Tiger 1050 Fork Oil Level

Tiger 1050 takes 579cc 10w oil per leg from dry. With fork off the bike, spring installed and fully compressed there needs to be a 30mm air gap at the top. That's what the technical manual says.

So top up with whatever is needed to get that 30mm air gap.

 

Hi Carl - I realise your question is a few weeks back, however, I am in the process of doing the same job on my 2008 1050 Tiger and have been rather confused by the official workshop manual and so have researched this to death. . .
First of all, one correction - the official capacity of the forks is 581cc and not 579 on the 1050 Tiger.
I decided to "cheat" when changing my oil but am now having second thoughts about it - all l did was drain out the existing oil by unscrewing the top cap and inverting the forks. I then screwed the top cap partially back into the outer leg, pumped the forks and repeated the exercise several times. I left the forks draining overnight and extracted exactly 550cc from the right fork and 535 from the left and simply replaced with the same amount. I am a little puzzled by the disparity as I am confident I removed all the oil which was going to come out and so either
a. I didn't and there was circa 30ml still remaining or
b. After 10 years and 12000 miles (this is the first time I have done the job), 30ml has found it's way past the fork seals - this is not an unreasonable assumption Although there is no evidence of any leakage, a small amount of oil is bound to make it's way through the seals.

My take on the correct technique is twofold
a. Either, strip and dry the forks, all internals etc and then reassemble with 581ml of fluid per side or
b. remove the top cap and then having done so, remove the cylindrical steel tube spring cap and the fork spring below. Now invert and drain the oil. Next, fully pump the damper rod assembly from top to bottom and continue to drain as much oil as possible. With forks still inverted, Slide the inner and outer legs from top to bottom of their extremities to expel any oil sitting between the inner and outer legs - leave to drain.
Now place forks the correct way up and slide the outer fork tube down "out of the way". Replace the spring but not the steel tube spring cap or associated washers or top cap - just the spring itself. Now add your oil and pump the damper assembly in order to expel any air. Also, slide the outer fork tube up and down in order to expel air from between it and the inner tube and draw oil into the space between the two. Once you are sure you have all the air out from between the two tubes and from within the damper assembly, push the outer tube down as far as it will go so that the dust seal is effectively resting on the caliper mounting casting. Push the damper rod down as far as it will go and with the spring in place, adjust your oil level to 30mm below the top of the OUTER fork tube. Reassemble and job done.

I was lazy and thought that just replacing what came out would be good enough but I'm starting to think that perhaps I should have ordered the special tools and done the job properly - hey ho!!

You expressed some concern that 30mm is insufficient. Don't forget that all bikes are specified differently and some do give readings of 120mm or more for the oil level but this is often with the fork extended and damper rods extended and this measurement will drastically reduce under the compressed state which the Tiger level is set at and so I would suggest to you that 30mm is very much the correct reading.

 

There is a third possibility to explain the oil disparity.......the original fill was inaccurate. Near enough not to be noticeable until you do a forensic change!

A fourth possibility is that the level was topped up to the same height and the volume of the internal castings is slightly different. The compressible air gap is itself part of the suspension.

 

I've switched plans and have just ordered a spring compressor so that I can reset both levels accurately to 30mm, if indeed that is the correct measurement. I know how much I have put into each leg and how much is needed to take them both to 581ml.
Maybe if I find time, I will take some photos and write a "how to" as I found very little accurate information on conducting a fork oil change.

