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5/1/2022
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After a season with both a '23 350 SXF and '24 KX450 I have made the decision to commit to the 350.
I am willing to spend some money to get the most comfort out of the 350, since I do not see myself upgrading for a couple of years. Unless there are some significant advances in the next gen 350 or a Japanese manufacturer releases one.
I am running an XPR mapped Vortex and full FMF system on the 350 and satisfied with the power for my skill, speed and riding frequency.
I would like to address chassis and suspension comfort. I know spring conversions, bladder kit for the shock, linkage, split clamps, engine mounts are often recommended. The bike is already sprung for my weight and sag.
I am planning to do the JBI DIY shock kit.
Where I am stuck - is I am considering the JBI DIY mid-valve kit for the forks as a potential alternative to a spring conversion. I am hesitating to spend the money on the DIY kit though, knowing that although it will be an improvement, it will likely still not match a spring conversion and still retains the air. However, a spring conversion will run close to 2500 CDN including valving. Quite a lot more.
Where I am stuck - is I am considering the JBI DIY mid-valve kit for the forks as a potential alternative to a spring conversion. I am hesitating to spend the money on the DIY kit though, knowing that although it will be an improvement, it will likely still not match a spring conversion and still retains the air. However, a spring conversion will run close to 2500 CDN including valving. Quite a lot more.
I am unsure if instead I should start with the DIY kit and then purchase a linkage and potentially clamps? Maybe add the '25 350 engine hangers? Or forgo those things and instead just do the spring conversion?
Would there be much if any notable improvement to the ride adding clamps, linkage, hangers AFTER doing a spring conversion?
I realize I am not going to get the same feel out of the KTM as the KX. But I would at least like to get as much comfort out of the bike as I can (actually feel) without spending money unnecessarily.
Interested to hear from others who have some experience and opinions to share.
I don’t have any direct experience with them. But if I were in your shoes, I would give the MxTech Blackjack inserts a shot.
Thanks. Have read about them but thinking if I go full spring, I would be better off sticking with the 6500 or KYB conversion for local suspension tuner knowledge and support.
What terrain do you mainly ride? If it's softer dirt I would stick with air forks and try the JBI kit, if it's more hard pack choppy conditions I'd go a spring kit. My recommendation for spring would be kyb or dal soggio.
On my 23 350sxf I felt little to no difference between my well setup stock forks to full kyb's on sand tracks. Where the difference became noticed was on hardpack choppy conditions.
Can you tell me what is it about the engines that you like one from another. It seems one is low rev torque, the other is high revving and feels lighter. I have no basis of comparison, but I do like from what I have heard, the 350 is a lot of fun to ride.
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I have 2024 Husky forks, and rear linkage, on my 24 350 SXF. I had the stock, JBI DIY kit, and now JBI 6500s. My regular track is very deep and rough. The JBI DIY was pretty good. Flat corners and hard pack was the only place I wondered about that led me to try 6500s. Only ridden them one day so far. They are softer on the small stuff for sure and in the corners. It’s the initial movement of the air forks on smaller stuff that feels stiff. In the big stuff they are fine. On the rough stuff and jumps I’d be hard pressed to tell a difference between the JBI DIY and JBI 6500s as both feel good to me.
I am seeing used 6500 kits for under $1k US. The 2025 engine hangers help a lot on big hits.
I race a 23 GasGas MC350F with XPR vortex.
I am in steamy hot love with the red 350F. It has more than enough power everywhere on the track and has given me consistently good starts plus several holeshots.
On my chassis the REP linkage works extremely well combined with better shock valving in the standard shock body / standard adjuster.
I don't remember riding a motorcycle with better rear wheel traction.
I'm a biased source on the fork stuff since I make drop in KYB conversion kits.
I do think KYB stuff has the best mix of front tire grip and performance.
There has been discussion on the comfort in OE vs billet fork lugs. My kits retain the production WP fork lugs without any modifications.
https://www.vitalmx.com/forums/moto-related/easier-kyb-spring-conversion-wp-xact-48mm-forks
My buddy has a 23 KTM 350SX-F with the Twisted Vortex. Great bike, but I think I would do the linkage on that one and suspension for sure. it rides higher in the rear and is more active / pitches more than I like on-of throttle or brakes.
I have a '24 KX450F, but I haven't ridden it yet... I may get both bikes to the track next weekend or maybe the week after the Washougal national to see if I hate the green bike. I'm not really much of a 450F guy, but the Kawi was inexpensive and the KX chassis is intriguing.
Thanks!
Mostly intermediate. If prepped, typically starting out soft and tilled in the mornings, changing to dusty hard pack as the day progresses. Some tracks do develop more square edged braking bumps and acceleration chop while some tracks develop more rolling bumps. Many of the tracks do have a combination of sand, but sand-only. Only sand-only track I ride is the Gopher Dunes national track. But that is a different beast.
Most bikes are going to feel good in the smooth soft dirt. I am most concerned about comfort when the track starts drying out and developing the sharper square edged chop.
My experience is similar to what can be found in many reviews and other riders experiences. I like that the 350 revs quicker. It feels livelier and more playful. The KX obviously has more torque, but it is slower to build its power (slower revving). To me this does result in the bike feeling heavier and I do feel the weight. I feel it braking, coming into corners, through corners, and when changing lines. I feel the engine mass. When going from one to the other back-to-back I find the 350 feels like a pedal bike in comparison despite the overall weight being close. The 350 feels lighter, more nimble, more precise in the steering, quick pick-up. You can lug the 350 in 3rd gear a lot of the track or optionally rev it out much further than you can the 450. I find I have the flexibility to ride it multipple ways based on track, track condition and how I am feeling.
