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RENOVATION PROJECT OF 1972 YAMAHA YR5
BY STEPHAN MORRIS

Parts 15-19

The R5 is a complete redesign from the previous R3 model, with very few common parts, and the last model before reed valves and disc brakes were introduced on the RD350A model in 1973. Many R5 design features went through all subsequent air cooled models until the LC in 1980 such as the frame and swing arm design, oil tank as side panel, crankshaft and crankcase design. Even the LC models still used the same base gaskets as the R5 demonstrating similar crankcase design, and it was not until the powervalve (YPVS) models came out in 1983 that 5 cylinder studs were used instead of 4.

The rebuild has been shown here in chronological order, it is possible to jump to any installment by clicking on the links below:

March 2008 - Part 15
OK then dear reader more progress to report with this restoration. Exciting times! I collected the parts sent for powder coating from Triple S in January. The great work that they have done in the past - which is the reason I used them again - has been repeated I am pleased to say. There are loads of pictures of nice clean parts to see this month.

I have also fabricated some parts from stainless steel sheet myself - some parts that I wanted in stainless steel but could not be made by manufacturers.

Other news is that I have found some new flashers from Steve Cooper, an expert on old Yamahas with whom Paul put me in touch. £110 for four flashers, which is £10 more than I paid for the bike back in 1980 but there you go. To summarise where we are now:

1. Wheels taken for stainless steel spokes and rims but cannot contact the business to which I took them. Bought new second hand ones off eBay and have yet to take them somewhere else.

2. Paintwork still to be returned from Dream Machine.

3. Clocks need to be stripped and the cups chromed. Still trying to find someone to do this.

4. Waiting for the shocks to be returned from Rob Evans, but should be ready soon.

5. Some parts still not made out of stainless in Egypt . I have asked that the parts be returned now and I will get them made elsewhere or do them myself. I hope that they are not lost...

6. Asked Phil Denton to supply a few more things in stainless such as the rear sprocket carrier stub shaft, stand springs, flasher mounting hollow studs.

Not much left to do! I could start some reassembly in the very near future if I had any sort of deadline, but I am not sure that I will yet. I am still in clean, paint, chrome and stainless mode.

I went to the Classic Japanese Motorcycle Show at Donington Park on 2nd Feb. That is where I met Steve and bought the flashers. There were some nice restored Japanese motorcycles there. I hope mine turns out as well. Nothing much that I was interested in buying however. I can't believe the rubbish people try to sell at these places and how damaged they are not from use but abuse where perfectly good parts are thrown into boxes and jumbled about getting scratched up. Some traders do have some nice NOS bits still in original packaging, but it would be unusual to find what you want.

Yamaha R5 1972

This is a picture of the rust under the frame headstock before I took it to Triple S.

Yamaha R5 1972 stator
...and afterwards no rust to be seen.
Yamaha R5 1972 wiring
The swingarm before cleaning and powder coating.

