Yamaha RD350LC restoration.

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Ben
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Re: Yamaha RD350LC restoration.

#31 Post by Ben » Thu Apr 23, 2020 8:20 am

Top work, Tipper! What a great way to spend time in forced isolation.

Project bikes should be commanding a premium on eBay!

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mangocrazy
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Re: Yamaha RD350LC restoration.

#32 Post by mangocrazy » Sat May 16, 2020 5:40 pm

I think the lockdown has warped some people's estimation of how much 'project' (i.e. incomplete basket cases) bikes are worth...

Anyway, the lockdown has kinda forced me to get stuck in with rebuilding my 350LC motor. You may remember at the beginning of the year it was in this state:
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Since then (and thankfully prior to lockdown) I've stripped the motor to its component parts, got the crankcases and crankase covers vapour blasted and the crankcase covers powder coated, had the crank completely refurbished and balanced and had the barrels rebored and acquired new (Japanese) pistons and rings. The barrels still need some external work doing to them (more on this in a few days, hopefully) but I'm happy to report that the bottom end is now back together.

Proof:
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The oil pump is scheduled to be sent off in 3 or 4 weeks time for a complete overhaul, and I'm currently stripping the fork legs with a view to removing the powder coat on the fork bottoms and returning them to standard (bare aluminium, but protected with wax). I've also got a bunch of old fasteners in various stages of rusting away that will get the citric acid treatment then be sent for olive drab passivate (the original dark green finish that Yamaha used).

I'm desperately trying not to over-restore it or get carried away, but I know what I'm like...

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Re: Yamaha RD350LC restoration.

#33 Post by Falcopops » Sun May 17, 2020 2:26 pm

very very nice mate, excellent work

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Re: Yamaha RD350LC restoration.

#34 Post by fatboy » Sun May 17, 2020 2:31 pm

Wow ! Very impressive before and after images.
Apart from the homemade rod protection and bearing retainers that looks like it could be on a factory work bench
Cleverly disguised as an adult !

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Re: Yamaha RD350LC restoration.

#35 Post by mangocrazy » Sun May 17, 2020 10:29 pm

I'm just wondering whether I should trim down the surplus gasket paper on the clutch side. The flash has really accentuated it...

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Re: Yamaha RD350LC restoration.

#36 Post by Falcopops » Mon May 18, 2020 6:10 pm

mangocrazy wrote:
Sun May 17, 2020 10:29 pm
I'm just wondering whether I should trim down the surplus gasket paper on the clutch side. The flash has really accentuated it...
and chance damaging the new paint/powdercoat!

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Re: Yamaha RD350LC restoration.

#37 Post by mangocrazy » Mon May 18, 2020 8:41 pm

Wise words. I think I'll leave well alone... :smt004

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Re: Yamaha RD350LC restoration.

#38 Post by Ben » Tue May 19, 2020 9:53 am

mangocrazy wrote:
Mon Mar 09, 2020 11:36 pm
Thanks Bobbi! :smt004 Bike manufacturers don't make 'pretty' bikes any more. They're all angry, angular Terminator-styled things or galumphing great adventure bikes with ridiculous amounts of panniers, headlights and bash plates. Or sad, dull utilitarian things.

Ho hum. Must be getting old...
Just seen this. I totally agree but would add in 'Japanese' to that statement. All modern Japanese bikes seem to be super-angular and in your face. There European manufacturers aren't immune but there are not a lot of subtle bikes coming out of Japan.

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Re: Yamaha RD350LC restoration.

#39 Post by mangocrazy » Sat May 30, 2020 9:47 pm

The restoration thing has expanded from the original 'fix the motor ' brief and now includes 'sort the suspension'. Consequently I've ordered up a YSS shock, YSS forksprings and YSS front fork cartridge emulators. I do remember the suspension as being particularly iffy back in the 80s and I can't believe it will have improved in the intervening years...

So the fork are now in pieces awaiting their new internals and I've shipped the fork lowers off to have the black powder coating I had done in the 80s stripped off and then vapour blasted. This is a photo of one fork leg as it came back from the vapour blasters and the other after it had been scotchbrited and wax polished:
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I've also started to get the top end (barrels, head) ready for paint. The head just needed vapor blasting and masking, the barrels will need some serious de-grease and clean up. Here's the cylinder head fresh from the vapour blasters and masked up ready for paint.

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Re: Yamaha RD350LC restoration.

#40 Post by Gio » Sun May 31, 2020 8:14 pm

Where dem pics mate
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Re: Yamaha RD350LC restoration.

#41 Post by mangocrazy » Sun May 31, 2020 8:44 pm

Seems to be a bit of a problem. Not sure if it's just me or forum-wide. Can't seem to upload pics.

<Update> Looks like we'd hit some predefined limit on storage for images. I've raised it by 20% and it seems like we're OK now.

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Re: Yamaha RD350LC restoration.

#42 Post by Gio » Thu Jun 04, 2020 8:24 pm

mangocrazy wrote:
Sun May 31, 2020 8:44 pm
Seems to be a bit of a problem. Not sure if it's just me or forum-wide. Can't seem to upload pics.

<Update> Looks like we'd hit some predefined limit on storage for images. I've raised it by 20% and it seems like we're OK now.
Someones got deep pockets!
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Re: Yamaha RD350LC restoration.

#43 Post by mangocrazy » Sun Jun 07, 2020 12:21 pm

Time to go back about 30 years and (possibly) understand why I neglected the poor thing for so long. It all goes back to the early 80s when I bought the bike and (unwisely) decided to have it 'tuned' by a guy I worked with. He proddy raced LCs so I assumed he knew what he was doing.

