Front Suspension

[Snow Drift]

I've just recently replaced all the bearings in the linkage, shock, and swingarm. It has made a huge difference and the rear suspension is a lot softer and looser now.

 

I now need to focus on the front suspension and carry out any necessary work. I'm not really familiar with how the front suspension works or what needs to be done. It seems the fork seals are leaking a bit so I think I'll need to do those. I don't understand what people mean when they say they have fitted fork bleeders.

 

I find the front suspension very firm and even when I try to adjust it at the top it seems to make very little difference. Therefore can anyone walk me through what type of things I should consider doing to the front forks to service and make them adjustable etc.

 

I also wondered if anyone knows what weight the standard suspension set up is designed for? I weigh about 138 pounds.

[grayracer513]

Year model??

[katze300rr]

You sould (get and) read the manual first.

 

Anyway... fork bleeders are some kind of button action screws, meant to replace de screws that you see in the upper part of the fork (not the clickers, the smaller not in the center ones) When you loose those screws (you should after every ride) you let the air inside get out so you get even outer and inner air preassure. The bleeders will make that faster for you, avoiding unscrewing and screwing.

 

The clickers on the top of the fork are for REBOUND control. The clickers on the bottom (under rubber cap) are the compression control. You should try to soften from there first. Two o three clkicks counter-clock wise each time and you will start to feel the difference.

[Wintyfresh]

Rebound is at the bottom of the fork, compression is at the top. 

 

Edit: For 2012+ models as pointed out below, thanks! 

Edited September 19, 2014 by Wintyfresh

[GuyGraham]

Front forks as std are rubbish

 

read this

https://www.thumpertalk.com/topic/683007-08-wr450-fork-valves/

 

 

fork seals hardly ever fail.

Leaks are usually caused by dirt under the seal.

You can rescue the seals like this

http://www.ebay.co.uk/itm/like/121059312192?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108&ff19=0

Edited September 19, 2014 by GuyGraham

[woods-rider]

Rebound is at the bottom of the fork, compression is at the top. 

 

Not if he has a pre 2012.

[GuyGraham]

He has an 07, so compression at bottom, rebound at top

[Snow Drift]

GuyGraham where did you get your Racetech kit from? Did you buy in the UK or import from the US?

 

Did you change anything else on the forks? Did you do anything to the rear shock?

[flyandride]

WRs come set up for a 160 lb rider here in the states.  So if you weigh 138 and the bike came set up for 160, the suspension would feel too stiff.  

[Snow Drift]

I'm hopefully going to be joining a gym and trying to build up a bit in the future. Am I compromising the handling by not having a softer spring setup or is it really just comfort that I'm losing out on by not going softer?

[GuyGraham]

GuyGraham where did you get your Racetech kit from? Did you buy in the UK or import from the US?

 

Did you change anything else on the forks? Did you do anything to the rear shock?

 

PDQ in Bershire, they are UK distributor for RaceTech stuff

 

Proper 0.46kg springs in forks (I weigh 14st) - tried 0.44's first but they were a bit soft so went up a rate to 0.46

 

Not done anything to rear shock except for correct spring for my weight to get the sag figures correct  (6.0kg/mm)  and a change of oil and regas

Edited January 2, 2015 by GuyGraham

[Snow Drift]

Thanks I will give them a call.

 

Are the springs you bought all Race Tech too from the above place?

 

Is there a way of working out what the correct springs would be for my weight? Also do you know whether changing the springs for my weight would significantly improve handling or is it mainly for comfort?

[GuyGraham]

I got WP springs in the forks, and a K-Tech spring in the rear, as they were available at the time I needed them

 

Have had RaceTech springs in my road bikes without issues, so would have no issues using them either

 

Racetech Website   has an online calculator, to give you the spring rate required based upon bike, riding discipline (MX, enduro, supercross) and your weight

http://racetech.com/ProductSearch/1/Yamaha/WR450F/2007- enter your details by clicking on where it says Calculate Spring Rates and Display Available Springs

They usually come up a bit high on the forks (so if it says use 0.48's I'd go for 0.44's), so go a couple of rates lower than what it suggests, but the suggested rear spring rates are usually pretty close

Edited January 4, 2015 by GuyGraham

[foggy3061]

I got WP springs in the forks, and a K-Tech spring in the rear, as they were available at the time I needed them

 

Have had RaceTech springs in my road bikes without issues, so would have no issues using them either

 

Racetech Website   has an online calculator, to give you the spring rate required based upon bike, riding discipline (MX, enduro, supercross) and your weight

http://racetech.com/ProductSearch/1/Yamaha/WR450F/2007- enter your details by clicking on where it says Calculate Spring Rates and Display Available Springs

They usually come up a bit high on the forks (so if it says use 0.48's I'd go for 0.44's), so go a couple of rates lower than what it suggests, but the suggested rear spring rates are usually pretty close

 

I did the same as Guy, got an idea of spring rates from the racetech site calculator and then double checked with Kayaba Europe as to what rates they thought I should be using.

 

Kayaba (Kyb Technical Touch) came back with the same rear spring rate but a fork spring of about one rate less (0.49/0.50 rather than 0.52).

 

It can be a little expensive but it is well worth getting the bike re-sprung for your weight.