Ohlins front fork cartriges

Hi im running ohlins front fork cartridges in my 2013 450sx

Anyone know what spring preload is recommended or what there using

Im about 80kg

2mm of preload is all you need, just enough to keep the spring from wiggling when its unloaded.

I am thinking of upgrading to these cartridges..

 

Are they lighter than stock as they claim?

 

Were they easy to install?

 

What headaches did you hit with them?

 

Let me know plz

Im not sure if they are lighter than stock, the stock fork inserts are very light, Im fitting a pair of Ohlins carts next week I can weigh them both for you when I do it and post the weights of both standard and ohlins

I have been running 2mm preload and really like the forks but the only problem is that they blow through the stroke and bottom to easy on the flat and big landings

I have been testing oil heights and getting some where with it at last

Im 85kg kitted up

using 46 springs front and they may be a bit soft but I always run my forks softer than most 

54 rear spring 

ktm 450 13 

For motocross.46's in the front are a tiny bit light for a 450 AND your weight. I'd say .48's would do the trick for ya. The 5.4 rear MAY be ok, if you can get sag and don't have a shit-ton of preload, then you should be OK with it... but its for sure on the soft side. Soft forks in motocross are actually a big issue because you won't get good preload off jump faces AND the last thing you want is the fork to blow through the stroke on landings, just imagine if you made a mistake on a double what would happen! Most people prefer a heavier spring in the front over a lighter one for this reason. The bike also will stay up in the stroke more, which does make it handle better.

The Öhlins cartridges are not lighter then stock, neither are the complete forks.

If you blow through the stroke, you will need to first try adding oil, maybe bring it up to 380cc's and see what happens.

Edited by tye1138

Good comment that I agree with all you have said

Im thinking of getting one spring (48) mixing it with the 46 to =47

think you mean 380 not 280

There forks were amost perfect but they would bottom on the big landings when they had 350cc oil and I put it up to 380 when I changed the seals and it would not bottom but they felt harsh

So will up a spring and try 360cc and add 5cc of oil till there right

Yea, 380 woops! heh.

I think if you increase the spring rate (yes using one 46 and one 48 would be fine) you can probably keep the oil level low.

Spring rate, oil height and valving are the three main keys to harshness.

Spring rate is easy to fix and test. Throw a spring in the bike, turn all the clickers out, and measure the unloaded fork's exposed tube length, then sit on the bike and measure the same thing. Getting this fork sag number will help determine if the spring is right for you. Usually fork sag on a motocross bike should be between 50 and 60mm with 2mm of preload. Too much preload on the spring can also cause harshness as the coils get closer together.

Once the spring rate has been verified as good, then you focus on valving and oil level which go hand-in-hand. Oil level changes the size of the air chamber in the fork and helps reduce that air build up as the fork goes into the stroke. However, the side effect of lowering oil is of course, changing the bottoming resistance. So you start with a high oil level (380cc) and test... then you lower the oil level until it bottoms. Do some math and find the perfect level for you and your riding, its pretty much that simple. However, just because you have the right spring and right oil level for bottoming, doesn't mean the fork still has harshness. Thats where the valving comes into play.

A lot of tuners under-shim as their methodology of helping with harshness, they believe less valving equates to less harshness. There is some truth to that, if they run just enough valving to keep it from diving. Most tuners run that fine line between diving and keeping the fork up in the stroke and likewise, a few clicks of compression +/- can make a big difference, especially with the Öhlins shimming. But having the right shim stack for the spring rates AND the rider, is a tricky situation. It does take a lot of tuning to get it nailed, but when you do, harshness DOES ABSOLUTELY decrease, even with stock OEM WP forks.

There are some lazy people's quick fixes like more constrictive spring perches, which will allow you to run less oil in the tubes (300cc's) but that doesn't change how much the fork dives... So from my perspective, fix the valving (diving) issues before resorting to buying aftermarket parts.

Finally the last issue comes from slow riders vs stiff tubes. The stock KTM WP closed cartridge fork tubes are pretty strong. They are designed for fast riders, hitting big obstacles and those of us who aren't fast, who aren't getting big air, we actually don't get the forks to flex enough over the small stuff (especially light guys like myself). Its not a defect, its not a design flaw, its simply our speed as riders. The Öhlins forks have lots of flex built into them, so slower people get a bit more of that flexing. As a consequence, really fast guys don't like Öhlins forks because they flex TOO much.

So there ya have it! The reasons why harshness exists and hopefully a direction to put you on in order to resolve it.

Edited by tye1138

I weigh 210 ready to ride. I'm using 51's with 350 oil and 5.8 with 100 sag out back. So far its works good for me in both mx and off road

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