YZ400D Swingarm Flex

[Tahitian_Red]

I not ridden my YZ400D anywhere, but up and down the street once, so I'm not aware of any stock swingarm flex so far. 

Almost all the old magazine tests mention a flex problem to some degree.  MXA said they didn't really experience any and therefore were not going to discuss something they did not encounter.  MXA seems to have been the most "picky" when testing bikes and that struck me as odd that they did not find enough flexing to mention it in their test.

Could there have been a quality control problem with early YZ400D's and then the factory addressed it in later runs?  Have any of you YZ400D riders had problems with the stock swingarm?

 

[Iain Cameron]

I have campained a 250 and 400 77 d's Ive never noticed any flex .

[BultacoMacca]

I can't recall any problems when I had mine "back in the day". Ran straight and strong, thru whoops & jumps.
The only drama I had was a bad Stator winding (from new) which would short out and stop the bike with a backfire till it cooled off then would start once more.

[Tahitian_Red]

Well I'm updated the thread.  I finally got around to racing the beast and what a sweet bike these YZ400D's are!  Great torquey motor and it turned better than I thought it would.  Maybe I just can't push it hard enough to find much swingarm flex.
 

[Cabmkr]

I installed a YZD swingarm and shock on my IT400D and it works great. Also I thaught the motor would be a handfull but it is a tractor comming off the bottom and you can drop the rev's super low and just pulls away!

[Tahitian_Red]

I liked it so much I'm gonna race the Ol' Gal at the next few events to get her totally sorted out.  Here's a pic of the D with a little dirt on it.

[Iain Cameron]

Tahitian red  have you got a remote reservoir shock on her ? Iain

[Tahitian_Red]

Yes.  I'm running the Works Performance shock for the YZ400 D&E with an adjustable reservoir. (even with rez it weighs almost 3 lbs lighter than the stock shock.)

After I purchased it I ran across some negative comments about the shock on the internet.  I had never ridden the bike with the shock when I took it out to race and was very apprehensive about riding it, but it ran great! (the thought of "yama-hop" already had me freaked out) 

Right out of the box the bike had 2 1/2" of sag and ran well over small whoops and ruts, while bottoming softly over jumps.  I was shocked (no pun intended) after having read the negative comments, but everyone's idea of a nice suspension is probably different.

[Tahitian_Red]

Found a low hour Profab YZ400D swingarm!    It's in nice shape with no chain rash in the usual areas.







 I'll test it out next season and see if there is any difference for a slow fat guy. 

[motomaniac]

Thats nice! I dont think thatyou will notice any reduced flex they are lighter and longer which improves the handling on rough straights.

[topari]

Just some observations. On My IT400F the swingarm axle is designed with flex in mind. The outer ends are 16mm OD and the inner portion is 15mm. Previous models were all 16mm. There are also thrust washers on the axle ends. The bottom shock mount is mounted using a rubber and steel bush. Some flex, to accommodate natural alignment,  is probably what the designers intended. Also the swingarm is made of steel. Flex wont bother steel.

I would just ride the bike. If it feels okay, keep riding

[Tahitian_Red]

I've already raced the bike with the stock arm and loved it.  The swingarm is for the bling-factor mostly, although I may paint it black. 

[Iain Cameron]

Nice score , If its not to rude how much (Im sitting down ) ?  Iain

[Tahitian_Red]

Such an amazing great deal I'd rather not say Iainyz. (The guy is now on my Christmas list)