 

Hi Carl, thanks for your response. Is your bike the Tiger 1050 or Tiger Sport? Perhaps the forks are different.
I’m currently doing the valves but will shortly revisit the forks - my plan is to add 31ml to the right fork and see where the level comes to - if it is 30mm as per the manual, then I will know that both the 30mm level and 581ml capacity are correct as per the manual. If adding 31ml gives me a level which is wildly different from the specified 30mm then clearly the manual is wrong. It does contain some errors and so I won’t be surprised either way.
Interesting that you collected 580 to my 550 and 535ml - does tend to suggest 581 is correct - I will be intrigued to see what level this gives!!
I will follow up as soon as I have done the job!,,,

 

Well . . .if any of you guys had been watching me working on the bike today, you would have been well within your rights to have been whistling the Laurel & Hardy theme tune over my shoulder - I got into a bit of an oily mess to say the least and progress has been mixed but here goes

First of all, my manual does state 581ml for the Tiger 1050 - mine is 2008 non-ABS. After a little research, I have discovered the Haynes manual states 579ml for VINs from 438381 and a fluid level of 81mm without the spring and 581ml for VINS up to 438380 and a fluid level of 74mm. This would imply that the Tiger 1050 was fitted with different forks at some point in its production life and BEFORE it was replaced by the Tiger Sport. I can find no verification of this and even the forks on the 1050 Sport SE do look identical to those fitted to my 2008 bike. If this is the case, then it could explain why some folks get contradictory results. That said, I bought both my bike and official Triumph manual back in 2008 and so I am bound to take more notice of this than perhaps the numbers quoted in a Haynes manual . . . .

So, this morning I took my right fork to which I had added 550ml after having removed this amount a week or so earlier. I removed the top cap, washer, spacer and spring tube, before sliding the outer tube all the way down to the caliper casting and pushing the damper rod fully home. I failed to measure the oil level at this point but merely added 30ml so the amount I had added now came to 580ml. I measured the level and found it was 53mm. It took 28ml to bring the level up to 30mm. OK, I would have lost a little oil when I removed the top cap and spring tube but . . . surely nothing like 28ml and so it would seem that either 581ml is incorrect or indeed the 30mm level is wrong.
I tackled the left fork and again, added enough oil to mean that I had added 580ml and the level this time came to 60mm. I calculated this would take 36ml to bring the oil up to the 30mm level which would have meant that I had added a total of 616ml, less any oil lost whilst removing the top cap and spring tube . . . this wasn't stacking up.
I decided on a compromise and opted to set both forks with a level of 50mm and so finished off the left left before revisiting the right with a view to removing some of the oil as I had already set it at 30mm.
I unscrewed the top cap, withdrew it and the spring tube and then had a brain fart . . . I compressed the fork fully so the outer tube was down on the casting - pushed the damper rod fully home and rechecked the fluid level. It should have been 30mm right?? . . less of course a small amount to account for the oil lost when I removed the spring tube and top cap a & internal rod. Wrong . . . . the level had gone from 30mm to 59.6mm. The simple act of removing the cap, central rod and spring tube had caused me to lose almost 30mm in level - I still find this hard to believe but it's exactly what happened - granted, I pulled the spring tube out and dumped it without waiting for it to drain etc and I dribbled a bit here and a bit there but 30mm!! This discrepancy would explain my initial findings when I first opened both forks up in the morning as removing the spring tubes would have caused the oil level to drop by the same amount and in which case 581ml and 30mm could well be correct but there's only one way to find out . . . . .

I am in the process of draining my right fork leg once again. I've pumped it to ensure the damper unit has been scavenged and now plan to simply leave it upside down for a day or two in order to allow every last drop of oil to drain out of the entire assembly. Having done this, I will add exactly 581ml and see where the final level settles and this should provide the definitive answer . . . at least for my bike.

Interesting to note that the Triumph manual is not perfect either. The manual calls for 16mm of exposed thread above the locking nut when attaching the top cap . . .not possible. If you screw the lock nut down as far as it will go, you still don't quite get 16mm of exposed thread. I was aware of this at the outset, having read another post and so measured the position of my locknut immediately after removing the top cap. It required the nut to be turned through 17 flats in order to screw it fully home and so this is the same position I used on reassembly rather than worrying about having exactly 16mm of exposed thread or as near to 16mm as possible - I just put it back the same as it came apart.
Sorry for the ramble!!!!

