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Oil Question - 1976 Yamaha RD400

Discussion in 'Mechanical & Technical' started by rg4, Feb 1, 2009.

  1. Yesterday we spent the afternoon getting my old 1976 Yamaha RD400 ready to start after sitting since 2002. She started with no problem. We decided to change the oil. I used a synthetic oil.

    My question, is it OK to use synthetic oil in the 1976 RD400?

  2. I would look at what WAS in it.
    There is a common myth that synth oil will make your clutch slip. Not true. It's molyebdnium that will make it slip. Moly will also make your trans shift nicely.
    Go get some good oil an dchange it often
    I'd be more worried about the cran seals drying out after 7 years of just sitting.
    Nice bike by the way.

  3. o hell yeah and thats what they look like with no toomys...sweet ride
  4. Nice bike! As for your oil question, it all depends on whether the ENTIRE engine has been recently rebuilt or not. If it has, then you will have no problem running whatever oil you choose to run. If not, you should stick to "dinosaur oil" and not any type of synthetic. The reason is that the gasket form micro cracks over the years. dino oil is much thicker than synthetic oil, therefore, not leaking out of these formed micro cracks. The synthetic oils will find just about every micro crack that has formed in your gaskets and rear their ugly little heads for you.

    Hope that answers your question clearly.
  5. Uh....
    Synthetic oil is thinner than Dyno oil?????????
    Oil thinkness is a function of viscosity.
    10w40 synth is exactly the same as 10w40 dyno.

  6. Mic

    Mic Retired


    Weight and Viscosity of two oils, regardless of Dino or Synthetic, if the same, are the same.

    Of the two oils, Dino oil breaks down at a much more accelerated rate than Synthetic oil.

    What that means is, of the two oils, synthetic will hold its viscosity for a much longer period than Dino will. That is why Synthetics can be ran in motors for much longer intervals than dino.
  7. MichelinMan

    MichelinMan Moderator Staff Member

    Yup. What these 2 guys just said.
  8. Rippn

    Rippn Human Race Qualifier<br>FREE and clean

    OIL?... YES, definitly OIL.
    Hopen yer crankseals are good too!!!!!!!!!!!!!!!!!!!!
    Be caurfull to run good old yamalube type stuff in the injecter, thinner or thicker is a NoNo.
    FREE and clean, Ripp'n
  9. +1 on that. All my injected RDs have run on Yamalube for the past 30+ years, never a problem, and never a pump failure. You might want to check
    the pump setting for accuracy. I have a factory manual, so if you need any specs just PM me.
  10. Rippn

    Rippn Human Race Qualifier<br>FREE and clean

    Quick, Knows her 2 smoke!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    FREE and clean, Ripp'n
  11. mjn

    mjn Forum Admin Staff Member

    Damn cool bike man!! :thumbup:
  12. Nice ride! What everybody has said. Hopefully the crank and case seals are good. This is a pretty black and white issue, if the motor lays down under load - air leaks are always a suspect. Synthetic oil shouldn't hurt a thing in the tranny/clutch. Lot's of good 2-smoke oils out there, Yamalube is one of the better ones. Keep using Yamalube and you'll have no problems. Man, that really is a nice bike.
  13. If those tires are original or over 5 years old.

    Chuck them!!!!! The hot street setup is bridgestone BT-45s 90/90-18 front and 110/80-18 rear from MAW (motorcycle accessory warehouse). Never had a problem w/ an order and the price is reasonable. I don't order the High performance set, but the cheaper version...i think the high performance is V rated? The ones i buy are probably H rated or something like that. Between 74-80 bucks a tire i think. The first time you hit a wet patch, you'll wish you did.

    There are some Transmission oils (synthetic) that will make your clutch slip. Mine is currently slipping right now. (probably old plates, etc.) You can't go wrong with staying with yamalube transmission oil for the tranny, if you aren't sure what to run in the aftermarket out there, as was mentioned before. Might also try adjusting the clutch per manual to see if the problem lies there.

    I'm probably gonna replace both the steel & fiber plates in the clutch basket this spring.
    Last edited: Feb 1, 2009
  14. shelbyguy

    shelbyguy Picture Whore


    id like to know what bike stand that is (lift)?
  15. james1300

    james1300 Track School Dazed

    More pic's when ya get her up and on the Road Please!
  16. are going to love the smell:mrgreen:

  17. Speaking of Castor.

    If you use Maxima Castor or any other castor, better shake it up in a gas can for about 5 minutes straight and use it right away. This shTwill foul plugs on the street like no tommorrow. Doesn't stay in suspension very well and likes to separate and gum things (plugs) up.

    found this out a couple months ago when i tried to use it on the street.

    Right now i'm using this torco snowmobile two stroke oil (you have to special order yamalube two stroke by the gallon now). Works good. no plug fouling.

    castor is just a pain in the ass on the street.
  18. true to all that but god it smells good.
  19. My favorite!

    I could run maxima in the RZ, but the RD seems to not like it for too long w/o fouling. Then again, i might have mixed it in a 5 gallon jug before i poured it in.

    Redline sorta smells like castor, so you could probably run that, but i seized on Redline and heard stories of others with similar problems, so i'm kinda spooked on the stuff now.

    It would be really hard to run the castor in the cold weather up here...probably better in the heat of summer, is my guess.
  20. Yamalube R is the equal of castor and doesn't tend to separate. Kind of moot when you run oil injection though. I run Burris castor in my kart motors and never a failure due to oiling. Hard to say about fouling plugs, I mix it 16:1 and it doesn't matter what oil you run, plugs won't last long. The only time I've separated it was mixing it with Trick gas in 25 degree weather. Castor dropped out in the tank and the carburetor got a big dose. If the specific gravity of the fuel is too low, this is a known problem with castor. Yamalube R solves the problem. But..... Bubba's right, there's nothing like the smell of castor in the morning.
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