TW200 Forum banner

1 - 20 of 26 Posts

·
Registered
Joined
·
299 Posts
Discussion Starter #1
My fork oil kit has arrived along with a quart of 10W fork oil, so it's time to check the fork oil level. I put my bike on the rear axle stand to hold it level, then felt the bottom of the fork for a drain plug. My TW is a 2003 and I thought it wouldn't have drain plugs from what I have read, but I felt holes just behind the axle. And after looking inside I can see large allen screw heads. So my first question is, are these drains or something else?
 

·
Registered
Joined
·
299 Posts
Discussion Starter #4 (Edited)
Those allen bolts hold in the damping rods, dont remove them unless you want to do a complete teardown.
Thank you scotti158 & jb882. I didn't think they were drains, but since they were there I had to ask. This will be tomorrows project. I bought one of the fork kits that sucks the fluid out. Not ready to do a full drain, because I may be installing new springs if this doesn't cut the mustard. In fact now that I think about it, I should just check level and add if needed, then test it first...
 

·
Registered
Joined
·
1,076 Posts
To get all the fluid out, you really should remove the forks. It's not hard at all. That way you dump them out, then cycle them a few times to pump all of it out before adding the new fluid.

If you're trying to firm them up a bit, try adding a little more fluid than is normally specified... like an ounce or two per side. Otherwise, thicker oil would be an option, like 15wt instead of 10wt.
 

·
Registered
Joined
·
19,551 Posts
I would remove the forks and invert them so all old aluminum sludge buildup since 2003 can be flushed out with ATF or fork oil until forks rinse clean. With forks vertical, compressed and no springs, spacers, etc oil can then be added carefully to desired level which should never be less than 120mm( someone please double check me on this) measured from top of fork otherwise you will not have enough air for the "air spring" effect and instead will blow out your seals.
Please just don't add an once or two of additional fluid without checking fluid level or you might be asking us next how to replace fork seals. Overfilling will blow out seals, there is not much volume available like on more sophisticated forks you may have experience with. Clean everything nicely before reassembly.
There are several good "How To" threads on this forum that go into the details of the how and why of what I am trying to repeat. It is a bit of an iterative process, but yields pleasant results. I ended up with 10w fork oil 125mm from top of tube. I am 190# and have another 30 to 40 pounds of larger gas frank w/ fuel, cycle rack, heavier tires, and some tools and I ride moderately rocky trails at moderate speeds ( i.e. bike rolls out on the trails at ~ 330 pounds fueled up ready to go).
 

·
Registered
Joined
·
7,051 Posts
The only adjustment I made to my forks was to "adjust" the fork oil level.

When I took them apart the oil level was 157mm and the forks would bottom out hard all the time. No fun. I "reset" the level to 130mm and now they seldom bottom out and when they do it is no where near as hard.

The air inside the fork acts as a spring. The less air the stiffer the spring. By increasing the oil level you may find you don't need new springs. That was my experience.
 

·
Registered
Joined
·
1,379 Posts
I would remove the forks and invert them so all old aluminum sludge buildup since 2003 can be flushed out with ATF or fork oil until forks rinse clean. With forks vertical, compressed and no springs, spacers, etc oil can then be added carefully to desired level which should never be less than 120mm( someone please double check me on this) measured from top of fork otherwise you will not have enough air for the "air spring" effect and instead will blow out your seals.
Please just don't add an once or two of additional fluid without checking fluid level or you might be asking us next how to replace fork seals. Overfilling will blow out seals, there is not much volume available like on more sophisticated forks you may have experience with. Clean everything nicely before reassembly.
There are several good "How To" threads on this forum that go into the details of the how and why of what I am trying to repeat. It is a bit of an iterative process, but yields pleasant results. I ended up with 10w fork oil 125mm from top of tube. I am 190# and have another 30 to 40 pounds of larger gas frank w/ fuel, cycle rack, heavier tires, and some tools and I ride moderately rocky trails at moderate speeds ( i.e. bike rolls out on the trails at ~ 330 pounds fueled up ready to go).
I agree with everything here. If you are unsure if they have ever been serviced i would pull them down completely, clean everything and replace the seals and fresh fluid. Not an expensive or hard job to do at all and once done you will have a good baseline for any adjustments.
The directions are in the service manual and there are some great tutorials on this site. You can make a cheap and effective damping rod holder out of 2 10" long 1/2" bolts and a threaded coupler and some red locktite or a tack weld to hold it together. Motion pro sells a nice tool for tetting the oil level as well. If you plan to mess with the levels its a nice tool to have.
 