 

Thanks for the info Carl. I will most likely do this later today, having allowed the fork to drain for 24 hours, I can't believe anything else is going to come out of it.
I'm now intrigued to see what my findings are.
I also plan to research the 16mm setting a little further. I've been thinking about it overnight. The post I read previously implied that if you don't screw the locknut down as far as it will go in order to achieve as near 16mm as possible it will "mess up your damping" but . . . . no explanation was forthcoming other than "don't ask me how I know"
On thinking about it, changing the length of the exposed thread will have two effects, the first definite, the second supposed on my part and I plan to investigate . . .
1. The fully extended damper length will shorten as more thread is exposed above the locknut and hence both need to be the same but should only come into play if the forks ever "top out"

2 As for the importance of the locknut position, This is subject to further investigation and I will report back as soon as I have sussed out how it all works!!!

 

OK, nearly all forks on any make of bike are filled when the leg is fully compressed and the spring in ! The measurement quoted is from the top of the tube to the top of the oil !! I have done my own services on the front forks of a Suzuki GSX 750 mid 70's, a Laverda RGS 1000 1983 and several Triumphs. Every time I disassembled them there was a difference in the oil levels ! And sometimes the oils looked like Black water, I do the oil changes at 20 to 25 thousand KLM intervals. The oil should be topped up until both forks have the same height/depth measurement, as it's the Air gap that is important !!! It affects compression damping, and so must be measured accurately ! It's more important that it is as near to the same in each leg than the quantity of oil in each leg ! As to disparity in oil that is removed at service , the oil degrades and can pass through the seals easily when it is thin With the degradation of time/use/wear etc.. It's really simple to service forks, remove them from the machine, remove top cap's and where fitted the lower drain plug/bolt, pump them until no more oil comes out. Flush with liquid of your preference ! This includes warm soapy water if you wish ! Let them stand in a position that will allow further drainage ! For a day or more if you so desire ! Flush With fresh oil pump through and drain ! The springs in , compress the leg/fork fully fill to desired level and reassemble ! Simple's really !!

Cheers capt

 

OK . . . Job done.
I measured out and added 580ml of oil as accurately as I could and after having pumped the damper numerous times and likewise the outer fork leg, I then slid the outer leg down to the brake casting. I pushed the damper rod fully down and with the spring installed but no spring tube or other niff naff, the level was measured at 49mm and not the 30mm claimed by the manual. In order to ensure I didn't then accidentally "overfill", I fully dried the spring tube (inside and out), spacers and washers etc before installing the top cap.
For point of reference and for those wanting an easier solution when changing the fork oil, with the top cap installed but merely with the outer leg unscrewed and slid down to the bottom of the forks, the oil level was 37mm. This means that an easier option for changing the oil would be to simply remove the forks from the bike, undo the top cap from the upper leg, drain out the oil and then top up to a final level of 37mm. It would be more difficult to purge the air as pumping the damper rod would be a little more difficult and likewise, measuring the level isn't as easy since the spring tube gets in the way and viewing the level is more difficult but hey ho . . .it's a figure that can be used for those who really don't want to dismantle their forks any more than absolutely necessary and so Carl1050Tiger you were absolutely correct. It is still the case that 30mm could be correct and 581ml the wrong figure but given how much we both extracted from our individual bikes, I suspect that 581ml is the true figure.

