What does the ap motoart rear link actually do?

[phanomenal07]

I'm slowing building an fz07r and I wanted to know how the ride height linkage will affect the bike handling? I'm not exactly sure what its suppose to do other then raising the ride height. Is it suppose to pitch the bike forward at all? And i read on another thread that I'm suppose to raise the fork tube in the triple to match. I'm pretty much a novice at this and just want to build this properly. 

Edited September 19, 2019 by phanomenal07
Grammer

[mossrider]

The link does some things, other things it doesn't do. Seriously tho, it adds more angle to the rear swingarm which makes it accelerate better by limiting squat under power, aka better drive/less front wheel lift.

To a lesser degree it also makes the suspension linkage ratio closer to linear. It also raises ride height. Is it necessary? Not absolutely, but many folks like it. You can go fast w/o it certainly.

Moving the forks up or down puts more or less weight on the front wheel and can sharpen steering and side to side transitions. Is it necessary? Not absolutely but some folks do it. It depends on a lot of factors like riding style, speed, track shape and surface make up, etc. 

All suspension changes can/will have positive and negative effects. Only you can determine if one outweighs the other for your purposes. 

Having said all this, generally a little more rear ride height (swinger angle) and a little more weight on the front wheel is a good place to start when converting this great street bike into a more track orientated machine. 

Hope this helps

[blackout]

Yes, what Mossrider says.

The AP rear link's main purpose is to increase rear anti-squat geometry by increasing swingarm angle from roughly 10 degrees to 13 degrees (from my memory.)  On corner exit, you are on throttle to drive out of the corner, you want enough anti-squat geometry to keep the rear from squatting, thus keeping the front tire planted.  Otherwise, with rear squat, the front gets light, and your line can drift wide under acceleration.  Adjusting anti-squat geometry is why the more expensive super sport bikes allow you to adjust swingarm pivot height at the frame with a different bushing.  This allows anti-squat to be adjusted without making changes in other geometries of the bike.   Swingarm angle changes, but nothing else does.

[phanomenal07]

I see. Very helpful answer. Thanks guys

[mossrider]

I realize that was almost a non answer but understand for simple track use you can go pretty dern fast and it'll handle pretty well and you'll be happy as a clam in bone stock form. Add a shock and fork upgrade and you're next level. Add a link and a whatever and you're at level 3, and so on and so forth. All fun but you will run into limitations as you gain pace.

The big difference shows up when you go from an enjoyable trackday romp (which can be fast as hell for some) to and intense red mist race pace where I'm gonna impose my will on you and my machine whether you like it or not. When you go to the last 2% of available performance and beat that 2% like a red headed step child all those little changes and upgrades add up to a measurable advantage. When I require my bike to do something like tighten a line in traffiç at apex by 1 foot under brakes then that's what I need. That never happens at a trackday. 2 bike lengths in a trackday means squat. 2 bike lengths in a race can mean 4th instead of 1st place. 

It's just a matter of what you're trying to accomplish or what your expectation of fun is. At a trackday I take what's available and have fun. In a race I make what's available to have fun. It's kind of a sliding scale. 

Edited September 19, 2019 by mossrider

[blackout]

I am not a racer, only a track rider, and have only been playing with motorbike dynamics for a few years as a hobby.  But, I also have experience with race cars and can tell you first hand, poor rear anti-squat geometry can create dangerous handling issues.  I feel Yamaha designed less anti-squat into the FZ-07 to make the bike more "stunt friendly", easy to wheelie.  Combine this with a rider that weighs 225 pounds with the stock shock and you have a swingarm angle quite low along with a lower ground clearance to hit parts easier.  I have a buddy in this exact situation and I tell him you either get a stiffer spring (new shock) or a shorter link (AP Link) before going to the track.   I feel the AP link or similar should be one of the first mods for any track bike.

A little more on anti-squat.  Not sure where the typical FZ07R ends up, have not made the computations, but here it is any ways.

100% Anti-squat, the rear stays neutral under hard acceleration.

Less than 100%, the rear lowers some.

