RD350 in DT frame

[ola_martin]

A friend wants to put his RD350 watercooled engine in a DT 400 frame to make a TZ flattrack lookalike funbike. Anyone know if something like that has been done before??

[Marc.com]

No but it sounds like something that needs doing. BTW Ola when is the grand unveiling of the HL.

[cyclegod]

Do it, but don't forget to include the stabilisng mounts that go underneath the engine or it will wobble itself to pieces.

[ola_martin]

I haven't looked at it yet, but is the stabilising mount something I can cut from the rd frame?? I think it will be possible to make that bike wobble anyway....

Marc, the plastics, seatcover, decals etc is on its way, but my uncle's bodyshop is doing the paint, and unless you have had family doing work for you before i can tell you that it will take quite a while longer than what was expected......
Also the wife want's a bigger house, so I've spent a lot more time with a hammer and saw than my garage-tools lately...

[DR]

I'd reckon even if it were a handfull to ride the looks and sound of a screaming twin would all but compensate for any deficiencies or shortcomings the pic below courtesy of aircooled-rd.com. Champion frame with a nice ol' R5 350 slotted in..cool of cool

[cyclegod]

I haven't looked at it yet, but is the stabilising mount something I can cut from the rd frame?? I think it will be possible to make that bike wobble anyway....

The two stabilisers bolt to a common rail under the engine and would be an easy fabrication with a piece of square tube, the wobble they stop is in the crankshaft as 350's use the same crank as the 250's (which is what the crankshaft was deigned for).  The cranks have always been thier weak point but the twostrokeshop has a 90 degree crank and ignition setup specifically for the 350 (For the RZ but will work in an RD350LC)

[4V5]

I'm always one for an experiment...


RT3 frame RD350LC cases...
the pipes would foul the front downtubes.. but jeez otherwise it fits in there tidy.

Cheers!
Leslie

[Lozza]

There is a MASSIVE difference between the cranks for the air cooled RD 250/350 and the water cooled cranks(LC and RZ). The air cooled cranks are works of art, properly balanced rebuildable with simple tools. The water cooled cranks are pieces of shite in comparison. CG is correct about the wobble bars they stop any sideways movement while allowing fore and aft rocking.The bars first appeared on the LC and it was (or so the story goes) through the intervention of Yamaha's Mr Fix-it (and current Yamaha MotoGP head engineer) Masao Furusawa who devised the bars to combat the arm numbing  crankshaft rocking couple forces. An air cooled RD with the crank set at either 90 or twingle format would be a quick way to fill a trophy cabinet.A water cooled one would need the TSS crank which is properly balance to begin with, or machine the cases to accept the Banshee crank and buy used ones from the US and rev the ring off it.Ignore those bars at your peril.

[firko]

If you're going to do it properly I'd advise you to bring the rake in to about 25 degrees as shown in the MX360 below. It'll be more stable in corners and will pitch in much better. Yamaico showed how to do it on the budget flat tracker thread
http://ozvmx.com/community/index.php?topic=9177.0 Cool project, keep us posted on its progress. We're doing a similar rake job on a TM250 to make a TM version of the bike below.
                         

[ola_martin]

Mabe an old aircooled RD400 twinshock frame would be a better startingpoint? I have doubt this bike will ever se a track ( or even if the plan will ever see the light) it will be more to make it for the looks.

[mx250]

An interesting project. I have often wondered why it wasn't tried 'back in the day'. I know the Yanks had a few flat track RD's. I'm not quite sure why someone didn't adapt an RD for Dirt Track here in OZ. Power and top speed would have been the clincher.

"Back in the day' I use to punt my bog stock RD along dirt road with cred. Weight, tyres and quality/appropriateness/tune of the suspension were the biggest limitations. I'm sure frame geometry could also be improved but it wouldn't show up until the above were addressed.

I would probably 'cut and shut' an RD frame rather than the other way around.

Good luck, I'll be interested in the outcome  .

[firko]

I have often wondered why it wasn't tried 'back in the day'.

I was curious myself Graeme as to why they weren't used more often so I asked my ex flat track pro mate Mike Middleton. His answer..........                 

"Because of their peaky, high rpm, power output, perfect, tacky, track conditions are needed or they spin up, and the average talented guy finds them hard to ride versus say a TT 500."
                       

[firko]

Here's another one:             http://omarsdtr.com/gallery106.html

[colmoody]

A bit over thirty years ago I had one of many any similar lame brain idea's. That was to put an air cooled 1978 RD250 engine into a  Grass Frame. Could have been an Elstar or Antig but I think it was an Ansell. Anyway the RD250 was a great little road bike with a bullet proof motor. I was convinced that with this combo I would be Champion of the World (or any other big place for that matter) in a matter of days.

At about this time I should pay homeage to a guy by the name of Malcom Mapperson whom lived in a little village (maybe ten or twelve houses) by the name of Premer, maybe about eighty or a hundred K's from Gunnedah who did all or most of the work in setting this thing up. Up until this time I kinda knew Mal was the real deal but it was'nt until I made the first of many trips out to his place in Premer that I got to fully understand the genius of the man.

He was a bit of a sidecar nut and had had a bit of a go at all of it including Speedway, Short Circuit and Road Racing. In his earlier days it was on pommie twins and at about the time I got to know him it was using Kawasaki 750 two stroke triples.

In his tin shed out the back of his house in Premer with limited resource's, machinery and money Mal grafted another cylinder on the the end of the 750 triple crankshaft. Having a bad back it was kinda at the end of Mal's riding days but if my memory serves me correctly Mal might have done a couple of road race meetings on it with Rusty Scrivener as his swinger. At one stage he thought he might put that motor into one of his Speedway chassis and give it a go. Dont think he ever did a meeting on that thing but do remeber at a bit of a practice day at the Blue Vale Speedway at Gunnedah he was good enough to offer me a ride on that weapon. Up until then I had never ridden any sort of sidecar let alone a 1000cc Kawasaki Triple. No you dont need to ask. Anyway as is often the case he was a great competitor and a fantastic engineering talent held back by resource's and money.

There is much more to the Mal Mapperson story and I dont prentend to know any more than five or six years of it but I'd love to hear from anyone whom can add anything.

Ola, just tell your mon to do it.

[DR]

4V5, Leslie I reckon that frames a goer so long as the sprocket alignment is somewhere in the ballpark. The twin downtube can so easily be modded to a single downtube and whilst at it the rake could also be gathered in which is a bonus find a donor frame and go for it I reckon