve timing to give the performance you want because there’s a lot of overlap between inlet and exhaust and you can change where it produces the power. I’d sooner just be told set it here and that’s the best compromise but the race boys want to change it according to the circuit.

The hardest part of the job is getting the link into the cam chain because the valves are trying to push the cams back and it took a lot of swearing before I worked out how to do it. I moved the cam chain on the sprockets until the join was over one of them rather than between them as stated in the book then used a set of modified internal circlip pliers to wind the two ends together until the link went in. Setting the chain tension is a case of find the slackest point and adjust a plunger but mine only needed 1mm taking out of it before it was inside tolerance and I’ve loads of adjustment left to work with. The chain looked new when I took it apart and along with the new looking pistons and lack of carbon I think it was probably replaced not too many miles ago. I did fish the chain out and measure the length compressed then under it’s own weight because maximum wear is 2% of the compressed length and it was just under 1% when I checked hence me not buying a new one.

Getting the chain to skip a tooth on the crank or remove it completely is pretty easy because the oil filter is a removable/cleanable one that gives an access hole about 2.5” diameter directly under the crankshaft so you take that off then drop a small nut on a bit of wire down the chain tunnel to pull the chain through. Obviously it’s easier when the top end is off but if you do drop one end when joining the chain taking the cam out and using a magnetic probe to get the loose end works

I wonder why the book said to join the chain in the middle of the run?
It's a standard method to sit a split chain on a sprocket in order to join it.

Tarka said:

I wonder why the book said to join the chain in the middle of the run?
It's a standard method to sit a split chain on a sprocket in order to join it.

Click to expand...

I think it’s because you have to juggle the cams into the correct position and it’s supposedly easier with equal lengths of chain. It probably is if there’s enough slack in the chain but yesterday was a pain in the arse.

One suggestion I’ve received is to split the chain in the centre, put a paint dot at the top of each cam then use a cable tie to get enough slack in the chain to be able to remove the cams and change the shims. That sounds feasible so I’ll give it a go but I’m considering putting the engine back in the frame because that gives access to the hole in the bottom of the engine giving access to the chain from below so I can move it on the crank without needing to remove the slipper part or the tensioner assembly or move the cams.

I’m going to have a look at putting a straight edge over the cam sprocket bolts then use a digital inclinometer to record the angle so I know exactly where I’m moving things. Yes, it just so happens that I’ve got a small digital clino and a selection of small straight edges, toolmakers clamps etc so I can do that kind of thing.

It might seem a bit masochistic but once things get to what I consider the technical engineering side of it I’m more at ease with it because I can write down and take photos of various settings, do a spread sheet showing valve opening positions relative to TDC and then sit and look at them to compare what 1 tooth either way does. Latest advice is to advance the exhaust by 7 degrees and retard the inlet a similar amount away from the numbers in the ‘official’ valve timing tables I’ve got my fingers on. Well that would involve slotting parts but I can get 6 degrees on the sprockets so I might give it a go because it’s supposed to give an increase in mid range for a tiny drop off at the top which would certainly suit my needs more than a peaky engine.

I’ve got a wide angle endoscope I use for work that I can put in through the spark plug hole to have a look at valve/piston clearance to reassure myself if I get worried