SWM Guanaco from Gori: completed bike

The finished bike; prepared for trials and ready to use. It’s now a Guanaco, but with some better bits

The project has finished, but has taken a little bit longer than expected: too much work and too much holiday.

The bike is now more a 1978 – 79 Guanaco than an 1981 Gori because of the paint scheme change, but it has the good bits (which as I have an original 78 Guanaco I can vouch for).

Completed bike

These include:
– clutch action. The engine is a 1981 133*** serial number rather than an earlier engine (78 engines are usually 110*** approx). One major difference in the later engines is that the clutch arm has ball bearing races which provide a smoother clutch action.
– Betor front forks and yokes. seem more responsive; slightly steeper steering angle also.

The engine pulls well and with the change of barrel and piston it runs really smoothly and has plenty of poke.

Original and the 'project'

Comparing the converted bike to the original 1978 Guanaco, there’s not too many difference. Most noticeable is the Betor front forks, and a slightly different steering angle. Apart from that, much of the bike is same, including frame, engine, tank, exhaust and the rear cush drive arrangements of the early SWMs

Getting there…

It now looks like a 79 SWM, but doesn’t really run like one.

The engine is back in the frame and running. The only problem was that whilst it was ok at tickover, there was a complete lack of power under load and it wouldn’t really rev out.

So, after think timing, disk valve, carb set-up, crankseals and all other nasty thoughts, 10 minutes in the shed with Gavin and hey-presto. Running it without the end-box on the exhaust and no problem. The exhaust back-box has never been cut, weighs a ton and is obviously blocked.

Looking the part

I used some petrol on it, followed by a blow-torch on a long pole to try to loosen the crud, but although better, its still not perfect. So time for surgery and cut it open and potentially remove some of the baffle plates. Did this on the Jumbo and its run fine since.

Ready to finish ?

Cutting the rear box open revealed the problem, one of the baffle plates had come loose and was pushed back against the next plate, basically blocking the flow and any power from the engine.

Surgery for exhausts

Got Pete to weld the box together again (did a good job) and resprayed it with stove black. Job done. Put a new front brake cable together and installed the new plastics. Completed bike.

The Gori->SWM project

The aim originally wasn’t to restore the bike, but this seemed to be the best course of action…it was too good to split for spares.

The only problem is the restoring a Gori is that the green plastics are not available. The tank had already been sprayed a different colour and the only things I had to work with was the already faded (and painted) side-panels.

Prior to Strip

So, as its mainly an SWM, I could “convert” it ethically. Though a 1981 bike (I think) the yellow SWMs of the period had different frames (no bottom loops) and were not cush drive. Having both a 1978 and 1980 SWM, the best option would be to make it into a Red/White SWM, though it would have different steering geometry, Betor forks and some other subtle differences. Also, both front and rear plastics were available for the early SWMs so decision made. She’s going Red and White.

The strip down showed the following:
– the kickstart shaft splines had been rounded slightly, but were no worse that those on some of the other bikes. The bottom knuckle had been renewed, but it did seem to be thinner than normal, so perhaps this was causing it to slip off.
– the barrel, bore and piston all seemed fine, with no marking and no obviously large gap between piston and bore.
– the clutch plates were firmly glued together by old oil and lack of use. Will run up the bike and then see if the clutch plates need replacing, but should be ok.
– the clutch basket was badly notched, preventing the plates moving under action. Filed these out to allow for smooth movement


– On Gavin’s TL320, when he reassembled it, there was a significant knocking that was caused by the gaps between the conrod and the crankshaft being greater than tolerance and allowing for too much free play. This also seemed to true for this crank, so split the cases and pressed the crank so that the gap was correct. – the flywheel was of the better, heavier type so all seemed good there.

Crank setup

– the frame was straight, with no dings in it, as was the swingarm, forks and top-yoke.
– the original rear shock units worked, but would probably need replacing if the bike was going to be competitive.
– chain and sprockets were all servicable and should be ok with a clean-up, rather than replacement.
– the carb worked fine after an initial clean, so should be ok with some further cleaning. The exact jetting needs to be checked however; the jetting seems to be different for every bike I’ve seen.

The strip down went ok, except that removing the front boss/bolt on the crank took some heat, a long bar and two people. It’s a standard left hand thread btw; iie normal (we had to check…). Compared with some of the other bikes, engine is in good condition and really looks it hasn’t done too much work. The small and big end bearings have been swapped before at some point (the old ones were supplied in a box).

So onto the rebuld and sorting out the paintwork.

Rebuilding the engine wasn’t too bad. The test run of the bike showed that all the gears were there and hopefully by keeping the gear cluster and selector in place I’ve managed to ensure that all the gears are still there.

Spent sometime cleaning the clutch plates and removing all the old oil. The clutch cover and cases are all fine, with no holes or cracks, which is a good sign for an SWM. After sorting out the big-end side gaps, also cleaned up the bottom chamber, which as it had been stood for a while, the bike had picked up marking on the magnesium. Nothing too serious.

So the decision was made, to turn the Gori into a Red/White SWM, so set of work on the frame and tank.

A neighbour shot blasted the frame for me and I applied a liberal amount of Nitromors to tank, followed up by some time with an air-sander.

With painting, I had a couple of choices:
– powder coating; though this is what I’d done with the Jumbo frame, I’d not been too happy with the final durability, as the coating on swingarm had split and flaked.
– painting, could get a local paint shop to do the work on frame and tank
– paint it myself.

I learn’t a while ago that although tempting, doing your own paintwork could at times be a little fraught and be time consuming. Trouble was, that it was a while ago, so the lesson needed re-learning all over again. Though I had access to a compressor and sprayer, I wasn’t that keen on getting involved with two-pack paint. So a trip to Partco and Halfords quickly identified that VW Mars Red is a very close match to the original red.

With the aim of producing a decent bike that could be used in local club trials. and maintained cheaply, I thought that this may be a good option. So 2 tins of VW Alpine White, 4 tins of Mars Red, some primer and some petrol proof lacquer were purchased.

Frame Respray

The frame came up really well and finish was pretty good. The only problem was when I put the lacquer on the tank and it effected the lining (black lining used in modelling) and caused it to move slightly. The only other issue I had was with the plastic (and green) side panels. You can’t currently get the red panels, so opted for spraying with plastic primer and then red and white cellulose. The finish is not brilliant and it shows up some of the scratches and marks on the panels too well. But overall not too bad.

Tank preparation

The Gori Details

A quick review of what I think is a 1981-2 Gori

Ebay is you friend, well sometimes. Just for a change the bike turned out to better than than the listing (well before the engine strip). The bike was complete and the unique paintwork wasn’t too bad. Its a Gori as there is some green paint underneath the tank


The bad bits:
– I don’t know if it runs (yet)
– can’t select all of the gears, but know what that feels like after an engine build.
– the kickstart shaft spline is knackered, no change there then. There is a new kickstart bottom knuckle, which is a plus
– paint job, a little non-original

The good bits:
– its complete (good for spares or repairs)
– its been kept in the dry and been maintained, so overall the

Just need to work out what I’m going to do with it, but I think a restoration is the best option. Getting it back to its geniune Gori status (in terms of colour etc) would be good, but maybe easier to make it a red-yellow or yellow SWM