Yamaha RD350LC restoration.

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mangocrazy
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Re: Yamaha RD350LC restoration.

#61 Post by mangocrazy » Thu Jul 16, 2020 11:38 am

Yes, I've seen too many 2T pistons with score marks down them, so wanted to do something to protect the pistons long term. As you say, the law of unintended consequences will bite your arse...

I just unearthed the original registration document and the bike was first registered on 8th August 1980, so on 8th August 2020 it will be 40 years in my possession.

I now have a target date for 'back on the road'. I have to say it's a (ahem) 'challenging' target...

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Re: Yamaha RD350LC restoration.

#62 Post by fatboy » Sat Jul 18, 2020 2:31 pm

Well Graham, with your diligent rebuild and advances in 2t oil technology it should be many many miles before Freddie Kruger has dragged his fingernails down those pistons
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Re: Yamaha RD350LC restoration.

#63 Post by mangocrazy » Mon Aug 03, 2020 11:59 am

Well, I'm perilously close to being able to put the LC engine back in the frame. Ignition timing sorted (it was only about 0.03mm out when using the lines I'd scribed when disassembling the motor), just button the side cover up and the motor is done...

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Re: Yamaha RD350LC restoration.

#64 Post by fatboy » Mon Aug 03, 2020 7:04 pm

Looking good, the excitement is building and fingers are crossed
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Re: Yamaha RD350LC restoration.

#65 Post by mangocrazy » Mon Aug 24, 2020 10:43 pm

The motor is now back in the frame, and the other night I connected up the radiator and hoses to the engine stubs and filled it up with coolant. Unfortunately, not all of the coolant stayed where it was supposed to. A small but significant amount made its way to the shed floor, via the head gasket...

It transpires that the two cylinders have subtly different deck heights - the LH cylinder is approx 0.15mm 'shorter' than the RH cylinder (at some points, at other points it's less). After briefly thinking of giving up and selling the wole shebang on ebay to the highest bidder, I consulted the gurus on the RDLC Crazy forum, and one chap (Rob) came up with a way forward.

He has made a jig/surface plate that allows 350LC cylinders to be bolted to it and then skimmed as a pair. It's a hefty piece of kit - it has to be at least 30mm deep (probably more) and it's kept at the premises of some proper old-skool engineers in Rugeley, Staffordshire. As I used to live in Stafford (about 10 miles away) and frequently return there, today I made the trip to their premises and left my barrels with them for surfacing/skimming. They are two brothers - Graham and Stuart.

I'm not going to forget their names - one name is my forename, the other my surname (albeit spelt differently). How spooky is that?

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Re: Yamaha RD350LC restoration.

#66 Post by fatboy » Wed Aug 26, 2020 6:14 pm

Well Graham, the names bit is a bit spooky!
Really pleased you didn't give up, that is one helluva curve ball chucked your way, positively weird way for a finished engine to leave the factory.
Well done fella
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Re: Yamaha RD350LC restoration.

#67 Post by mangocrazy » Thu Aug 27, 2020 5:10 pm

Cheers Paul, no that wasn't the way it left the factory. The LH barrel has 'history'. That's the one that needed the exhaust flange rebuilding with weld and then machining back due to a mishap before I acquired the barrels. 'My' fresh from the factory' barrels were 'tuned' by a workmate who had less knowledge of the dark arts than I gave him credit for, and were effectively rendered scrap. I had to locate a secondhand pair and these were they. I suspect the problem has come to light because the genuine Yamaha head gasket has changed over the years (now on revision 9) and the earlier ones were more tolerant of a deck height mismatch.

No-one ever said it would be easy. Or cheap... :smt002

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Re: Yamaha RD350LC restoration.

#68 Post by fatboy » Fri Aug 28, 2020 5:36 pm

Well done for persevering, cant wait to see the passed the 'mot' pics, you're so close to the finish line now Graham
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Re: Yamaha RD350LC restoration.

#69 Post by mangocrazy » Sat Aug 29, 2020 8:47 am

Got the barrels back yesterday, reassembly will start on Sunday, with any luck.

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Re: Yamaha RD350LC restoration.

#70 Post by mangocrazy » Thu Sep 03, 2020 7:06 pm

A sunny afternoon somewhere in Sheffield, and the air becomes thick with blue smoke and the burble of a two-stroke motor...

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Re: Yamaha RD350LC restoration.

#71 Post by Viking » Fri Sep 04, 2020 1:18 pm

Oh my.... That looks brilliant! Well done, sir!
It's the V-twin thing. There's just something about it that inline-4s don't have at all, and V-4s don't have enough of.

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Re: Yamaha RD350LC restoration.

#72 Post by fatboy » Fri Sep 04, 2020 3:33 pm

:smt038 Fantastic, well done that man
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Re: Yamaha RD350LC restoration.

#73 Post by mangocrazy » Fri Sep 04, 2020 8:36 pm

Cheers chaps. All the hassle and setbacks have been worth it. Today it went for its MoT and passed with no advisories, so Graham is a happy (and slightly smug) boy. But as the only V5C (registration document) I have for it was transcribed by mediaeval monks onto parchment, taxing it might yet prove to be a challenge...

But it lives, and on the ride to the test centre it felt better than any 40 year old bike has a right to feel. The suspension felt almost modern and the brakes were far better than I expected them to be. And it was great to look in the mirrors and see a blue haze of two-stroke smoke following me... :smt003

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Re: Yamaha RD350LC restoration.

#74 Post by fatboy » Mon Sep 07, 2020 5:09 pm

Mega result Graham !
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