Wrong.

Basically he turned a perfectly good pair of barrels into scrap by raising the top edge of the exhaust port too high. Exhaust port height is critical - too high and you have no low down power and a knife-edge high rpm power band. This is what happened to my barrels. So I needed another pair of barrels and my local dealer (the one who never told me about any recalls) happened to have a pair that had been damaged but repaired. The LH barrel had lost three quarters of the exhaust flange as a result of an accident and the damage had been repaired by alloy welding. When I inspected them they looked serviceable, so I bought them.

Fast forward seven or eight years and in summer 1989 I took the LC for a new set of tyres and on the way home became aware that something was amiss in the exhaust area. Basically the piece of flange that had been welded back on had fractured and come loose and the exhaust was blowing like a steam train. When I discovered this the LC was retired pending further examination. At some stage I stripped off and sold all the go-faster goodies I'd bolted on over the years (sound familiar?), put it back to standard and took the engine out of the frame intending to repair it. When I discovered the extent of the damage my enthusiasm cooled rapidly and the rolling chassis and motor were shoved to the back of the garage and forgotten about .

For around 25 years.

This what the offending barrel looked like:

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And this is a close up of the broken flange. As you can see, blowby from the exhaust, laden with two-stroke oil, had seeped further and further into the repair and ultimately weakened the weld to such an extent that the weld failed completely.

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About 5 years ago the rented lockup garage in which the LC had been slumbering was sold, and I had to empty all my crap out of it, which coincidentally got me thinking about restoring it. In the interim I'd moved to Sheffield and uncovered a wealth of contacts for engineering, metalwork, welding, machining, blasting, polishing, plating etc. etc. So what was an impossible task in 1989 had now moved into the realms of the possible. First thing I did was to get the barrel and flange fragment hot tanked and then doused in some vicious chemical concoction (only available to the trade) that contained hydrochloric acid, phosphoric acid and other hazardous substances. This is what the barrel looked like now:


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It''s not going to win any beauty contest, but there is now clean metal to work with. The welders I entrusted the work to (JNC Welding in Sheffield) advised me to forget about re-attaching the broken part of the flange as that would just break again in the same way at some point. Instead they would grind back to fresh uncontaminated metal, build up the area with alloy weld and then get the weld machined back to something like original. This made sense to me and a short while later I returned to find the barrel looking like this:

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They'd had the other barrel to use as a guide to where metal needed to be added so I knew we were on the right track. Turn the barrel upside down and it reminded me somewhat of the Elephant Man. But I've always had a slightly odd imagination... :smt033


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To be continued...

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Re: Yamaha RD350LC restoration.

#44 Post by fatboy » Mon Jun 08, 2020 2:38 pm

Sadly it seems to be harder and harder to find engineering shops that do stuff like that.
Another hurdle jumped through Graham !!
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Re: Yamaha RD350LC restoration.

#45 Post by mangocrazy » Mon Jun 08, 2020 5:26 pm

That's one of the benefits of living in Sheffield, Paul (that and proximity to the Peak District)! There are no end of really good small machine shops around. But anyway, as promised, I will continue...

The next stage was to turn a mass of alloy weld into something resembling an exhaust flange. Nick and Chris recommended a machinist they knew as 'Ginger Dave' to do it. As he was only about half a mile away from where I worked, this was very acceptable. It was actually his daughter Emma who did the work, as Dave was unwell. This is what came back:

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Considering what it had looked like a few short months previously, I was delighted with this. Emma had even faithfully replicated the slight inward angle that the flange sits at. And it was obvious from the machining that there were no air pockets or inclusions in the layers of weld, just good solid metal. Top job all round. I had to do some cleanup grinding with the die grinder and some carbide burrs to smooth down the back of the flange and try to make it look more like the RH side barrel, and this was done with more than a degree of trepidation. Die grinders are unforgiving tools, they dig in and gouge metal and skin on the recoil given half a chance, so I took as much as I dare off with the grinder and finished off with a detail sander as best I could. There is no way I could visually match the LH cylinder to the unmolested RH one, but I was happy enough with the result. Heres' the view from the barrel base:

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You can clearly see that fully three-quarters of the flange had to be recreated in new metal. Using a conical burr to try and shape the lower edge of the flange was a scary business. I had to be so careful only to take small cuts and not let the burr dig in. The sander has cleaned up the worst of the marks... The top of the flange was easier to get at and clean up, but again I didn't even try to get close to the original shape as cast. As long as it wasnt too lumpy and was reasonably smooth I was happy. The barrels and exhaust flanges will largely be hidden by the radiator anyway. (That's my excuse and I'm sticking to it). Here's a view of the top of the flange with the barrel masked up for paint:

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The masking took up a fair time and was a fiddly business - especially the base of the barrel. The undamaged barrel hadn't gone through all the treatments with noxious chemicals that the damaged one has, so looks a fair bit dirtier. It's actually had no end of scrub downs with isopropyl alcohol and acetone so if there's any dirt left it's clean and grease-free dirt... :smt003

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So all that remains now is for the weather gods to smile on me next weekend so I can empty the shed of bikes and turn the shed into a temporary spray booth. I've had enough of trying to spray stuff outside. Even on the calmest days, there's enough breeze around to send paint anywhere but where you want it.

The Autolube oil pump has been sent off for a full strip down and service and I've now started thinking about getting the petrol tank sealed against the dreaded ethanol. When I looked inside it looked in really good condition - no visible rust - so I'd like to protect it before it has any chance to degrade. I think I'll be calling on Paul's experience in tank sealing for pointers.

Restoration of an old bike, eh? Where does it end?

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