WR Suspension Service; Turning Brake Rotors

 

Hi John: I own a '03 WR 250 and have thrown some screws in it to blast around Scugog through the winter.Since the ice is leaving now it's time for some WR TLC. Just starting the annual "to the frame once over" and was considering getting some suspension work done.I guess my riding would be classed as slightly above average.Right now the bike is stock engine/suspension wise and seems to work pretty good.What sort of work/mods would you suggest?What's it gonna cost?

 

Congratulations on doing some chassis and suspension maintenance to your bike, you are definitely in the minority.Of all the forks and shocks that pass through my shop, they can be divided up as follows: Road Race Ė guys and girls are recognizing the importance of excellent suspension compliance and proper spring selection to optimize their performance on the track.I usually get forks after they have tried them at the track a few times and have either fallen down or canít put their finger on why they have limited confidence in their tires.The more experienced riders give me their forks and shock before they even turn a wheel in the spring, having already learned their lesson.OEM shocks are typically replaced with Ohlins units and the stocker is left with the body work in storage.Street Riders Ė They too have come to realize that riding at a brisk pace or the occasional track day requires some suspension adjustment.I am also getting more and more shorter guys and girls bringing their bikes or suspension for custom lowering so they can enjoy the bike they want, and not have to settle for a tiny motorcycle.Then there are a select few off road riders Ė They keep riding their bike year after year after year with little or no maintenance.When the shock or forks start to leak they make a mental note to look at it soon.Then 5 or 10 rides later (with absolutely no oil left in the suspension) when they get bucked over the handlebars for the umpteenth time they get it serviced.By then, it isnít a simple overhaul, but the shock may even be trash from stroking at crazy high shaft speeds with no oil, which scores the main body and destroys the seal head.Then there are the true off road competitors (MX, enduro, hare scramble), who recognize that suspension and chassis set up is very important, and you can only ride around a problem for so long before it becomes limiting.

 

Sorry about the rant, back to your question:The absolute minimum that should be done every year (or two at the most) is a shock and fork service.As for the shock, it is cleaned, disassembled and inspected for wear or damage.The piston gets disassembled and removed from the shaft with all shims cleaned and inspected, then the seal head, wiper, cap, and bump rubber are removed, inspected and cleaned.Nine times out of ten all that is required is a careful grease and reassembly with fresh oil and nitrogen.However if the shock failed under the abuse mentioned above, the seal head, body and shaft may need to be repaired or replaced.Price will range from $75.00 up to $700-$1000 to replace the whole shock if it is bad enough.Custom valving or a spring change can be done at the same time if required.

 

The forks get a very similar Ďspa treatmentí, they come right apart, outer tube off the inner tube, damping rod out, pistons apart, shims inspected and cleaned.The seals and bushings will be removed, cleaned and inspected for wear or excessive play.At this time, I will consult with the customer about the intended application of the fork and what they are looking for to give them the most confidence in their riding style.I rarely put a set of off road forks back together without doing some basic modifications.Have you ever pushed on your front forks and played with the compression and rebound clickers?Do you feel any change?I donít! (Or, it is so subtle that I can hardly feel the difference).Quite often the OEMs will design in a whole pile of leakage into the high speed valving of the fork.The total leakage flow area is quite often much larger than what the low speed circuit is trying to control, subsequently moving the adjuster in or out makes a imperceptible change to the low speed function of the fork.I think they do this to protect the uninformed rider from closing the adjusters, then promptly getting pitched off the first jump right into a courtroom.At the very least, I modify this part of the fork to give your clickers some function, and may make other larger changes if our conversation indicated it was required.Cost is between $200 and $500 depending on the range of modifications and whether springs are required.

 

Hi John, Quick question for you - can bike brake rotors be turned? Is it something that is done?Is it safe?The ones on my ZRX pulse pretty badly at low speed and I ain't keen to spending $700 to get new ones.  Thanks, Rog.

 

Pardon Rogers grammar, I hope he isnít in the literary field.The quick answer to your question Roger is no, motorcycle brake rotors arenít really thick enough to be turned down (put in a lathe or on a mill to remove high spots) effectively.What usually causes the pulsing Roger is feeling occurs when the brake rotor has run out when measured left to right.This pushes the pads back as you are squeezing, showing up as a pulse felt at the brake lever.Excessive brake drag can cause so much heat that a rotor can become permanently deformed.I have had a machinist using a press try and straighten the spot locally on an impact damaged rotor, but it is real tough to do without stressing the carrier or moving the bend elsewhere.If you do succeed, identify why it happened either by impact or if it was tremendous heat and take steps to ensure it doesnít happen again.However, having said this, it is always better to replace the rotor with a new one if runout above itís spec is identified.