Questons RE: 16' 450FX

I accidentally posted this in the WR thread and meant to post it here...


I pulled the trigger and I'm heading up to the dealership in a few hours to pick up the new ride... Super stoked!


Couple of questions as I've never owned a Yamaha... All KTM's prior to this...


- I plan on greasing all wheel, steering steam, linkage, swingarm, etc bearings and loctiting bolts...  Anything in particular I should look out for?


- I'm picking up the tuner and also have an FMF slip on coming today. What is a good base MAP setting for hare scramble racing in tight single track and the FMF muffler?


I'm ordering a couple sets of fork and shock springs for my weight. I plan on riding it with the stock valving for now as I've heard it's pretty good. What sag numbers should I start with for offroad use? I'm sure it's in the manual but thought I'd ask y'all what you've found works best as a base starting sag.


Thanks and I'll report back after riding it this weekend!

You will need to get a few hours on it before you really worry about sag it needs to settle in

Agreed... I'm pretty lucky as I live on 5 acres which joins hundreds of acres with trails. I plan on putting a few hours on it today and checking it after that. The reason I ask is I'm 6'3" 250 and will definitely need to spring it for my weight so I was looking for a starting point.


Also, are there any vids out there showing how to change the fork springs. I've changed plenty on my KTM, but never in a Yamaha. I'd like to watch one or two before I tear into them.

There are likely several.  It's a piece of cake, and can be done without opening the cartridges at all, although changing out the OEM oil fill is not a bad idea. 


Loosen the cartridge slightly from the top of the fork before you remove the from the clamps, then:


  1. Unscrew the cartridge from the top, lower the inner tube a ways, and dump the oil from the outer chamber
  2. Screw the cartridge back in a couple of threads to keep the threads out of trouble and invert the fork
  3. IMPORTANT: back both rebound adjusters all the way out (if you don't know your current setting, count the clicks to turn one all the down first so you can reset it)
  4. Put a bar through the axle lug and remove the rebound adjuster from the lug
  5. Push down against the spring and slip a rod holder under the lock nut (a slotted piece of aluminum is best, but any number of things will work, including a pair of needle nose pliers)
  6. Unscrew the lock nut and then remove the adjuster from the rod. Remove the rebound valve push rod,
  7. Drain any remaining oil from the bottom, then unscrew the cartridge from the top and pull it out.  The spring will slide out the top. 

Read this post for details on reassembly regarding an obscure reference in the service manual:


This regarding bleeding the cartridges if you open them:

Thanks grayracer13, much appreciated my man!

Thank you for ditching KTM. your now riding the best brand made.

I would leave the mapping and see how you like it before tuning it further. I don't think there any FX maps yet. Here is some for the YZ. I would ride with default and then try one that really takes the hit out and try one with the biggest hit. Then you can compare what you got.ImageUploadedByThumper Talk1456536342.570948.jpg

ImageUploadedByThumper Talk1456536668.080725.jpg

ImageUploadedByThumper Talk1456536596.070707.jpg

Edited by RMK800

Ive just brought a 450FX after 20 odd Hondas the last being a 14 CRF450,so ime still

getting used to it.I down loaded the Smooth linear/Slippery condition map and added 1

tooth to the rear.The bikes just got grunt everywhere,im not really into balls out riding and 

like the slow going single track stuff.The rear of the bike is way to tall for a guy with

stuffed hips.Today was my 3rd ride on it.

Yamaha finally added a few 450FX specific maps to the tuner specs page on their site. Here they are.


Thank y'all for the replies, much appreciated! I'm gonna break out my tuner today and try some of the settings.

I've greased all the bearings, installed the rekluse, FMF pipe, hand guards and earth X battery. The YZ has been great to work on. It's laid out well and easy to work on. Can't wait to ride it!

Thank y'all for the replies, much appreciated! I'm gonna break out my tuner today and try some of the settings.

I've greased all the bearings, installed the rekluse, FMF pipe, hand guards and earth X battery. The YZ has been great to work on. It's laid out well and easy to work on. Can't wait to ride it!

You have put together the exact package I hope to put together this year sometime. Nice job and definitely let us know your impressions.

Thanks! Just finished a short ride. I'll post more pics and some feedback after some supper.... Bike is pretty amazing!

Edited by jwilson32

Hey, Mr Wilson. 


Here are two excellent videos of a YMC KYB AOS SSS fork rebuild (gotta love all of the acronyms...)




Watch these each 2-3 times and follow his steps with the workshop manual page by page. Then get into it. I managed to rebuild my '15 YX250FX forks without any previous experience. RT main springs, RT pressure springs, RT reservoir piston assemblies. Gold comp and res valves and re-valved all stacks. It's do-able, just do your homework first, get all of the tools you need and take your time. Keep everything spotlessly clean! 











