Front fork adjustment

[philshizle]

Hey guys i have a 82 xs400 maxim. The front forks are a too soft for me and i was wondering if i can fill the front forks with my compressor or does it take a lower pressure input or perhaps not even air? i have no idea.... thanks guys

 

[bentwrench]

Front forks are full of oil, and a spring. You can change it out to a higher weight oil, and a custom spring (there's nothing out of the box that directly fits, but some people on the site have figured out how to order new springs from Progressive that fit - search will work.)

If you don't know how long it's been since the fork oil was changed, that's probably a good place to start.

 

[Lou Ranger]

Front forks are full of oil, and a spring. You can change it out to a higher weight oil, and a custom spring (there's nothing out of the box that directly fits, but some people on the site have figured out how to order new springs from Progressive that fit - search will work.)
If you don't know how long it's been since the fork oil was changed, that's probably a good place to start.

For sure. The Yamaha 250 I got last fall (and sold when I got my Maxim in April) had soft forks. I was selling to an old friend and decided to change the oil in the forks for him.
Almost nothing came out. What did was as black a coal. I put in fork oil, one grade more viscous than the manual recommended, and the difference was remarkable - mostly due to having the correct amount of oil I am sure.
Don't be surprised if you PO maintained everything but the fork oil. I was sure surprised.

 

[drewpy]

I use 20w oil and 6cm from the top

 

[philshizle]

6cm from the top? perhaps there is a thread that can help me.

 

[Lou Ranger]

6cm from the top? perhaps there is a thread that can help me.

I won't speak for Drewpy but my guess is that he has done it enough to know where the proper level is on his bike and now doesn't need to measure out the specified volume and pour that and only that (without spilling) down the tubes.

I read you have the Maxim. While I haven't changed the fork oil in mine yet, I have read the SECA manual (on-line here on the Forum) and, according to it (pg 2-49), each Maxim fork takes 263 cm3 of oil. But I am not sure if the SECA uses the same forks with the same internals as the Maxim - the engines are the same but other things are not - so maybe someone else can confirm for us.
The reason to be cautious is that if Drewpy tried to put 263 cm3 in his forks, they might overflow. The manual for the XS400 sohc (pg 1265) says 142 cc. in each. 6cm from the top starts to make even more sense now.
My little 250 took 168 cc.

 

[bentwrench]

I used that same manual - I may have even written it up in "the restoration thread" in my signature line.

It's not a super challenging task. The Seca manual does a great job of walking you through it. I had to rig a tool to loosen the hex bolts at the bottom of the fork, and I replaced my seals at the same time (with is a PITA for old seals, as they get quite stuck.)

But a little elbow grease, some confidence, and lots of pictures up here, and you'll do fine.

Or, you could just leave them as they are.

 

[Lou Ranger]

I will have to check your thread B-W, thanks.

Philshizle, I would definitely change the oil, at least, based on the difference it made on my 250.
One quart of fork oil will do it twice. Or, 10W-30 per the Seca manual - but 20W might firm it up a bit.

 

[bentwrench]

I went a little light on description, but here's the post: http://www.xs400.com/forum/showpost.php?p=58619&postcount=68

 

[drewpy]

the reason its best to fill the oil to a certain level rather than cc's is because there is always some residual oil in there unless they were stripped clean.

 

[Lou Ranger]

I had to rig a tool to loosen the hex bolts at the bottom of the fork.... Or, you could just leave them as they are.

Quite the tool, but the report left me wanting - no pics of the giant thing in action - and what, exactly, is the 6mm hex bolt for anyway?

Since leaving them as they are is always an option if oil isn't dripping out, now I must confess to the "work-around" I did on the 250. I couldn't compress any fork caps and couldn't find anything that resembled a circlip with either an ardox or a plain nail. And I had already drained the small amount of black ooze from the tubes. So I made a tool too.
It consisted of a few old tires and a hill in the lawn. After siphoning the gas tank empty and removing the battery, I lay the bike downhill on the tires, propped with the top fork tip slightly raised. Using an oral syringe (which the drug store gave me for free) I injected oil into the drain hole 17 times (10 ml capacity). Then flipped the bike over and repeated.

 

[bentwrench]

My giant tool (ahem) was used to loosen the 6mm bolt in the bottom of the fork. That bolt holds the inner tubes to the outer tubes (lots of tubes in a fork tube.)

If all you're doing is replacing oil, you don't need to worry about it. If you're replacing seals, that's when you have to completely disassemble.

 

[philshizle]

well one of the forks has a leaky seal but its not to bad. so the manual explains this process? or were can i find this. to refil oil/replace the seals. i dont have a manual but i hear its on the thread?

 

[xs400neophite]

type key words in the search box and it should come up

 

[Lou Ranger]

well one of the forks has a leaky seal but its not to bad. so the manual explains this process? or were can i find this. to refil oil/replace the seals. i dont have a manual but i hear its on the thread?

Post #3 on this thread - http://www.xs400.com/forum/showthread.php?t=4503

If one seal is leaking just a bit, you could try doing just the oil (20W, 6 cm from the top) to test whether that's all it needs to stiffen it up enough. Then you could ride a while until the leak merits seal replacement. If it still isn't stiff enough, then you could decide what new parts you want to install in addition to the seals - and if you want to eat up part of the riding season or wait until this winter begins paying us back for last winter.

 

[philshizle]

sorry to reopen this thread but what type of oil is used? i get 20w but theres a lot of different types of oil or maybe im just dumb...

 

[Lou Ranger]

sorry to reopen this thread but what type of oil is used? i get 20w but theres a lot of different types of oil or maybe im just dumb...

The manual calls for type SE motor oil (SAE 10W30). Since you want to try thicker oil, I would say 20W50 or straight 20W so long as it is SE type oil.
You also can't go wrong with a 20W oil packaged up and labelled as "Fork Oil" but it likely costs a dollar or two more per litre.
Here's what I used on the 250 in 20 wt: http://www.mxsouth.com/maxima/maxima-suspension-fluid-fork-oil.htm Got it from Royal Distributing

 

[drewpy]

I tried engine oil and it frothed too much and cavitated.

I only use proprietary fork oil in the 20w for the xs

 

[Lou Ranger]

I tried engine oil and it frothed too much and cavitated.
I only use proprietary fork oil in the 20w for the xs

I forgot about the frothing - at the time, I had read about it, and that was why I chose to buy the fork oil instead.

I've read a few articles and there is fork oil as thick as 30W out there. But there is controversy about using it since the regular gets much thicker in cold temps. Synthetic fork oil's viscosity is apparently much more stable with temperature change, so maybe synthetic 30w could end up being be the most useful to you.

 

[xschris]

I use old f-type atf in my crap tracker and it seems to work fine My 79 has spectro fork oil and that work well to just costs a lot more.