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Author Topic: RD400 - Back from the Dead  (Read 14479 times)

Offline AimlessMoto

  • Posts: 156
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Re: RD400 - Back from the Dead
« Reply #80 on: Jul 12, 2017, 17:22:59 »
Been plugging away. Got all but the clutch-cover in paint... still have to strip and blast the clutch cover. Replaced all the seals, and will have to flush and check the oil pump. New lines were ordered in clear so I can see what's going on.

Split the cases, cleaned up the mating surface and all the old gas from the crank case. New seals in, transmission and shifter dogs look brand new! Not bad for 12k miles!

Got my new tires in as well as painted and polished the fins on the heads... next will be the cylinders. Got the rear MC pained and threw some new guts in it... almost looks new!

Offline e30 gangsta

  • Posts: 15
Re: RD400 - Back from the Dead
« Reply #81 on: Jul 14, 2017, 14:23:58 »
You going to rebuild/weld that crank back up?

Offline AimlessMoto

  • Posts: 156
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Re: RD400 - Back from the Dead
« Reply #82 on: Jul 14, 2017, 20:17:13 »
You going to rebuild/weld that crank back up?

Outside bearings and seals only. Inside bearings are in great shape. Weld what?

Offline clem

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Re: RD400 - Back from the Dead
« Reply #83 on: Jul 14, 2017, 21:50:36 »
He's probably talking about the crank pins.

Sent from my SAMSUNG-SM-G930A using DO THE TON mobile app

"After every war there are soldiers who refuse to surrender. To this day there are still thousands who cling to their 30+ year old motorcycles, thinking that the war is still on, refusing to concede that the four-strokes have won"

1972 DS7 http://www.dotheton.com/forum/index.php?topic=45886.msg505995#msg505995
1983 CB550sc bobber http://www.dotheton.com/forum/index.php?topic=30599.30

Offline AimlessMoto

  • Posts: 156
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Re: RD400 - Back from the Dead
« Reply #84 on: Jul 26, 2017, 12:49:51 »
Crank is fine. No play in inner bearings or lower rod end bearings... so it stays.

The oil pump on the other hand... sheesh. I had the bright idea to take it apart... stupid me. Lost one of the tiny detents on the manual pump bypass. I ordered some 2mm x 10mm rods from England a couple weeks ago... they should be in soon, going to cut them down and make a few extra 2mm x 3.5mm rounded detents just in case that happens again.

I also painted the frame... I am NEVER using PJ1 paints again. The nozzles clog constantly, and the finish is really poor on the gloss black. I am leaving it, as the worse parts won't be seen... but it's not worth $15 a can for the finish it provides. I'll stick to VHT Engine/Caliper/Rollbar and Chassis paints from now on.

Parts are coming together nicely...

Offline Turnturtle

  • Posts: 70
Re: RD400 - Back from the Dead
« Reply #85 on: Jul 26, 2017, 13:24:01 »
Those oil pump pins look just like lock pins. I have some in 2mm x 4mm in brass. A locksmith would have the size you need.

Offline jpmobius

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Re: RD400 - Back from the Dead
« Reply #86 on: Jul 26, 2017, 13:51:46 »
Right, those little pins come out like bullets if you don't know they are there.  Trick is to do that part of the disassembly inside a clear plastic bag.  Be sure to inspect the check valves.  They are under the brass nipples pressed into the pump case that feed the two carb oil supply lines.  Probably they are fine, but check with WD40 or something similar while you have the pump apart.  Don't use compressed air.  If they don't seem right, pull out the brass nipples.  Usually they are fairly easy to twist a bit while pulling on them.  There is a spring and check ball inside so be careful.  Rusty spring is the only problem I have seen which is rare as the thing is always full of oil.
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0

Offline AimlessMoto

  • Posts: 156
  • Blood, sweat and beers.
Re: RD400 - Back from the Dead
« Reply #87 on: Jul 26, 2017, 16:59:04 »
Right, those little pins come out like bullets if you don't know they are there.  Trick is to do that part of the disassembly inside a clear plastic bag.  Be sure to inspect the check valves.  They are under the brass nipples pressed into the pump case that feed the two carb oil supply lines.  Probably they are fine, but check with WD40 or something similar while you have the pump apart.  Don't use compressed air.  If they don't seem right, pull out the brass nipples.  Usually they are fairly easy to twist a bit while pulling on them.  There is a spring and check ball inside so be careful.  Rusty spring is the only problem I have seen which is rare as the thing is always full of oil.

Good call. The first thing I did was drain, clean with parts cleaner, then threw my new clear lines on and ran the pump slowly on a drill from the plastic gear (a small flat-head fit in the hole by the cotter pin). I manually held the pump at wide-open and spun the drill... a bunch of old oil and gunk came out. I then threw a little 0w-20 I had laying around in and it pumped it out nice and clean with no air bubbles. Drained, cleaned again, and now it's in pieces waiting the pin.

I never thought of using a lock pin... the original are steel, so I want to keep them steel if possible.

Offline AimlessMoto

  • Posts: 156
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Re: RD400 - Back from the Dead
« Reply #88 on: Jul 27, 2017, 18:54:19 »
Cut down a 2mm dowel to replace the one I lost. Back to putting this fiddly thing together. Just waiting on the gasket and oil seals to come in.

Offline AimlessMoto

  • Posts: 156
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Re: RD400 - Back from the Dead
« Reply #89 on: Jul 31, 2017, 14:05:54 »
BIG progress this weekend. Closed up the cases, new sprocket, all new seals, re-painted the cases to a more stock-color... semi-gloss black instead of satin.

I was also able to get the clutch side closed up, and put the piston and jugs back on, but haven't taken pictures yet.

Everything going together smoothly so far.

Also re-did the forward controls for the handlebars.

I checked the run-out on the pump at "idle" with no cable on the pump, and it's got about .007" of throw... manual says it needs .008-.012, so I'm probably going to order a new shim.