What is the BEST gear oil for a 2 stroke motocross bike

[hawaiiguy]

2006 yamaha YZ250, with, obviously, a wet clutch.
I change it very often, and am thinking about trying the two2cool additive.

I guess since the crank and piston are lubricated by the fuel/oil mix, the gear/engine oil has a different requirements than the gear/enginge oil on a 4stroke bike.

Is the shell SRT still a good choice ?

I'm currently using using BelRay sae 80w gear oil intended for 2strokes.

 

[Mackelroy]

the longer you run the oil the more metal(aluminum) developes, then grinds on everything.

something cheap like 15w40 and dumped every couple rides will keep your tranny and clutch prestine for a long time.

 

[sunruh]

use ATF type F automatic transmission fluid.
change it ever ride.
i ran it in my '98yz250 for 2 racing seasons and the clutch plates all measured as new with a micrometer.

 

[Jaybird]

I am another TypeF ATF fan. Changing every ride is no problem @ ~$1 qt.

Why the snakeo....errr...two2cool? Are you boiling over?

 

[Master ACiD]

i dont kow if it matters much what you run, so long as you change it out frequently. these little high output dirtbikes/quards really beat on the transmission and clutch. change it frequently to keep wear metals at bay. also a magnetic drain plug is a great idea. can pick one up on ebay for around $10 shipped.

 

[wileyE]

Atf here too, but have used motor oils and all kinds of stuff. Some bikes liked MO, some didn't. All were happy with atf.

As far as coolant temp on your twostroke. Ideal temp is when you can stick your finger into it for a quick second and pull it back out. If you touch it and go 'ouch! fn hot, you need to think about getting it down. If you can hold your finger in it easily for a few seconds than your running to cool. Adjusting the coolant/water ratios and duct tapeing off parts of the radiator guards is a couple things I used did to get them dialed. All your final jetting should to be done with proper coolant temp, something that is often overlooked. Also avoid silicated coolants.

 

[Cujet]

Interestingly enough, 2 stroke gearboxes are not high wear items. It seems that nearly any type of oil will provide enough lubrication for long life. It may be that the time spent on the bike does not add up to much over the years. Or it may be the type of use the gearboxes see. For instance, it is much harder on small gears to have a constant high load, such as road riding a dirt bike on the highway. This is evidenced in the gearbox siezures of CRF450X's ridden on the highway. (with too low a lube level).

My guess would be that localized heat buildup is the problem with street use. Not a problem with most off road bikes.

I use Mobil 1 ATF in all my 2 stroke gearboxes. I change it farily often. So far, my 1985 RZ350, 1994 Husky 360WXC, 1986 KDX200 and my 2 stroke Yamaha Zuma scooter are all on the original gearboxes with no failures.

Whatever you choose, change it fairly often to keep it clean.

Chris

 

[Master ACiD]

rz350 is like my dream bike. lucky you!

 

[Cujet]

The RZ350 is one of those fantastic motorcycles that can be had for cheap. I see them for 1000 bucks all the time. They all need work, so getting a cheap one is a good idea.

Chris