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Discussion Starter #1
Hi everyone, I have just joined. I live in Spain and generally ride on both bumpy and smooth trails and I have an 05 YFZ450 I have had around for around 5 months. I have been reading a few threads about my dilemma. I am sure this question comes up time and time again.

I am trying to get to grips with the handling of this quad above around 20kmh. It's just smashing the teeth right out of my mouth or just generally trying to rip the bars out of my hands on every bump. It really does not want to hold a line. I have tried almost everything to make a difference. My friend has a Suzuki LTZ400 and he just glides along taking every rut, rock, root in its stride and just laughs at me. The difference in these two quads is night and day. I am almost at the stage of migrating to Suzuki or Honda.

It is in generally very good condition although it had clearly had a knock on the front left at some stage before I bought it as the lower A-Arm was bent about 15mm back and there is a dent in the wheel and a light bend in the steering stem.

In my quest to get it 100%, I replaced the lower A-Arm, wheel and steering stem. In fact I removed the entire front supension and checked it all, refitted, and regreased it, I had the frame checked at a local bodyshop and it is in perfect order.

The suspension geometry is now spot on. All the wheels are level, all point the right way and measurements from wheelnuts front to rear on both sides are perfect.

So having replaced the A-Arm, it did make a marginal improvement to the handling and did hold a line better. I must admit, being 15mm out I figured it would make a huge difference as the castor was way out one one side... but not really. I then set the toe-in to 7mm with the wheels on the ground and have checked and rechecked it several times. I have around 6 threads of preload on the front.

So overall, the front suspension is impossible. In all my years of riding all manner of quads and sports bikes I have never found a suspension that has such a wide range of adjustment that makes such an insignificant amount of difference. You have hard, very hard or rigid.

So finally, questioning the quality of 14 year old shock fluid, I stripped both shocks.

Whilst the spring was off, and I was playing about with the bare shocks, it seems that the rebound only seems to work in appx the 2-6 click range, beyond this makes little difference. Adjusting the compression all the way from around position 6 makes little difference either. It's certainly not a linear range.

So I replaced the fluid with race quality 2.5wt. To be fair what came out was probably the cleanest fluid I have seen during a rebuild and the shocks have definitely never been stripped before. The quad wasn't used very often and was garaged. Anyway, after re-assembly I had the reservoir pumped to 175psi with nitrogen.

Refitted the shocks, set the rebound and compression to the standard 11 clicks and guess what!!!!

Yep. This made absolutely no difference to the ride. It was still unimaginably hard and I may as well have just welded the lower A-Arms to the frame instead and saved myself around 50 euros in the fluid. I just can't believe that these quads ever sold when new with the suspension this hard!

So what is the next step does anyone think? I didn't really expect to buy a quad that is voted year on year one of the best quads yet have such minimal adjustment, a painful ride and requirement to change to a $3k suspension upgrade just to actually be able to ride it. For fun.

Am I missing something? The $3k dollars for a suspension upgrade could just buy me a good condition Suzuki LTZ or Honda TRX instead which would be perfectly suited to the terrain.

My wife has an automatic Kymco 250. And even that, with its budget Chinese shocks, performs better than this quad everywhere :(
 

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Discussion Starter #3
165lb roughly. I found some Works 150lb springs (used) on ebay that will fit for $40 from usa with $35 shipping. These are not dual rate either which would be better. I do not do any MX, its all XC.

I suppose I can order these and see how the standard valving performs with these springs as step 1...

If necessary, where could I get a valving kit for 05 shocks?
 
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