Hi my bikes a MK3 with 10000 kms on the clock, if I paid a decent suspension firm to rebuild the rear shock and front forks, am I going to notice the difference off road? the rear shock and front forks still appear to damp ok! so would it be worth it? are there any aftermarket shocks worth considering? Advice will be gladly taken, witnter comin looking for upgrades! Stuff to keep me busy in the garage, when I am not out on it!

Probably cost around 250 quid for the pros to do it, an it would most likely be exactly the same. I wouldnt bother with the rear shock till it needs a new seal. Maybe worth servicin the forks, fresh oil, seals an bushes, an its not too difficult to do yourself. I did mine an i was a fork virgin, was tricky at first but really wasnt difficult an i'll never pay for someone else to do it again

what i did with mine is , jack up the front end undo the fork caps , lower it down a bit untill the caps and rods rise out of the forks about 2 inches so there is room to pour in a 100 mils extra of fork oil in each leg ( no need to dismantle any thing ) then rise up the front end again screw on the caps with the front of the ground ( it keeps the air out and the forks will be set up the same ) then put it down, this will firm up the forks and when braking will not dive as much,

back shock use a air line and put in 150 psi, ( i know people say that you should use the hydrogen gas ) but theres 79 per cent of hydrogen in the air we use, and given the rear shokers have lasted 10 - 20 years with very little gas in them or no gas in them , i do not think it will make much diffrence to the shocks end of life,

if the shock will hold air, then it will firm up the rear end ,some say 180-200 psi but i only put in 150 psi as the shock will be a bit old, you could start off with 100 psi ,
but you must be fast at disconecting it with out letting the air out, ( as its a small unit that will take high pressures )

make sure your side stand has a bit off wood under it to help the bike to stay up right as you put the air in the rear as it will rise the back up a bit that could make it lean the stand more over especially if the stand is worn/ bent,

Xander - Improving the suspension on a CRM will improve the handling hugely, particularly off road.

There is information about this on the forum. Try the suspension posts in 'FAQ - Check here first' to start.

Both the rear and especially the front suspension are undersprung and underdamped.

The easiest way to improve the forks is to get a set of CR125 forks that fit. You will have slightly stronger springs and damping. You could get a set of CR250 forks that will be stronger in both accounts (I used to say don't get CR250 forks as too hard but I have some experience now)

You can improve the shock by getting a stronger spring and revalving but I would recommend that only a specialist does this.

With regards to DIY and cheap. You can improve the damping in the forks by increasing the weight of the oil. Fork oil comes in different thicknesses up to 20wt. You can also increase the amount of oil in the forks to resist bottoming and change the spring rate to reduce diving.

A suspension specialist will be able to test your spring rate and recommend a change.

With regards to what Eddie says -

The first papagraph is increasing the oil level. Raising the forks so the wheel is off the ground is to let air in not keep it out.

The rest we have disagreed on before. The gas concerned in Nitrogen and all suspension companies use pure Nitrogen to pressurise shocks in this way. They use Nitrogen as there is Oxygen in the air which reacts with the oil and the suspension components to degrade the oil and 'rust' the components. There is also a small amount of water in the air which speeds up this process. Using a pressurised gas is to stop bubbles forming in the oil which reduce the damping considerably.

Hydrogen is an explosive gas and should not be used in any way .

Raising the pressure in the canister attached to the rear shock is dangerous. And by doing so you are are only increasing the preload, the spring rate slightly and the compression rate slightly. You are reducing the rebound damping and suspension sag, so although the rear will feel firmer you will find the suspension 'kicks back' over bumps more.

It is very likely that after nearly 20 years of use the rear shock will be in dire need of a service. Take it to a suspension specialist and get it serviced (~£90 without revalving and new spring).

you know i ment to say Nitrogen !!!!

why is it dangerus to presurise the rear shock ?

thats what they do with the gas up to 200psi !!!

i will say it again, in the 70s and 80s Nitrogen was never hurd of on bike parts so they used air, the same as they still do in front forks of today on most bikes with valves on the fork tops,

is there much diffrence in the internels of a rear shock and a front fork ( not realy )
front forks have always used air, the only things that goes mostley wrong are, seals / week springs and the odd internal brocken rod,

if air was that bad why dont they put Nitrogen in the front forks stead of air, and fill your tyers with helium,

eddie has got a point there ive known a few of my mates pump up rear shock with air and it worked just fine, however i do know why you cant put helium in your tyres has anyone ever priced a pilots licence?!! better to ride on the ground! ha ha

Eddie I know you meant Nitrogen as we have discussed this before .

All I can say with the Nitrogen/air thing is that is not recommended.

i thought the helium would make the bike lighter and would just hover over the off road bumps , but make sure you bolt it to the ground when your parked up or it will drift away,
( only jokeing )

i know the right way is to fix your rear shock is to get it rebuilt with the gas, but if the shock is old / and needs replacing and all the gas is gone out of it and you havent got the money at this time to buy / repear, then pump it up ,thats what i would do, its going to be sorted sooner or later any way, mines been pumped up now for months with out any probs, BUT I USE MY BIKE ON THE ROAD ALL THE TIME, so the shocker dose not have to work that hard,
if you are using it off road it will as my freind said bounce back quicker, if theres no gas in it at all, just put 30 -50 psi in to take out the vacum ( or lack of presure in there ) this will help the shocker to rebound better than none, then you can still use it while looking for a nother or getting some money together,
if you use your bike more on the road then my tips are worth looking in to,
BUT FOR OFF ROADING GET THE RIGHT/ BEST STUFF YOU CAN , BECAUSE EVERY THING HAS TO WORK AT ITS BEST IN HARD CONDITIONS,
ON THE ROAD ITS A LOT EASYER ON THE SHOCKERS AND FORKS, SO IF THEY WERE ROCK HARD YOU COULD STILL RIDE IT OK,

Every type of riding benefits from a different suspension set up.
A good trail riding and enduro suspension setting will be softer than Motocross and road riding.