Yamaha R5 1972 stator

...and after
Yamaha R5 1972 clutch
This is the end of the swingarm showing the slot where the wheel spindle goes through and has space to move backwards to tension the chain. The marks should show the same distance both sides of the swingarm so that the rear wheel is not misaligned, but they are notoriously inaccurate. If I assume that the swingarm pivot shaft is correctly located in the frame, then I can check the accuracy of my swingarm by measuring the distance from the front to the marks at the back.
Yamaha R5 1972 parts
This is the bottom of the centrestand with the old black paint only concealing a small area of rust.
Yamaha R5 1972 clutch removed
…and the beautiful finish achieved by Triple S. Should I carry some carpet with me whenever I ride it to avoid scraping up the bottom of the stand?
Similar standard for the sidestand…
…and the footrest bar.
The licence bracket and the tail light base were the only two items painted in silver.
This was the top of the bracket before painting where you will recall I had removed a small dent.
Now invisible I am pleased to say.
The bottom yoke looks better than new.
This is the sidestand bracket I made and got welded to the bottom of the frame.
This part of the frame under the top frame rail locates the airbox. A metal tang goes through the slot and the hooked part retains a rubber grommeted post.
Yamaha R5 powder coated frame
The complete frame
More frame detail showing where the footrest brackets bolt on and how the necessary areas have been masked to avoid powder coating where it is not wanted. The good thing about Triple S is that they understand motorcycles, so you don’t have to specify things like this – they get it right anyway.
The front part of the frame showing the casting for the steering lock, the petrol tank locating fixture, and the post at the bottom retains the steering damper friction plate.
Cylinder heads came up well
Front view of cylinder heads
Yamaha R5 powder coated head
Top view of cylinder heads showing central spark plug hole and the four holes for the cylinder head sleeve nuts
Cylinder heads after I removed the coating from their sides and the edges of the fins
Number plate completely black
Halfway through removing the coating from the numbers and letters. This has to be done very carefully to avoid marks on the black surface
Finished number plate very classy in black and silver denoting no road tax necessary!
Seat bitties - these are the two hinges and the seat closing bracket and lever
This is the right hand footrest bracket/brake lever pivot plate before restoration
…and after restoration
The clutch cover as it came back from Triple S. The oil pump mounting plate remains uncoated as does the recess for the kickstart shaft oil seal
Same clutch cover with the oil pump cover in place
Here is the left side engine cover showing the mounting position for the clutch adjuster
…and with the points cover in place
Where the allen screws go through these engine covers to attach them to the crankcases, it is necessary to remove the coating so that the base of the allen screw contacts the aluminium of the cover. If this is not done, then the powder coating cracks around the base of the fastener. As Paul has shown elsewhere on the website, a modified stepped drill is best to do this work.
Left side engine cover with paint removed from the raised ridges to give the characteristic appearance of the engine of R5 and DS7 models. This changed for the RD250 and RD350 models. Clutch adjuster cover now in place.
Clutch cover after the same work was done. The stepped drill would not reach some of the holes on this cover, so it needed some careful work with a small grinding stone on a Dremel to remove the coating
Cylinders also look pretty
Shiny black surfaces
347cc from 64mm bore by 54mm stroke.
Cylinders and heads with all superfluous powder coating removed now looking like a proper top end!
This is the tail light base as it was when removed from the bike in 2006
…and now all silver and shiny. The earth lead was riveted to the plate where the hole is in the centre here. When I reattach it I will use a nut and bolt.
Those of you paying attention will remember that I was really pleased to have found this battery box stay from the Swedish Kawasaki importer recently, but it is not stainless steel, so I had to make one didn’t I? This is the rough shape in 2mm plate.
I then marked it up and cut it away to get a more accurate shape…
…then bent it and drilled it as you can see and polished it up a bit to look pretty

This is one of the original flashers showing the corrosion manifesting itself as the whitish specks you can see here. All four were like this – not bad, but not good enough either.
Steve Cooper sold me four original Yamaha flashers to replace my original ones. Yamaha varied the specification for these flashers quite a lot in the early seventies. These were not quite the same as the ones I had because the mounting studs were longer and they were solid instead of hollow with the wire coming through the middle. The arms were also different in length to mine, but Steve convinced me that mine were incorrect! I will now fit two different lengths, longer at the back and shorter at the front.
Two of the flashers had this type of bulb holder, and two had the type shown in the previous photo.
This is one of my original flashers. I took this reflector out to replace the type shown in the previous photo
Before and after cleaning the reflectors
The original flasher mounting washer is shown on the right here. These are now unobtainable from Yamaha, and difficult to make because they are not circular, and have a rim around the edge as you can see in the photos below. I decided to make my own and design in tangs to bend over to retain the washer in the correct position in use. Basic cut out shown above, which is the oval shape on the inside of the original washer, and the tangs to be bent over.
Drilled and tidied up…
I realised that the top tang would not bend to give the right shape because of the curve on that part of the oval, so I made two smaller tangs instead. 240 grit wet and dry gives this finish.
…and bent to the finished article
Inside view
This is how it fits the flasher mounting damper
Other end
…and how it will look when assembled.
Here are the before pictures of the speedo…
…and tacho, showing marks from cables on the chrome surface. I must send these away to be disassembled and chromed because special tools and methods are required. Watch this space!

June 2008 - Part 16
Well it’s been some time since the last instalment. Some of you have even noticed and emailed asking me what is going on! Paul has not been pestering me too much because he has been busy with other projects, and there were so many photos in number 15 that it was a lot of work to configure them for the website. He has asked for the photos in a more easily uploadable format, and that is what I have done this time. I am not sure how the appearance will change…

So although I have not been working on the project night and day there are a few things to report.