·
Registered
Joined
·
299 Posts
Discussion Starter #9 (Edited)
Thanks for all the input. I will be changing the oil and cleaning once I know the results. This sucker is basically new (<500 miles) and stored covered in a temperature controlled garage. Won't be changing the seals out unless they start leaking.

Got side tracked this morning putting out fires, but may still get to it today...
 

·
Registered
Joined
·
299 Posts
Discussion Starter #10 (Edited)
This turned out to be easy to complete. Put the TW on a rear axle stand and lifted the front wheel off the ground with a jack stand under the exhaust pipe giving the front forks full extension.



- Loosened the upper fork clamp bolts
- Unscrewed the fork caps
- Slid the spacers out by hand
- Made a wire hook to pull the spring and washer on each
- Removed the jack stand and slowly let the forks fully compress



- Checked the air gap using the syringe with stop like a dip stick
- Air gap measured 150mm (NOT CORRECT! But, oil was like new and clear red in color)
- Sucked up a little over ~35mm into the syringe from the 10W fork oil quart
- Put half (~17.5mmm) in each fork tube
- Set the zip tie to 135mm and sucked fork oil out of each tube to that level
- Measured with the ruler like a dip stick after adding a tape stop to it for a double check
- The oil line cut diagonally between 130-135mm on the ruler (132.5mm air gap)

Here are all the tools I used.



- Put the front wheel back off the ground with the jack stand under the exhaust pipe
- Reinstalled the spring, washer, spacer and fork caps at full extension
- Tightened the upper fork clamps back up
- Removed the jack stand and rear axle stand

Took it for a test ride on the street… Not much stiffer, but noticeable change. It functions more like I think it should; although still a bit soft for my weight. I repeatedly accelerated up to 25mph, then grabbed the front brake hard and it dips, but doesn’t bottom out. The dip is more controlled and it comes back up MUCH nicer than before. In fact, I think the biggest improvement after my minor test ride is noticed on the rebound and general smoother/proper operation. It’s not as springy and slightly firmer, so dampening is improved. Much more controlled operation.

As many of you suspected, the oil level was low. Now I need to test it off-road for a day… :thumbsup:
 

·
Registered
Joined
·
3,477 Posts
....
- The oil line cut diagonally between 130-135mm on the ruler (132.5mm air gap)
Now I need to test it off-road for a day…
After exercising the forks for a few days, you may want to add a little more oil to about 125mm. Since you know the level now you can just extend the forks, take off the caps and add about 3-5cc to each fork. It looks like your syringe is pretty close to the fork diameter so you could use that to approximate 5mm. No need to pull spacers and springs.

When I did mine, I found the levels were not the same in addition to being nearly 20mm low. I guess the factory thinks all Americans weigh 130 lbs. :p I'm about 200 with gear and 130mm turned out perfect for me.
 

·
Registered
Joined
·
299 Posts
Discussion Starter #12 (Edited)
I just went back to the Fork Oil - Changing sticky in the Techincal Help section and reread it; specifically LB's SAG setting check. I think that's close just by eyeballing and feel, but I'll figure out a way to measure that without removing the fork boot. Probably just pick two fixed points above and below the seal.

