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1966 T120C TT Desert Racer Restoration Week 2

July 7, 2015

Update 19th August

 

After some intial delays in receiving parts, progress has now moved ahead at full steam on the '66 TT! Tank mounting bracket has been re-welded on frame, together with  a Baxter's replacement sidestand bracket which was provided with the bike, and a new rear tab on the spare tank. Terry had rebuilt the bottome end, barrels are back, rebored to + 40 with new 9:1 LF Harris pistons and rods, bearings all round. Hoping the cylinder head work being undertaken by The Cylinder Head Shop will be complete by the end of the week.

 

In the end I had nuts and bolts zinc-plated by Derby Plating due to the difficulty of getting them cadmium plated - not too keen on the finish which is a little bright for my liking, but it will dull over time. I think I'll use stainless Allen screws from Andy Molnar for the covers, for practicality (remembering that this bike is being built in a desert racer style similar to that in which it had spent most of its life).

 

 

 

Frame and associated parts have been stove-enamelled and look fantastic, and John has painted oil tank, switch panel and wheek hubs, all of which look superb. Hubs have been sent to Bob Wylde's to be laced with stainless spokes to new rims from Devon Rims - I'm thinking along the lines of non-valanced alloy ones. Most TT racers were fitted with alloy rims in the late '60s and the specification for the 1968 version (which was never produced) requested by JoMo during the US Sales Conference held in November 1966 included alloy rims. It seems to me that alloy rims are therefore entirely in keeping (and the non-valanced type - similar to those fitted to the Harley XR750 flat tracker - look great!)

 

Good quality reproduction standard shocks have been sourced from Supreme - these will be kept so that the bike can readily be converted back to standard spec, if desired. Custom built Maxton ones will be obtained and fitted for general use. These are far better shock absorbers than the standard ones and widely used for classic racing - they look fantastic too.

 

Braced trials handlebars have been sourced from Sammy Miller - similar to ones fitted to Triumph desert racers and shown in photos with Bud Ekins (std bars will be stored).

 

I've been considering varous colur schemes and top of the list at the moment is Alaskan White with Sherbourne Green racing stripes edged with Gold, in the same design as original. Sherbourne Green was the colour used for the Jack Pine T100C scramblers, and was in fact suggested by Steve, the previous owner (my original idea was to have Pacific Blue stripes, in effevt a "reverse" 1966 Trophy Special design. Still undecided on this!

 

Photos to follow...

 

Week 2 (3 - 10 July)

 

Wed 8th July

Engine loosely assembled. Waiting on cams, cam bushes and correct con rod nuts from suppliers - still! (Hurry up, Supreme!) Down tools till these arrive.

 

Conrods fitted to crank, awaiting nuts from suppliers

 

Other components laid out ready for reassembly waiting pateintly for suppliers send the correct parts which have been ordered (and paid for!)

 

Original nuts and bolts packaged up ready for plating (plus surplus ones).

 

My preference is to get these cad plated, which is how they were originally. Cadmium provides sacrificial protection to the underlying steel, corroding at a slow rate in place of the steel. It is now only available in the UK for aviation and military purposes due to the toxicity of the associated waste products (what's makes an aeroplane or a submarine more important than a motorcycle, I can't help but wonder? But that's the way it is, apparently!) Our colonial cousins have a far more enlightened attitude towards it, and cad plating's widely available over in the States.

 

I've looked into shipping the lot over to a supplier in the States but all in all, I don't think it's a realistic option. Firstly, the shipping costs will be high, then it's going to add a month's delay to the build, then there's the risk of parts being lost and finally, what happens if it ends up not being done well? Not something which is exactly going to be easy to sort out.

 

The alternative is zinc plating. I'm not keen on it. It looks too bright and corrodes at twice the speed of cadmium. On the plus side, it's relativey cheap, widely available and there is a duller version, I believe. It looks like I may have to go with it. Unless I can convince someone that the nuts and bolts are off a TT Special helicopter. I suppose I'd have a better chance if this was an MV Agusta project (or even a Moto Guzzi one)!

