Cone valve wp forks on an Alta

Jayfox911

Well-known member
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Location
San Diego, CA
#1
Cone Valve suspension should bolt right on? What about rear? Is there a type, size or year that fits best? 16+, 48 vs 52mm, small axel or large?
I think @TCMB371 has a set.

I have a 2018 mxr and wanted to swap out the AER for a set of used cone valve forks.
I am coming off a 2018 crf450r and I wanted to see if anyone has swapped out the forks or shock for different styles. This bike moves around a lot under me and there is some harshness to the front end.

I heard the kyb sss internals are a good option also.

Any thoughts of forks or shock replacements?

I live in SoCal and race once in a while but mainly ride with friends and so far I can’t keep up with them yet but with suspension dialed and a 120/80 rear maybe I can haha.
 

Philip

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Ann Arbor, MI
#2
Your namesake @Mark911 has the WP Cone Valve suspension on his MX. He installed a KTM front end and rear linkage.

I have arrived to a conclusion that the "moves around a lot under me" attribute is inherent to the Alta. It could be due to the lower center of mass, or a higher concentration of mass (a lower pitch moment of inertia) compared to gas bikes.

I tried many suspensions on my bikes, yet I always seem to have to pull or much on the handlebars more than I do on other bikes in order to keep the bike flat.

The ease with which an Alta rider can control the bike's attitude with the throttle when jumping, or the supernatural ability to prevent an endo, is partially due to the instant and monstrous torque, but also partially due to the low pitch moment of inertia.

Has anyone ever seen an Alta skimming the whoops perfectly? It my experience, the bike pitches and squats through the whoops too much. Josh Hill probably didn't have the best suspension in Paris when he beat Ricky Carmichael. He almost got passed by Ricky in the whoops section.

A good verification test would be to duct tape a dumbbell to the end of the rear fender. Maybe another dumbbell on top of the LCD display. This would increase the bike's pitch moment of inertia and hopefully calm it down.
 

metallic88

Well-known member
Likes
171
Location
utah
#3
Your namesake @Mark911 has the WP Cone Valve suspension on his MX. He installed a KTM front end and rear linkage.

I have arrived to a conclusion that the "moves around a lot under me" attribute is inherent to the Alta. It could be due to the lower center of mass, or a higher concentration of mass (a lower pitch moment of inertia) compared to gas bikes.

I tried many suspensions on my bikes, yet I always seem to have to pull or much on the handlebars more than I do on other bikes in order to keep the bike flat.

The ease with which an Alta rider can control the bike's attitude with the throttle when jumping, or the supernatural ability to prevent an endo, is partially due to the instant and monstrous torque, but also partially due to the low pitch moment of inertia.

Has anyone ever seen an Alta skimming the whoops perfectly? It my experience, the bike pitches and squats through the whoops too much. Josh Hill probably didn't have the best suspension in Paris when he beat Ricky Carmichael. He almost got passed by Ricky in the whoops section.

A good verification test would be to duct tape a dumbbell to the end of the rear fender. Maybe another dumbbell on top of the LCD display. This would increase the bike's pitch moment of inertia and hopefully calm it down.
i had my mx glide across woops just like my other bikes, but for it to ride like i liked it had to have the sag set around 115-120 more than any othe bike i had. it road awesome like that, i just hated how if i went over woops over 40mph those 4cs would clunk like mad nomatter what i did. and if i remember right the rebound was way down compared to normal bikes. and the fork springs i was way heavy for my weight, to get it to my liking.
 

TCMB371

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#4
I borrowed @Mark911 's 52mm WP Cone Valves for SX futures last year, and ran his set of factory KTM triple clamps, KTM front wheel (+Spacers), and SXS front brake. The forks were set up for a pro desert racer i believe. Stock valving on the AER48 on the MXR is too soft for anything faster than C class motocross (my opinion), so those CV's were still stiffer than the stock AER's. The forks still weren't stiff enough for SX Futures, as i was bottoming in some of the transitions, However, I road with them on a motocross track a few days before SX Futures and they were really good.

For SX Futures this year, i'm sticking with my AER48's with a stiff revalve. Stiffening up the valving allows you to lower the fork pressure slightly. If you're near my skill level, i'm sure you've had to add extra fork pressure so the fork doesn't bottom, but having excessive pressure means the initial 1" or so of travel is really harsh both because more force is required to move the stiffer spring and because of the increased stiction that comes with increased pressures. So with stiffer valving, you wont need excess air pressure to keep the fork held up. You'll be able to run just the right amount of air pressure to achieve about 10-20mm of front end sag.

A lot of local pros seem to think the stock WP shock is fine with a revalve, however the linkage ratio on a KTM 450 is pretty different than our Altas. I'm 180lbs and had to go up to a 6.4kg/mm spring with stiffer valving to prevent the shock from bottoming. I'm going to be going stiffer in the valving for supercross. Eventually i'd like to experiment with a KTM linkage, spring rate, and valving.
 

Jayfox911

Well-known member
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Location
San Diego, CA
#5
I borrowed @Mark911 's 52mm WP Cone Valves for SX futures last year, and ran his set of factory KTM triple clamps, KTM front wheel (+Spacers), and SXS front brake. The forks were set up for a pro desert racer i believe. Stock valving on the AER48 on the MXR is too soft for anything faster than C class motocross (my opinion), so those CV's were still stiffer than the stock AER's. The forks still weren't stiff enough for SX Futures, as i was bottoming in some of the transitions, However, I road with them on a motocross track a few days before SX Futures and they were really good.