Overall the idea to get stainless steel parts made in Egypt was not a good one. Everything took a long time to do, some of the parts were so badly made I could not use them, I had to refinish virtually all of the parts that would actually fit and work OK, and some of the parts were never made at all. After a long while with nothing happening, I asked for the remaining parts to be returned to me. I would either get them made here in the UK or make them myself, although the former is expensive and the latter amateurish. Even that went wrong and there were 10 parts that were apparently lost, but they did turn up a couple of months later after they had insisted that I did not send them in the first place!

Those parts that could be made on a lathe or a milling machine or both were sent to Phil Denton in North Wales. He has made quite a lot of items for me in the past and they are superb quality – better than new not only in terms of the material used but also in the manufacture.

I collected the paintwork from Dream Machine, but there were a few items that were not quite good enough. They unhesitatingly agreed to repaint these when requested. I now have all the items back.

I also collected the wheels the same day from Central Wheel Components. All I have outstanding now is the seat which is ready for collection, some small stainless steel items from Phil Denton, and the clocks. I should be able to get all these in time for my friend Dave’s visit from the US to help me start the rebuild in mid July!

One of the problems with the cylinder head bolts made in Egypt was that the internal threads were not parallel with the axis of the bolt. The two upper bolts are original, the two lower ones are made in Egypt.

I have asked Phil Denton to make eight of these for me.

One of the parts that was not made was the steering lock cover, and I knew that being fabricated from sheet stainless, not bar, I could not ask Phil Denton to do it, so I did! Here is the bit of 2mm stainless steel sheet I used as my raw material, and the original item.

I scratched the shape of the cover onto the piece of stainless using a Stanley knife and the original as a template, then cut away excess metal and ground it back to the scratched line. The shape of any bent metal must be measured and incorporated into the shape drawn. A scratch is more durable, easier to see, and a thinner line than pencil or similar.

I tidied up the edges, then drilled the hole for the 4mm screw I will use to attach the cover to the steering lock housing. I will need to make a 4mm thread in the frame to take the place of the original rivet. A thread and screw allow for much easier disassembly, but it will need to be checked occasionally for tightness because the cover pivots on the screw and may loosen it. I then marked the position to make the circular boss that locates the cover in the closed position when it engages the indent in the steering lock. I made a tool with a 5mm bolt by making the end spherical as you can see, and then pressed out the boss with the vice into the recess offered by a 5mm nut…

…this worked quite well as you can see, except that the boss is slightly too big – I should have used a 4mm bolt to make the tool. I reckon this will be OK for now.

I cleaned up the edges and bent over the lugs. It is difficult to gauge exactly where to start the bend for it to finish up in the right place. If you mark a line as a position to start a bend, in practice, the bent surface always extends a little back from that line even if it is clamped tightly in the vice. Anyway, finished item looks close enough to the original and will not rust!

This photo and the other photos of rusty wheels were in instalment 13. I reproduce them here to show the contrast between unrestored and restored.

This is the front wheel brake drum looking somewhat better than the previous photo. The part number 246 25111 00 shows that it is the same hub as the DS6 250cc two stroke twin from 1968 I think, because 246 is the DS6 model code. The centre part of the part number is interpreted as:

1. 2 = cycle part
2. 5 = wheel part
3. 1 = front wheel part
4. 11 = wheel hub

The last 00 = part unmodified (if it was 01 it would have been modified once.)

Other side of unrestored front wheel.

Yamaha R5 Stainless Steel wheel rim & Spokes

Polished front wheel hub. I did not really want such a mirror finish because other aluminium wheel components will now need to match it using only my elbow grease! Central Wheel Components only offered this finish or the shot blasted finish for the other side of the front wheel hub you can see above however.

This rim and spokes were simply thrown away…

To be replaced with the stainless steel items you see here.

Here is the corner of the side panel before painting…

…and after painting. The finish is now better than new as you can see.

The whole side panel…

…with the chrome flash and the 350 emblem. Believe it or not it took me a few days to figure out what was wrong with this. I am sure that both of you spotted right away that Dream Machine have painted the chrome section in that lovely orange and the orange section was left as chrome!

The correct combination of chrome and paint can be seen in this pre-strip down photo!

