Suspension upgrades?

[jjmaine]

I plan to upgrade the suspension on my 2005 ninja 250. The soft, mushy suspension is the only thing I can find to complain about and probably the only "mod" I will do to this bike. For the rear I was thinking about an '08+ rear shock and maybe some BCB big boy links. Does anybody have experience using the big boy links and would they be a worthwhile investment or will the 08 rear shock do the trick by itself?

What is the best way to make the forks stiffer? The simpler (and cheaper) the better as I want to do the work myself. Thanks!!

[RacinNinja]

Originally Posted by jjmaine

I plan to upgrade the suspension on my 2005 ninja 250. The soft, mushy suspension is the only thing I can find to complain about and probably the only "mod" I will do to this bike. For the rear I was thinking about an '08+ rear shock and maybe some BCB big boy links. Does anybody have experience using the big boy links and would they be a worthwhile investment or will the 08 rear shock do the trick by itself?

What is the best way to make the forks stiffer? The simpler (and cheaper) the better as I want to do the work myself. Thanks!!

The links don't do anything other than raise the rear up. They don't change the spring rate and they don't do anything about the crappy damping in the stock shock. Basically, they're good for cosmetics and that's about it.

Get springs for the front rated for your weight and a rear shock to match.

[Ghostt]

I have the BCB links, and I'm running the ZX600 shock, both work nicely together. I installed the link this season. They do nothing are far suspension goes like spring rare, etc.... They do change the geometry of the bike, making for quicker turn ins.

As far as the forks go, there is a number of options, you can cut the existing OEM springs, and then add spacers to get the rate, and sag needed, you can also do the some with a set of springs from a NewGen as well, as they are a higher rate, and less to cut. And finally just order a new set of springs to your liking/rate.

I opted for cutting my spare set off my EX500, and switched to 15w fork oil.
@InvisiBill has a lot more detail on the subject, and is better at explaining it than me.

[jjmaine]

Thanks for the info guys.

The 08 rear shock is adjustable right? So I should be able to set it to my liking. I am 6ft tall and 180lbs, there must be a way to figure out how much adjustment the forks need?

Is it quite a task to remove the forks and change the springs/oil? I'll have my haynes manual next week so I'm sure it explains it in there somewhere...

[Ghostt]

The NewGen rear shock has settings, but it only effects the sag.

The front forks are easy, to do,

Here's a link to the EX-500.com wiki page, the EX500 is a close brother to the Ninjette, and shares a lot in common.

Here is their link for upgrading the fork springs

http://www.ex-500.com/wiki/index.php...the_Suspension

[jjmaine]

Thanks, I will check it out!

I think my forks are more of an issue than the shock. They seem very soft, possibly due to old fork oil? I don't remember my old 250 having mushy suspension like this one but it only had 300 miles on it when I bought it. I will do my research before I open them up and change the seals and oil. I wan't to get it right the first time!

[InvisiBill]

Originally Posted by jjmaine

I plan to upgrade the suspension on my 2005 ninja 250. The soft, mushy suspension is the only thing I can find to complain about and probably the only "mod" I will do to this bike. For the rear I was thinking about an '08+ rear shock and maybe some BCB big boy links. Does anybody have experience using the big boy links and would they be a worthwhile investment or will the 08 rear shock do the trick by itself?

What is the best way to make the forks stiffer? The simpler (and cheaper) the better as I want to do the work myself. Thanks!!

The PreGen fork springs are very soft. You want 33% stiffer just for a 100lb rider. I haven't seen much about spring rates for the PreGen rear, but assuming it's similar to the NewGen and 500, the stock spring should be good for ~140lb.

Figure out what spring rates you need to match your weight. Buy new fork springs, or cut yours down if they're close enough. 500 or NewGen springs might be an option, depending on your weight, and you should be able to find them cheap.

For the rear, the NewGen spring/shock might be a decent cheap bolt-on (again, depending on your weight) that will also raise the rear a bit. A DIY GSXR swap will give you more adjustability and you might be able to find a spring rate to match your weight better, but it's also more work to install and tune it.

Upgrading the damping is nice, but just replacing way-off springs with ones that match your weight will do amazing things for how the bike handles.

[Ghostt]

If your going to do the forks, you must do the rear as well, to maintain the balance of the bike, doing one without the other is unsafe IMHO, and will cause the bike to react unfavorably.

Cutting the fork springs is easy enough, and the only cost is new spacers, and new fork oil, I personally used 3/4" black steel pipe, I don't trust PVC pipe, I cut 5.5" off the EX500 1st gen springs, stock length was 20.5", final length was 15" I added 6" of black pipe, and 15w synthetic fork oil. This is the set-up that works best for me, and my riding style.