Now then . . . the real eye opener - the exposed thread above the locknut and on this subject, the manual is absolutely wrong as was the post I referred to earlier which suggested screwing the locknut down as far as it will go . . . . definitely do not do this!!!
It helps to understand how the fork works. . . . The top cap has a main body which externally, simply screws into the outer fork leg whilst it is threaded internally to accept the top of the damper rod and which is secured by the use of a locknut. The blue preload nut operates three steel rods of about 1.00mm in diameter which on turning the nut, move downwards and apply pressure to the washer seated on the top of the spring tube. In turn, this is pushed downwards, compressing the spring and adding preload. Centrally within this is the compression/rebound adjuster which comprises a slot screw head attached to a rod which runs down the inside of the damper rod and which is perhaps 0.5mm smaller in diameter than the internal diameter of the damper rod itself. The end of this adjustable rod terminates in a precision machined point which will create a restrictive "port" by mating with a hole within the damper unit itself. Compression damping is increased by turning the slotted head clockwise which screws the central rod further down into the upper leg of the damper rod and serves to close the "port" and restrict still more the flow of oil into the bottom of the damper when the forks are compressed. Screw it fully home and the flow is restricted maximally, Screw it right back and damping is minimal and results merely from the hydraulic "drag" caused by the fluid being pumped upwards inside the fork, between the inner rod and the inside of the damper rod and then being finally expelled through two small holes in the base of the Fork Cap. and thence back into the fork "oil reservoir".
OK - so the extended length of the fork, is dictated by how much exposed thread above the lock nut is screwed into the fork cap. If the locknut (which is symmetrical and does not have one flat side as suggested by the manual) is screwed as far down the damper rod as possible, I was left with just over 14mm (the manual suggests 16mm is required) of exposed thread above the nut BUT and it's a big BUT . . . . when I now screwed the fork cap onto the damper rod as far as it would go but turning lightly by hand, the fork cap will stop short of the lock nut. Indeed, in this scenario, it took six anticlockwise turns of the locknut to contact the under surface of the fork cap. The reason the fork cap wouldn't turn any further down the thread was because despite me having backed it off fully, the compression adjuster rod had bottomed out within the damper rod itself and this left me with zero compression adjustment. ie . . . prior to assembly, I screwed the compression adjuster fully out, locknut fully down and then screwed the Fork Cap onto exposed 14+mm of damper road thread and finally, tightened the locknut . . . . the compression adjuster is fully out but I couldn't screw it in because it was bottomed out in the damper assembly - period!!!
So, the bottom line is this . . . the manual is wrong on this point - it has to be. Given this issue, the question remains as to how much thread to have exposed on the damper rod and how far to screw down the fork cap before locking the two together?? I referred to the riders manual which suggested that compression/rebound is full when the adjusters are screwed in fully clockwise and that for normal riding (let's consider compression only) the adjuster should be backed out 1 turn and for heavier rider or two-up, 0.5 - 0.75 turns. I suspect that much beyond one turn of backing off, the damper port is fully open and thus opening the adjuster more than a certain amount will not reduce damping any more. Thus, I opted for a full range of travel on my compression/rebound adjusters of 1 1/2 full turns from fully in to fully out. By setting these the same, both fork legs will be the same length when extended and also the locknut will be in the same position on both damper rods . . . it has to be by definition. So . . . a revised and much more appropriate assembly technique would be as follows

1. Add new oil to forks. Pump forks and damper rod to purge all air. With outer fork leg resting on the brake casting and with damper rod pushed fully down, 581ml of oil should give a level of 49mm as measured from the upper surface of the OUTER fork leg. If you would rather use a final level of 30mm, it's your call. You will need to add circa 605ml of oil to achieve this.
2. Fully dry spring tube, lower and upper spacer and washer prior to installing so as not to inadvertently add yet more oil - install.
3. Now decide how many turns of "adjustment" you want on your compression/preload adjusters, bearing in mind that if you opt for too much, say 4 turns . . it will probably be only the first 1 - 1 1/2 turns from fully closed which will actually affect damping and the remaining 2 1/2 turns of adjustment will do NADA!!! Whatever your choice, turn the adjuster clockwise ie inwards, the required range from fully closed.
4. Now lightly screw down the fork cap onto the damper rod until it stops due to contact of the adjuster rod with the base of the damper unit. Now turn the locknut by hand until it snugs up against the base of the fork cap. DO NOT TIGHTEN.
5 Remove the fork cap and be sure to screw the compression/rebound aduster fully out.
6. Compress the fork spring and insert your spacer tool under the lock nut, trying not to turn the nut any more than necessary.
7. Place a 14mm spanner on the locknut and a long reach 32mm socket on to the large hex on the top of the fork cap body. Ligthly nip both together.
8 Turn the compression/rebound adjuster fully clockwise. You will almost certainly find that it will no longer turn by the amount you wanted, either slightly too much or too little. let's say it doesn't turn enough . . . . Back off the adjuster fully, undo the locknut. Now turn the fork cap counter clockwise by a small amount, back the locknut up to meet the fork cap again in this new position and lightly nip up. Screw the adjuster fully in and again,count the number of turns. Repeat, repeat, repeat
9. I aimed for a full adjustment range of 1 1/2 turns and thus when the fork cap and locknut have been "nipped up" and the above has been achieved by trial and error, again, back off the adjuster perhaps half a turn (this is to avoid crushing the end of the adjustable rod against the base of the damper unit and should be done every time the fork cap and locknut are being tightened together) and then torque to 22nm as per the manual (jeez, I hope they got this figure right - if so, it's one of the few that is!!!)
10. Repeat for the other fork so that both are identical.

