[elime]

I removed the caps, spacers, and springs from my forks. I compressed them both and measured the distance to the oil level which was 157mm. Based on my forum readings the oil was doing zero good, right? No damping whatsoever!



Based on Lizrdbrth assessment of 135mm is right on the borderline of good and no good, would setting the oil level at 130mm, or even 125mm, be a reasonable second choice option rather than going through the add a little, try it out plan? I read that an oil level of 100 mm to 110 mm is in the danger of blowing out the seals, so there should be very little danger at the 125 mm level.



I still plan on setting the sag at 1.25" to 1.5" and using 10wt. fork oil or the Dino Dexron.



Opinions. Errors in my logic. Let me have it. I can take it.

 

[lizrdbrth]

Actually, too LITTLE oil is what you're trying to avoid. Obviously too much is equally bad for different reasons.



I've found you get little or no rebound damping out of our forks at the factory recomended oil level, but that is the minimum I'd put into the forks if you're not into the incremental approach.



You should be good at 130 but I'd ride it before going to 125.



I now have longer fork tubes which put the rebound orifices more under water at 135 than they would be with the stock tubes, if that makes sense.

 

[elime]

Thanks. I will take your advice.



Yep! Longer fork tubes puts the innards further from the top and deeper into oil if the oil is 135mm from the top. Makes perfect sense. What fork tubes are you using?



One fork cleaned and reassembled and one to go and what a huge difference it has made.

 

[elime]

I was just thinking, do you have to replace the seals every time you take the forks apart to clean it? The reason I ask is the seals I just replaced looked really good.and in hind sight I think now I would have taken a chance on them. They actually seem to grip the inner tube tighter than the new All Balls seals do.



Of course I didn't know that until I replaced them.....but now I am a little more experienced..... and what do you think about that idea? Or is it "they're apart -- replace them and save yourself headaches down the road".

 

[Rainman]

You shouldn't have to replace the seal every time you take the fork apart. They are more of a wiper than a seal. Unless they are leaking, keep them in there and keep them clean.

 

[lizrdbrth]

Yep! Longer fork tubes puts the innards further from the top and deeper into oil if the oil is 135mm from the top. Makes perfect sense. What fork tubes are you using?

They're early YZ80 tubes. But before anyone goes to the trouble and expense of converting, let me be clear on what they will and won't do for you.



I switch back and forth between an ATV tire and the stock knobby, and have an extended swingarm. The extra length allows me to compensate for loss of trail due to the added rear ride height from the ATV tire and swingarm extension. Basically I can lengthen my front end to change the trail. With stock tubes you can only shorten it.



It also cures the rebound starvation issue and gives me two more inches to play with oil levels.



Other than that it's no better than a stock front end. It's TW fork legs and internals, on longer tubes, shimmed to proper sag and with the oil levels set by increments to my personal "feel". Total travel is no greater than any other TW. A stock front end with proper sag and oil level can be made to behave nearly as well.



If you want more travel you'll need a different front end and accept the nosebleed ride height that goes with it. I mostly use mine to improve handling by slipping it up and down in the trees.



Here it is at roughly stock height:

This is it in "chopper mode, for a long road trip. The ATV tire setting is somewhere in between. 2 inches adds a LOT trail. You'll never need all of it.

 

[elime]

I have checked the original oil level in 4 fork tubes prior to pouring the oil out and they all are right at 157 mm. I am guessing this was the factory oil which is well shy of the manual's recommendation of 135mm.



I used Pennzoil Dexron-VI in the first two tubes. The next two I will use actual fork oil 10wt. I compared the ATF and fork oil on a piece of plastic and they seem about the same viscosity which is very very thin.



Setting the level at 130 mm seems about right. I have yet to try it off road.

 

[flingwing1969]

Actually, too LITTLE oil is what you're trying to avoid. Obviously too much is equally bad for different reasons.



I've found you get little or no rebound damping out of our forks at the factory recomended oil level, but that is the minimum I'd put into the forks if you're not into the incremental approach.



You should be good at 130 but I'd ride it before going to 125.



I now have longer fork tubes which put the rebound orifices more under water at 135 than they would be with the stock tubes, if that makes sense.

Has anyone determined how much oil in oz etc would be required to bring it from 125 to 130mm? Seems those of us with factory new units at 125 could simply add the necessary smidgen to bring each fork to 130 without the need for full disassembly and fiddling with height measurements.

 

[PalmStateCrawler]

Can anyone tell me what their 130mm rises to with the springs in? I really dont feel like taking my forks all the way apart again...

 

[lizrdbrth]

Everbuddy wanna,go to heven but nobuddy wanna die.

 

[flingwing1969]

Everbuddy wanna,go to heven but nobuddy wanna die.

Ya got it!

 

[PalmStateCrawler]

Everbuddy wanna,go to heven but nobuddy wanna die.

Lol. You got me there. But come on, this would be useful information that others as well as myself could use to spend more time riding and less wrenching!

 

[lizrdbrth]

I can't help you there. I have the longer tubes and my fluid measurements will be different.



Maybe the next time I drain Purple's stock forks. 'Bout a year from now, since I just did them

Seriously, the liquid measuement is pretty much uselss. If there is any residual fluid left in the legs after you drain them it will result in a higher level than intended. The only way to get this right is to grab a ruler.



