I am more used to fettling Big Zeds from Kawasaki than Vee Twins, but have an 850 MK1 to restore. The engine isn’t high mileage, but there seems to be more slop in the guides than I would expect in a Z1000. The earlier Z1/Z900s used bronze guides which wore out pretty fast. There also doesn’t seem to be any valve stem seals. Assuming that I’m going to have to replace the guides, is it possible to get guides that have a fitment for stem seals? I’m presuming that the original guides are bronze; are there cast iron ones available for retro fit or are the valves stainless? I don’t have three angle valve face cutters big enough for this head and given the cost of them, it’s not worth the investment for one pair of heads. Is there anyone who specialises in these heads. I do wonder if it would benefit from harder valve seats while it’s under the knife, given how crap modern petrol is? Big Kwakas are very tolerant of the pump crap available these days, it’s only the alcohol that causes problems rusting tanks and corroding carbs due to the hygroscopic nature of the muck they ruin our fuel with.
I was rather surprised to find a screw on cartridge oil filter can INSIDE the sump Is that likely to be some worm of ‘upgrade’. I know big Laverdas can have filters added as an upgrade as the original factory considered a coarse gauze sufficient filtration
I need to strip the distributor for cleaning as it’s minging as is all the motor. It had a form of electronic ignition pick-ups inside with all the bob-weights gone for the original cam. It looks as though I need to remove the driving gear from the bottom of the shaft which appears to be held on with a taper pin with one end ‘riveted’ with a patterned punch in the factory? Does one need to drill grind of the patterned rivet reaction off to drift the pin out ? I ned to change the bearings as well as they don’t feel too special so it has to come apart. Oddly, above the gear is a spacer that is held with a roll pin which is designed to be easily removed. It appears that the advance/retard plate is permanently joined to the shaft? or have I got it wrong?
With regards the head and valves refurb, Seager Engineering do some pretty amazing work. They are near Ipswich.
Alternatively Nigel at NBS in Stafford is a Guzzi expert.
The oil filter inside the sump is factory standard fitment.
It sounds like you could do with a manual and parts book to see how things come apart. You will find them all here. https://www.guzzitek.org/gb/accueil_gb.htm
I was advised not to add seals to the valve guides. It may be nonsense, but the wisdom is that they need a bit of oil or they wear rapidly.
I had mine K-lined, which keeps the concentricity with the seat and avoids re-cutting.
Ian
I’ve had two of the older big blocks over several years, never lost oil through the valve guides. If they needed seals they would have been fitted at the factory, so obviously don’t need them.
Yes the filtet cartridge is inside the sump I’m afraid, so a bit of a pain. However gives the opportunity to wash out the sump pan with petrol + paraffin, which I did every time it was taken off.
I was concerned when unleaded came along, but was assured the seats are unleaded compatible, and so it has been proved. (Whereas my R80 needed upgraded seats and valves.)
1000s, 4 new guides, 2 hardened exhaust valve seats+2 new exhaust valves… it had done about 30000 miles.
The dreaded unleaded had done the exhaust valves and seats.
I don’t need to set up a DTI to determine there’s a shed load more than 2 thou slop in the guides! I mic’d up the valves and they’re well within spec.
I guess if there isn’t a whole lot of oil sitting on top of the guides in this head design perhaps seals are unnecessary. Doggy stem seals make Big Zeds smoke like a pig when they start as there’s a shed load of oil sat on top of the guides and that doesn’t drain down. I guess with a Vee Twin it’s less likely to sit there. That said it may go some way to explaining the early demise of these guides on a low mileage bike.
Are sump gaskets especially expensive on this model? The original owner had used a cereal packet fashioned gasket, which in fairness hadn’t failed; but did offend my engineering sensibilities
I suspect that burying the oil filter in the sump may discourage regular filter changes, which could explain why the engine internals were so filthy. Surely the whole point of spin on cartridge filters is they they are easy to change and from the OEM’s perspective easier to add to an engine design than making a place in the motor for a more environmentally considerate naked filter element as on most seventies Japanese bikes, before the bean counters took charge.
The owner wants a 950cc big bore upgrade; I presume there’s enough meat in the liners for this?
The solution to upgrading to 950 is a barrel and piston kit, usually made by Gilardoni and has Nikasil lined bores. You should be aware that the crankcase mouth is to narrow to fit the standard Guzzi 950 round barrel cylinders .
The kits coming up on a quick search (Gutsibits and Stein Dinse) are the low compression T3 versions.
General opinion is that the extra 100cc makes very little difference.
There is a 950cc kit on the club Facebook buy and sell page at the moment.
I am not sure if your barrels will have liners. Most were plated with chrome or Nikasil onto the alloy bores.
The compression ratio is higher on the Le-Mans than the T3 etc. I don’t think Guzzi ever made a high comp 950cc round barrel model. I would have thought it to be a backwards step to fit a 950 low compression kit to an 850 Le-Mans
Would it be possible to use pistons from something like a Le-Mans 3 in a round barrel engine?
I guess Guzziology would have the answers to such a question.
It might be possible to bore out chrome or Nikasil plated bores but the finish is very hard, then you would have to get them replated. Although in theory not impossible I believe that it would be difficult and so quite expensive.
My own experience with Convert barrels is good, I am happy with the lower compression than a Le Mans as it runs well (from distant memory) at lower revs. As I have had the heads reworked to take larger valves and 36mm carbs with accelerator pumps, when a bit of acceleration is required it does that too.
The other benefit of lower compression is that the engine is not trying to force oil out of the gaskets. I cannot wait to get it running again. Maybe next spring?
Bear in mind it’s an upgrade on previous models, which had no oil filter at all, apart from the wire gauze pick-up strainer (which is still included). Hence there was no obvious place provided to put an external spin-on filter. However there is, or was, a sump extension kit that provides external filter fitment. Won’t be cheap though.
Standard LM1 850 also had liners in alloy barrels, so I think the answer is ‘no’. Having had one, pretty sure the liners aren’t thick enough, and have never heard of it being done. Most usual route is 950 conversion kit.
i convetred my t3 cali in the 80s to 950 cc with a lemans pistons and heads kit.
the 950 barrel spigots are too big to fit cankcase and can be machined to fit, not really recommended tho. The way i did it was have crank case mouths machined to fit ( this can facilitate larger barrels up to 1000 or maybe 1100 i was told by teo lamers in nijmagen, a long time ago) my pistons are 88mm.
anywayi wish you good luck. charlie calimans
Gutsibits, "Complete 950cc big bore piston and barrel kit including gudgeon pin, piston rings and circlips. Piston is Le Man spec (higher compression) and barrel is Nikasil coated.
“Components for one cylinder, this kit has narrow wall barrels and is designed for 850cc crankcases which have a smaller aperture for the barrel.”
£299 inc. VAT each, (2 req.d) cheaper than I expected to be honest!
This looks like a sump extension for an external filter click here but the add doesn’t say so and there is not a photo of the threaded projection. If you are interested you could ask the seller, it is very cheap at the moment.
Is that likely to be some worm of ‘upgrade’. I know big Laverdas can have filters added as an upgrade as the original factory considered a coarse gauze sufficient filtration 
