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Fork Spings for 2001 kx85 forks on Crf150f

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Hey guys i have a 2003 crf150f with kx85 forks on it they are off a 2001. And christmas is around the corner and Dad told me to get a little list together. I was just wondering what springs to get to make the front end stiffer. I have a cr85 rear shock in the back with a bbr spring so the rear is alot stiffer then the front. I am running 10w oil in the forks right now. I see .33 and stuff like that when looking for fork springs just dont know what ones the stiffest, Not very knowledgable when it comes to suspension work. I am 6'0 at 170. Please let me know what fork springs you guys think would do the best for me.

Thanks

Greg:thumbsup:

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No, no, no... Call Cannon Racecraft and get some .44's up front, and a 9.0 out back. The springs will handle the compression, now you have to get the shock and forks revalved in order to control the rebound of the heavier springs. I don't think the BBR rear spring is enough to handle the weight of that bike (it's a 6.0 spring rate I believe). From experience-- I know that you'd need around a 9.0 KG (stock rate for a 150F) rear spring to match the .44 fork springs. That 150F has got to be about 90 lbs. heavier than a CR85.

Note-- make certain the springs you get from Cannon are the correct length. If they are even 10mm longer than the springs that come on the suspension components that you're using, then they will have too much preload on them, and will feel way too stiff. I'm having this problem as we speak with a set of Cannon springs in my own 150F. I have to send them back, and get a set of shorter, (stock length) springs from them. This is a common problem with aftermarket springs I'm told. I'd get ahold of John at Hlebo Bros suspension. He's well versed in setting up the 150F's suspension. It's best to get it set up correctly the first time. --L*64

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Really cant afford to revalve them. And i know quite a bit of people run the bbr. Im not racing it just having some fun with friends. And whats a reasonable length or whatever the .33 numbers are for.. Im not doing huge jumps,mostly power lines and farms and trails and a track here and there.

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I see. What I'm saying, is when you do get new springs, make sure that they aren't longer than the springs that come in the forks. If they're longer, then they'll feel too stiff due to too much preload.

BTW-- I mis-thought your rear suspension. I was thinking that you had a CR85 rear shock for some reason, with a BBR spring for a 150R on it. When I thought about it, I realized that you had a stock 150F rear shock, with the BBR spring on there. The BBR spring is supposed to be 30% stiffer than the stock 9.0 spring. That would put at almost 12.0 I guess. That's pretty stiff-- too stiff IMO for a 170 lb rider.

Up front-- if you go with .33 springs, they'll feel the same as the stock springs. they're rated at .32. If I were you, I'd go back to the stock rear spring-- and get a set of .44 fronts. For some reason, Honda didn't get the spring rates matched on the 150F's. The spring rates will match up front and rear w .44's up front and the stock rear. I weigh 150, I'm running that setup, and it's slightly stiff for me. Add 20 lbs., and I imagine it'd be sweet.

The stock shock sucks! Even for trails. The Hlebo revalve makes it work really well. I can ride the bike alot harder in the turns with the revalve. It was only $200 shipped. --L*64

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No i do have the cr85 rear shock with the BBR rear spring for the shock not for a 150r. And can i get .44 springs without having to special order them? And what is the stock length so i dont get that messed up?

Thanks

Greg

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Greg-- I get my spring rate info from the Race Tech spring rate calculator, which isn't always exact. It IS a pretty solid baseline finding tool. I went off of it when dialing my own 150F in. I'm using stock suspension components for this particular bike, but I have another 150F that I plan on building to the max.

If you're running the BBR CR85/150R shock spring on your 85 shocked bike-- then the spring rate is 6.0. Now-- that spring rate would be perfect for your weight if the shock were on a CR85 or 150R. the problem is that you have it on a bike that weighs a ton more than either of the other two bikes, and probably has a more aggressive linkage ratio as is common with Honda trail bikes. This means that the 6.0 spring is 3.0 lighter than what comes stock on the 150F. I know for sure that the stock rear spring rate 9.0 would be perfect for your weight. You have to be bottoming that shock that's on your bike when you're riding it-- no?

I kept trying light weights on the R/T spring rate calculator, and I couldn't even get a rider weight that would call for a 6.0 spring. I even tried 25 lbs. I know you're trying to improve your bike, but it's fairly easy to go backwards with mods.

If you aren't going to get a revalve- the correct 9.0/.44 spring rates on the CR85 shock, and KX forks will make the rear very unsettled in the turns. If you do go this route- I think Cannon will only charge a few bux more for custom spring rates. If you ARE happy with the rear the way it is, then I'd go with .30 front springs. That would be a match for the rear spring rate on that bike. You've got .26's in there now if they're the stock springs I believe. Hope this helps you understand suspension a little bit. --L*64

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Okay, I am pretty content with the rear shock it raised the ass end up a bit and its to the stiffness that i want when i knock her down a little bit. Now as for the forks would you only go with .30's or would you go with some .33's? For christmas i want to ask for the fork springs and bar risers.

Thanks

Greg

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Well you could go with .33's, but here's how I got to the .30's. The chart calls for the 9.0/.44 spring rates we talked about above for your weight. If you've got the 6.0 BBR rear spring-- that's 66% of what's called for. All I did was reduce the recommended front rate by the same amount (33%). I multiplied .44 X 66% (.66). I came up with .2904. I rounded it up to .30. This way your suspension will at least be balanced as far as the spring rates go.

Another thing to be concerned with is that the bike only has 10 inches of ground clearance stock, maybe 11 with the 85 suspension on it. Your suspension has 11 inches of travel. This means that you have to watch on bigger jumps that you don't whack the bottom frame rails and engine cases on the ground.

I'm planning on a 150R front on my own 150F, along with probably a Race Tech shock. I'm going to limit the front travel to 10 inches with a larger than stock internal bumpstop, and the rear to 10 inches as well. You won't miss the last inch of travel, and it will minimize any frame to ground exposure. --L*64

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No one asked if the OP is trail riding or MX. For trail riding the Racetech spring calculator yields too stiff a spring.

I have a set of CR80/85 USDs on a XR200 used for trail riding and .32-.36kg springs seem right in the ball park, .32 seemed too soft and .36 seemed too stiff so I used one of each for a .34 effective rate, but as always YMMV. So you can fine tune spring rates by mixing springs. You can also increase bottoming resistance by running a higher oil level. The KX forks are KYB cartridge units and require a 5wt oil for proper action, using 10wt oil will make them too harsh. I recommend Maxima fork oil (5wt), Racetech Light US1, or Honda Pro HP fork oil (5wt). As previous posted be careful of the free length of after market springs.

As far as rear spring rate the shock doesn't matter; it is the linkage ratio so use CRF150F data to determine what your rear spring rate.

There are some threads on setting static and rider sag, which will help you determine if the installed springs are too soft or stiff.

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Yep--^ ^ ^. Just thought of that. Mixing the springs together by getting the .33's and trying them out. If they are too stiff, then use one .33, and one of the stock fork springs that you already have installed. That would give you the .29-.30 we talked about. I use my bike for pit bike moto. If you're only doing trails, then a third less spring might just work fine. Might be plush actually.

You may be able to run full rebound damping on the adjusters to control the rebound. You're not going up a ton on front spring rate-- so you can probably compensate with the adjusters. The shock is going up quite a bit on the rate. I'd run full damping on that, and if it acts up-- you may get a revalve later on. Good luck, and post a few pics of the bike, and give a ride report when you get it all set up. --L*64

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