I'll try to fine tune to my liking without a "ziptie" and boot removal as well. Should be able to get it close by feel and whether or not I am bottoming out. We'll see...

The one thiing I didn't see LB mention was at what point you should consider upgrading the spring itself to something like the 20% or 40% stiffer units being sold? It sounds like if you go stiffer spring, you will need to go heavier oil to get proper compression and dempening with the fixed size fluid holes on the TW.

I'm no expert in this reguard. This is the first time I've ever experimented with fork tuning. My pre-teen and teenage racing bikes back in the 70's were setup by someone else that knew what they were doing.
 

·
Registered
Joined
·
3,477 Posts
Yes, you can check static and rider sag by measuring two points on either side of the boots. You'll need a helper to do the rider sag. Bounce a few times.

Deciding on stiffer, or possibly progressive springs is a personal preference. If you are over 250lbs. and ride aggressively, give them a try. Don't change oil weight until after testing the new springs.
It is easy to get it too stiff. Remember it only has 6 inches of travel and you need to use it all. I would rather have occasional bottoming than a stiff ride. It will never be a KTM, no matter what you do, unless you replace the entire front end.;)

Oh, and rider sag is very sensitive to air gap....you should do that measurement before adding any more oil as I said above. If it is close to the recommended amount, leave things alone for a while until you are very sure you need to get stiffer springs. I am not sure of exactly what the relationship between mm of air gap and mm of rider sag is, and of course that is dependent on rider weight, but if you are only a couple of mm over the desired rider sag I would only add 2mm of oil before retesting, not 5.
 

·
Registered
Joined
·
299 Posts
Discussion Starter #14
After exercising the forks for a few days, you may want to add a little more oil to about 125mm. Since you know the level now you can just extend the forks, take off the caps and add about 3-5cc to each fork. It looks like your syringe is pretty close to the fork diameter so you could use that to approximate 5mm. No need to pull spacers and springs.
Exactly what I was thinking.

Yes, you can check static and rider sag by measuring two points on either side of the boots. You'll need a helper to do the rider sag. Bounce a few times.

Oh, and rider sag is very sensitive to air gap....you should do that measurement before adding any more oil as I said above. If it is close to the recommended amount, leave things alone for a while until you are very sure you need to get stiffer springs. I am not sure of exactly what the relationship between mm of air gap and mm of rider sag is, and of course that is dependent on rider weight, but if you are only a couple of mm over the desired rider sag I would only add 2mm of oil before retesting, not 5.
Good idea. Thank you so much for your experienced thoughts. I have a feeling that I will be zeroing in on the 130mm setting (that seems to be common among the full grown men riders of the TW). It just might be the ticket for a basic stock front fork oil level setting.

Have to go check the setting on that rear shock. If it’s not on the 3rd notch (top), then I will go straight to that now.
 

·
Registered
Joined
·
299 Posts
Discussion Starter #15 (Edited)
I posted this in the wrong thread, so I'm squeezing it in here...

Addressing SAG can easily be done by measuring from the top of the lower fork clamp to the bottom of the dust cover. With the front wheel off the ground that measurement is 10-1/8” on my bike. With the bike sitting by itself on the rear axle stand it measures 9-3/16”. Easing onto the pegs into a standing position at 235lbs. it measures 8-1/8”. If I bounce up and down while standing on the pegs and let it come to a rest with 235lbs. it measures 7-7/8”.

The important numbers here are the fully extended 10.125” and the two measurements while I’m standing on the pegs with riding gear on at 235lbs. of 8.125” and 7.875”. Current SAG is 2” and 2.25” (10.125” - 8.125” = 2” and 10.125” - 7.875” = 2.25”).

Everyone says the TW has 6” of travel in the front (my manual says 150mm or 5.9”); but good enough. Using the stated norm setup for Dual Sports of 25% of total travel for SAG, we get 1.5” (6” x 25% = 1.5”).

