Vintage Dirt Bike Q & A

What viscocity should I use in my 1979 gearbox please?
Is SAE10-40 the way to go?
many thanks

I use Honda HP4 10W-40 in all of my Honda motors, vintage and modern.
It provides more than enough shock protection, works well for the
clutch and is relatively inexpensive. What more can you ask for?

dogger

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1973 CR250M
1979 CR250R
1993 CR250R
2008 CR500R
2009 CR250R

You can go with the engine oil suggestion or straight SAE 80 weight gear oil. I have used both Bel-Ray and Maxima. It is far more important to change it regularly than fret over the brand.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Ruairi
jim from sydney here,just rebuilt my 73 250 gearbox with the help off a ex mx star from the 70 here in aus and he is also a exerlent motorcycle mechanic and still a shit hot rider in vmx.he told me to use stuff like castrol 4t.the modern gearbox oils are for the modern bikes which get the clutch faned more time in a rase meet than the vmxs get in a year.in my cz i use almost diff oil as there is now wet clutch.
ps
how is your yz400 going.and is there a new web page for antig as the old 1 is goone
cheers
jim

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Jim Garvey
1x honda cr250m 1973 in bits
1x honda cr250 champion dirttracker
1x yamaha tt500 dirttracker 1976
1x yetman triumph dirttracker
1x tt500 longtack speedway bike
1 x 1940 350 ariel speedway bike
1 x bultaco astro grasstrack bike antig

Castrol 4T with Trizone Technology is a modern engine oil designed specifically for 4-stroke engines to ensure good all-round protection for your bike’s three critical zones, the engine, clutch and gearbox. Exceeds all current industry 4T standards.
Benefits
The engine is protected against wear and deposits
The clutch is protected against slippage and grab
The gearbox is protected against pitting and wear
Applications
Suitable for use in all Modern Japanese and European Bikes.
Performance Levels
Castrol 4T provides the following performance:

API Service API SE
JASO (T903) JASO MA
Viscosity Grades SAE 20w40

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Jim Garvey
1x honda cr250m 1973 in bits
1x honda cr250 champion dirttracker
1x yamaha tt500 dirttracker 1976
1x yetman triumph dirttracker
1x tt500 longtack speedway bike
1 x 1940 350 ariel speedway bike
1 x bultaco astro grasstrack bike antig