some people dont have syringes :) I use the pump from hand gel, i use a bit of card make hole in it and push the tube through that will keep to keep the pump square and flush to the tube, then i measure 100mm underside of card and cut the tube, over fill my shocks and let the dog see the rabbit and pump pump squirt the fork oil into bottle :)
Stupid Fork Oil Questions: (From Canada if that explains anything). Are all fork oils sythetic? Many of the bottles here don't make it obvious. (Do I care?)
great vid , I've got a gen 2 hayabusa and I need to do the fork seals, the service manual says 95mm from top tube to oil level but everywhere else and on RU-vid vids people seem to be doing 120mm , and if I type it in on Google it says 110mm so what is the best to go with do you think as I don't want to get it wrong , the manual does say compress the tube and check oil level without the spring , i ride two's up with the wife just normal road riding, any advice would be great . thanks 👍🏼
Good video. Theirs a problem with syringes, I've bought loads, reusable ones, to do this, over the years. You use them once or twice, and the rubber tit on the end of the plunger swells up and then you need the strength of Goliath to to draw the syringe. I need to find ones that don't have this problem. Another way to measure air gap is to use a cable tie because the serrations stop the oil creeping up and throwing your measurement off. All you do is straiten it and cut it a bit longer than you need . Then use a pair of cutters to nip the side of the tie, to mark the measurement that you want. The only problem with this method is if you over fill, you need to remove some oil out of your fork, but It's better than trying to use a ruler etc.
Some manuals call for a volume of fork oil, which is easy to measure, but you are not going to get every drop of the old oil out and with every change you will have a higher volume of oil. That is, unless it’s a full flush with kerosene which makes for an accurate change.
I use a plastic horse insemination tube. Fits to the syringe perfectly, just cut it a bit as it is too long! Just go scrounge one off of your local horse-vet! My colleagues in the UK are going to kill me for this.
Do you think it is Ok to use this method with the forks still in the bike? Because even if the bike is completely upright the forks are on an angle from the yokes to the wheel.
If you took the middle of the tube then yes, but you'd have to be in the middle. You could calculate the angle of the oil, which would be the angle of the forks but from the horizontal and not the vertical
When I was doing forks regularly (working in a Dealership) I used a small diameter tube just like the the one you have but I used a hand vacuum pump with a reservoir bottle in between tubing and the pump springs in out makes no difference to the way it works. Has long as you dount use a string in distance without the spring in or vice versa. Good video! The hand vacuum pump is a handy tool that can help with diagnosing several components.
Brilliant, simple accurate method this subject always scared me this video has educated me I will have a go myself now as youv shown it's not rocket science as I was led to believe by others..keep up the great channel...cheers matt
matt you need to block the bottom of stainless tube of with solder and drill a small hole in the side of the tubing then the level of oil will be more accurate i use a air brake bleeder to do this it can only suck oil in from the side pal to stop the vacuum affect and sucking more oil out than intended
More accurate than my dipstick method. Will you be touching on use of Hydrophilic oil over Fork oil? Have used it in the past as it's constant viscosity and i can more or less guarantee that viscosity from manufacturer to manufacturer. have used ISO 68 in place of 20W and ISO 32 for 10W. Also cheaper than "fork" oil.
At some point I'd l9ve you to take a look at the Honda anti dive system from the 80's. Rebuilding a set of forks that use different components in each and different oil levels in both was confusing as fuck. That tool/method is genius btw. Stealing that. Have you seen the Ohlins tool for rebuilding forks that fills with a premeasured amount of oil under pressure to get it exactly right?
On an old moped fork that I had no clue about the amount, and previous guy filled it all the way up which made it hydro lock I opened the top and compressed it all the way and then sucked out like 50-100mm from the top and that worked fine.
Worth mentioning that you need to bleed the air out of the hydraulic system before measuring oil level, Either by exercising the chrome tube up and down in a damper rod fork 10/20 times or exercising the damping rod up and down in a cartridge fork 10/20 times Also the level is measured when the fork is fully compressed
Did you see Daves response in the comments ? TBH I think what he is getting at is if the tyre is too hot to keep your hand on then its fine but if it just feels kinda warm then its over-inflated; probably based on the threshold for pain due to heat. Not really scientific obviously, but I suppose he was saying it is somewhere to start for guys without the gear (although the infrared thermometers are not really that expensive...a cheapo one will be plenty good enough and definitely better than the palm of your hand)
Looking at those plastic wheels in the top of the shot, I'm guessing he's going to copy DB customs tube roller. Pro Tip: remember to put the plug in the bottom of the fork BEFORE you try topping it up. If you don't you're left thinking "Fucking hell, how much is this taking (Fork oil is not cheap) until you notice the growing puddle of oil. Knob head.
The Workshop Yeah, I had the fork bodies on my old GT250 anodised Candy red to match the rest of it. Luckily my mate was doing an apprenticeship at the local anodisers. Looked brilliant at the time but this was early 80s. As they were stripped and cleaned for that I used my mum's measuring jug to fill them up. Worked well but had to wash it before she came home !
It depends on the exact forks used, but some USDs are filled without the spring in place and some are. But the method is the same. The Z900 for example gives you 434 ml of oil, and also gives you the oil level as follows Oil Level (fully compressed without spring) 99 mm +-2 (from the top of the outer tube) From the Service manual
Without a manual, how would one figure out how much oil forks need? For example I got a 125cc sm with both forks leaking since I got it, can't find a manual for it and the specified mechanic for my bike says to put in as much as I need until I get the stiffness I want.
You don't, the manufacturer does. You don't have access to all the information you'd need like: Oil Flow rate Hydrostatic pressure of the oil Viscosity index Harmonic spring rate include oil drag...
Where it goes tits up.If one leg has .1 more or less,would that be a problem?Just interested.Even a retard like me know how to level it out using that trick,but if one just chuck in quantity using eye-sight,how would one feel if the difference is significant in the two fork arms?
Does oil height really matter? For example my bikes takes 150cc(ml) in each leg , I buy a bottle of 500ML ..fill one leg until bottle shows 350ML and pump the leg twenty times to get any air out .Then do the same to the other leg until bottle shows 200 ML. At the end I fill an extra 10CC on each leg because I like it more firm. Anything wrong with this process ?? thanks
Those are excellent points, but remember, once the air is worked out, the actual measurement isn’t as critical as you might think. On most adult sized dirt bikes, 90-100mm air gap will get you in a safe range to avoid bottoming out on the one hand, and hydrolocking on the other. Your CR250 will be fine. But you might need to add more or remove some to suit your riding style.
Just a question Matt. Would there be a calculation on the angle if topping up or removing oil in situation? Or asking as both forks are equally filled and balanced via this method would it matter if calculation from manual is within say 10% of cc advised.
How will it "siphon if you do it too quickly" ? ! As soon as the oil is below the end of the tube, it can't draw oil anymore. Come on Lad, thing 'ead on ;-)
@@dirtygarageguy So, you are saying that a siphon will still work even when the end of the system is clear of the fluid and open to the atmosphere. Please make that your very next Demo.
I commend you on your tutorial Matt, excellent presentation and an effective use equipment. But I will just stick to my old method of guesstimating with a cheap jug from the local supermarket 🤫 probably over filling them but not by a great deal. It’s not like I’m racing. Thanks for my early evening entertainment. 👍