My plan will have aluminium

[Roostmaster]

Hey guys, couldnt work out what section to post this in so Ive dropped it here.

I know Bobs into speedway and maybe others too, so Im after input into my idea of building a CR500 powered speedway bike.

To race against the mx bikes at flat track, the bike must not be rigid, have brakes, and run on petrol.

Can anyone see any flaws in fitting a CR500 engine into a long track or grasstrack chassis?

The benefits will be that she is built to go sideways, will have a power to weight ratio advantage, reasonable running costs, look and sound waaay cooler and should destroy everything it slides up against !


A CR250 powered grasstracker




The kind of chassis Id like to use




What do you think???

[AlisoBob]

Build it with a air cooled, early motor.

Radiators, Speedway, and scalded gonads dont mix.

[bearorso]

Would be an interesting bike.

I know little about speedway rules - never seen a Speedway bike in 2t format, from that I've assumed that the rules precluded them. But have seen longtrack, grasstrack and short circuit bikes with 2ts, many times.

Many years ago (mid 80s), I'd get both Motocyclismo and Moto Sprint (Italian monthly and weekly magazines) airmailed to me, and I saw the GM motor revolution, with the laying down of the motors for speedway (it had been done with longtrack / grasstrack a long time before this), and watched the change over to slopers.

I'd be surprised if you really could get a power to weight advantage over a modern 4t sloper speedway/longtrack engine. They weigh next to nothing, and put out serious (and perfect speedway etc) power. Perhaps you are talking about like for like class racing, as in, going up against other fully gearboxed, production dirtbike engines based bikes?

Could you expand upon the actual class you be racing in?

A CR based speedway/longtrack bike sounds intriguing.


Where I live, we have a short circuit track (Nepean) - friends of mine have got back into it and have enormous fun. They've been hassling me to have a go again, as I always use a Michelin Trials tyre, so I would not have to change a thing on my CRE to just blat around. Most of them are older blokes, have gone through their MX phase and have families - having a local circuit like this fits in with family life, and, providing you don't take your brain out, injuries seem to be a lot less frequent. Mind you, I've seen some truly awful prangs out there, and I myself got carted off after a full lock highside 'orbital launch' off my 320 Maico. I'm considering going back again, if only to get my older brother to make use of his YZ250, and get back into bikes. He's getting rounder than me (I'm pretty bloody solid, hence the nick name Bear), and he's always been a rake of a bloke till recently - he's a massive heart attack in the making.

[Roostmaster]

Thanks guys,

Bearoso, the class Im looking at is the mx flat track, where methanol is not allowed - hence the CR500 engine, maybe a xr600 engine would be better suited? But then I wouldnt be interested.

And your right, not even a bombed CR500 motor could come close when up against a speedway engine on a flat track, on the other hand a CR500 in a long track bike should do well against mxers at flat track

For this class the bike must have front and rear suspension and brakes, which is why the long track chassis would be best. Its designed to slide and the power to weight ratio over conventional mxers would be good.

Since Im up in Darwin Im going to need feelers out over the rest of Oz to find a donor chassis, this will be the hard part, Ivan Mauger sponsored me a long tracker in 99 to race the JD / SBS long track series but since the sport is so low key in Oz finding a chassis is going to be the hard part, if you know of anyone 'in the know' Id appreciate any help.
On the other hand they are relatively common and a lot cheaper in Pomgolia, and since I work in Africa it might be possible to pick a roller up on the way home as excess baggage - maybe, getting one in Oz would be easier though.

All Id like to do is to remove my steely's motor once or twice a year and drop it into the slider to compete in the NT titles at flat track and maybe do a club meet here and there, so the motor part isnt a problem, just have to find a chassis at a reasonable price.

Maybe Im just better off racing my AF at flat track, but there is nothing like throwing a slider into a corner at full noise!

[Roostmaster]

Imagine this with the speedway clutch removed, new engine plates modified to hold a CR500 engine which would be direct drive to the rear wheel, a flat track pipe and a single rad mounted at 45* under the fuel tank.

It looks too easy, which means there must be a catch to it

["SOLID Bro!!"]

Try to figure out a way to run the coolant through the main tube of the frame because you wont need the the primary chain oiler. That extra volume will help offset the loss of 1 radiator.

[bearorso]

Hey Roosty,

The penny dropped and now I realize your a fellow OZ rider - so we both know Short circuit / long track . I was taking it as a US bloke literally doing Speedway.

So yes, use your 500 - bugger an XR. As a side note, I'm of the generation that raced when Gally decided to go up against the sliders on his MXers, the noses put out of joint years ago by him and other MXers was hilarious to see!

