Vintage Dirt Bike Q & A

Hello Everybody,

would love to know what transmission oil everyone is using. I recently did an oil change and, as suggested by dealer, used Honda HP trans SAE80W/85W transmission oil. Although the Owners Manual specifies SAE 10-30 or 10-40 the thinking is that this was before modern transmission oil was available so we should be taking advantage of new technology and using the Honda brand tranny oil.

However, and honestly I don't know if this is linked to the oil change, but imagine my surprise when I hit the power band leaned over and the rear end slides. Initial hopes of increased power were ruled out once I saw oil on the tire and the only source I can see it coming from is the crankcase breather. Pic shows a little dried oil on the tire- it's been 24hrs- but originally it looked like the very first time time I oiled the chain ....with 3 IN ONE.

I was worried that oil out of the crankcase breather was a sign of blown seals of some kind- I know on a 4-stroke it means piston and rings beyond it's life term- but have no idea what this means on a 2-stroke. Motor runs great as far as I can tell- to be honest seems powerful but that could be because I've been running around two up on the gfriends CB125.

What I'm hoping is that all of this could be solved by just draining the tran oil and refilling with good ol' engine oil- but any opinions would be gratefully received.

Chris

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'75 MT250
'78 Sportster
'81 RD350LC
'86 FZ600C
'94 CBR400RR (track bike)

I think that you need to go back to the dealer and basically say...WTK?...Transmission oil has absolutely no business being in that motor. The oil lubricates not only the transmission but also the clutch. I am surprised that anything works...and I'm certainly not surprised that this stuff has been pushed out a seal.

Transmission oil is about as thick as a milkshake...10/30 is more like milk. These products are not interchangeable. And if you have a spare moment, take a look at your manual. This is a really easy procedure...and despite that fact your dealer screwed it up. It is fun and rewarding to work on your bike,

Mike

http://meditarivemachinery.blogspot.com/

castrol 4t (four stroke) in your gearbox is the only way to go! it has clutch protection technology, and im damn sure oil cant tell the difference between two stroke and four stroke gears! I run it in my 96 cr250 and 1980 cr125. never had any issues with gearboxes. cheers.

Been using Belray 80W to a fresh clutch for years. Hondline has good oil too.Changing oils might not be good for the clutch.
Plates are cheap and easy to change, soak in your favorite oil and install.
Ride Red!

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73' Honda CT-70
77' Honda CT-70
78' Honda XR-75
80' Honda CR80R
85' Honda 350X ATC
75' Yamaha GT80A
73' Kawasaki H1 500
76' Kawasaki H1 500
76' Kawasaki KZ900