More than 100%, the rear actually rises under hard acceleration.

A stock Kawasaki ZX6R has 130% rear anti-squat.  (Read this in an article doing research a year ago or so.)

I would love to have a potentiometer on the rear shock to data log all this on track.   But that is more money.... 

 

[sorkyah]

1 hour ago, blackout said:

 

I would love to have a potentiometer on the rear shock to data log all this on track.   But that is more money.... 

 

Would it be though? 

With all of the arduino systems and accessories out there I'm sure a pot for shock/swingarm data would be a fairly inexpensive system to add on. 

[phanomenal07]

I really just want to have fun and progress my skills on the track. I honestly can accomplish that on any bike I'm sure. However I tend to get very obsessive with my hobbies and really try to see how much I can push myself and my equipment. I doubt I'll notice it now on the fz now but ill still get the linkage as I do plan to get better.

[sorkyah]

38 minutes ago, phanomenal07 said:

I really just want to have fun and progress my skills on the track. I honestly can accomplish that on any bike I'm sure. However I tend to get very obsessive with my hobbies and really try to see how much I can push myself and my equipment. I doubt I'll notice it now on the fz now but ill still get the linkage as I do plan to get better.

https://www.instructables.com/id/Racing-Datalogger-With-an-Arduino/

 

Follow this and add in a pot input as well as whatever other inputs you want

[mossrider]

Just now, phanomenal07 said:

I really just want to have fun and progress my skills on the track. I honestly can accomplish that on any bike I'm sure. However I tend to get very obsessive with my hobbies and really try to see how much I can push myself and my equipment. I doubt I'll notice it now on the fz now but ill still get the linkage as I do plan to get better.

Welcome to the obsessive bench, I'll skooch over n make some room. Now, 'bout that (insert dumb idea)... lol 

[phanomenal07]

Suck that I can probably only make it to one more track day before the season end.

[blackout]

4 hours ago, sorkyah said:

https://www.instructables.com/id/Racing-Datalogger-With-an-Arduino/

 

Follow this and add in a pot input as well as whatever other inputs you want

Cool.  Thanks.  I have played with Arduinos a little.  I'll look into that.  A trap speed project for radio controlled model boats.

[blackout]

5 hours ago, phanomenal07 said:

I really just want to have fun and progress my skills on the track. I honestly can accomplish that on any bike I'm sure. However I tend to get very obsessive with my hobbies and really try to see how much I can push myself and my equipment. I doubt I'll notice it now on the fz now but ill still get the linkage as I do plan to get better.

I think the AP link will help even a novice.  Part of the process of completing a corner is both accelerating and adding steering input to straighten the bike back up.  Doing both splits the work of corner exit to both the front and rear tires.  This gives you a greater amount of total available traction.  So, even a novice, should be on the gas in corner exit.  This is explained well in Lee Park's book, "Total Control".

[Roberto Tuzii]

Hi guys, I am Roberto and I live in Australia in Melbourne; I have a Yamaha MT07 HO here it is the unrestricted one, and I have a k-teck back shoch R and K TECK FRONT CARTRIDGES. I am looking for the AP back shock bone link, and I really cannot find where it is sold and how I could order one.

Could anyone please help me in locating the source of this link? That would be appreciated.

[Evill_Ed]

19 minutes ago, Roberto Tuzii said:

Hi guys, I am Roberto and I live in Australia in Melbourne; I have a Yamaha MT07 HO here it is the unrestricted one, and I have a k-teck back shoch R and K TECK FRONT CARTRIDGES. I am looking for the AP back shock bone link, and I really cannot find where it is sold and how I could order one.

Could anyone please help me in locating the source of this link? That would be appreciated.

Roberto, Is  your rear shock adjustable for length? The end clevis is usually threaded to adjust overall shock length.  Extending the length of the shock will increase swingarm angle similar to what the linkage does. Have you tried extending the shock length? 

Ed

[Roberto Tuzii]

Hi Ed, no I haven't as yet but it is on my do list, you 'r right though, I shall try that first and see how it handles thanks for the hint. Cheers.