Here is the oil tank. Fortunately I had not one but two new sets of the paint and chrome flashes in the pale gold DS7 colour. I have now sent one of these to Dream Machine for the right bits to be painted orange! Unfortunately the chrome on these incorrect parts would have been “keyed” to accept the paint, so the process cannot simply be reversed.

Here is the headlamp shell before painting…

…and after.

Here is the back of the petrol tank before painting…
…and after. I will have to protect the paintwork to prevent the seat causing the same damage.

This is a side view of the whole tank. Dream Machine replicated perfectly the pearl ivory colour of the tank – not easy to see on these photos.

The headlight bracket before painting…
…and after painting

Side - by - side. You can see where the wire went through the headlight mounting hole on the lower bracket. Obviously this will not be visible when it is assembled.

Right. Just got to make sure that I get the remaining bits and pieces before 16th July and the rebuild commences! Wish me luck, and watch this space…

August 2008 - Part 17
Dave has arrived from the States and the time for starting the reassembly has also arrived. Have I been putting off this moment? Maybe I have in a strange way. I have caught myself several times thinking that there is no reason that I could not start assembling the engine, but then putting it out of my mind as something that I should not yet be contemplating. There always seemed to be something else to do, no matter how minor, and I had become comfortable with all my restored parts in various corners of the garage. I know from experience that the actual rebuild never goes according to plan, but if I did not start it then it could not go wrong, could it? I am glad now that Dave and I had agreed that we would start when he came. If I had not done that, I am quite sure that I would have continued to procrastinate. So even though I was missing the clocks, some stainless items, the front footrests, the seat, we walked into the garage on 17th July to begin.

We did not take long to become confused. What position should the gear selector drum and forks be in when the two gearshaft assemblies are laid into place? In this position we can't get first gear, in that position we can't get any gear above second. Disassemble, reassemble many times, we could have done it blindfold in the end but we still did not have a gearbox. Sometimes you just have to walk away from things, so we did.

Let's do something simpler...

Here is the rear light baseplate that had been powder coated silver. I had removed the riveted earth lead and the wires so that this could be done. We needed to get the wires through some heatshrink tubing...

 

...and attach the earth lead with a screw and nut on the inside instead of a rivet.

The baseplate 6mm studs you can see in the first picture are used to attach it to the licence bracket with a couple of dome nuts, and the wires in the heatshrink tubing are passed through the hole and underneath the licence bracket arm as you can see here.

The rear light lens and the number plate are screwed on and then the assembly is bolted to the rear fender.

Those of you paying attention will recall the dent in the top of the licence bracket arm which is now not visible.

The rear fender is ready to be bolted onto the frame, but we will not do that yet.

Here is the underside showing the greased surfaces to protect against corrosion, and the rear light wires clipped to the side of the fender to avoid the rear tyre.

At the other end of the bike, the forks are ready for assembly. This is one of the nuts that hold each fork tube to the top yoke. The top has been chromed, and storage since then has seen the non-chromed surfaces rust as you see here.

The trusty Dremel is fired up to deal with it. When installed, these surfaces are protected by the fork oil.

The right hand slider clamps one end of the front wheel spindle. I have replaced the 8mm studs with stainless steel items and tapped out the threads as shown here to ensure fault free assembly.

The fork tube with the damper rod assembly hanging out of the bottom is inserted into the slider. The fork seal can be seen in the slider – one of the few parts I did not remove at all. I hope that they are OK!

The fork cap bolt is then screwed onto its very fine thread specially designed to make cross-threading easy! You can see the large washer just next to the O ring in this photo.

Then to borrow the famous phrase repeated many times in all Haynes manuals, “…assembly is the reverse of disassembly”! In this case that means compressing the spring under my pillar drill bench again, and using an impact driver to tighten the socket head screw that holds the damper rod assembly in place.

Finished articles on the carpet in my garage.

Dave’s help was invaluable while he was in the UK . Here he is putting in a front wheel bearing, using an old one as a drift. It was just the right size for the job. In fact by the time the new bearing had seated, the old one was stuck! Real experts the pair of us!

I was really pleased with the wheels when I got them. The only problem was that they could only polish the hubs or leave them a very rough finish. I did not really want them polished because I knew that the brake plates would look bad in comparison. Here is what I mean. In fact it looked worse than the photo shows. I could only make the hub look worse, or the brake plate look better, so obviously I had to choose the latter, at the expense of much elbow grease, both mine and Dave’s.