Come on, guys. As long as you're just checking your existing levels and ADDING fluid this is 15 minutes' work. Slightly longer for you milk crate guys:



1. Set your purse down.



2. Lift front end off the ground and support bike.



3. Loosen upper pinch bolts. Remove fork caps and pull springs. Try not to chip your nails.



4. Let front end down until it bottoms.



5. Measure fluid level. Add fluid to 130mm, both legs.



6. Reinstall springs and fork caps. Tighten pinch bolts.



7. Ride.



Lather, rinse, repeat.



Tony, unless you're dealing with severely neglected fork legs full of semi-solid nasty gray gack you should never need to disassemble them at all.



Take them off, dump out the old oil, refill them with a small amount of ATF, cycle them by hand a few times then dump the dirty oil. Do this until the fluid is clear and you're done.



I've said it before, but fork oil doesn't wear out. Thersimply isn't enough going on in a fork in terms of heat or friction to promote oil breakdown. What does happen is that moisture and acids turn it into sludge. That's just a function of time, not use. Your fork tube is a somewhat sealed environment in which is it always "raining".



Air contains water. Water and oil do not mix. They emulsify into gray gack.



Do it at least annually and you'll probably NEVER need to fully disassemble them or disturb the seals for cleaning.

 

[elime]

Tony, unless you're dealing with severely neglected fork legs full of semi-solid nasty gray gack you should never need to disassemble them at all.

Now you tell me! HA HA.



I don't mind taking them apart this first time and getting them thoroughly clean. These are '87 forks and I strongly suspect this is the first cleaning. The oil is black and full of metal flake. There is the dark gray crap at the bottom of the tubes that seems packed hard in place. When I completely collapse the tubes (sans springs) they stick in that position and are hard to pull apart which they don't do after cleaning and fresh oiling.



I am also changing the seals. The old ones looked pretty good but being 25 years old I figure it is time. I went with the All Balls brand and hope the pricey entry fee will pay dividends down the road as in never having to do it again in my life time or as long as I own the bikes, which ever comes first! Next time around I will do as you suggest and simply change the oil.



BTW, thanks for your help and thanks to others that posted videos and what not on how to work on the forks. I used to consider the forks a complicated mystery but they aren't. They are actually very simple and easy to work on.

 

[lizrdbrth]

Rejoice, brother. You've got fork drains. lol. Now that you've got them spotless a drain, flush, and refill will cost you half an hour, annually.



Grab a handful of front brake and slosh the fork up and down a few times to flush them. Undo the drains, drain and refill. Done. Same simple procedure if you want to change oil weight, as well.



Those two little screws may have saved Yamaha few cents but when they eliminated them they turned this into a 3 hour job for most folks.



Basically they and the other manufacturers condemned all their forks to an ickygooey death because the average guy is now gunna put it off indefinitely. Truly visionary.

 

[admiral]

Those two little screws may have saved Yamaha few cents but when they eliminated them they turned this into a 3 hour job for most folks.



Basically they and the other manufacturers condemned all their forks to an ickygooey death because the average guy is now gunna put it off indefinitely. Truly visionary.

..."ickygooey death" and "drippy". Just finished helping (or doing in my case ha ha) changing my son's fork seals and fork oil on his 2000 Triumph Legend and a couple weeks ago on my other son's 81 Honda CM400. Talk about "ickygooey stuff" ofta were they bad.



I'll take changing the seals and fork oil on the TW any day! Even the new model TW without the fork drain screws!!

 

[flingwing1969]

Seriously, the liquid measuement is pretty much uselss.



Do it at least annually and you'll probably NEVER need to fully disassemble them or disturb the seals for cleaning.

Great writeup. Thanks on behalf of all.

 

[Stromper]

You young punks have it easy



Back in the sixties the japs used REAL FISH OIL



New it was smelled like cod liver oil

5 years later it had spontaneously generated life bent on world domination achieved by chemical and biological attacks



I wish I had bigger cojones as I was SO temped to drill and tap bleeders on my

V Strom but was to chicken I would pierce something unintended.



Any you guys feel like giving it a go an a TW ?

 

[flingwing1969]

You young punks have it easy



Back in the sixties the japs used REAL FISH OIL



New it was smelled like cod liver oil

5 years later it had spontaneously generated life bent on world domination achieved by chemical and biological attacks



I wish I had bigger cojones as I was SO temped to drill and tap bleeders on my

V Strom but was to chicken I would pierce something unintended.



Any you guys feel like giving it a go an a TW ?

My '72 Honda XL250 - bought new and ridden hard - used fish oil.

 

[flingwing1969]

. . . I wish I had bigger cojones as I was SO temped to drill and tap bleeders on my

V Strom but was to chicken I would pierce something unintended.



Any you guys feel like giving it a go an a TW ?

I considered that but it doesn't look like there is enough "beef" in the fork to handle a the plug threads and a recess to keep the plug from getting hit. If I trusted my TIG skills a bit more (and knew the alloy of the lower fork) I might consider building up the area, grinding it to match the original lowers and then tapping it for the plug/gasket. B I G ifs. At $222 a side, I think I'll stick with the annual PITA.