1980 Yamaha RD350 LC restoration begins

1980 Yamaha RD350 LC 4L0 Restoration – Part 1

Project Elsie Part 1…

RD350 LC BarrelJanuary 18th – that’s when it happened. It was one of those moments where you have to take a minute or two to let things sink in because you simply can’t believe your luck. Let me explain: I am a bike breaker by trade but as well as taking bikes to bits I rather enjoy putting them back together again too. It’s something I have always enjoyed but had a long break from as a career got in the way of things. I got back in to bikes in a big way a couple of years back – mainly big Jap 4’s but the occasional vintage jobby found it’s way in to Powell towers. Anyway, my mates Scott and Ian got in touch with a rather interesting two stroke project proposal – would I like to rebuild their 1980 Yamaha RD350LC 4L0 for them? 

RD350 LC headlightTo me that was a bit like asking if I would like to take some super model out for dinner all expenses paid followed by 6 weeks in the Med on a private yacht. It should have taken me about ½ a second to answer in the affirmative but what actually happened is that I forgot how to speak and started dribbling uncontrollably. After a few minutes of inane babble I was able to give my answer, which was of course a resounding “yes”. Two days later Elsie arrived in the back of Ian’s van and she was duly rolled out in to the winter sunshine. The reality started to dawn as my initial inspection commenced – there was an awful lot needed doing. I shall state here and now that this is not going to be a concours restoration (more of an oily rag restoration!), the brief is to get it running well, get it looking nice, get an MoT on it and then hand it back. I can live with that, I think older bikes should wear their age with pride anyway. I waved Scott and Ian off the premises, wheeled her round to my workshop and then danced around like a little girl for about an hour and a half, not quite believing my luck – there is no way I could afford to do this for myself.

Yamaha RD350 LC bounty petrol tankWith the bike strapped firmly to the lift I started having a brief look see to see what will need doing and what parts will need to be sourced – that’s Scott and Ian’s job, I’m just the spanner man. The list was fairly extensive but for a bike of this age it was actually pretty good. It needs a new indicator lens, brakes rebuilding, a new horn (it came with one instead of the twins it should have) new fork stanchions and a fork rebuild, the battery is dead, the tyres are both knackered, it has no chain and the teeth on the sprocket look like shark’s fins in a force 10 so they need to be replaced. The whole thing needs a really good clean up and lots of service parts will be consumed along the way. The carbs are in a box along with a few other bits and pieces that will come in handy.

project RD350 LC 4L0 commencesThen I got to the 4L0 engine. Oh dear. Oh deary, deary me it has had a hard life. It looks like it has been rebuilt badly in the past and the first most obvious issue was a deep gouge in the right hand bore – a classic example of why it’s so important to use new good quality circlips and make sure they are installed properly – you don’t want your extremely hard to find RD350LC or any other barrel looking like this one:

When measuring the barrel I found that it was a different size to the left hand one. The standard bore is 64mm, the left hand one was a few thou over that but under the 64.25mm of a first overbore so I believe that is worn but standard. The right hand bore appears to be about 64.5mm so on it’s second re-bore. I am hoping that the gouge is not too deep and that it can be saved, it may have to be offset 0.25mm so that less material needs to be removed – that decision will be made by whoever does the re-bore machining, I don’t have the kit to do it.

RD350 LC bottom endThe rest of the engine looks pretty much OK but the right rod was tight on the crank pin. I treated the whole caboodle to a dose of Dave’s special mixture – 50% acetone and 50% auto transmission fluid. I learnt abut this trick from an American car magazine years ago – they compared this mixture with a number of penetrating lubricants e.g. WD40, PB Blaster and all that and this mix came out very well. I have no idea about the chemistry behind it but I know it works brilliantly. After ½ an hour of soaking everything was moving smoothly again. I am yet to remove the crank for a full inspection but everything feels and looks good at the moment, the rods are straight and there is no sign of major contaminant damage.

The left hand side all looks pretty good apart from some minor marking of the bore, which will come out with a hone but as we are going to have to bore out the right one the left will be done to match. I also think that running will be improved by putting some pistons in there. It’s much lighter without them but I think the old girl would benefit from actually having them. So that’s more bits for the chaps to source. So far we know the engine needs a gasket set, pistons and associated bits and crank seals, we may need bearings too, I’ll know that once I’ve got it out and had a proper look.

RD350 LC rear subframeI have had a quick look around the frame, it looks really good – straight, not bodged or repaired, only a couple of minor patches of surface rust that will be dealt with forthwith. I cleaned a few small patches on the wheels, tank and side panels and all of those can be used with just very minor work, the tank is in really good nick, which is a bonus. The front mudguard has had a hard life but I will most likely leave it honest, we’ll see how we go.

Next job is to drain the gearbox and get the engine on the workbench so I can get the crank out and really see what we have. In the mean time I will drop off the barrels for machining and draw up a more complete list of the parts I think we need.

So that’s it for part one, do come back and see what madness prevails, I hope you are as excited as I am an that you enjoy the series through to it’s conclusion, whenever that may be.

Article sponsored by Wemoto.

Article provided by David Powell of Boston Bike Bits.

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