Drz400sm suspension - Compression/rebound and old oil question

[Rob132457]

Hi everyone, I’ve just bought a 2008 DRZ400SM, great condition and has a decent engine service history. I’m new to this thread (and this type of bike) but have a bit of experience of rebuilds and home repairs.
 

Having got it home and started reading up on  suspension settings I’ve noticed a couple of things. 

I weigh around 75kg-80kg geared up and I’ve bought it from a much heavier rider. (And I’m a short arse)

when I picked it up the shock was wound right up, no static sag and about 30mm rider sag. Rebound was wound all the way out. Front forks are set at 5 clicks in on both compression and rebound

1. I’ve wound the rear shock back down so I’ve got 80mm rider sag(kitted up with a full tank). The rebound is still all the way out and it doesn’t seem to bounce up quickly (thought this was a bit strange). The back end feels ok now though and it’s much closer to stock height. I’m still yet to play around with high and low speed compression. I’ve got a tie wrap around the rear shock and it’s 20-30mm off bottoming out

2. Front the fork compression and rebound are still set at 5 clicks in. Even with rebound wound fully out it doesn’t bounce up before it settles (again I thought this was a bit strange)
 

It feels ok around the streets but when I come to a sweeping bend it feels a bit lollopy like it’s weaving slightly, maybe I need more rebound dampening? Occasionally when I’m on the straight it’s a bit bouncy so I’ve probably answered my own question there.

 

im considering a full rebuild as the dust seals are perishing (no leaks though) and I’m wondering if a lighter oil might be appropriate or whether I’ve understood the whole compression / rebound wrong

 

any advice is greatly appreciated 

 

thanks in advance

[Tony Wyp]

1 hour ago, Rob132457 said:

Hi everyone, I’ve just bought a 2008 DRZ400SM, great condition and has a decent engine service history. I’m new to this thread (and this type of bike) but have a bit of experience of rebuilds and home repairs.
 

Having got it home and started reading up on  suspension settings I’ve noticed a couple of things. 

I weigh around 75kg-80kg geared up and I’ve bought it from a much heavier rider. (And I’m a short arse)

when I picked it up the shock was wound right up, no static sag and about 30mm rider sag. Rebound was wound all the way out. Front forks are set at 5 clicks in on both compression and rebound

1. I’ve wound the rear shock back down so I’ve got 80mm rider sag(kitted up with a full tank). The rebound is still all the way out and it doesn’t seem to bounce up quickly (thought this was a bit strange). The back end feels ok now though and it’s much closer to stock height. I’m still yet to play around with high and low speed compression. I’ve got a tie wrap around the rear shock and it’s 20-30mm off bottoming out

2. Front the fork compression and rebound are still set at 5 clicks in. Even with rebound wound fully out it doesn’t bounce up before it settles (again I thought this was a bit strange)
 

It feels ok around the streets but when I come to a sweeping bend it feels a bit lollopy like it’s weaving slightly, maybe I need more rebound dampening? Occasionally when I’m on the straight it’s a bit bouncy so I’ve probably answered my own question there.

 

im considering a full rebuild as the dust seals are perishing (no leaks though) and I’m wondering if a lighter oil might be appropriate or whether I’ve understood the whole compression / rebound wrong

 

any advice is greatly appreciated 

 

thanks in advance

What methodology are you using to test the bump and rebound.

Unless the owner revalved the shock and forks, they should be way too soft on 5 turns in.

Factory settings on a 2005:

(Screw the adjusters fully IN to the hardest setting. Try the feel of this setting)

.Forks: Comp13 clicks out. Reb 17 clicks out.

Rear. Comp 10 clicks out. Reb 14 clicks out.

I would def try this first.

Edited October 19, 2020 by Tony Wyp

[roleyrev]

2 hours ago, Rob132457 said:

Hi everyone, I’ve just bought a 2008 DRZ400SM, great condition and has a decent engine service history. I’m new to this thread (and this type of bike) but have a bit of experience of rebuilds and home repairs.
 

Having got it home and started reading up on  suspension settings I’ve noticed a couple of things. 

I weigh around 75kg-80kg geared up and I’ve bought it from a much heavier rider. (And I’m a short arse)

when I picked it up the shock was wound right up, no static sag and about 30mm rider sag. Rebound was wound all the way out. Front forks are set at 5 clicks in on both compression and rebound

1. I’ve wound the rear shock back down so I’ve got 80mm rider sag(kitted up with a full tank). The rebound is still all the way out and it doesn’t seem to bounce up quickly (thought this was a bit strange). The back end feels ok now though and it’s much closer to stock height. I’m still yet to play around with high and low speed compression. I’ve got a tie wrap around the rear shock and it’s 20-30mm off bottoming out

2. Front the fork compression and rebound are still set at 5 clicks in. Even with rebound wound fully out it doesn’t bounce up before it settles (again I thought this was a bit strange)
 

It feels ok around the streets but when I come to a sweeping bend it feels a bit lollopy like it’s weaving slightly, maybe I need more rebound dampening? Occasionally when I’m on the straight it’s a bit bouncy so I’ve probably answered my own question there.

 

im considering a full rebuild as the dust seals are perishing (no leaks though) and I’m wondering if a lighter oil might be appropriate or whether I’ve understood the whole compression / rebound wrong

 

any advice is greatly appreciated 

 

thanks in advance

@Tony Wyp has a good point.  Set the bike up as it comes from factory. I weigh about 82Kg and find the SM well set up.  I have not deviated  from factory with the clickers and have the required amount of static sag (70mm).I push the bike hard in cornering usually on "B" roads so the surface isn't that great.  It performs like a champ.

