BOTM

* Sponsors


Author Topic: RD400 oil leak  (Read 520 times)

0 Members and 1 Guest are viewing this topic.

Offline kart74

  • I'm a regular here
  • Posts: 56
  • Karma: 0
    • Location: Wisconsin
RD400 oil leak
« on: June 10, 2013, 08:01:57 PM »
Had the 77 rd400 out yesterday for a ride. Right before home I got on it pretty good. When I pulled in I noticed alot of oil all over the left side pipe chain and all over the left side of the rear tire. It was dripping from the left foot peg. The oil was coming from behind the cover either from the breather or from one of the seals. I read that expansion chambers can cause the oil from the breather. I cleaned everything so hopefully I can see if it is a seal. If it is a seal can those be replaced without taking it apart? Any other ideas what it might be? Is this something rd400's are known for? Any help would be great. Thanks

Offline SUPERTUNE1

  • Addict
  • Posts: 1507
  • Karma: 91
  • I am a 2 stroke tuner for 30yr! not a post counter
    • Location: Clearwater, Florida
Re: RD400 oil leak
« Reply #1 on: June 11, 2013, 04:19:56 AM »
Hi Kart,
Yes,all the seals can be replaced except the mag crank seal. (IMO, it has been done, but a cheesy way of doing it.)
No chambers do NOT cause the seals to leak...being 30+ years old does!
Go to economycycle.com and order a seal kit or all of the separately OEM's from Yamaha.
You will have to pull off the countershaft sprocket so have a impact gun with a socket on hand.
Get a new neutral switch housing too with the o-ring. They're always cracked and leaking!
Like $25 more.
If you do stand up big wheelies then oil will come out the vent tube at the rear top of the cases, just get some tygon 3/16 fuel line form a mower shop and run a longer one up and zip tided to the frame, the racing rules make use use a catch bottle. (I use a pint sized vitamin plastic bottle) 

Racegas + Lots of oil = HORSEPOWER
2 time Daytona AHRMA Formula-500 winner '06
'78 RD400E
RD machine work, boring, porting, cranks and engine building.

Offline kart74

  • I'm a regular here
  • Posts: 56
  • Karma: 0
    • Location: Wisconsin
Re: RD400 oil leak
« Reply #2 on: June 11, 2013, 07:29:00 AM »
thanks for the reply. I cleaned it all up last night so I can see where it is exactly coming from. There is no dipstick so how do you know if the oil level is correct? I am going to drain it and add the right amount. Should I use 1500cc or less? If it would be coming out the breather does that mean that the crank seal is bad? Thanks

Offline kart74

  • I'm a regular here
  • Posts: 56
  • Karma: 0
    • Location: Wisconsin
Re: RD400 oil leak
« Reply #3 on: June 11, 2013, 05:36:16 PM »
So after sitting for a day now that its clean I can see it is leaking from the output shaft seal. It also seems thatnit is leaking from in between the collar and the shaft. How does that that fixed?

Offline SUPERTUNE1

  • Addict
  • Posts: 1507
  • Karma: 91
  • I am a 2 stroke tuner for 30yr! not a post counter
    • Location: Clearwater, Florida
Re: RD400 oil leak
« Reply #4 on: June 12, 2013, 05:09:47 AM »
When replacing the countershaft seal, after you pull out the collar and seal, clean up the area with contact cleaner, and you want to use some Yamabond #4 on the end of the collar that rests against the bearing. This will seal the collar from leaking through the splines.

For the oil level, I always pull off the clutch primary cover to drain the trapped oil that doesn't drain out through the drain plug, then I know I'm dry, then add 1500 cc's of 2 stroke transmission oil like Maxima MTL, Belray gearsaver etc. I like 80w for street bikes and use 75w for track bikes.

Chuck
Team Scream Racing
Racegas + Lots of oil = HORSEPOWER
2 time Daytona AHRMA Formula-500 winner '06
'78 RD400E
RD machine work, boring, porting, cranks and engine building.

Offline kart74

  • I'm a regular here
  • Posts: 56
  • Karma: 0
    • Location: Wisconsin
Re: RD400 oil leak
« Reply #5 on: June 12, 2013, 09:53:00 AM »
thanks for the reply. That makes sense. After my last post it dawned on me that the reason it was most likely leaking from in betweek the shaft and the collar was because i had the sprocket off. so i once again cleaned everything and reassembled. I moved the breather tube to a catch bottle and took it for a ride. It wasnt a very long ride, but i did get on it several times hopeing to reproduce what i saw the other day. I came back and everything is completely dry. Nothing in the bottle and not a hint of oil by an of the seals. It doesnt make sense to me. When i came back the other day it was every where. Dripping off the bike. I did order the seal kit and neutral switch as suggested, but now i am wondering if it is something else. I am going to try to go for a longer ride tonight. Only think i am thinking is that it needs to get good and hot? dont know...

Offline Clem

  • 2-Stroke Tuner
  • Posts: 569
  • Karma: 5
Re: RD400 oil leak
« Reply #6 on: June 14, 2013, 10:35:57 PM »
As you accurately fill it, make your own dipstick.  I've done this with gas tanks on race bikes as well as transmissions that dont come with a stick(especially ones that leak, YSR comes to mind.)  I'd probably do 1000cc and up every 100cc and probably use 1300 - 1500 as the acceptable range if there was enough difference to easily see it.
Obsession is a great substitute for talent.
IBA 45686
Motoseries 710