RD350 Dirt Tracker

[yamaico]

Thanks Steve. We still need to get that T20 ready for the twin series, so start saving those pennies...

[SON]

Not for 1 second do I think people on this forum don't know what they are doing,
That said occasionally people make mistakes,
Not putting some new parts in that bottom end would be a big one,
I would gladly give you the parts for nothing than have it go ar$e up,
Cant waste any twins entries can we.

[firko]

This is along the lines of my T20 Suzuki weapon that Pete was keen to help me with, injury and financial's put a stop to that

Hey Steve, do you still have the Suzuki Hustler? I reckon once you make a start start on it, the motivation to finish it will come back. Finishing the little 360 tracker that had sat gathering dust for two years has pumped a lot of my previously missing mojo back into my system to the point that I'm jumped straight into the next job....finally finishing the Hindall motocrosser which has had four or five false starts over four years. Finishing a race project is the best cure to all sorts of ailments, I'd almost forgotten why I started doing this in the first place but it's all clear now. Give it a shot Steve, you know you want to blow Jimmy and his new/old Trumpy off
                                                                
                                                                              

[firko]

I just love this super clean RD350 tracker........
                                                             
                                                             

[SON]

Lovely bike, but I have seen better pipes

[Lozza]

From my perspective there is a flat spot as each piston reaches a point of zero speed at the same time. The 90 degree crank was just an idea to reduce the inertia torque period. It could just as well be 10 degrees. "Big bang" is a bit of a black art anyway - Hope you got some sleep last night Mick
The ignition is no problem and I will discuss the difficulties of balancing it with Frank from "Frank's Cranks", even exploring the twingle option.

Pistons have to stop but the crank keeps turning, the crank provides the inertia not the piston. The rod is being pushed by the piston to 90 deg then to 180 the rod is pulling the piston, then to 270 the piston pulls the rod and finaly the rod pushes the piston to TDC.
The tyre is there to work not to rest and the theory of big bang engine 'giving the tyre time to rest' was put out to pasture by Masao Furusawa.Was never a black art to him just the rest of us didn't know what was going on.
The only way 90 deg firing works in a twin is with a  90 deg V twin with crank pins in line would work a treat in a inline 4.

http://www.sae.org/mags/aei/5586

[SON]

Already a great engine been developed by the best,
For Dirt the mods are a Long Rod "DT200" crank, still 350cc but works better or a capacity increase,
stroker like the 400, a big bore, or a combination of both.

[firko]

Here's another nice RD and a TZ/LC.......
                                                                             
                                                                             

[SON]

Keep going Mark the more the better,
Especially the TZ
I am waiting to see a photo of Askland / Roberts on a 350.

[firko]

                                                                     

But enough of hijacking Pete's thread. This is about his bike not other peoples interpretations

[yamaico]

Pistons have to stop but the crank keeps turning, the crank provides the inertia not the piston. The rod is being pushed by the piston to 90 deg then to 180 the rod is pulling the piston, then to 270 the piston pulls the rod and finaly the rod pushes the piston to TDC.
The tyre is there to work not to rest and the theory of big bang engine 'giving the tyre time to rest' was put out to pasture by Masao Furusawa.Was never a black art to him just the rest of us didn't know what was going on.
The only way 90 deg firing works in a twin is with a  90 deg V twin with crank pins in line would work a treat in a inline 4.

http://www.sae.org/mags/aei/5586

From my memory of high school physics Newton's first law of motion defines inertia as the property of a body to resist a change in motion. A piston has mass and is therefore a body and when in motion exhibits inertia. As I understand it, piston inertia is what generates the positive and negative torque pulses prevalent in a conventional 180 degree twin crank. A 90 degree crank virtually eliminates the positive and negative pulses because as one piston is slowing down the other one is speeding up. The inertia that the decelerating piston is gaining is negated by the inertia that the accelerating piston is losing, resulting in an overall kinetic energy flow of almost zero. This, I believe, is said to be what is responsible for the better throttle control and decreased tyre wear of the 90 degree configuration.

Anyway, enough cyber building and on with the job  ., although I'm reluctant to build any pipes for it if the ones on this bike are not considered up to scratch 

I just love this super clean RD350 tracker........
                                                             
                                                             

Pulled the head angle back to 25 degrees with the aid of a porta-power, digital spirit level and a bit of heat to relieve the stress once the angle was right.






This has of course shortened the wheelbase even further so I'll have to make a new swinging arm to get the wheelbase up to around 55-56". Next, I'll cut up what's left of an old DT frame and graft the backbone and seat rails into the RD frame, after I've cut off all the side frame components from the RD frame.

[Curly3]

You're rekindling my interest Pete
Interesting to see how similar the RD frame is to the early T20 chassis.

[TT5 Matt]

are rd400's allowed in the twin dirt track class?who sell that digital spirit level and was the bending of the frame tubes done cold or with the aid of a oxy torch?

[yamaico]

You're rekindling my interest Pete
Interesting to see how similar the RD frame is to the early T20 chassis.

That's good Steve, let's get 'er done.
The frames are similar. I don't know about the T20 but the RD is a heavy lump. The bikes weighs about 350lb, but I reckon with the alloy rims, little hubs, fibreglass tank and seat, lightweight chambers, the frame mods and binning the side covers, battery box, air box, lights, mudguards etc I should be able to drop off at least 100 of those pounds. Combine that with probably 40hp (at a minimum) it should be a bit of a weapon.

[yamaico]

are rd400's allowed in the twin dirt track class?who sell that digital spirit level and was the bending of the frame tubes done cold or with the aid of a oxy torch?

SON should be able to answer the eligibilty question Matt, but I don't see why not.

I bought the spirit level when I was working in the US a couple of years ago. It's a "Husky" brand but it doesn't have a model number. I bought it from Home Depot, but here's one of hundreds on ebay that will do the job:

http://www.ebay.com.au/itm/Aluminum-Digital-LCD-Angle-Slop-Finder-Meter-Protractor-Spirit-Level-/350753968456?pt=AU_Input_Peripherals&hash=item51aa90d148

I just used a bit of heat to get it to move to the desired angle and then heated all around the downtubes and then let them cool naturally, with the porta-power still in place. It didn't spring at all once I released it.