Front Fork improvements

[deano123]

hi there did a tbec enduro yesterday on mk2/2 and found the front suspension to very soft bottoming out in places also

could any one recomend oil weight , quantity and level to use to improve settings (13stone kitted up) also if any shims could be changed basically anything to improve the front forks

also any other members found any other forks to be any better that fit straight in? eg cr125 or cr250

bike is used for fast enduros

any help thanks again Dean

[knackeredMk1]

Why do I bother ..................................

[back off road]

no idea knack it looks like folks cant be bothered to do a search

[SkidMark]

and he's been around for a bit...

[deano123]

yes ive used the search and looked in the faq, but all that says is 5-7.5 which is standard settings its does also state oil levals and quanity but again these are all standard settings. Ive also been through search but again its says cr250 forks no year or any recomended setup for them. SO imformation seems to be very vaugue. SO im afer peoples recomendations on setup of standard forks and their experiance im after help thats why i did a post. I have been around for a while and do know how it all works !!!!!

[knackeredMk1]

So you have read this - viewtopic.php?f=20&t=5266&p=32165#p32165

[deano123]

yes that the first one i read , but all it says it 5 or 10wt can be increased up to 20 doesnt really help i know what oils are available

[Eddie Evans]

If you don't know what oil is in the forks I would suggest filling them with 10 wt oil with an air gap of 100mm
The standard air gap on the Mk2 should be 107mm but is 90mm on the Mk3. The air gap is the measurement from the top of the oil to the top of the fork tube with the spring out and the fork fully compressed.

My understanding is that a smaller air gap should make the fork become stiffer just before they bottom out.
It is also my understanding that during an off road ride most of the fork travel should be used. Lightly bottoming out a couple of times is OK but using 90% of travel being the ideal. Using less means the forks are too hard. Regularly bottoming out obviously means they are too soft. There is no rebound adjustment and only 4 position adjustment on the compression which is at the bottom of the forks. Most dirt bikes have 20 clicks for rebound and comp damping although most effective adjustment takes place. So although it is possible to revalve the original forks there is little adjustment available there after.

My suggestion would be to change the oil and see how that helps then start looking for different forks.

I have fitted XR650R forks to mine, The main reason being that I already had a spare pair and yokes,
I had also had some experience modifying these these forks on my own XR.

These forks were very stiff and were poor at absorbing bumps when riding over rocks and roots as standard but would take big hits with no trouble.After searching the web for info. I have drilled the compression valve out for the XR and this made them as near perfect for me as possible. They are conventional forks but are meant to be good as Honda designed the whole bike to win the Baja 1000 race which it did several years on the run. Yes the forks were re-valved on the race winners but there is also a lot of info available on set ups.

I did the same to the forks I fitted to the CRM, drilling out the holes in the comp valve and filling with 2.5 weight oil but will use 5 wt next time I change. I fitted the CRM head stem to the XR yokes and bolted them on. Other than this I bodged a couple of steering stops up and a bracket to fit the clocks. The wheel fitted straight in along with the speedo drive and brake calliper but I did need to use the XR wheel spindle.
I also took the opportunity to lose the ignition switch. (just need to find a way of not needing the key for the fuel cap now),

Now as to whether it is better than the originals I would say yes. They are nice and plush meaning they absorb the small hits without deflecting the bike and they can also take the oh poo moments as well. Yes the XR is a heavier bike but only 15KGs or so on paper but feels a lot more. I am way heavier that the theoretical person Honda sprung the CRM for so it goes some way to cancel that out.
The down side is that the forks have a couple of inches hanging down below the wheel spindle, this can occasionally catch rocks or the edges of deep ruts.
The forks have not turned me into David Knight over night but I am just as much at ease riding my CRM as I am riding my 08 Husaberg so they are not too bad either.

There is no doubt there are better forks out there now and you can fit anything to the CRM by using the yokes, wheels and brakes from the donor bike. You will need to fit the CRM head spindle to the donor yokes.
Keep an eye on e bay if you are patient real bargains turn up ( I have a garage full of them )

I am no expert but I hope this helps. If nothing else it was fun making something fit.

[knackeredMk1]

Eddie you can use the petrol cap off an MTX is you want somthing without a key.

[Eddie Evans]

Eddie you can use the petrol cap off an MTX is you want somthing without a key.

I just know I will end up trying to fill up without a key one of these days.

[back off road]

http://www.ebay.co.uk/itm/HONDA-CRM250- ... 500wt_1202

any good Eddie

[ukgraydog]

Hi Eddie, I know it has nothing to do with the original post but I snapped my key in the petrol cap, managed to get the cap unlocked and then just ground off the locking mechanism with an angle grinder, cap still fits, hey presto....

[Jonorow]

The best improvement i made was fiting the cr250 91 forks, they were cheep and in good condition, but then needed an axle, a caliper mount, new seals. Then machineing the axle to fit the speedo drive. So in a way yes easy to do. I dont know if a new set of spring would have done the same thing, but you do get the damping adjusters on the cr forks, which is good. I think the best thing is use the standard forks with an oil change, then if no difference, try new (correct for your weight) springs, and heavier/lighter oil. All in all it is personal choice.
This has been on the website before somewhere at least twice, but I would rather repeat myself to someone that is willing to carryon the project, than hear about someone who has done the same mistakes, but done it worse.

[lgingell]

stiffer springs are definetly worth the money (imo).

the standard fork springs on my ar were 3.8 n, i now use 4.6n springs as i weigh 15 stone (without riding gear)

i am using 15wt oil, but the fork feel harsh on small bumps now - i will try and improve the shim stacks when i have time.

i plan on buying another set of crm forks to modyfy, as i use the bike daily, so dont want to have the bike off the road while im playing wit the shims.

good luck!

[Eddie Evans]

stiffer springs are definetly worth the money (imo).

the standard fork springs on my ar were 3.8 n, i now use 4.6n springs as i weigh 15 stone (without riding gear)

i am using 15wt oil, but the fork feel harsh on small bumps now - i will try and improve the shim stacks when i have time.

i plan on buying another set of crm forks to modyfy, as i use the bike daily, so dont want to have the bike off the road while im playing wit the shims.

good luck!

What are you using the bike for?

15wt oil is very thick for off road bikes and no doubt contributes to the harsh feel of the forks on small bumps.