Have you tried aftermarket spring perches? (+susp. internal parts chat)

As another option, 20-40cc more oil costs less than $104.  

I'm saying that additional oil volume addresses the same issue (increased bottoming resistance) and is cheaper/easier to try/eliminate before buying the perches.

Adding oil through the bleed screw has some drawbacks on twin-chamber forks.  The oil is going to the wrong place.  It will migrate eventually, but ideally you unscrew the top caps of the forks and add the oil direct to the outer chamber where it needs to be.

We use them on a lot of our higher end builds!

I don’t have experience with that particular perch however I ran the JBI Pro perch in my Honda’s with the Showa 49mm forks for the last 5 years and absolutely loved the performance. I’ve always hated the feel of too much oil in the forks and with the perches you get a better compromise between bottoming resistance and keeping that plush action. 5ml changes are noticeable so you can fine tune the feel. To be honest though for the last 6 months I have ran well setup kyb forks on my honda and found they performed better than the revalved Showa with the perches so your YZ forks could be setup to not need them but $100 is cheaper than I revalve so it might be worth it for you. 

I used the jbi 2.0 perches on my ktm closed cartridge forks. I had those forks for roughly 7 years. I had multiple reputable companies do revalves (some multiple tries, even had huck valves at one point) and could never get good plushness with good bottom resistance. Over the last 2 years of owning those forks I started making valving changes myself and eventually got them decent, still not anywhere near great. 
 

I installed the jbi perches with 30cc less oil than I would normally use, did a one hour desert race and the forks were amazing all around. 
 

i felt some closure with that, didn’t ride the bike again and sold it. 
 

I have showa twin cartridge 47s and added 5cc a few weeks ago with almost zero difference. I added 5 more yesterday and the feel is alot better, I ended up going 8 clicks out on compression and was surprised to still have decent bottom resistance 

If your forks already feel good then the jbis would likely make them better. They won’t fix bad valving, but will improve a good setup. 
 

and I don’t recommend going the route I did with valving. I think I did 15 changes within 6 months or so, and I’m burned out on working on forks now 

Zeta Light Free Piston for the KYB Twin Chamber was a nice upgrade to my forks. It made them feel plusher overall. Added in a few more CCs of oil based on the Zeta recommendation. For the $70 bucks, I felt like it was worth it. I had to do a rebuild on my forks anyways.

For my shock, Racetech Spring for my weight with the recommended Nitrogen PSI change they recommended.

My son has used the MX and SX spring seats from Factory Connection along with oil lock collars and pretty much everything else they had to put in them lol but it was also tuned by their experience technicians made all the difference in the world got rid of the mid-stroke harshness and still had bottoming resistance!

5cc is noticeable with perches installed because they restrict the flow, 10cc is a standard increment on a stock setup. Like mentioned earlier, open fork cap and pour in 20cc to try first. If it doesn’t work go the perch option. I would recommend jbi 2.0 but the sdi would work similarly for half the price. 

Are there any negatives to aftermarket spring perches/spring tubes?  I had never used them before until Enzo recommended spring tubes on my 2023 KX450.  Those forks came from the factory incredibly soft so even going up to 5.2 NM springs for my 200 lb naked weight, they were bottoming very easily but part of that could be because Enzo recommended quite a bit less oil since the spring tubes took up a lot of that volume. I played with adding oil and it did help with the bottoming. Not sure if it was as good as it could be, we then went up 1/2 spring rate and that took care of the bottoming but it was really stiff in the chop and braking bumps so I felt like I had to pick one or the other. 

After voicing my frustration with the Showa forks, several people (including Keefer) recommended I try a YZ450 so I recently picked up a 2022 YZ450 and can't believe how much better those forks are even bone stock.  At 200 lbs, I need to up the spring rates but even so, the versatility blew my mind as I over shot and flat landed a huge booter yesterday and thought I was screwed but it sucked it up, while still being way softer/plusher in the top of the stroke compared to the Showas on my KX. 

I'm only getting about 20mm of free sag so I know I'm undersprung and will be sending it out to get resprung/valved for my weight but it has me questioning if replacing the stock spring perches with aftermarket would be a mistake.  I've talked to several suspension companies and when I mention how important bottoming resistance is (I have a fully fused ankle so no ankle joint), they usually recommend spring tubes/perches to help with bottoming resistance.  The cost is a non-issue but I'm wondering if there is any downside to aftermarket perches/tubes vs stock because of my one experience.  The suspension companies say that plushness and bottoming resistance increase so there shouldn't be any downside but curious in real world experiences.  Thanks!

I'm the OP. I ended up with gold valves and these perches and am so happy with the bike. The SDi Perches are great, and the other options mentioned here are probably really good too. I can only vouch for what I've used and for $100 the SDi perches rock. They make a noticable difference. Mkae sure you get the right bushings for yours. @sgrimmxdad can get you setup, he took good care of me. Just an option.

