how easy is it to do?
is the allen key at the bottom of the forks the oil drain? so you can do them in place?
do you just then take the caps off the forks and refill? if so how much?or do you measure the air gap?
what are the two black knobs on top of each of the legs for(air i assume) but what are you supposed to do with them,what effect has it ?
thanks in advance

Have you got the Leisure Trail handbook? - Gives a guide to the structure of the forks.

Servicing them is relatively easy provided you have some experience/ability. Your questions don't suggest that you have the former. Have you got any motorcycle maintenance guides? If so the basics are in there. If not come back.

You will almost certainly need a full set of bushes (4), oil seals (2) and dust seals (2) and the required amount of fork oil (2L of I suggest 10-15wt).

The allen bolts at the bottom hold the forks together but the caps at the top are for releasing air pressure that will build up with constant use.

You will need a bottle brush or some kind of pressure washer to clean out the sludge that will have collected at the bottom of the fork tubes.

Basic oil wt and height info is at http://www.crm250.com/specs.asp" onclick="window.open(this.href);return false;

take your point,but i did manage to buy it siezed and rebuilt it including crank,so yes i can handle a spanner(given enough time)
i have never owned ridden a two stroke or enduro and never done forks on any bike,so a bit clue less

i only want to check and change the oil for now, (i know thats lazy,but i intended to do it properly over the winter) was hoping you could do it with the legs in place,i suppose thats not the case.

i do have the leisure trail book but as you know its just exploded diagrams-no method
and does not say what those black knobs on the top of the forks are,i thought they were for bleeding air ,but i did /dont know how ofton or what you should do,maybe for now if i opened them and expelled some air that would help ?

is the 132 measurement the gap from the top of the oil to the top of the tube --ie the air gap?

Are the forks leaking ? relieving the internal pressures using the schrader valve is best done with the front end unloaded and cold .
If the seals are duff you will need to take them out of the bike .
the easiest method of getting the old seals out is to hydraulic them using the old oil .
Remove dust cap AND circlip , undo top threaded nut , [ best loosened whilst still in the bike ] caution under spring tension .
remove springs ,noting which way up which leg they came from , and the washers and spacer arrangement.
Pour all the oil into one fork .
remove all the air from the fork by using the valve .
Now put the fork on a trolley jack . [protect the top of the fork with a socket or similar] , with the fork top located under something fairly unmovable , door lintel , ect , i have a large sash clamp for the job , carefully start to pump the jack , it shouldn't require a lot of force .
you should see the seal start to ease out , this will releive the pressure so it shouln't squirt out .
Be ready with a clean container to collect the oil , that you will need to repeat the operation on the other fork .
Watch out for the bushes falling out .
Keep the old seals as a drift to relocate the new ones .
Regards Mike
I love right way up forks , their so easy to work on

Yes .

mmmmmmmmmmm whilst i can handle a spanner i am a bit thick,sorry(did not really understand any of that)

thier is a bolt with a copper washer on the lower part of each stantion /fork leg is this a fork oil drain plug as some older bikes have them,is thier one one the crm mk1?

if its not i understand i will have to take the legs out to do it true?

the black screw tops on the top of the forks are just caps?they dont actually do anything?

to expell any excess air you have to remove them and loosen the nut underneath and then just tighten both back up?

cheers

[quote="fallenmikethebike"]Yes .[/quote]
crystal clear understood that thankyou

sorry no as far as i know not leaking just seems soft on the front and was badly maintained so i guess a long time since fork oil changed

Screw at the bottom is a drain down hole .
Yes to replace seals and bushes will require the forks to be taken off the bike .
The plastic cap is the same as on your tyre valve , and the valve is the same as well , elevate the front end and push the valve , air pressure should escape .
you only need to undo the large nut for a service , or to add oil .
If you only need to change the oil, use the drain down screw .
Replace the screw when drained down , undo the top nut and replace with a 12.5 weight oil .
Remember that top nut is under some spring pressure .
Use a good quality spanner to undo the top nut , they look horrible when mullerd .
Regards Mike

thankyou understand now(nearly)
two questions if i may

1) is thier anything/you can pour down the tube to clean/get some of the crude out
2)how much air should you let escape /or just trial an error--little bit at time to stiffen it up a bit
(told you i was a bit thick)
ta

Just to avoid confusion the small bolt at the bottom of the fork, on the back side, is the bleed hole not the allen key. You can drain and refill without taking the forks out.

There is no way to clear out all the crud without dismantling the forks. You can pour in the new oil from the top but as you will not have been able to get rid of a lot of the crud and this will then mix in with the new oil. If you are not going to do a full service until the winter then you might as well leave alone until then as you will make only a small difference to the action.

All CRM forks are soft - particularly the Mk1. This can be improved by fitting heavier springs (takes harder knocks to use the same travel), using heavier oil (increases the damping and thus slowing the compression) and/or raising the oil level from original (increases the fork springing and damping particularly at the middle and towards the end).

If you want to go further then you can fit the forks off a CR125 1989 but this requires milling the yokes out from 41-43mm. But this gives you cartridge forks (much better control over damping), compression damping adjustment and just the slightly heavier springs needed. This is what I have done. You can get the forks from eBay really cheaply.

If you really want to push the boat out then get some yokes from a Mk2/3/AR and buy some CR125 upside down forks from more recent models - for that Veyron touch. Don't buy CR250 forks as they will be too heavily sprung and damped; unless you want to do supercross - and then you've really got the wrong bike.

You need to balance your suspension so what you do at one end you should think about doing at the other. A rough way to do this is to bounce up and down on the bike with someone holding the bike. If the the bike moves the same back & front then you are in the ball park. There are lots of guides on the web about setting up unweighted sag, rider sag etc..........but take these with a pinch of salt as a CRM does not have quite the travel of an MX bike and generally needs to be softer.

thanks got all that nearly thier

what about the air valve on the top---how do u use it --little and ofton and test(not sure how you could equal both sides that way though--or just let air out fully---never ever seen or heard of air release on forks?

Air valve - put bike on a stand so wheel is off the ground (or other way of getting full extension on forks). Push in 'nipple' on valve until no air comes out. You should only need to do this, say monthly, unless you have been beating hell out of the suspension.

Some old seventies/early eighties MXers used to put positive pressure through the bleed valves to increase damping/resistance at the end of the travel. Worked quite well but blew the seals v. quickly.

[quote="knackeredMk1"]Air valve - put bike on a stand so wheel is off the ground (or other way of getting full extension on forks). Push in 'nipple' on valve until no air comes out. You should only need to do this, say monthly, unless you have been beating hell out of the suspension.

Some old seventies/early eighties MXers used to put positive pressure through the bleed valves to increase damping/resistance at the end of the travel. Worked quite well but blew the seals v. quickly.[/quote]

got thier ,
thanks--much appreciated