Author Topic: Pidjones' bicentenial build (a '76 RD400)  (Read 5070 times)

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Offline pidjones

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Pidjones' bicentenial build (a '76 RD400)
« on: August 13, 2020, 11:42:58 PM »
I guess my attachments were too big when I first tried to start this.

Brought the '76 RD400 basket case hoe today (well, roller with engine in frame, but a BIG bin of parts cam with it.)

I've already ordered new keys from the ebay vendor that cuts them by code#. There was a lot more there for it than I thought, but a few things that I'll have to find or make - one thing is the air cleaner cap. Also needs rear fender, rear "stay" tail light and bracket, rear signals, speedometer (the one with it was mangled), mufflers, one air cleaner joint, air filter (has a nice nest in place of one). I suspect that it needs a throttle cable, but that has yet to be proven. Needs a new chain and set cover, latch for the seat, grips (I have several new sets), tires. That should get me started.... to poverty.

I pushed the starter down by hand (no plugs) and it felt like the amount of resistance was correct. The reeds are still in place on it.

I want to clean X years of "stuff" out of the case - don't know how it was stored although it does not show typical signs of being left in the weather - more likely in the dry in a shed or barn. I want to check compression, but want to also protect it. How should I flush/oil/etc. or should I just go ahead and buy a gasket set and pull it apart? There is no gear oil in it, so I'll probably flush that side with marvel Mystery Oil and then fill with an oil good for wet clutches like Rotella T6 5W40 (which I have used in my GL1800 since new, now with 123000 miles).

BTW, check out the unmolested disks on it!
« Last Edit: August 13, 2020, 11:51:26 PM by pidjones »
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Offline Motty

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #1 on: August 14, 2020, 09:26:34 AM »
I wonder why he changed the discs?

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Offline stevie747

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #2 on: August 14, 2020, 10:13:14 AM »
The only safe way in going about this is to strip the whole thing down to bare frame and crankcases.  Hoping for any short cuts on a rebuild, particularly if you don't know it's history, will pretty much always bite you up the arse. 

Once stripped you'll know exactly what's needed plus it'll help decide whether you wish to have a 'correct' resto (good luck chasing all the rare parts you need) or rebuild it to your taste with the tons of after market stuff out there.

Top Tip: Don't rely on repro bearings and seals, buy OEM  ;)
74 RD350 (pre A), 74 RD350'R', 72 AT2, 97 Aprilia RS250, 73 Widowmaker (x2)... (and a Wes Cooley GS1000S Diesel for the missus)

Offline pidjones

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #3 on: August 14, 2020, 12:57:25 PM »
My goal is a stock-looking (no chambers) rescue. Lower handlebars would be the only visual change. Pulling the engine is no problem. I would just rather avoid major engine work. How can I make it safe to just test compression?
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Offline robrd

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #4 on: August 14, 2020, 02:41:43 PM »
Hi, you don't have to start the motor to check the compression, just make sure it is turning over clear of any obstructions and do your test. Just because a motor has good compression it doesn't mean that it is ok, i, like others would suggest splitting the motor to be on the safe side. It doesn't cost a fortune and gives you piece of mind. Good luck with your project.

Offline stevie747

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #5 on: August 14, 2020, 03:31:41 PM »
My goal is a stock-looking (no chambers) rescue. Lower handlebars would be the only visual change. Pulling the engine is no problem. I would just rather avoid major engine work. How can I make it safe to just test compression?

We'd all prefer not doing any major engine work but it's a total false economy restoring something nearly half a century old and hoping for the best  :o  It'll cost thousands to restore it anyway, whether you like it or not.  Usually there's a reason why bikes are historically stuffed into 'barns' - engine problems maybe...

You called it a 'basket case'...  There's a clue there somewhere  :D
« Last Edit: August 14, 2020, 03:34:10 PM by stevie747 »
74 RD350 (pre A), 74 RD350'R', 72 AT2, 97 Aprilia RS250, 73 Widowmaker (x2)... (and a Wes Cooley GS1000S Diesel for the missus)

Offline betty foRD

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #6 on: August 14, 2020, 10:25:28 PM »
Engines don’t get any easier than these to take apart and put together but as like a few others recently new to them then a risk free approach is to find a very cheap broken engine and pull it apart just fir the learning value. Play out all those imaginary nightmare Scenarios and reach the usual ‘eureka’ moment when you say to yourself ‘is that all there is to it’

We should have a club trainer engine...pass it around for folks to have a stab and bust their screwdrivers on !
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Offline pidjones

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #7 on: August 15, 2020, 01:19:23 AM »
Certainly not afraid of disassembling the engine. But, I agree a dry-run would be helpful. I bought a junk GL1000 for spares and pulled the engine apart on it (much more complex than the RD). Discovered that it was a good call to only pay junk price - it had severe rust on interior components including the gears. Pistons rusted so tight that it took two big crowbars and a big sledge to get the cases apart and yet, after removal the pistons looked good (cylinders were another story).  I've also rescued one that I used single-edge razor blades to shave rust off cylinder walls Had great compression and runs great now. I don't want to start it, just check compression. Just want to make sure it has lubricant to keep the bearings happy. Won't be for a week or so as there just isn't room in the garage (four GoldWings take up a LOT of room!) Anyone want to buy a '78 GL1000? Busted clocks solved by an ebay purchase that includes a seat latch! But, looking closer at the seat pad reveal pretty bad rust on the edges. Might have to replace it or at a minimum patch it. I don't want a custom seat.