Put the amount of oil you want to add in a plastic syringe (no needle, just a tapered end that will fit firmly in the air screw hole).

Insert the syringe into the air screw hole, pull a vacuum, then push the oil into the fork.  The fork will suck in the oil.

REP Spring perch…

The SDI perches are awesome, we use them a lot.  The JBI perches are super nice as well but a lot more pricey.  We recently did a set up for an aspiring pro, on his YZ250 smoker we used the SDI perches but on his 23 YZ450 we did not.  Used Goldvalves on both and tuned similarly.  He could tell a difference and likes the stuff with the perches better.  He didn't know there was a difference in the builds, proved a lot to me....

Are there option for yz450f 2023 also? Its not listed sites I found part. 

I had KYB kit fork perches on my last 450. They worked really well and allowed for a plusher feel in the upper stroke while retaining anti bottoming properties. They were in the same price range as the SDI perches. 

They should be the same for the '23 450. '06-'17 would use the 24mm perch and '18+ will use the 25mm perch because they went to the larger cartridge/mid-valve. 

I had jbi perch on kyb fork and did not like it, the ramping effect was too much but I think it can be real good for supercross application

Is that a normal characteristic of after market perches/spring tubes? That's kind of what I experienced with the first setup I got from enzo with the spring tubes on my 2023 KX450.  Landing on bigger jumps, it would quickly move through the stroke and then ramp up quickly at the end. Granted, the KX450's forks are like wet noodles so that may have been more of what I was feeling. I don't know if it's the stock spring perches or the valving but my stock 2022 YZ450f forks have a nice smooth progressive ramp up. I don't want to lose that characteristic but need to go a spring rate or 2 stiffer so I'm questioning if aftermarket spring perches or spring tubes will alter that. Anyone here used the enzo spring tubes and can comment on if what I experienced in my KX450 was more an issue of the KX internals, or the spring tubes themselves? I believe the ones enzo uses are longer that some of the others here and not sure what that changes.

In my experience, SDI is an awesome company to deal with.  I buy shims and some other things from them for my personal projects and to help out my buddies.   I bet their perches are good if you're willing to play with port area and position.

I do run some restrictive perches in two of my bikes.   First, I built a set of my own to test with 20 holes at 7/64" diameter (2.78mm).  They were too restrictive when I tested them in my 2019 YZ250.  I enlarged half of the ports and they work well.  Currently they are in a YZ250 fork on my 1990 KX500 wit.  I have a leaf-spring mid valve conversion (my own parts that are almost identical to SDI's mid-valve cups) as well as the restrictive seats.  That fork is one of the best settings I've ridden.

In my GasGas MC350F, I have some SX style seats (FC and PC sell them) on a KYB conversion (photo below).  It's an R&D mule for the drop in KYB kits I developed and will be selling soon. With the KYB style bottoming cups, longer 2020 YZ450F fork springs and 340cc of oil, I don't notice them, but when I do bottom I don't feel it at all.  Even with a softer fork spring than I should be running, it feels great.

A note on the three lengths of KYB springs...   Early YZ SSS springs are the shortest.  KX KYB Springs are a middle length.  Later YZ-F springs (I think 2020 and later) are the longest.   I believe that your oil height and the length of springs you run combine with the position of the perch and it's restricted orifices to stage the damping a bit.   I have not measured oil-height with various springs vs oil-volume in these forks, but I would like to someday.   The other issue is that the oil height isn't constant since the lower fork leg is almost like a paint-shaker.

Red7,
My local pro buddy who runs one my KYB stuff in his 250SX swears by the Enzo national spring tubes.  I haven't tried a set in one of my own bikes yet, but I have ridden his stuff which is valved by JMR.   Eventually I'd like to play with some Enzo tubes on this GasGas.    The kawi valving uses a different philosophy (mid valve vs base valve) than Yamaha.  I run a '12 KX450F cartridge in my MC350F with more of a current Yamaha style valving setup.   The ramping up from restrictive spring seats is probably somewhat due to the flow-area of the orifices.   The blue seats in the photo below work awesome.  The first rendition of the ones I made had a very firm shelf in the bottom 1/4 of the stroke.

SX style seats with my custom spacers to run YZ450F springs on a KX cartridge within a GasGas.

The first photo below is the first (too restricive) perch I mentioned in my previous post.

The second photo is a comparison of my restrictive perch paired with a 2020 YZ450F spring next to an OEM Yamaha perch and an older spring from a YZ250 two stroke.   I believe that position of the perch delays the point in the stroke where that extra damping kicks in, assuming you run the same oil level in each setup.

We run the MX SDI version so we can tune it to our liking.  The SX version you can't tune.