Topic: 1204cc - 120rwhp track bike by RPE in Oz

[Retro Rocket]

I've reposted this here so the HIPO guys can see it...

this one says "130 to 150HP

Power wheelie

There's info on the engines at the start of the top two videos..

[bwaller]

He's a hard charger. What a riot seeing this bike out there with those others. Snarling, bawky shifting, skinny forked, squealing braked old timer....awesome. Those other riders should be ashamed. 

[Retro Rocket]

He's a hard charger. What a riot seeing this bike out there with those others. Snarling, bawky shifting, skinny forked, squealing braked old timer....awesome. Those other riders should be ashamed. 

Yep, I enjoyed it for the very same reasons...

[mrbreeze]

Never get tired of hearing an old SOHC winding up!!

[Jerry Rxman Griffin aka MuthaF'er]

That sum#$%* sounds ANGRY!

[johno]

Thanks Mick,
Thats pure medacine, .......ahh feel better now

[Retro Rocket]

Thanks Mick,
Thats pure medacine, .......ahh feel better now

Thank Hotdog mate, he posted it in the "Australian" section, I moved it here because i knew you guys would like it...

[hotdog]

Offset barrel/rods combo, allowing bigger bore.....? Is anything bigger than 73mm pistons limited by the studs..?

[PeWe]

Nice sound!

[BPellerine]

so with most not recommending big bores for the street,I wonder how that engine stands up to road racing,and yeah I know it takes a lot of skill to build that bike,but a lot of them wont take too many runs down the 1320.bill

[stikman]

Very cool!  I doubt I'm the only one who wants pictures of that engine build.

[gschuld]

There are some photos, at least of the cylinder boring prep(very unique solution BTW) if you look through Facebook photo archive.

The calssic road racing rules are unique in Australia.  Most notable be is their unlimited displacement and allowance to run methanol in the pre 1972 class.  This has forced competitors to go as big as possible, yet the methanol has a great cooling effect compared to normal race fuel.  That great cooling effect of the methanol presumably gives these engines a much higher tolerance regarding cylinder and head heat control.  Notice how relatively small the oil cooler is considering the displacement and hp levels.

George

[bear]

Your dead right George.

Most people think methanol in it's self produces big HP, it doesn't.
What it does do is help control temperature allowing us to achieve tighter tolerances,  as you mentioned.

The other big plus with these motors running methanol is the cylinder pressures that you can achive.

In my opinion,  if you want big HP from these motors your better off working on their strengths.
For me that's high cylinder pressures not high rpm.

Methanol helps me achieve that.
It has a high flash point and more importantly a high auto ignition point.

One small correction mate, the engine capacity isn't unlimited we're capped at 1300cc.

Cheers,
Brian

[simon#42]

is that 1300cc per cylinder bear ?

[Tintop]

is that 1300cc per cylinder bear ?

You didn't think it was a total for 4?  Know wonder you Brits don't do so well at Philip Island.  Ozzy rules  

[bear]

I wonder how that engine stands up to road racing,and yeah I know it takes a lot of skill to build that bike,but a lot of them wont take too many runs down the 1320.bill

I would argue that it's just the reverse Bill.
We do the equivalent to "a run down the 1320" as you put it, at the start of every race.
Then we flog the siht out of them for another twenty minutes.

Cheers,
Brian

[bwaller]

   +1

[bear]

is that 1300cc per cylinder bear ?

You didn't think it was a total for 4?  Know wonder you Brits don't do so well at Philip Island.  Ozzy rules  

Don't go poking Simon with a stick Brian.
They nailed us at PI last January,  it's going to be on for young and old next month though.

Cheers,
Brian

[BPellerine]

I wonder how that engine stands up to road racing,and yeah I know it takes a lot of skill to build that bike,but a lot of them wont take too many runs down the 1320.bill

I would argue that it's just the reverse Bill.
We do the equivalent to "a run down the 1320" as you put it, at the start of every race.
Then we flog the siht out of them for another twenty minutes.

Cheers,
Brian

I did not mean that road racing was easier on an engine bear,just the opposite,the big bores take much more care to dragrace it seems ,just wondering how they get a big engine to last on the roadrace end of things,where they are run hard and for much longer.bill

[gschuld]

Now that's some creative cylinder/sleeve work....

George

[Tintop]

Now that's some creative cylinder/sleeve work....

George

+1   Brilliant interpretation of the vintage racing dictum re 'original castings'.

[MRieck]

That's pretty interesting. Why not just Nikasil and forget the iron sleeves? I think there would be enough material for the oil return passages.

[754]

What about the spigots on the bottom if you nicasil ? Ot do you mean build the inserts with spigots on the bottom.
 How big is the bore and are they offset?

[chewbacca5000]

Thanks Mick,

This will help me kick that nasty morning coffee habit that I need to ditch.  Just kept imagining myself out there on the track.  Really gets the juices flowing.  That thing is a monster.  Would like to see the actual dyno numbers though.  Just can see how you can get that much out of a naturally aspirated carb bike? 

Thanks for posting.

[gschuld]

Mike,

If I had to guess, I'd say that the method they chose for making the cylinder pairs, a casting in house, made the difference.  The photo below if from their instagram site, showing them melting down used up pistons for the pour.  Great recycling BTW.  The resulting cast sections may well have some porosity or other modest contamination that would not allow the perfectly uniform cylinder bore that a block of machine made billet (like you used) would offer.  The casting would be perfectly fine strength wise, with the sleeves not only giving a machined bore surface but also adding rigidity in the critic area between the bores.  It's pretty thin there.  Even if they used billet material instead, I imagine that they were uncomfortable with such a thin aluminum wall between 1/2 and 3/4.

Frank,

1204cc at stock stroke of 63mm is 78mm bore!  The flanges on the sleeves needed to be cut a bit where they meet since they  would overlap otherwise.  Less than 1/8" of (aluminum) meat between those sleeves.