[Rob132457]

I stood at the side of the bike, front brake on and plunged it forward, I’ve also stood in front of the bike and pulled it down as hard as I could. 
 

I've made a rookie error, the rebound was set to 5 clicks in, compression was set to 5 clicks OUT!
 

I thought it should be bouncing back faster, I’m not sure whether the previous owner has put different oil in due to his size/weight, not sure if this would make a difference but assume it would

 

Either way I’ve set us up as above so I’ll take it out tomorrow and test it, it appears to have been way of factory settings so may be a bit less like riding a moose, thanks for the advice

[Gary in NJ]

Used bike with an unknown history of the suspension...I would at a minimum change the oil and return it to OEM settings, this way you can make educated assessments of changes verses uninformed guesses.

[Rob132457]

6 minutes ago, Gary in NJ said:

Used bike with an unknown history of the suspension...I would at a minimum change the oil and return it to OEM settings, this way you can make educated assessments of changes verses uninformed guesses.

Thanks, I’ll do that, I was kinda thinking that was the way forward and this has reaffirmed it. I’ve been informed it’s an easy but messy job land the only specialist tools I’ll need are an impact driver and a seal driver, can anyone confirm this?

thanks

[Gary in NJ]

Do you have a copy of the FSM? The entire procedure is well documented there.

[Rob132457]

15 minutes ago, Gary in NJ said:

Do you have a copy of the FSM? The entire procedure is well documented there.

I don’t but was considering buying a Haynes manual, is the FSM any better?

[BillDirt1]

Haynes is the worst. FSM is the best. Clymer is good.

Edited October 20, 2020 by Diverdown

[Rob132457]

I’ll have a look for the FSM, I haven’t seen them available in the UK so far (haven’t really looked that hard either) thanks for the heads up

[Gary in NJ]

32 minutes ago, Rob132457 said:

I’ll have a look for the FSM, I haven’t seen them available in the UK so far (haven’t really looked that hard either) thanks for the heads up

Do some digging. You may find a copy on-line for download.

[Rob132457]

Think I’ve found it and downloaded it free, seems too easy, should it look like the below pic?

I’ve also now located the supplementary manual for the SM. 
 

They’re all here if anyone else needs them....https://www.manualslib.com/brand/suzuki/motorcycle.html#D

Edited October 20, 2020 by Rob132457
Found more info

[Tony Wyp]

6 hours ago, Rob132457 said:

Think I’ve found it and downloaded it free, seems too easy, should it look like the below pic?

I’ve also now located the supplementary manual for the SM. 
 

They’re all here if anyone else needs them....https://www.manualslib.com/brand/suzuki/motorcycle.html#D

Dont you have upside-down forks on your SM ?

Those pics are of conventionals.

Edited October 21, 2020 by Tony Wyp

[Rob132457]

6 hours ago, Tony Wyp said:

Dont you have upside-down forks on your SM ?

Those pics are of conventionals.

Yeah I do, I realised after posting it that there’s a supplementary manual for the SM, looks more complicated but I’ll give it a crack, worst case scenario I’ll take them to the shop to be rebuilt

[Tony Wyp]

4 minutes ago, Rob132457 said:

Yeah I do, I realised after posting it that there’s a supplementary manual for the SM, looks more complicated but I’ll give it a crack, worst case scenario I’ll take them to the shop to be rebuilt

? yeah my sm forks are finally leaking after 15 years. I have been wiping the leaky seals for years.

 

Edited October 21, 2020 by Tony Wyp

[hinksy]

On 10/20/2020 at 11:28 PM, Rob132457 said:

Thanks, I’ll do that, I was kinda thinking that was the way forward and this has reaffirmed it. I’ve been informed it’s an easy but messy job land the only specialist tools I’ll need are an impact driver and a seal driver, can anyone confirm this?

thanks

if all you are going to do is change the oil , then you will only need some 12/17 mm spanners /sockets . Have a look at some youtube vids , it is very easy , greg

[Rob132457]

27 minutes ago, hinksy said:

if all you are going to do is change the oil , then you will only need some 12/17 mm spanners /sockets . Have a look at some youtube vids , it is very easy , greg

Just had a look for some vids, I’ve found some for the conventional forks but not USD ones. The dust seals are on the way out anyway so for the little bit of extra time I’m going to fully service them I think....or maybe just take them off, panic and run them up the the bike shop ?

[hinksy]

here`s one 

 

[ohiodrz400sm]

Factory service manuals should be simple to find as you have Suzuki dealers in the UK. The parts department will order one just like any other part 

Twin chambers are not that hard. You'll need the appropriate wrenches to remove the inner from the fork cap.  The inner cartridge takes a set amount of oil so you'll need need to be able to accurately measure cc's. The outer oil is set by height. Even though it can be done,  a fork seals driver makes installation the oil seals so much easier. Otherwise, you have to take your time and very carefully tap them in with a flat punch. Another option is cut an old seals in half and use it as a buffer between the punch and new seal . Remember to slide the seal package over the edges of the bushing seats like a condom before sliding the wiper and seals on the legs so you don't cut them. Speaking of bushings, I would change those too while you are in there.

Edited October 22, 2020 by ohiodrz400sm

[Rob132457]

I’ve found one online now thanks, and done some YouTubing so now I feel like a pro. Thanks for the advice, I’m gonna give it a go, got a fork wrench on order and I’m always looking for excuses to buy power tools so might try and sneak a torque wrench into the garage without the wife noticing. Any recommendations for brands of seals or are they all similar?