Pomgolia First time I've heard that one! I think that's a really good idea - try getting a long track roller from there. You've obviously got Internet where you are, so check out various Pomgolia web sites - there's a lot more chance of getting a good long track chassis there than OZ, though you could be lucky. A roller like that #46 with a 500 in it, tilted as far forward as possible, with the pipe looping up and into the main frame ( as with tilting the engine, the cases would be where a under slung pipe would go - better to have the engine low and the hollow pipe through the main frame). The limitations on the tilt of the motor would be the carb/ manifold for the float chamber, (I think you can get Lectrons etc with remote / adjustable float chambers) and of course, the crank positioning that is desired. I've no idea what the current thoughts on crank height and crank to wheelbase centering is. But with a unit motor like the CR, adjustable / replaceable engine plates would be a simple thing to do, so you could experiment with set up

I love speedway bikes/ short circuit/ long track bikes. They are so utterly minimalistic and purposeful. In the 80s I made a few short circuit chassis for a mate and his boys - They were known as BBRs - Bear Bradley Racing .I think a couple still exist in his basement. I've been thinking of checking out the scene whilst trying to get my brother back into riding, and seeing if there is any niche I might be able to fit into - I'd like to make something in between other contracts and my continuing Uni commitments. An old mate of mine whose into XS650 based flat trackers has been making noises about wanting a frame made up to replace his aging Champion one, for the last few years. I wish he'd make up his mind, as I'd really enjoy doing a flat track frame.

[asteroid500]

Roostty...you just cant let it go can ya...bloody flat tracker/speedway guy's....Richard at Alicross, Clive Baxter, Matty Johnstone, they know were the NT bikes are collecting dust...
My mate Chris is restoring Clives brothers Outfit for the club house as a permanent display...
when you home.

[Roostmaster]

Dudes,
Asteroid, yeh Bro Im home in a weeks time, outa Africa tommorrow then off to Marcei to see Tiktakboom, he is hiring a 600 roady and Im riding his shit hot AF motard along the sth coast of France, through Monaco to Italy, its going to be one mega fat time that would put a horn on a box jellyfish, talk about penis pumped!!!
Mate theres a enduro in Katherine on the 18th, Im in, Deni is keen and his mate on a 97 Steely is too, all we need is you & weve got the 4 horsemen of the apocalypse, that will get em talking.

Im calling you when Im back on Aussie soil ok, got shit loads to do to the bikes and need your help with the AF, mate wait to see what Im up to, it will blow your tits off!


Hey Bearoso,

Geeze mate Id love to spend a night on the piss with you in your shed!
I contacted the builder of the grass track bike with the bombed CR250 engine in it, he told me the speedway frames dont handle the 500 2 bangers because of the brutal power hit wrecks the frames, also said the langhurst frame was the only one strong enough to cope but it is too much of a handfull to ride with the 500 motor, but then again he is a Angleshmahn, prolly had too many cups of tea & cucumber sanga's and hadnt showered in a week.
Im going to get the word out through my old speedway mates when I get home and see what comes up.
Hows you ally tank for the CRE coming along?

[Tharrell]

"Geeze mate Id love to spend a night on the piss with you in your shed!"

I'm sure there's something lost in translation!

Anyway, I want to see that bike run. Where can I see some video?
As far as the 500 being a brute, yeah but, so are the Jawa's on traditional speedway bikes.

[bearorso]

Hey Roosty,

Sounds like a good ride in France - I scored the use of a NVT750 (not sure if the letters are right - it was a French market Dakar Rep anyway) last year at the MXDes Nations and rode it from Italy, along the south of France, through Spain to Portugal - bloody fantastic time!

Asteriod sounds like he has the heads up on rollers - there's always something gathering dust in someones shed!

Perhaps the Pomgolian if referring to the 'shortness' of the mounting of the 500. I'm probably talking though my arse here, but when you combine the separate gearbox, engine (and perhaps the lay down engines have a barrel / head mount?) you probably have a loonnnnng combined mount, to spread tortional loads better through the sliders frame? As against the , roughly, 325mm from front mount to swingarm pivot on the CR.

That bloody tank - I stopped everything last weekend, after letting it rot for the last few months,and worked pretty much without sleep to finally finish it. Not quite done, just the cut out(s) for the KS (to take my short GAS Gas lever, and if I can be bothered, the CRF lever I also have for the eventual death of the midget GG unit), and sorting out brackets to go from my radiator cage to the forward rad shroud mount - the other 3 pairs are all mounted to the tank. so it's held on by the back strap, a single mount on the back bone behind the steering head, and just the 2 rad shroud mounts - and they should be DZus fasteners with 8mm bolt heads welded on. But It should be good to go this weekend, I'll post up pics probably next week. Should look truly shithouse, brand new 250 shrouds,semi shiny tank - I hate polished alloy, at the most it will be scotchbrighted - with no stickers, and the rest of the plastics scarred to death.

So much for the tank and subframe being Xmas break projects!

Have fun on your Frog ride!

[asteroid500]

I'm just finalising payment on the gearbox parts via the USA now...might be a close 1 but i'll run the 250 if the 500 aint done, she is a 2 banger so that atleast should be socialy acceptable....

see ya soon & the alloy shop's ready to go.

[jarnott71]

i flattrack race in mi a rider hear ran gas to his jawa put brakes on it and smoked are asses on nice half miles. if the track got shitty by the main it didnt work though.