I am looking for specs for a 73 Yamaha 360 MX 1. how much and what kind of gearbox oil? 2, How much and what kind of oil for the forks; and what kind of gas oil should I mix for the engine? Thanks!
That's a great vintage racer!
On your forks each fork leg takes 194cc of 10wt fork oil.
They now make special gearbox oils for 2-stokes, but back in the day, you just used 10-30 oil in the gearbox. Unless the entire motor and tranny has been rebuilt, I would stick to the old oil and just use 10-30. Put in half a quart, level the bike and check the dipstick. Add to bring it between the lines.
I would use the best gas you can find. If you are in the US, that would be premium, non-ethanol. Higher grades are available in the UK and EU. Never run the lower grade fuels or an ethanol blended fuel.
Are you still running the oil pump? On the 360 they recommended running pre-mix in addition to the oil pump. The ratio will depend on the oil you are using. If using a mineral based oil, I would run the same oil in the tank and in the mixture. Mix it at 32 to 1.
If the oil pump has been removed, you have a wider range of oils that can be used. Check the oil you intend to use. Many of the new synthetics mix at 50 to 1 or higher. I would not go leaner then 50-1 and prefer to use around 42 to 1 unless there is plug fouling.
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Thanks for the details. I am the original owner, but the bike has been sitting at the back of the garage for a long time. The tires sill have hex-headed screws from the last time I went ice racing.
Your comment about running the pump and using pre-mix is interesting. When I raced it and a 250 MX I justthe pump. I figure I will go with pre-mix for now since I am not sure how well the pump works after sitting for years.
Do you have a suggestion as to which modern day spark plug you would use?
Professional motorcycle mechanic since 1978. Vintage motorcycle restorer.
I always use NGK plugs. The B8EVX replaces the B8EV plug that is no longer available although you might still find a few if you dig around. If you are not using the oil pump, be sure to block it off or it can be a source of air entering the motor. Good thing you kept the bike. Fully restored they go for $3-$4K. One in original condition like yours could bring close to $2k. I've got a bunch of vintage Yamahas, but I haven't been able to get one of those. They sold mostly DT's here. My first race bike was a DT125 that I raced in a two-day national enduro qualifier back in 77. Doug