I do have an XPR mapped vortex and full FMF on the 350. Not sure if the FMF made/makes a notable difference but theVortex definitely woke the bike up, to the point where I am satisfied with the power delivery and output. When the tracks are tilled deep the torque between the two is quite noticeable, but if I adjust my riding technique, ride more like a sand track with weight bias over the back too lighten and carry the front tire more, I can easily make it work. This is coming from a 245-250lb (with gear), C level vet rider. So, take it for what it's worth.
I have just been finding that because I do not ride enough these days, I do not maintain my on-the-bike fitness like in the past. As such more of my ride time is focused on riding the bike effectively as opposed to riding the track. For my weight and height (6'4) the KX 450 is not what I would consider 'too much' bike, it's just that I do not get the same enjoyment riding it because I cannot ride it as effectively. I feel the weight, corner tip-in. the increased torque does take more out of me as I put in the laps, and I need to be more strategic about line choice. The 450 is running stock gearing, removed the airbox grommet but have not removed the exhaust insert.
Not sure if that helps or not.
Great feedback. Thank you!
I am very interested to hear your thoughts as you get more time on your new setup.
Did you find much positive improvement of the JBI DIY kit on the smaller, choppy hard pack stuff over stock or mainly just in the fluidity, responsiveness in the first 1/4 of the travel and overall hold-up?
Have you done anything with the shock to this point?
Trying to determine if there is a best/better direction to go with the shock depending on what gets done with the forks - whether JIB DIY mid-valve, 6500's or KYB conversion. Is shock setup dependent on the fork setup? In other words, does the shock need to be matched accordingly based on which direction is chosen for the fork?
Thanks for sharing your experience!
I would be interested to hear your thoughts after you get a few hours on the KX!
I am and have been leaning towards the KYB kit to be honest. For the sake of a couple hundred dollars more, I would prefer to know I am going in a direction that offers the most potential. I realize they will not perform the same as on a YZF that everyone raves about, but I have limited track time on YZ/YZfs over the last several years anyways, so I don't know any different.
Initial bump comfort is important to me as I am a slower dude anyways. I would prefer the most comfortable cushy ride I can get.
I know there are differing opinions between the 6500 drop-ins and the KYB conversion, but from what I gather, those riders that prefer the feel of the 6500 over the KYB are faster guys. For the slower vet c level rider, it sounds like the KYB would offer the more comfortable ride?
I have not ridden the 6500 kit installed in stock tubes nor the Dal Soggio cartridges.
Of the stuff I've ridden, the KYB has given me the best front tire contact and comfort without sacrificing hold-up and performance.
Ohlins and Showa stuff I've ridden have a firm damping feel on a KTM or any other chassis
I'm coming up on age 45 and getting slower, so maybe I want more comfort these days?
While there is a general character or feel to each cartridge, good settings are probably more important than which components you choose.
Some tuners will give you a very firm setting and others will trend toward comfort.
I learned to valve my own stuff to get exactly what I want without a communication barrier or the bias of a tuner testing at some far away track with a different rider.
You can make the stock air fork hold up well with the right settings, but in my experience comfort won't be as good as any spring fork.
Slapper landings are the most obvious place the air fork loses comfort with a more aggressive setup.
On the YZ-F vs KTM chassis...
I do think the KTM chassis I have experience with (2017 - 2022 and 2023+) require a bit less damping force than the Yamaha chassis. They seem to load the fork less while still creating excellent front wheel grip. I actually recommend most of my customers to run a YZ250F cartridge in their 450SX-F with a YZ450F spring rate. That is a great starting point for the average rider and I'd race it year round here in the northwest. In the 350F, I would start with the YZ250F cartridge and the YZ250F springs or something between the YZ250F and YZ450F.
There was a Kris Keefer podcast with Mark Johnson discussing the comfort in the fork lugs, clamps, etc when doing KTM / KYB conversions recently. I haven't tested back to back, but they seemed to agree that there is more comfort in a stock WP / KTM fork lug than a billet lug. I can't say I've done that comparison back to back, so I have to defer to them.
I have created settings that I like for my own 350F. I have a setting for older 24mm KYB cartridges and for the current 25mm KYB. I keep forks around with each size cartridge for testing on my 350F. I'm pretty open to sharing those settings with people who want to try them. They are somewhere between a YZ450F and YZ250F in damping force. For my riding style and the tracks I race, the front end comfort is amazing with very confident grip. I am currently still running the stock GasGas clamps, rigid bar mounts and Neken bars.
Stock triple clamp on the KTM/Husky are terrible and a split clamp really helps the feel of the newer Austrian bikes. I prefer the Luxon clamp.
I have KYB spring from Enzo with Luxon clamp, but I would pick air fork with Luxon clamp over KYB spring with stock clamp.
22mm offset (same as stock)
Helps a lot. Listening to Keefer or MXA just isn't the same as I am someone NOT hucking the huge jumps, just someone turning laps and having a good time doing it. So, Thank you.
Finally got some laps (3x 15 min sessions) on a good track where I could really feel the setup. Track was rough, but not crazy like previous rides. JBI 6500s, Ride Eng 23.5 clamps, 2025 engine mounts, TwinWall 996. Bike felt fantastic. Bike turns really well now and bump absorption was really smooth. This was the first time the front felt consistently very good in the corners. Prior to the day I raised the forks to the 2nd line and still have 105mm rear sag. So happy now!
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