Purple Dave's SC 500 Project

[Paul552]

Water blasting those parts would probably work ok.

I did a cylinder and head and it came up real nice.

I got it done at cambells classic bikes.

They don't recommend it on steel because it will rust straight away but if you asked them to blast then oil them they would come up great.

No real damage also.

[Purple Dave]

Things are moving forward now.......Took engine to Matcho Mick's today and we TOTALLY DISMANTLED.......New Conrod kit, rebore to 2nd oversize, new main bearings and all new crankase seals and Bob's your uncle.........Too Easy
Ordered piston and ring tonight from USA ( $210 delivered ).......other parts available, just hunting around for best price.







Thanks again Mick for all your help

[JAP 454]

Great stuff on the progress report, Alvin and Matchy, I can't wait to see and hear one of those beasts in action again !!, last time saw one was in '94 at Wyalong with Kevin Horton aboard, well hangin on, anyway !
Foss

[80-85 husky]

While its in bits, dont forget to get the case transfer ports matched to the barrel and clean up all the casting dags and match to the base gasket. You need as much power as possible from those SC's they were way underpowered.........

[Slider29]

 Yeah,
     'bout as much power as a pedal car  

[Iain Cameron]

While you have it in bits Dave are you going to go with the 360 MX gear cluster and dump the balancer for a 5 speed box ?

[firko]

The DT 360 wide ratio gear cluster works well in an SC500,especially seeing you're only using yours for DT. That's what I had in mine and I found that the big grunt easily pulled the wider 5 speed ratios .

[Purple Dave]

Leaving it as a four speeder..........If I dump the balancer, will there be any detrimental effect on the engine ? When I pulled it down the balancer was still there, but the chain was gone.
I've ordered all the parts I need for the rebuild, but I will need to get another balancer chain if you blokes think it is necessary.

[Purple Dave]

I did the front forks today, no dramas, the I went to take the knobbies off, ready for the new Mitas, ALAS !! no tool to remove inner tube valve......in the old days I had steel dust caps with the tool built in.
The seat looks SCHMICKO !! 

[Rossvickicampbell]

I must of ridden a different bike to you guys - it was an SC 500 in a YZB frame and that thing fair roars - torque and go?

[OverTheHill]

My advise on the balancer is to "leave it operational". Disconnected the chain on one i borrowed when new in "74 cos "we wanted max power & less flywheel effect" [wrong] bloody soon hooked it back up [before the boss found out or went to ride his bike & would've found out straight away!!] vibrated annoyingly & did notice the less flywheel effect too but turned a nice motor into a horrible one. Damn short stroke too for a 500 [70mm] which might be why they revved pretty hard & came on hard at about 1/3 throttle, don't lean it off much from std or she'll seize for sure, especially if you lean off the slide needle to much, it'll seize when you roll it back from a full song run. Left ours stock std & no problems but numerous guys tried different needle & jet combo's & i suppose smaller main jets & everyone suffered seizing. Were trying to no doubt overcome the needle rich blubberyess but [i think] when you're racing your either on full song or shut off [sort of] but not cruising on the needle as such so isn't noticeable like when you're cruising up the paddock. Anyway--long winded way of saying -- be careful. Cheers. ps, all the above stories are umm, hell, close to 40 years ago [is that right-add it again] Now, if i can only fit a 90mm piston in my RT2 without the fins falling off!! [same 70mm stroke].

[Purple Dave]

Received a second oversized piston from USA yesterday, and today, have sent barrel and piston to Serco in Qld for reboring. I'm expecting new conrod and roller bearings to arrive from Speed and Sport next week, so rebuild should be happening after Mrs Purple and I return from the Triumph RAT Rally in Jindabyne at the end of the month........we took the Grump for a spin on Sunday.

[pancho]

 Only a dash of purple to be seen there on the jacket 'Alvin' what's goin' on?
cheers pancho.

[Purple Dave]

Only a dash of purple to be seen there on the jacket 'Alvin' what's goin' on?
cheers pancho.

As an old ROCKER Pancho..........BLACK for the Road........


And PURPLE for the Track.........


It reminds me of Griffith in '72 and '73.........Reg Southgate would arrive at the track with his Cossacks 1%er mates, get changed into leather suit and race his 350 JAP.......

[Purple Dave]

At last I have some news......and pics !!
Thanks to a LOT of HELP from Matcho Mick and Phil from Road and Race on the Central Coast, the rebuild has begun.......





Front and Rear shocks are on, Mitas tyres are on and seat is done.......guards, sidecovers and tank are being sprayed this week...