RT1 frame mods.

[Lozza]

If your dropping the countershaft by that much(I'll have to check) you will be introducing a lot of squat or anti squat into the rear suspension.Which might have some unintended consequences.

[mx250]

What happens at the Swing arm pivot, does the chain run on the pivot now the motor is 2 " lower or an i missing something here ?

My understanding is that the engine cradle including the s/w pivot are dropped as a unit. All the cuts/joins are above the pivot. The relationship between the c/sprocket and the s/w arm doesn't change.

[vandy010]

What happens at the Swing arm pivot, does the chain run on the pivot now the motor is 2 " lower or an i missing something here ?

My understanding is that the engine cradle including the s/w pivot are dropped as a unit. All the cuts/joins are above the pivot. The relationship between the c/sprocket and the s/w arm doesn't change.

Graemes answer is spot on!
my RT1 has seen about 5 track days {including the conondale nats}since the frame chop and the worst of it is the bike occasionally drags a peg in a turn.
the benefits are unanimus!
i'm almost finished doing my DT1 frame but this time have opted for a 40mm drop and am raising the pegs a touch.
i spoke with a local guy in depth about the chop before i did my RT1 and he said he'd love to do a 3" drop frame.
i don't think thats neccesary but might be cool for flat track.

[firko]

My DT1 frame's lowered about 2.75 inches but if I did it again I'd only drop it 2" for the reasons Vandy days. I lengthened the square swingarm 2'' and deraked the frame about 3-5 degrees. It was all experimentation and a bit rough when I did it in the late 80's and the raking process was done by cutting the top rail, applying a bit of heat. running the bike into the wall and then filling the gap and then externally gussesting it. As I said in another post, you may not need to change the rake as my frame is a combination of OSSA front and Yamaha rear sections and when I fitted the OSSA front section, the rake was too "chopperish" so it needed to come in a bit. Looking back, as trick as 'The DT1 from Hell' is, the frame mods are pretty rough and being a welder/boilermaker by trade, a bit embarrassing. If I did it again, I'd be far more traditional and would tig the mods using two frames like Vandy did instead of the oxy welding (not brazing) sleeves that I used. It's not that difficult a job but if you're not handy with welding it's best left to the experts.

[vandy010]

the raking process was done by cutting the top rail, applying a bit of heat. running the bike into the wall and then filling the gap

bloody hell Firko!
a bit of rope or even a tie down from wheel to wheel tightened up would of done

  the frame mods are pretty rough and being a welder/boilermaker by trade, a bit embarrassing.

same here!
a boily by trade and i've been welding mine with 1.2mm fluxcored MIG.
lucky the tubes are thick hey

It's not that difficult a job but if you're not handy with welding it's best left to the experts.

the basics are straight forward but should a problem arise, thats when the expert is handy.

Vandy.

[Freakshow]

I have enough frames to do a cut and shut, but was looking at the picture of the motor section dropping 2 " then i forgot the pivot was with it, the cut being above it.      i get it now so how do you pick up the 2' differant in the shocks drop then or what ever it ends up being back there ?

Sh are you saying its best to long cut 2 frames and then just reweld em ? i have 2 here one is hit at the back and one shit at the front ? so is that the go there ?  if i have to pay someone i what to be clear on the instruction or it might get into an ugly 2 day experiment , and that might start costing me...........