Go and have a hard earned pint of beer!!!!

.

 

Bloody hell mate you should write a book if you haven’t already
Couple of more pints and I wouldn’t be able to read all of this

I’m working on it

 

Hey sorry mate . . . you'll probably have to start all over since I spent a good 30 minutes editing, rewriting and reposting stuff which I thought was ambiguous or didn't make sense. Hopefully the finished explanation is reasonably easy to understand

 

No need to apologise mate
It’s a good read
Glad you’re getting stuck into it and obviously enjoying the challenge and the rewards
Good on ya

 

Hi All
Just don't get it I'm doing the fork oil on my 2018 Sport. Keep getting different oil levels. On compression side measured 120mm from top fully compressed without spring, 90mm from top with spring, took out 560ml of oil, a difference of 30mm. BUT on the Rebound side measured 90mm from top without spring, 42mm from top with spring, a difference of 52mm, took out the same 560ml oil.
This is driving me crazy, I've pumped legs to check on air locks, even stripped the forks down AGAIN. Gggrrr. But get the same measurements. Any ideas before my brain falls out

Cheers

 

I would really like some clarity on where the measurement of the air gap is taken. Unclear weather it from the top of the inner tube or the outside slider . the difference is about 8 to 10 mm when compressed i believe so pretty significant.

 

Well meadland, after a bit of trial and error the way I've done it is, measure 130mm from top of oil level to top of inner tube with fork fully compressed and cartridge fully compressed and NO spring. This has given me funnily enough about 130mm of fork travel when braking as hard as I could over a bumpy road. This leaves 20mm left from the 150mm of full fork travel in case of a real emergency stop. I pumped the rebound cartridge and forks numerous times because, although I put in only 450cc I was at 110mm level. Wierd. Must be an air lock. So I left the fork overnight without spring or endcap. And bugger me in the morning the level was 150mm. So put in about more approx 50cc of 5W oil to bring it up to 130mm. Hope this helps.

 

OK, I've just proved that you guys on this thread are correct, in that 581ml and 30mm gap are incorrect on a Tiger Sport 2013.

I used these measurements and my fork was bottoming out half way down travel, I put a tie wrap round the fork to show its extent of travel and deliberately rode up a dropped kerb at speed. Bang!

So I ratchet strapped down the front end of the bike to the point of this tie wrap and that is as far as it would go. Undid the tops of the forks and released a big hiss of compressed air.

I've just syringed out 30 ml from each fork, the gap is now 85mm with the fork fully compressed but the spring uncompressed (i.e. the fork caps and tubes are sticking out above the triple clamp by 175mm)

I'll put it back together, reset the tie wrap indicators, take it for a ride and post up how it behaves and what the travel is.

Don't use 581ml and 30mm on a Tiger Sport, you'll blow your fork seals!