OzVMX Forum
Clubroom => Vintage Track => Topic started by: Curtis on May 30, 2016, 09:13:51 pm
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Iv decided to play around with the old girl again. Iv got a standard set up 76 XT500, I do a bit of everything with it.
Id really like to sharpen up the steering for dirt track, grass track mx..etc.
Whats my best options, de rake frame? 19" Front wheel? Drop the forks? Different triple clamps?
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I deraked a frame years back around 27deg what's a modern bike rake ,
But it changed the look of it to much because the rest of the bike was standard just my taste.
The tt500 I race now I just left it near standard and pushed the forks up through the triples to make it turn a bit better .
All the usa flat track bikes run 19 inch fronts 26/27 deg rake for the right corner speed .
You can try diffrent off sett triples but if it's a early model Tt,xt500 76 77 models the triples will hit the tank on full lock , it's allways the way you fix one prob and make another.
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also get a yamaha radian swing arm from the states fits in just change shock mounts
jim
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ask brent j on here about derakeing, id send you the pm's he sent me on it but ive got no idea how to resend as i wasnt born with a keyboard and mouse in my hands like the kids of today ;) ;D
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Jacking up the rear of the bike with longer eye to eye shocks could be a way of trying the decreased rake before you cut and shut the frame.
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I wouldn’t worry too much about changing the rake. Trail is far more important and has a greater effect on the bike.
Changing the rake does change the trail and most of the effect you feel through changes is from the change in trail.
Tony Foale proved this pretty well. In his book “Motorcycle handling and chassis design” he gives an example of changing the rake on a BMW from 30 degrees to 15 degrees to 0 degrees but in all cases the trail was kept the same by reversing the triple clamps and/or fork offset (by reversing the lower fork legs)
As the rake became steeper the bike had less tendency to follow ruts or cambers but the suspension tended to bind up during braking.
The overall balance of the bike is more important than any one thing. Personally I would get the suspension fixed first and see how it goes then. To change the rake with the std crap Yamaha suspension means you will be chasing other problems all the time
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Back on the topic 3 years later..haha. Do later TT500 have different offset triples to the early ones??
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Yes the 79,80,81 TT500 triples have less off set than the early TT500 models
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That would help with sharpening up the turning wouldnt it?
Yes the 79,80,81 TT500 triples have less off set than the early TT500 models
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That would help with sharpening up the turning wouldnt it?
Yes the 79,80,81 TT500 triples have less off set than the early TT500 models
lt will put more rider effort into the steering process, gives the bike more trail, hence more stability at speed. Every bike l own l have reduced triple-clamp offset to get more trail.
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Don't forget that the later XT/TT models that have less offset in the triples is because they are leading axle forks so it is quite a large change
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Well I dont more effort I want to make it turn easier..haha
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Geoff have you ever de raked a XT/TT500?
Don't forget that the later XT/TT models that have less offset in the triples is because they are leading axle forks so it is quite a large change
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I de raked a TT500 frame years ago 27deg it turned better but it lost it original look and value.
The Flat track TT500 bikes in the USA are all de raked 25-26deg but this isn’t mx riding .
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if you derake it youll need to lengthen or replace the swingarm for something longer.a klx swinger that's 1.5 inches longer goes in with not to much work and the distance from the pivit to shocks mounts is the same as the std xt swinger but youll need heavier springs/dampening
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As said earlier just move the forks in the triples, I have a 77 and it handles great on dirt track.
Also have a couple of 77 dt's, 250 has the original fork and the 400 has the leading axle forks and are totaly different animals in the handling dep.
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Geoff have you ever de raked a XT/TT500?
Don't forget that the later XT/TT models that have less offset in the triples is because they are leading axle forks so it is quite a large change
No, the sort of job I avoid because it gets messy with the oil tank in frame so its hard to do a neat job of it.
I have re raked frames of other models a few times to put them back to normal though!
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Im not to concerned about original look and value. I always though they look like a chopper when you put long travel on them with the standard rake.
I de raked a TT500 frame years ago 27deg it turned better but it lost it original look and value.
The Flat track TT500 bikes in the USA are all de raked 25-26deg but this isn’t mx riding .
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How far are we talking on the fork drop? Im guna have a play this weekend.
As said earlier just move the forks in the triples, I have a 77 and it handles great on dirt track.
Also have a couple of 77 dt's, 250 has the original fork and the 400 has the leading axle forks and are totaly different animals in the handling dep.
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The limit on how far you slide them up is when something hits something else when the forks compress. It's always a good idea to take the springs out to make sure there is clearance before you go for a ride.
25 mm makes a big difference to the steering.