Nice and clean Gaz, I like it!


Thanks again to all that replied and posted, it was much appreciated and very helpful!


So I was able to ride the FX for a few hours this past weekend and really enjoyed it! I put some goodies on it, changed the springs, greased/gassed her up and took it out. I'm pretty fortunate to live in some great riding areas and have 8 miles of trails as soon as I pull out of the garage. There's about a 1/2 mile of rocky, rooty single track that I generally test on. I usually ride a base setup for 10 minutes then turn the shock reb in 6 clicks and ride for another 10 minutes. I then go out 12 clicks from there (6 clicks from my baseline) to feel the difference. I then go in a couple clicks at a time until it feels bad then back it out a click or two, then move on to comp... I have to say I got so caught up in riding the FX that I didn't even think about touching the clickers. It soaked up the 1st/2nd gear trail trash and took the 3rd gear higher speed log hits like a boss! I'm extremely impressed with just how good the stock suspension is right out of the box...


I'll probably get flamed for this, but to be honest, I had a preconceived notion about japanese bikes and their quality. I felt like they were cheap and couldn't hold a candle to a KTM. What's even more ignorant about my thought was I had never even ridden anything other than a KTM or took the time to look at them... I know, pretty stupid, huh?.... Boy, was I ever wrong! The FX is built with quality parts, fasteners, thoughtful engineering and looks bad ass sitting on the stand, not to mention how it rides! :)


There are a number of things that I noticed when tearing it down to grease it up and install some parts that the KTM is lacking. One, it's really easy to work on. I love the placement of the airfilter and that the shock clickers are on the left side which is the side I get on and off of and probably 95% of all other riders do too. It's also laid out really well. The tank is in a great location and really lowers the CG. I also like how the throttle cable is tucked between the number plate and bars. The KTM cables come down in front of the bars and gets in the way at times and just looks kinda silly.  The pegs are also oversized and slanted in... No more "shoe gooing" a penny to the frame where the peg stops are to achieve the same thing! :) It's the simple things that they did that I really appreciate. It also comes with some nice features like a skid plate and rear disk and caliper guard. The guards on the pipe are also nice as well. Plus, the FX starter blows the KTM out of the water, even with the stock battery! I have an EarthX ETX12A on the KTM and it's not even close to the FX in starting ability.


The weight of the FX was kind of a worry initially, but after riding it for a while and getting used to it, I really didn't feel much of a difference between it and the 350. I ran it in a hare scramble Sunday, and was getting pretty worn out after about half a lap, which generally never happens. I was riding in 2nd gear a lot with some 1st gear sections. I finally put it in 3rd gear and let the motor do it's thing. This helped a ton and I felt much better after the first lap. In fact, my lap times dropped by about 40-60 seconds per lap throughout the race which is awesome... I'm usually going in the opposite direction! haha...


All in all, I'm really liking the bike and looking forward to a great year with it. A dozen or so of us are going on an 80mile loop in the national forest just south of us this Saturday so I should get pretty comfy with her after that! I'll keep posting my thoughts...













I'm not a racer or an expert rider, but I've got some time on these big Yamaha 4 strokes and I've learned a few things along the way.


1) Suspension matters a lot.    Yamahas have some of the best suspension around.  Better than most European bikes after they have had a suspension tuner work on their suspensions.


2) Suspension and how it turns matters more than small differences in weight between bikes.


2b) Where the weight is on the bike makes a big difference.  Don't believe me ?  Put a chainsaw or a small pack in front of the number plate and go ride.  Higher = worse.  Anywhere on the fork = bad.


3) You ride a big 4t totally differently than you ride a 2t or even a smaller 4t, especially in tight woods.   With a 2 stroke a lot of riders are constantly blipping the throttle and doing clutchwork.  Lots of shifting gears.   With a 4t the power is instantaneous and there is lots of it.  And 4ts have engine braking.  If you aren't smooth on the throttle when riding a 4t, you'll quickly tire yourself out accelerating and decelerating.   Not to mention that a big 4t will slip the rear tire accelleratiing and decelerating much easier in slippery conditions.   But it also hooks up better when you learn to use the right amount of power.   The secret is all in your right wrist and sometimes the clutch. 


4) It takes a while to get the feel of how to ride a big 4t.  At first they feel tiring and heavy.  But then you learn to point them very precisely and use precise amounts of throttle and they become easier and less tiring to ride than a smaller bike.  The engine does all the work.  Light 4ts and especially 2ts are twitchy and require constant steering input on rough trails.  Big 4ts are point and shoot and take big(ger) effort to make big or fast steering corrections.  Which do you do more of ?  


