Classic Dirt Track Images.

[jimg1au]

hoony
when i first took my bsa jap to amaroo race way i was told that i couldnt ride it in the 500 cc because they thought it was a 250 cc.they never seen a 84s before.it was fast past manx nortons up the hill but they would get past me every were else
jim

[Curly3]

Glad you mentioned Nitro Foss, most of the top guy's were on it at some stage, Billy reckons he still has all the mixing gear, he just never got around to using it of course.

[JAP 454]

Here's the cover and a couple of pages from a JAP manual , it gives the date of the introduction of the 4B engine and the manual was passed on to me by St. George rider of the '70s, # 515 , Alan Hill.

Alan bought his Hagon Sandracer fitted with a 4B JAP from Paul Spooner on Saturday, 13th July 1968 as noted in the book.







The Cam timing given is for the standard 4 stud,  later in the book it gives the timing for the Special Camwheel for the 4B as,
80, 50, 60, 80,

Oh yeah, Nitro , Slides we used polypropelene oxide as well, used to call it POP
Foss

[jimg1au]

STEVE
i have a contact to still buy that stuff gets it in ltr bottles.wonder what the elsinore would go like on 5%
jim

[Freakshow]

IS IT LIKE TOULENE ? octane boosting or do you have to regett to new volumes ?

[Curly3]

Get some Jim and we'll experiment, on your bikes.
Apparently you have to reduce the compresion because it produces oxygen in the Cyl, thats courtesy of TH, don't know how he'd know, bigg'n & Nitro = Rocketship, no wonder he got great starts.

[jimg1au]

there is a lot more of that in the 70s.some street motors were specials as well.
i think 10% in the dr will be great.i am not starting it you can
jim

[JAP 454]

Hey Freaky
Yeah , major re-jetting for nitro, depending on percentage, not quite so major for polypropelene, we used to call Nitro liquid supercharging. was banned in early '70s , I think.
Slides , you are right , used to drop compession down, for nitro and also alter timing, JAPs had shims under barrel as standard  to alter compression , check out my Bendigo Longtrack yarn that shows what can happen if you don't.
Foss

[pancho]

Reminds me of waiting at the grid for my heat to follow the line-up in front of us, at Nepean late, '60s parked behind an un named "A" grader . I was having difficulty getting my breath.
 I was telling mates back in the pits about it and someone said "thats because you were behind ********* ,he's loaded up with nitro"
 cheers pancho.

[Freakshow]

Dont they still use it in model cars ?  you can buy it over the counter here if its the same stuff.  Assume you cant mix with premix unless its that crazy oil stuff they use in the model boats.  Could be a fun experiment to see if it actual makes any differance today.

[JAP 454]

Spot on there , Freaky
I got my last lot from a model plane and car shop, for me 2T model plane motor, you can get premix with  Methanol , Shell M or Castor plus whatever percentage of Nitro ya want or ya can get a bottle of nitro on its own.
Foss

[pancho]

don't drop it

[Curly3]

This is what most were riding in the recent shots.

[Curly3]

Pit shot from Heddon Greta, 196?

[Slider29]

   That Ladies and Gentlemen is probably the best picture on here i.m.o.
   Two great champions and a pretty girl. I was  privileged to be there .
   Thanks so much for posting it Steve.       Regards   Mark