 

(I know there's another option - stainless. I've always used it for my bikes in the past, but it seems a shame not to use the original nuts and bolts which are in great condition - and the CEI thread stainless nuts and bolts I've purchased in the past have been expensive and generally of inferior quality (the suppliers outsource them as the demand is too small to make it economical to produce them themselves. So very much a last resort.)

 

Tue 7th July

Terry Macdonald has made speedy progress with the TT restoration since it's arrival on a pallet direct from California to his doorstep a couple of weeks ago. Dry build has been completed, bike stripped back down and engine and gearbox stripped completely. Frame has been taken to John the Welder to have the tank mounting bracket brazed where it has cracked on the attachment to the frame; petrol tank has been taken to have a rear lug mounted back on and then to be painted, together with the oil tank and side panel (to John the Painter too). Once the frame repair has been completed I will take it and other parts such as mudguard stays off for stove enamellling by my contact Grahame. 

 

A pair of Smiths magnetic speedos have been sourced on eBay from the States and will be sent off for restoration when they arrive. A replacement set of forks have been found but we need to ascertain their quality - they're not cheap! Classic braced trials handlebars similar to the ones on Bud Ekins' desert sled have been sourced.

 Engine and gearbox stripped down - note lumpy +40 11:1 pistons (they're going)!

 

Terry's checked over engine and gearbox thoroughly and pronounced it to be in overall good shape, with many parts having seen very little use. It will be built as a stock TT but with 9:1 pistons instead of the 11:1 ones fitted to the TT. Hardened cams have been sourced from `Supreme, matching the profile of the original E3134 ("Racing") inlet, with an E3134 profile one in place of the standard E3325 ('Sports') exhaust. I've decided on an 18T gearbox sprocket in place of the 17T one fitted. The 18T sprocket will give it the same gearing as the T120C Bonneville Scramblers, mid-way between the TT and the T120R Road Sports (which had a 19T sprocket). I'll be using this bike as a back road scratcher with occasional trail use, but not for motorway cruising, so this seems a good set up.

 

New main bearings have been fitted and camshaft bushes (which have needed some work to fit - unfortunately parts like these produced nowadays seldom fit without some modification). Sludge trap cleaned out and new one fitted, all oil ways cleaned up.

 

I asked Terry to convert the timed breather which runs off the exhaust camshaft to a Thruxton-type one (later used on the T140/TR7). The conversion - which Terry has completed several times before - involves drilling 3 x 1/16" holes in the drive side crankcase, below and behind the main bearing and fitting a bigger breather pipe to a modified crankcase filler plug. This mod was popular on racing Triumphs in the mid-Sixties and later and is a big improvement on the timed breather, resulting in better breathing and avoiding the drips of oil from the breather pipe common to this set up.

 

Because hardened cams are being fitted (which Triumph finally did as standard in 1970) there is no need for the oil flow through the crankcase to the tappets and cams, and this has been plugged with a ball bearing. This allows more oil to be fed to the big ends and avoids the potential for oil leaks from the cylinder base.

 

The engine sprocket oil seal (part number E3876) is now removed to allow the free flow of oil between crankcase and primary chaincase.

 

Finally, the sump scavenge pipe has been shortened by 5/8" to allow more oil to fill the crankcase, resulting in cooler running. Now that crankcase oil is shared with primary chaincase oil due to the 3 holes in the drive side crankcase there will be some contamination from the clutch in the oil and this is less likely to find its way into the oil system is the oil level is higher (or so the theory goes!) This is all detailed in Stan Shenton's classic "Triumph Tuning" (page 26)

 

 3 x 1/16" holes to enable breathing via the primary chaincase

 

 ​​​​ Modified primary chaincase filler plug for fitting of big-bore breather

 

 Ball bearing plugging cam follower/cam lubrication oilway

 

Sump scavenge feed pipe shortened by 5/8"

 

I'll be purchasing a Morgo plunger oil pump (as soon as they've made some) for fitting - they're well paid and provide better oil pressure than the original.