For SX Futures this year, i'm sticking with my AER48's with a stiff revalve. Stiffening up the valving allows you to lower the fork pressure slightly. If you're near my skill level, i'm sure you've had to add extra fork pressure so the fork doesn't bottom, but having excessive pressure means the initial 1" or so of travel is really harsh both because more force is required to move the stiffer spring and because of the increased stiction that comes with increased pressures. So with stiffer valving, you wont need excess air pressure to keep the fork held up. You'll be able to run just the right amount of air pressure to achieve about 10-20mm of front end sag.

A lot of local pros seem to think the stock WP shock is fine with a revalve, however the linkage ratio on a KTM 450 is pretty different than our Altas. I'm 180lbs and had to go up to a 6.4kg/mm spring with stiffer valving to prevent the shock from bottoming. I'm going to be going stiffer in the valving for supercross. Eventually i'd like to experiment with a KTM linkage, spring rate, and valving.
Thanks for the info. I’ll do a little more research, I am just biased towards spring forks. Air just doesn’t feel the same to me.

I raced your class at Sx futures, not sure I’ll do it again. It was fun but not enough track time. I talked to you briefly while in staging about the Alta. That was before I had mine.

we should meet up at Pala, Cahuilla or wherever you mainly ride sometime.
 

Jayfox911

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Location
San Diego, CA
#7
The cone valve are nice but didn’t wow me. Yes, they are better than AER but not enough to recommend them. A review I read before buying them was true...”if you can afford them get a set, but your not missing much if you don’t.”

I think with more time I can get them dialed in and feel better about the purchase.

Today was my first ride on the Alta as my full time bike. It made it through the day (three motos) with a Honda 110v eu2200 charging between motos. We were at the track from 10-1:30pm. The bike was flashing and loosing power at the end of the last moto. The bike has enough power to do all the big jumps on the main but some needed some body English. Reminds me of a Ktm 150 in a lot of ways.

Before it was my wife’s bike and we would play around on it when she was done riding. So today riding the main track with my buddy was quite a change for me and the Alta.

I need to get a 220v generator next.

One more thing, I need to get used to the sound of the bike while Riding. It sounds like it’s falling apart under me. Haha. Plastic crunching, chain slap, suspension noises... I had to pull off one to to make sure my rear fender wasn’t falling off.

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TCMB371

The Silent Assassin
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#9
The common misconception about suspension is that buying "A-Kit" components means you instantly have better suspension. Not always true. For example, you can install CV's that are not set up properly for your skill level and type of riding and they will feel worse than the stock stuff. I ran @Mark911 's spare set of 52mm CV's for Supercross Futures last year, but they were set up for an offroad pro rider, not supercross. They were awesome at rough tracks like Pala (late in the day), Cahuilla, Glen Helen, etc. But they were a bit too soft still for supercross. I did my own revalving on my AER48's and they are much better now than ever, and i think i can make the valving even better with some more experimenting.

By the way, let me know the next time you're riding here! We should link up. I'll probably be riding this coming weekend somewhere.

Also, do yourself a favor a pick up at least a 4000watt generator that supports 240v. It probably takes 4 hours or so to recharge the bike on that EU20000 on 120v. With the rapid charger on 240v, you can recharge from dead to full in 90 minutes or less, which is way better for track days!
 

Mark911

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695
Location
Corona Ca
#15
Cone Valves are notoriously tough to setup. The tolerances between cones, cone springs, etc make getting consistent and repeatable results difficult, even for the experienced tuner. Of my three sets of CVs only one still uses that valving design. The other two have been converted to standard shim stacks. The set TCMB371 used at Futures last year were the cone valve set, my softest setup.

I hate to say it but many tuners disable the "Trax" system on those shocks as well. Of my two Trax shocks I prefer the one with it disabled.

HOWEVER, suspension is so rider dependent there's simply is no correct answer to any of it!
 

Jayfox911

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88
Location
San Diego, CA
#16
I put on a 2015 450sxf triple clamps with the bolt in top clamp bar mounts and the lower clamp having the newer style fender mount. I really like the look of the 2015-2019 Ktm plastic.

And like people have said here the lower clamp hits the Alta frame, so I grinded off about 1 1/4 inch wide and 1/8” down. And put in 1.5” length bolts to hit the new clamps since the stock ones are too short.

so far it seems to be good to go. I tried to ride it without the lower clamp cut and it was too odd when turning the bike while moving the bike around but riding seemed fine.

A couple issues I still need to work out. One the spacers for the Ktm clamps need one Ktm spacer and one Alta (brake side) spacer with the Alta axel sticking out the non brake side. A 2016 Ktm stock axel doesn’t fit with the spacers.
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Redwolf

My dog thinks I'm cool
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1,289
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Brinnon, Wa.
#18
Wondering if that new, shiny, fancy, WP XACT PRO Shock with slanted bladder canister would clear our swingarm without any needed modification....

I did just get my work bonus.... :unsure::LOL:

View attachment 4691
Well, we're all willing to spend your money for you, let us know how nice it is!

Then we can tell you what accessories and mods you have to do too.:lurker:
 

Jayfox911

Well-known member
Likes
88
Location
San Diego, CA
#19
Yesterday I cut one of the Ktm wheel spacers by 4mm so the Ktm axle would go farther into fork lug (now flush with fork lug).

So the 2015 450sxf triple clamps, 2016 Ktm axle (small axle) and 2018 Ktm forks all now fit perfect with one cut KTM spacer and one Alta spacer (brake side).

also the stock bar pad and screen doesn’t fit too well with the Ktm bar mounts. The Alta bar mounts didn’t transfer to Ktm top clamp. I just tightened down the zip ties also but the screen still moves some.

here are some pictures. I hope this helps anyone else thinking about doing this to their Alta.

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