I'm 6'3" and 225 lbs with gear on.

[Ghostt]

Here's some more reading material for you, it's from our fellow brothers and sisters over at ninja250.org they have one of the best wiki pages for the Ninjette

Here's the link to their suspension section
http://faq.ninja250.org/wiki/Suspension

Main page link, bookmark this for future reference, it comes in handy.
http://faq.ninja250.org/wiki/Ninja250_Howto

[jjmaine]

Loads of good reading there!

[jjmaine]

Thanks Invisibill and Ghost! I will get a new gen shock and try cutting and shimming my fork springs.

[InvisiBill]

Originally Posted by Ghostt

If your going to do the forks, you must do the rear as well, to maintain the balance of the bike, doing one without the other is unsafe IMHO, and will cause the bike to react unfavorably.

The stock spring rates are completely unbalanced. You need around .60kg/mm (36% stiffer) fork springs just to match the rear, which is still too soft for a lot of people. Doing only the fork springs will make things a lot closer to balanced than they were from the factory. Yes, you should do both ends for best results, but you're still improving it over stock just with the front end upgrade.

I put 54% stiffer fork springs in my 500, and it was a massive improvement, without any other suspension mods at the time.

[Ghostt]

Good point, I was thinking the rear was softer that, I know PreGen is all around soft if you weigh more than 100 lbs

[jjmaine]

So I have changed the rear shock to a new gen and it has helped but now the front suspension feels even softer. Being short on funds at the moment I thought I may try to use this set of GS500 fork springs? They are supposed to be .59kg so it should atleast be an improvement over the stock springs. They are shorter than the ninja springs but the diameter is the same. Can I get away with just using a longer spacer?

[Ghostt]

If your short on funds, just cut down the existing springs, and make up that difference with spacers.

Or get a pair of NewGen springs, and if needed cut those down as well.

I myself cut down a spare set of 1st gen EX500 springs, and I'm very happy with them.

1st gen EX springs are 20.5" long, plenty of room to cut them down to 15", add 6.5" spacers and I'm dialed in the sag, and the springs are now about .85kg, I also changed the fork oil to15wt synthetic.

[jjmaine]

That may be my solution until I can grab a set of sonic springs. So if I lop 3 inches off the existing springs that should get me close to .70kgs? I did see a calculator in one of your links to the EX500 forum, Ill have to go check it out again.

[jjmaine]

Oops, just noticed that you cut the ex500 springs. I would be cutting my 250 springs

[Ghostt]

The stock EX250F springs are 0.440 kg/mm spring, while the EX has .585 kg/mm

IIRC stock length for Ninjette PreGen is 18.5"

So depending on what spring rate you want depends on how much to cut.

new spring rate = (original spring length / modified spring length) * original spring rate

So if you cut 3" off the OEM ones

18.5/15.5 X .44 = .52

As you can see the math, you may need to cut more depending on what your after.

In retrospect the EX has a slightly heavier spring .585, and 1st gen has a long spring as well.

So in my case 20.5/15 X .585 = .80kg/mm

I know the NewGen Ninjette has a heavier spring but I don't know what weight it is, maybe someone else does.

[jjmaine]

Thanks again Ghost, this is very helpful. I will tackle it this week.

[Ghostt]

It's easy enough done, just do the math, as far as spacers goes, I take the amount cut off, and add 1" this gets me in ballpark.

Doesn't forget you need to also add the OEM spacer length to the spacers.

So let's say the OEM ones are 2" and you cut 5" off the OEM springs, you'll need at least 7" to make up the difference, not including what is needed to set the sag height, let's say 1", so you'll need 8" spacer.

What to use to make spacers is up to you, some use PVC pipe. I used PVC to determine the final length, as PVC IS cheap and easily cut. After I find the length needed, I replace the PVC pipe with 3/4" steel pipe, personally I don't trust PVC for longevity, although many do.

Finally pick your fork oil weight, and don't forget setting the oil level is important as well, I've found that 5 1/4" from the top of the fork works for me. I've used this on both my 91 EX500, and Ninjette, as they both have the exact same forks.

[jjmaine]

I have the steel spacers that came out of a set of GS500 forks. They are 10 inches long so if I think they will be long enough to cut down for the ninja, but if not I may end up with pvc.

[Singh2jz]

I got my springs from sonic springs for like 90 I think. Pretty good deal, not gonna lie. You get full instructions and pvc pipe.

[InvisiBill]

Originally Posted by Ghostt

I know the NewGen Ninjette has a heavier spring but I don't know what weight it is, maybe someone else does.

.65kg/mm

PreGen Fork Spring Rate Chart has more numbers.