Once I get rid of the '78 GL, the show GL goes in the family room and I'll finally have some room to work on the RD. If the '78 doesn't sell this fall, it will swap places with the RD in the tractor barn (locked and dry). Either way, that is when the RD comes all the way apart.
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Offline 5port

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #8 on: August 15, 2020, 07:48:38 AM »
Yes, good luck with that RD400 rebuild!  The Rd is built as a twisty road bike, the whole way the engine and chassis is based on the race bikes, TR3, etc.  Agree, lower bars are good. :)
The engine is relatively simple,  but needs building well to work nicely.  You don't really know how good/bad a bike that has stood is inside the cases.  I have a 350 and a 250 that have never been split but, they came with oil in and assembled so, just needed the heads and cylinders off, first rebore for the 350 and just new rings on the 250 with original bores.  However, as others have said, you can find corrosion if the box is dry.   You are in a good place for used RD400 spares and NOS parts!  Cheers

5port
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Offline pidjones

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #9 on: August 21, 2020, 04:57:09 PM »
Ebayed a set of clocks, ignition switch, seat/helmet lock and matching key. Very restorable looking. Also bought a rear "clip"- fender, stay, signals, and tail light (with broken lens).

My airbox has no filter in it. Looks like Germany may be the only source of tbe correct,ducted filter. And there isno mailing to USA due to Covid. Might check to see if one of my co-workers from my previous German employer could ship it here in a company shipment.
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Offline pidjones

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #10 on: August 24, 2020, 02:52:33 AM »
Started digging through the bin of parts tonight. Pulled out the carbs and took them off ofbthe throttle cable. The cable is seriouslt freyed to the pump, so will all need replaced. Rear master totally dry and full of evaporated brake fluid, but no corrosion evident (yet). Brake light switch and feed adapter off. I'll pull it apart and check for corrosion in a few days along with the front master that held dark DOT3 syrup.  The front has a mirror stud broken off in it, so that is soaking in penetrant. The front brake lever is broken also (probably the same incident that dented the tank, distorted the headlight bucket and mounts, and smashed the speedo and indicators). All that I've done so far with the carbs was to place them in separate plastic boxes marked R and L.

Feels good to be starting on this, but would feel better if someone bought my '78 GoldWing to give me more room to work.
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Offline pidjones

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #11 on: August 24, 2020, 11:26:06 PM »
Today a friend gave me a check to hold my '78 GL1000 rescue bike for him through next week So, space will soon be available to bring the RD400 into the garage and tear it down. I pulled the bin of parts in last night and began taking the master cylinders apart. Front has a broken lever and a mirror stud broken off in it. Got most of the stud out and the rest of it looks a lot better than the GL1000s I've had for projects. Rear is full of wax left over from evaporated brake fluid but looks good so far.

Rear clip came in today. Some rust, but not too bad. Soaking in PB Blaster to be disassembled and cleaned.
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Offline pidjones

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #12 on: August 25, 2020, 08:47:06 PM »
Well, the friend changed his mind - and came over today with cash for the bike! So, with him happy and a newly opened space in the garage (which still makes for three bikes in it) the RD is now in the house. I parked it outside first and gave it a good blow-down with 100 psi (~6.6 bar) air. Dislodged a nice nest from the air box. Sorry - you are evicted! Discovered that the transmission drain bolt was missing. But, a spare GL1000 oil drain bolt from a junker that was dismantled fits perfectly! Ordered throttle cables (oil pump control has about four broken strands). Pulled the cover from over the oil pump and spun it a few times. Looks and feels Ok. Once I have obtained some BelRay and cleaned the tank out, I'll test it out. Still haven't dismantled the carbs more than enough to disconnect the throttle cables. Very hopeful that the masters are going to be rebuildable without even buying new kits. Cleaned up nicely inside and tomorrow I'll put them to the wire wheel to remove the failed paint on the outside before final interior cleaning and assembly using brake fluid to lubricate. Sure glad these aren't as rusted up as GoldWing masters get!

Onre other thing attended to was cleaning and gluing together the broken right side cover. The bottom part with the nipple for the grommet was broken off cleanly, so I wiped it with acetone, then plumbing clear cleaner, then glued it up with ABS plumbing cement and reinforced it on the inside with a bit of fiberglass cloth. Should be ready for sanding and painting.
« Last Edit: August 25, 2020, 08:50:00 PM by pidjones »
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Offline Motty

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #13 on: August 25, 2020, 09:57:59 PM »
The list of outstanding jobs has already got shorter

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Offline pidjones

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Re: Pidjones' bicentenial build (a '76 RD400)
« Reply #14 on: August 26, 2020, 11:06:36 PM »
Finished cleaning and assembled the master cylinders today (the front is a BEAR to get the circlip in). Stripped the rear clip so I can start attacking the rust on it. Started cleaning the oil tank. Got all of the connections off (heat gun helps a TON!) and 50% of the grime off of the outside. Drained maybe an ounce or two of oil out of it. Put in a couple ounces of isopropyl alcohol and it flowed out fairly well from the outlet, but I still plan to put a camera in and inspect the screen.

Also, called the sheriff's office to ask about verifying that the VIN was clean since I didn't get a title with it. Within fifteen minutes, a deputy came out and looked it over and signed my paperwork after calling the VIN in to be checked. Love living in the simple free state of Tennessee! Took the paperwork in, paid about 10% of the purchase price in taxes, title fee, and registration fee (but, won't have to pay taxes again on it) and was given new registration papers and I can transfer tags from the bike I sold yesterday to it. State will mail a new title in a few weeks.
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