 

Cylinder head was taken by Terry to The Cylinder Head Shop in Louth for a full overhaul. It was assessed as being in very good shape, although the seats were deeply recessed and need re-facing. Top quality Nucleus Classic Elite valves and guides will be fitted head will be gas-flowed (there was evidence of some attempted head re-working - nothing bad, but this will improve things). The Cylinder Head Shop are the acknowledged experts in this field and I'm expecting a great job - expensive, but worth it in my opinion.

 

The front of the primary cover has some roughly repaired damage, probably caused by a rock when being raced by Jed in the Mojave

 

Repair to damaged primary cover

 

Outside primary cover repair. Having cases polished but I'm not replacing this cover - the repaired crudely repaired damage in all likelihood caused by a rock in the desert - it gives the bike a bit of character, a badge of honour as a reminder of its desert racing days in the Mohave! [I revised this decision and replaced the cover with an undamaged one in the end!]

 

Overall, engine and gearbox are in excellent shape for a 50 year old bike, particularly a competition one. It is probable that Jed, the original owner, would have caried out all his own engine work and maintenance, like other racers at the time. Terry was overall very impressed with the condition of engine and gearbox which seems to confirm that, like most of the US racing fraternity, Jed was a skilled mechanic. However Terry did note some signs of hamfistedness around the timing cover, where someone had damaged the facings, in all likelihood by using a screwdriver to force it off. There were other signs of abuse, as if somebody else had been working on this part of the engine.

 

Recalling the proprietor of Bailey's Cycles words to former owner Steve when he bought the bike in 2000, and his description of Jed's nephew Bobby - on whose behalf he was selling the bike - as a "jackass" who couldn't handle the TT, it seems probable that this was the culprit!

 

 Engine loosely assembled. Waiting on cams, cam bushes and correct con rod nuts from suppliers - still! (Hurry up, Supreme!) Down tools till these arrive.

 

 Conrods fitted to crank, awaiting nuts from suppliers

 

 Other components laid out ready for reassembly waiting pateintly for suppliers send the correct parts which have been ordered (and paid for!)

 Original nuts and bolts packaged up ready for plating (plus surplus ones). My preference is to get these cad plated, which is how they were originally. Cadmium provides sacrificial protection to the underlying steel, corroding at a slow rate in place of the steel. It is now only available in the UK for aviation and military purposes due to the toxicity of the associated waste products (what's makes an aeroplane or a submarine more important than a motorcycle, I can't help but wonder? But that's the way it is, apparently!) Our colonial cousins have a far more enlightened attitude towards it, and cad plating's widely available over in the States.

 

I've looked into shipping the lot over to a supplier in the States but all in all, I don't think it's a realistic option. Firstly, the shipping costs will be high, then it's going to add a month's delay to the build, then there's the risk of parts being lost and finally, what happens if it ends up not being done well? Not something which is exactly going to be easy to sort out.

 

The alternative is zinc plating. I'm not keen on it. It looks too bright and corrodes at twice the speed of cadmium. On the plus side, it's relativey cheap, widely available and there is a duller version, I believe. It looks like I may have to go with it. Unless I can convince someone that the nuts and bolts are off a TT Special helicopter. I suppose I'd have a better chance if this was an MV Agusta project (or even a Moto Guzzi one)!

 

(I know there's another option - stainless. I've always used it for my bikes in the past, but it seems a shame not to use the original nuts and bolts which are in great condition - and the CEI thread stainless nuts and bolts I've purchased in the past have been expensive and generally of inferior quality (the suppliers outsource them as the demand is too small to make it economical to produce them themselves. So very much a last resort.)

 

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