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Old 04-05-2013, 09:32 AM   #1471
tdrrally
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according to racethech the r80/7 needs a 1.0 spring up front
the stock drz400 spring is a .40
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Old 04-05-2013, 09:43 AM   #1472
Ras Thurlo
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Originally Posted by Beater View Post
I think my DRZ forks need a stiffer spring .. but by lightening the bike I have been able to adjust the preload and dampener so that it is close ...

I love 'em. They are big and beefy, very reassuring, and confident. I am really thinking about doing the same to my GS.
what springs do you have?

have you shortened your forks?
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Old 04-05-2013, 09:52 AM   #1473
Beater
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what springs do you have?

have you shortened your forks?
The stock DRZ springs ... I think they are 0.43. The stock R80 needed 1.0?! Well ... that explains it.

Same length, I did put in a spacer though.

There are several places on the internet (and actually one here locally) that can make a custom spring for the DRZ fork. If you do the usual math and consider 'static sag with rider' ... I needed a ~50% larger spring. So I was looking at a 0.6. I'm also going to be losing another 3 pounds here momentarily ... (Valeo).
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Old 04-05-2013, 10:50 AM   #1474
naginalf
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Originally Posted by tdrrally View Post
according to racethech the r80/7 needs a 1.0 spring up front
the stock drz400 spring is a .40
Racetech isn't known for their spring calculations, they usually run way heavy. Also, the r80 doesn't have anywhere near the fork travel that the dr has, is billed as a mostly street bike vs a mostly dirt bike, and damper construction also plays a major role in spring selection. You don't need as heavy a spring to control a lighter wheel, with more travel, and much better damping. With a damper that is simply pushing oil through a hole, the spring is the only real control the fork has, the damper is only there to keep the spring from bouncing.

For example, I'm 240lbs. Racetech claims I need a .8 for the suzi, 1.0 for the stock r100, but a professional tuner says I need .64 for my shortened WPs.
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Old 04-05-2013, 11:28 AM   #1475
tdrrally
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i agree racetech runs a bit high on the fork springs for sure
always been near spot on for the rear.

my r80 is getting drz forks soon.
i'm thinking something about .7-.8 up front

right now the stock springs on the r80 suck dampeners suck too

i think with enough Japanese parts the r80 might be something one day
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Old 04-05-2013, 10:39 PM   #1476
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BTW- I have heard it said that DRZ forks perform better than WP50s on an airhead

I have heard similar tales.

I mean I heard a rumor Mr. Rooney was moving from WP50's to DRZ fronts for his race bikes, and civilian versions.
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Old 04-06-2013, 05:01 AM   #1477
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I'm running .70s in my DR forks on my R90/6 conversion. Started off with 15mm preload and have reduced it to 5mm. 10wt fork oil at 6.5" from the top. Racetech emulators too. I'm happy with their performance.
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Old 04-06-2013, 05:16 AM   #1478
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I mean I heard a rumor Mr. Rooney was moving from WP50's to DRZ fronts for his race bikes, and civilian versions.
Yeah last I talked with him the WP50's were getting very hard for him to source, especially reliably such as required for 'civilian' builds on a timeframe. I hadn't heard about the DRZ forks being the universal replacements though.
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Old 04-06-2013, 05:28 AM   #1479
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I have heard similar tales.

I mean I heard a rumor Mr. Rooney was moving from WP50's to DRZ fronts for his race bikes, and civilian versions.
My guess is that's a parts availability issue more than anything.