We started to sand the brake plate with increasingly finer grits of wet and dry. This dark ridge near to the edge of the plate was a real pain because it took ages to get rid of it using the wet and dry.

I resorted to the Dremel with its little sanding disc.

I resorted to the Dremel with its little sanding disc.

…and then wet and dry to remove the marks left by the Dremel.

This is the finished result. Yes I know it looks little different to the before photo, but it is not through lack of trying! In fact the photo struggles to show the difference that Dave and I convinced ourselves we could see.

Further additions to this catalogue of errors to follow soon!

September 2008 - Part 18
Hello All No preliminary waffle today – just pictures and notes.

Dave greases up a front brake cam.

The front brake plate is assembled and ready to install

Here it is on the wheel. Soon after this I reversed the two pivot pins on the long lever to conceal the R clips.

Here is the rear wheel with the chain puller, brake lever and brake torque arm installed.

The oil tank looked superb when I got it back from Dream Machine, but for some reason they had not finished the dipstick holding tube properly. I think that they thought it has a hose that goes over it as does the breather hose tube you can see next to it. In fact the dipstick sits on the lip at the top of the tube. I will just handpaint it with something to stop any rust because it is not visible under the seat. Here I am removing the old paint with a little wire brush on the Dremel.

The edge of the filler cap had a ridge of paint as shown here on the upper right of the recess which would have been prone to chipping in use. I stuffed a rag down the hole and sanded it down with the Dremel to the smoother edge you can see bottom right of the recess.

The ridge underneath the tank was slightly damaged where it had been sitting before the paint had fully dried I guess. I just put some white enamel on it.

Here we are fitting the Yamaha emblems onto the petrol tank. We needed to apply a bit of heat to get them to match the tank contour.

Petrol tap bolts on underneath the tank on the left. The hose to the right connects one side of the petrol tank to the other so that all the fuel can be used and the right side of the tank is not isolated. The clever design routing this hose under the frame tube means that every time you take the petrol tank off, you must disconnect this balance hose, lift up the tank and then reconnect the balance hose. While you are doing this, the rear of the engine is automatically cleaned by a shower of petrol.

…and here is the sub-assembly completed. No not Dave! (Stephan claims that Dave actually enjoyed his holiday-Paul)

Powder coated frame in all its glory before we started bolting things onto it.

This is the battery box which goes in the centre of the frame. The regulator sits under the battery and can be seen through the square cutout. The rectifier sits underneath the regulator and is held in place by 6mm nuts on the stud that goes though its centre. The wires from the rectifier and regulator can be seen at the bottom of the picture going down to the V of the frame. Later they have to go up the side of the battery box where they are held in place by the clip you can see and they join the wiring loom under the seat. The electrics on this bike are not the best designed in the world!
Here is a front view of the regulator on top and the rectifier underneath.

This is the right side of the frame showing the wiring loom.

The coils sit underneath the tank and above the engine.

Dave fitted the bottom steering race on the bottom yoke and then placed the balls on the race holding them there with grease. He also greased the shaft of the bottom yoke to prevent corrosion. We did our best to exploit the scope for sexual innuendoes in this situation. I am sure that any ladies who overheard us would have been offended, but genuine humour was somewhat lacking!
Bottom yoke fitted to steering head. We removed the paint from the lockstops so that the inevitable damage had we left the paint in place did not take place and possibly crack the adjacent paint surfaces as well. The top bearing cover and the castellated nut were made in stainless by Phil Denton and look superb

Top yoke and handlebar holders in place. The clicker for the useless friction steering damper can be seen behind the steering head nut. It sits inside a big black plastic knob and clicks from one indent to the next as you turn the knob which is attached to a rod that goes through the steering head to actuate the damper assembly beneath the bottom yoke. When you try to make it work it just makes the bike feel as if the front tyre has a puncture!

The previously assembled forks are put into the yokes and now hold up the front of the frame.

The headlight brackets locate with more of Phil Denton’s parts between the two yokes.

Most things now bolted to the steering head. Fork top nuts looking nicely chromed.

Dave protected the headlight brackets from damage.

Centre stand attached with the special stainless steel bolt and sleeve discussed in an earlier episode.

