Cone valve wp forks on an Alta

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17
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

Administrator
Staff member
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2,639
Location
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
95
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

The Silent Assassin
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1,291
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Temecula, CA
#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.
 
Likes
17
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.