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Old 04-06-2013, 06:16 AM   #1480
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yeah parts availability is an issue, as anyone running these forks is painfully aware of, but in our market here it is very hard to even find a decent set of WP50's to start with. If you find a set they are expensive but more importantly usually totally worn out (which was the problem Paul emphasised to me), which kinda comes back to parts again of course but is a moot point when just about everything in the fork needs replacing.
You can pick up decent sets for a $100-$150 in the US, but here, check out this guy, bearing in mind it is very rare to find these forks for sale, and when you do these are pretty normal asking prices.
http://www.ebay.com.au/itm/KTM-250SX...ht_1454wt_1400
http://www.ebay.com.au/itm/KTM-400LC...ht_1499wt_1400

I've got one set on the G/S and one set on the shelf and will probably snap up another set just for spares if I find another for cheap.
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Old 04-06-2013, 09:56 AM   #1481
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Parts avail and worn out stuff is true, and are very practical considerations but I'm not convinced they are some kind of holy grail, either.
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Old 04-06-2013, 10:17 AM   #1482
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The DRZ forks aren't as easily height adjustable though are they? I guess you can cut the springs maybe? I know the WP4860s can be adjusted by swapping a spacer and I thought the Extremes were that way too.

Of course, if you're extending your swingarm or building a bike for racing that's not an issue. Some of us are still getting our groceries on these things though.

I've always assumed that BMW owners tended towards WP forks because they're European and BMW owners are snobs Oh, and I'm an ass already so assuming things really only affects U.
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Old 04-06-2013, 01:12 PM   #1483
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Originally Posted by chollo9 View Post
I'm running .70s in my DR forks on my R90/6 conversion. Started off with 15mm preload and have reduced it to 5mm. 10wt fork oil at 6.5" from the top. Racetech emulators too. I'm happy with their performance.
I'm not sure what sort of valving there is in the DR/DRZ forks, but I recently learned that with shimmed valving, you should not try to tune the forks with oil weight. You can, but heavier oil causes shim deflection issues where the shims get permanently bent. I was told to go with 5 or even 2.5 on my WP forks. This not only saves the shims, it doesn't put as much pressure on the seals, and doesn't get affected by temperature as much, no need to change oil in the winter. Much better to have stronger shims and light oil than wrong shims compensated for by thicker oil.
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Old 04-06-2013, 02:44 PM   #1484
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I'm not sure what sort of valving there is in the DR/DRZ forks, but I recently learned that with shimmed valving, you should not try to tune the forks with oil weight. You can, but heavier oil causes shim deflection issues where the shims get permanently bent. I was told to go with 5 or even 2.5 on my WP forks. This not only saves the shims, it doesn't put as much pressure on the seals, and doesn't get affected by temperature as much, no need to change oil in the winter. Much better to have stronger shims and light oil than wrong shims compensated for by thicker oil.
There are different types of DRZ forks. With and without re-bound damping.

The best thing about the cardridge forks are that you can re-shim them so you can deside what type of oil you would like to use. To thick will be effected by temperature or can not go through the holes fast enough on fast movements.

Using thicker oil in a cartridge fork can be usefull when forks are worn and than there might be no controle on low speed movements of the fork when using the thinner oil. Replacing the worn parts is still the best option. But even WP them self don't have all the parts anymore to service the 50mm forks.
A lot of forks have bleed holes in the pistons, than using oil thats to thin causes the same loss of low speed damping as a worn piston ring. Than you can put more or thicker shims on the piston but that won't help if the oil leaks past the adjustment, or a worn piston ring or the bleed holes in the piston . All those shims will give more high speed damping.

That low speed damping is the thing that keeps your suspension from gaining speed. If it does gain speed you need more high speed damping to get it back in controle again.

Now lets stop talking about those DRZ forks before evereybody is looking for them and they get more expensive
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Old 04-06-2013, 03:44 PM   #1485
chollo9
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Originally Posted by naginalf View Post
I'm not sure what sort of valving there is in the DR/DRZ forks, but I recently learned that with shimmed valving, you should not try to tune the forks with oil weight. You can, but heavier oil causes shim deflection issues where the shims get permanently bent. I was told to go with 5 or even 2.5 on my WP forks. This not only saves the shims, it doesn't put as much pressure on the seals, and doesn't get affected by temperature as much, no need to change oil in the winter. Much better to have stronger shims and light oil than wrong shims compensated for by thicker oil.
You're right. Those are old methods that were used with non-shim stack dampers (ideal world, Prutser's comments above aside). Today you use what the manufacturer or aftermarket company specifies and tune the damper itself.
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