4b) Gearing matters a lot on a big 4t.  Big 4ts need to have a LOWER 1st gear than a 2t because 4ts will flame out and die if idled along the trail slowly.  Not only that, but throttle response for lifting the front wheel isn't good at low RPMs.   Luckily the YZ250FX and the YZ450FX have very low 1st gears.  Yamaha got this right.  A low first gear doesn't matter much for racers because they are never in 1st gear.   But it sure matters in really tight situations.


5) Most riders, especially 2t riders and even riders of smaller 4ts don't know how to ride a big 4t.


6) Big riders need big powerful bikes.  I found my WR a handful when I first started riding it.  Literally hadn't ridden in over 25 years.  And people criticized me saying nobody needs 40+ Hp in the woods.  They were wrong.  You don't need 40+ HP, but when you weigh over 200 pounds and you know how to ride a big 4t, it is the right bike for the application.   The 160lb guys won't like it, but then the 200lb guys don't like the 125s they ride either. 


I've got a friend that loves light 2ts.  He has a custom built woods 125.  He has also had 250 4ts and currently has a Sherco 300. 4t.  On the weekend we rode 25 miles of singletrack with icy sections on studded tires.  Our group does a lot of bike switching.   He and I switched bikes, I rode the Sherco, he rode my WR450. The Sherco weighs more than the manufacturer says it does, but it is still 25 pounds lighter than my WR.  And of course my WR has more flywheel effect.   I call it the gyro(scope)  bike for how stable it is.


I had a heck of a time riding the Sherco.  Yeah, its light and flickable.   But in those conditions it was twitchy and almost unstable.  And the suspension wasn't nearly as good as on my WR.  I was constantly doing steering corrections.  I was fighting it the entire time.   Back on my WR I was at least a gear faster and it was like someone smoothed out the trail and yet we were riding the same conditions. 


My friend liked my WR but complained about the power lunge big 4ts have at the bottom end.  Well, he is used to riding a 2t which doesn't have much bottom end power and has virtually no engine braking.   If my friend had better throttle control, he would appreciate the WR more.  


I previously rode the Sherco in perfect, dry conditions and really liked it.  Last weekend, on studs and in marginal conditions I didn't care for it at all.  It will be interesting to ride it back to back with my 250FX and see how they compare.


I am pretty sure that there is some sort of optimal bike weight for woods riding and that it isn't as light as the current 125 2ts.  After all, what can you downhill faster on, a dirt bike or a full suspension mountain bike ?   I'll take the dirt bike.   Much more stable.  I can go way faster on it, in spite of it weighing more.


I'm jealous of your upcoming 80 mile ride !

Edited by MidlifeCrisisGuy



I noticed in your signature that you lightened your WR450 24 pounds. I'd like to shed some weight off the FX... Any suggestions? I've put a ti FMF muffler on and a lipo batt which is a start, but wanting to drop a few more if possible

He took the starter off his WR to begin with.  He's got a thread about it in the WR forum. 



I noticed in your signature that you lightened your WR450 24 pounds. I'd like to shed some weight off the FX... Any suggestions? I've put a ti FMF muffler on and a lipo batt which is a start, but wanting to drop a few more if possible.


I'm dropping some weight from my YZ250FX.


- Shoria battery                 - 3.16 pounds  / $100

- kickstand assembly         - 1.76 pounds / $0

- aluminum footpegs          - 0.5 pounds  / $50 <- better grip too

- kick start assembly          -1.5 pounds / $40 < - not sure I'll do this

- Magura clutch                 - 0.25 pounds / $200, I want it for other reasons.

Total weight loss              - 7.17 pounds.


A Ti muffler/header will be lighter.   Most aren't increasing the power of the FX.  Not worth it for me spending that kind of money  I'm adding a spark arrestor to my stock muffler. 


I'm leaving the starter on my FX because it handles well with it on.  Removing it would probably lighten the bike by 5+ pounds.   Removing the number plates drops weight, but is it worth it ?


It is much, much easier to remove weight from a WR because it has a lot of extra stuff.  I removed as much as I did because I had to to get it to handle well.  Some people say it is still heavy.   It was well worth it (to me) to lighten it up.  I couldn't stand it stock.  It is now an excellent woods mount.   But is it as good as the new YZ450FX ?   Not sure.  I'll see when I ride one.


Keep in mind that the FX needs a skid plate, handguards and a light for my woods use.

Edited by MidlifeCrisisGuy

Nice thread.

I hate to fuel this fire but I'm trying to understand where everyone is getting this 20lbs difference between the FX and the KTM?


In stock form the 2016 KTM 450 XC-F (closest direct competitor to the FX?) weighs 108.5KG or 239.2lbs. Carries 2.5 gallons of gas or 15.5 lbs for a total curb weight of 254.7 pounds.


The YZ450FX curb weight is 262.


Yes the KTM carries an extra .5 gallons of gas but I'm comparing curb weight to curb weight for a difference of only 7.3 lbs.



Am I missing something here?

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