Airbox with the two outlets shown in the frame still upside down. The airbox was powder coated 27 years ago but still looks good.

Flasher relay mounts in front of the airbox and underneath the toolbox.

Sidestand bolts on to the homemade bracket also described in an earlier episode. I hope that it props the bike at the right angle!

Phil Denton supplied a stainless steel sidestand spring – the lower one in this photo. Clearly it is not the right length, so reluctantly I will have to use the original mild steel item.

Aftermarket brass swing arm bush drifted in nicely. Should be better than the original plastic items.

November 2008 - Part 19
Well Dave’s still here and we are still bolting things onto the frame as fast as we can. We usually have to unbolt them again when we realise that it has been assembled in completely the wrong sequence, but I kept telling Dave that was normal! It is isn’t it? It isn’t just me?

You will see in this instalment that we fearlessly tackled the gearbox that had previously defeated us, and this time we beat it.

We wanted to get the collection of bits looking more or less like a motorcycle before Dave left, although I was under no illusion that bolting things together was more than about 25% of the work involved in building an operational motorcycle. Nevertheless the later pictures in this instalment do show something that is recognizably a two wheeled motor vehicle.

Handlebars supplied as substitute for the original R5 bars are pretty good, even down to the knurled sections matching the spacing of the mounting brackets.

Here is the rear wheel mounted in the swing arm with the brake torque arm and brake lever in place. The arrow you can see pointing in the wrong rotational direction just above the swing arm is for front wheel fitment of the tyre, so don’t worry!

With both wheels fitted we could wheel the bike outside for a breath of fresh air and a photo.

 

Rechromed shock looks nice. The wire loop on top of the rear fender is to retain the wiring loom under the seat. At the moment the wiring is hanging down the right hand side of the bike.

The mounting brackets for the footrest bar you can see in the bottom right of this photo can only be removed if you take out the engine! The stainless steel ones that I got made in Egypt did not even have the right spacing to go through the holes in the frame, so I had to use the original ones. I will make some stainless steel ones at a later date and fit them when convenient.

Here is all the wiring as mentioned above. After I connected everything up behind the battery box, I could not get it to sit in the right position under the metal wire loop you can see in the very top left corner of this photo. I realised that the main part of the wiring loom that runs above the top frame rail here was supposed to run beneath it and inside it next to the vertical flat surface of the battery box. Square one became familiar location…

Airbox peeks out from the centre of the frame.

Reconditioned switchgear in place. There is no right hand switch on the R5. Grip looks OK here but in fact is a bit second hand. I will replace them at some point after the main part of the restoration is completed. As many of you will know, work on old motorcycles is never actually completed…

The toolbox sits on top of the frame and the flasher relay bolts underneath. The original toolkit is unavailable of course, so I bought an R6 toolkit off eBay which has very similar cheapo tools to the R5 despite 35 years of development, and a nice plastic bag with tuning forks on it. Sometimes younger people are a little nonplussed when I say that I have an R5. I can see them trying to work out where that fits in relation to the R1 and R6 models!

Nice stainless steel swing arm recessed washers, swing arm shaft, swing arm shaft nuts… This is before I fitted the powder coated footrest brackets that the swing arm shaft also goes through. You can see here that there is about 5mm of thread left with which to accommodate these brackets – nowhere near enough! I realised that with the powder coating on the frame and the footrest brackets, the swing arm shaft which had been made to the same dimensions as the original was not going to fit! Phil Denton is now making me a custom item.

Dave and I did not really know why our previous attempt at gearbox assembly had gone wrong, but after the diversionary activity of bolting things onto the frame, we gave it another go. I had bought a new selector drum because the old one was worn and the cam faces for the selector forks were breaking up. This was not the reason for the non-functioning gearbox, but there was little point in rebuilding it with this crucial item in less then perfect condition. Here is the new one going in.

This is a spring loaded plunger that screws into the bottom of the crankcase and engages with detents in the selector drum to give a positive stop to the gearchange mechanism.

The selector drum is in place, and the detents for the spring loaded plunger can be seen next to the left hand crankcase wall. One selector fork is in position, and the track for one of the other two forks is on the selector drum below the rectangular window. It is the faces of these tracks that were worn on the old selector drum.