Subtracting the measurement I want (1.5”) from the two measurements I’m working with (2” & 2.25”) I get a ball park spacer size of 0.5”-0.75” (2” - 1.5” = 0.5” and 2.25” – 1.5” = 0.75”).

Because the spring will be a little bit compressed and thus a little bit stiffer, I’m going to start with a 0.5” spacer and leave the fork oil level where it is. My thought is the spacer will take up a little air space too, so there will be less air to compress.
Time to find or make a ½” spacer, check the SAG again, then go riding off road… :thumbsup:

= = = = =

Found these 1" OD x 3/8" thick teflon spacers at my local hardware store for $0.50ea. and had some 1-1/16" OD x 1/8" thick lug nut washers lying around.



First tried the 1/8" and 3/8" together for a total of 1/2" in spacers, but it only put the SAG at 1-15/16". Then I jumped all the way up to the 1/8" and both 3/8" spacers for a total of 7/8", but that put me at 1-7/16" SAG. That would have put SAG at ~24% (1.4375" / 6" = 0.24), but I wasn't really comfortable with that much extra; just wanted to see if I was even going to be able to get where I wanted to be. I'm not sure at what thickness of spacers the TW short fork spring itself will bind at, so it seems better to error on the greater side of 25%; somewhere in the 25%-30% range.

Lastly I installed two 3/8" teflon spacers for a total of 3/4" on each side and the SAG came in at 1-5/8". 27% is good enough for me! (1.625" / 6" = 0.27)

Did a few runs around the block on the street with several hard stops, then added about 2.5mm additional 10W fork to each tube.

So after all was said and done, I ended up right where all the pro's on this TW200 forum said it would likely be, 3/4" spacers and 130mm air gap.

:hatsoff:

PS: Even without testing it off road yet, I think this will be the ideal setting with the stock springs. It's probably all you can really get out of these front forks without upgrading major components like the spring, valves or the fork tubes themselves...
 

·
Registered
Joined
·
299 Posts
Discussion Starter #17
Okay, I tested it out on the street for about 30 miles. It's still the pogo-stick king!

Just braking makes the nose dive hard. The bike doesn't feel safe with the soft front forks that come with the TW. The bikes confidence inspiring low seat and small size are trumped by the squishy front forks. Without even testing it in the dirt, I don't see how I can get away without upgrading the frok springs for my size and weight...
 

·
Registered
Joined
·
13,401 Posts
Sounds like you're not gonna be pleased until you get different springs, such as those offered by Procycle. I'm considerably heavier than you and I have been "mostly" satisfied with putting in the 3/4 inch spacers many have on the front forks. I still have some bottoming out in the hardest of situations, like the ones we saw at Moab this year. However, for general riding around on the street like you just did, it stiffened up the stop sign braking pretty darn good, comparatively speaking. Never had the pogo stick feel, so wonder if you have something else going on there which the rest of us haven't experienced or don't know it is. Lot better than stock in the less aggressive off road trails I ride. I've tweaking the oil level too, just can't remember and don't want to give you a guess of what it was, but I do know it was more than what the service manual mentioned.

I also moved my rear shock to the stiffest setting and this really helped a lot, me being a heavy dude and all.

Good luck with you seat and forks!
 

·
Registered
Joined
·
299 Posts
Discussion Starter #19
Since the tuned stock forks aren't going to cut it for me (functioning fine), realistically how much of a difference do the 40% stiffer frok springs make? I understand we are dealing with only 6" of travel and these forks are limited as to what they can actually do. Throwing money at something that can't be concerns me.
 

·
Super Moderator
Joined
·
17,650 Posts
I'm one of the biggest riders on the site and the heaviest springs from procycle worked great for me, along with the correct sag and correct oil levels for my size. I did all the standard recommendations before hand and it just wasn't enough. My bike feels like a real motorcycle now. Very pleased with them.
 
1 - 20 of 26 Posts
Top