what is the best motor oil to use on a newly rebuilt yamaha rd400 motor ?
I use motorcycle grade gear oil in the transmission and castor oil in the premix (fuel/oil mix) to break in new engines. I've never used a synthetic oil to break in a new engine. I'm sure it can be done, I've just never done it. My Hellcat has 707 horse power and only uses synthetic oil, so I know it can be done. But that engine was broken it at the factory before the car was assembled.
I hope this helps.
Rob
You are dealing with an old high tolerance low tech engine. Run whatever oil you want in there. a premium oil makes zero difference for your use. The crank seals will harden and leak before you have any chance of degradation of metal parts due to oil.
Or just search? Oil threads are stupid.
? legit question for those that dont know.
I typically run whatever im going to run the bike on. the heatcycles are what matters.
https://www.belray.com/industry/powersports/
https://www.belray.com/product/gear-saver-transmission-oil/
https://www.maximausa.com/product/mtl-transclutch-fluid/
https://www.maximausa.com/msds/transmission/MTL%20SDS.pdf
For Injector I used: https://www.shopyamaha.com/product/details/2s-2-stroke-all-purpose-engine-oil?b=Yamalube+Engine+Oils&d=30|30&ls=yamaha-motor-company&dealernumber=
For Pre-Mix I use Honda HP2: http://prohondaoil.com/engine-oils/2-stroke-engines/
I agree with Motodreams and add that synthetics might cause the clutch to slip. So don't use synthetics.
:whistle: https://www.youtube.com/watch?v=67pWcoSHy1c
Quote from: Jessup on October 02, 2019, 10:25:18 PM
:whistle: https://www.youtube.com/watch?v=67pWcoSHy1c
Love it. :whistle:
Quote from: top-jelopy on October 02, 2019, 03:18:28 PM
what is the best motor oil to use on a newly rebuilt yamaha rd400 motor ?
Any decent NON SYNTHETIC two stroke oil, and LOTS of it.
Don't use CastrolR, or any other bean oil UNLESS you plan on running bean oil.
Heat cycles matter more than the name on the oil bottle.
I think my attitude about oil may not be popular. I try to determine & use high quality lubricants. I also believe in changing oil frequently. Perhaps I spend a bit more than is necessary, but I feel like it is cheap insurance as compared to worn/seized parts.
I look at Honda as a large company that most likely has a good sized budget set aside for R&D. Their HP2 pre-mix comes highly recommended by a well respected racing Kart engine builder. Engine wear is noticeably reduced with HP2.
Your attitude about oil is fine with me. Today's oils are very good and their are certainly many choices but I scratch my head when people talk about cost. Mostly we are talking about small cc bikes that hold small amounts of oil. We care enough about these bikes to post threads on forums why worry about a few $ more for top dollar lubricants.
Use a good quality mineral based oil, this will allow the engine to bed in correctly,
synthetics are fine for an engine which has bedded in,
this type of lube is so efficient it does not allow a small amount wear to take place on important components like piston rings.
A good efficient bed in period promotes engine longevity .