Here I am installing the E clip that holds the secondary change lever in place. The primary change lever is the long shaft that comes through the crankcase from the left hand side where the gear lever bolts on to its splined end. It comes through the hole just above my right forefinger, and engages with the circular boss just above the screwdriver blade. It was this secondary change lever that had caused Dave and I our original gearbox problem. Dave of course can be excused, but I should have remembered how important the adjustment of this lever is. To the left of the E clip there is a screw and locknut. This controls the position of an eccentric shaft which sets the orientation of the secondary change lever’s engagement with the selector drum. If this is not correct, then you may be able to select one or two gears, but after that it does not spring back to the right position and no more gears are available! I hope that those of you remaining awake have followed this – it is explained in the various manuals, although not in an idiot-proof way as you have seen!

After we got the gearbox working we screwed the crankcase studs in place and coated the mating surfaces with Yamabond No. 4. ( I have never seen any of the other numbers!)

Here are the crankshaft and gearbox shafts sitting happily awaiting the top crankcase half.

Crankcase top half fits over the studs. The manual clearly states that the crankshaft seals should be fitted after the two halves have been joined. This is of course completely wrong as we were to find out later.

Here is the right side of the crankcase assembly. The primary drive gear at the front conceals the large crankshaft seal that had to be hammered into place with an appropriately sized socket because it has a raised ridge of rubber on the outside circumference which is a greater diameter than the seal housing. That is why it should have been in place before the crankcase halves were joined! I hope that it seals OK when the engine is running otherwise it will need a full stripdown. The two gearbox shafts are in line behind the crankshaft, and the clutch assembly goes on the first one. The kickstart shaft is on the far left of the photo and the kickstart spring can be seen hooked over the crankcase boss. The white plastic gear runs off the kickstart idle gear (not shown) and drives a shaft for the tachometer cable. Below the first gearbox shaft is the secondary change lever I mentioned above. There are two arms that engage with the selector drum on the left end of this lever, it is those which must be in the correct position for the gearbox to function correctly.

This is the rear of the crankcase assembly. The thread for the tachometer cable is on the top of engine mounting boss. The gearbox breather hose is routed to the gearbox output sprocket for some minimal drive chain lubrication. I have substituted the mild steel hose clamps with stainless steel ones.

Here is the left side of the crankcase assembly. The clutch push rod actuates the clutch via the oil seal in front of the drive sprocket and goes through the hollow centre of the gearbox shaft. The actuating mechanism from the clutch cable is not shown here because it is part of the left hand crankcase cover, but the cable comes through the square hole above the clutch push rod seal. The white plastic quasi-triangular item below the drive sprocket is the neutral switch. It sits over the left end of the selector drum, and when a metal knob on the end of the drum rotates into position with the metal contact in the right centre of the neutral switch, the little green light in the tachometer comes on!

Installing the clutch springs the easy way! This is a clutch from an RD350LC which amazingly fits straight on to the gearbox shaft and engages the primary drive gear (as shown here) and the kickstart idle gear with no modifications. The plates have a bigger surface area and the springs are stronger which cured the clutch slip problem I had 25 years ago.

Whack those gudgeon pins in with a screwdriver handle!

Pistons in place, but true to form you can see that the one on the right is back to front! The arrow should point forwards!

Installing gudgeon pin circlips.

A bit of an interval between this photo and the last as we battled with installing the cylinders over the pistons and rings without breaking the rings, and then repeating the task when we realised that the right hand piston was back to front! Starting to look like an engine now, and weigh like one as well…

…so we put it in the frame.

Cylinder heads installed with the stainless steel sleeve nuts that also hold the cylinders in place.

Right I will just tighten up this nice Egyptian made stainless steel engine bolt… Oh dear! Only two white knuckles of torque and the hexagon separates from the shaft! Instead of turning down some hexagon bar to make the bolt, the prats had welded a hexagon to some round bar! You get what you pay for I suppose.

Here is Dave smiling at the differences between his day job of making V16 5000 horsepower Caterpillar diesel engines in the US , and his holiday task of assembling a Yamaha 350cc two stroke twin in Lincolnshire . I think that those revolve mainly around the competence of the of the chief assembly technician!

Engine in frame with gearchange shaft showing under the drive sprocket. We bolted the gearlever on to test the gearbox mechanism – it worked!

Progress to date…

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