Nitrogen does not heat up as much as normal air when compressed and is therefore more stable which is why it is used in shocks.

The difference that a good set up on the forks can make is incredible. I am sure that a good rear shock can also make a big difference but I have not experienced it in the same way.

I would ride the bike a bit before spending any money and see what needs improving.

If you are struggling to control the front end over rough ground and stones then a lighter grade oil is best. If you are bottoming out landing from jumps then thicker oil and a higher level will help.

Air in the front forks for trail riding is bad news as it stiffens the forks up at the start of the stroke. It prevents the forks from absorbing the rocks and rough ground as smoothly. I have drilled my fork caps and fitted screws to be able to release the air. To do this the fork must be at the top of its stroke achieved when the bike is on a stand and the front wheel is off the ground.

There is loads of stuff written on the net about sorting out forks but the main thing is to know what you want from them first.

Air in the front forks for trail riding is bad news as it stiffens the forks up at the start of the stroke. It prevents the forks from absorbing the rocks and rough ground as smoothly. I have drilled my fork caps and fitted screws to be able to release the air. To do this the fork must be at the top of its stroke achieved when the bike is on a stand and the front wheel is off the ground.

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ON THE CRM250 MK2 / MK3 THE FORKS WILL LOSE THE AIR OVER TIME , WHEN THE BIKE IS OFF THE GROUND AND YOU FIT THE CAPS , THE AIR THATS IN THERE IS THE RIGHT AMOUNT SEALED IN. AND THATS WHAT WE WANT TO STAY IN THERE, THATS WHY FROM TIME TO TIME YOU SHOULD GET THE FRONT END UP IN THE AIR AND UNDO THE CAPS AND YOU WILL HEAR A HISSSSSSSSS AS IT SUCKES LOST AIR BACK IN , WHATS AIR IS IN SHOULD BE IN ,

I WOULD NOT DRILL HOLES IN THE TOPS, SOME BIKE HAVE VALVES ON THEM ETHER TO LET THE AIR IN AS WE DO OR TO ADD MORE AIR,

My husaberg moto has valves on, when you push em down it releases the air. Is there a ritual for doin pressin em - does it have to be on a stand etc? I just push em every now an again while im sat on it

The valves, if fitted, are to remove excess air.
This should be done with the front wheel elevated, and when the forks are COLD.
Air gets into the fork tubes when you have allowed the bushes to get worn, and the extra side movement allows air to enter the forks when they rebounding.
Adding extra oil softens the movement, this is because oil absorbs shocks, where as air does not.
Send a back shock to any reputable servicing outfit and they should ask your weight, riding style, and what sort of riding you need the shock for, they can then re-valve, alter the shim stack, and alter the oil viscosity to suit.
At the end of the day, the CRM is a TRAIL bike, as is reflected in the less than stellar standard suspension fitted, no front fork rebound adjustment, no back shock rebound adjustment, weak spring, ect.
IMO, the back shock gas should not be tampered with by the average home mechanic, you require a special "no leak" sealing tool, to add, or remove the gas, with any degree of accuracy, you could well end up with a useless pogo stick,and i speak from experience .
Mike

ive had lots of bikes with valves on the fork tops, most of the hand books recomend 6- 8 psi when the wheel is off the ground,

so this is adding presure to the air that has nornal air presure in the fork,

i have found that worn forks will lose presure rather than gain it under wear,
its easyer for the air to be pushed out by the weight of the bike pushing down on the forks and the force of a compresed fork, than it is for the air to be sucked back in on the slow rebound of the fork,

if air went in more than it came out, the forks would be solid after a long time if this was the case, but the constant down force of the weight of the bike and gravaty and the presure that would not biuld up on a leaking system it would slowly let the spring compress and over time the spring would lose its power ( hence weak springs ) , leads me to belive that it would be easyer to lose the air than gain it.this is what ive found on most road bikes and trail bikes,

This is where off road bikes differ from on road and also new (post ~1980) to old.

The caps on off road bikes are to let out pressurised air. As has been stated before that air pressure builds up over time and this needs to be released. I remember back in the 70s and early 80s putting air into forks to improve the stiffness and make them harder to bottom out. We even had Fox air shocks and forks .

However this is not done now and the caps (or screws on more sophisticated forks FMtB ) are very definitely to let air pressure out.

This may, or may not be relevant, but whenever I'm not riding my bike it's on a stand, wheels elevated.
I've noted that, with forks with worn bushings, there is always air escaping from the purge screws when slackened a couple of days after a ride.
Where as newly rebuilt forks have accumulated no air at all.
This is just what I have observed.
IMO adding air to forks does not improve their feel, or feed back, in fact the reverse is usually the effect.
Heavier oil can be used, but, with no re-bound adjustment, it will also slow down the re-bound, so the shim stack would need altering, again, a bit of a no go area for your average home mechanic.
Mike