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Old 04-23-2011, 02:17 PM   #1
OhioPT OP
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Joined: Sep 2007
Location: Columbiana County, OH
Oddometer: 1,095
Project WeeStrom 7.5

What Is It?
A 2004 DL650 with 7.5 inches of front and rear suspension travel, and 7.5 inches of ground clearance.







What I Did
I modified the damper rods of my front forks to gain 40mm of front suspension travel, and to increase the ride height. My front ride height increase is actually 27mm over stock, with the proper rider sag dialed in and accounting for the rake of the chassis. Custom springs and spacers were necessary to achieve the proper sag. I also have “widgets” installed in the forks, which basically act like emulators to control damping. These have no influence on ride height or overall suspension travel though.

Stock Fork, Full Compression Travel Measured:


Modified Fork, Full Compression Travel Measured:


Modified Forks Installed:


I also raised the rear of the bike with a custom made longer travel shock from Cogent Dynamics. This shock provides 41mm more travel than stock. The actual rear ride height increase with me in the saddle is 29mm with the suspension sag set correctly, which maintains the bike’s handling balance.



This Cogent shock is a premium unit. The shock uses a stiffer spring to obtain the proper sag numbers for my 225 lb weight. For damping, this shock has a remote reservoir with high and low speed compression adjustments, and adjustable rebound near the lower clevis. Rick made the shock with a 46mm body and a 16mm shaft (stock is 40mm and 14mm, respectively). This allows for a greater volume of fluid, therefore providing performance consistency and more accurate adjustability. The shock body and reservoir are both aluminum, which further aids in heat dissipation (the stock shock is steel, and is an emulsion type, with no piston to separate the fluid from the nitrogen).

Custom Cogent Shock Vs Stock Shock with aftermarket spring


Why I Did This
There are 2 major short comings of the DL650 when it comes to rough road/ offroad capabilities: limited ground clearance and limited suspension travel. I want to be able to ride this bike on basically any non-maintained dirt road and not have to worry about getting high-centered. I also want a plusher ride, but with bottoming resistance.

Stock DL650 High-Centered on a trail ride last year


I know the DL is not a dirtbike and I’m not trying to make it into one. I have a couple other bikes for real trail riding. I’m simply trying to improve it to the capabilities of the other adventure bikes out there, such as the Super Tenere, the GS1200, or the new Tiger 800. I know my modified bike’s offroad capabilities fall short of the benchmarks: the KTM 950/990 Adventure and the F800GS. However, those bikes have some reliability issues and price tags that I’m not willing to deal with, and I probably don’t need that much offroad ability for what I do with my Strom. FWIW, I used to own a 950 Adventure.

If you just ride on pavement most of the time, 5-6 inches of travel is all you really need, as it keeps the center of gravity low and minimizes chassis pitch during acceleration and braking, while absorbing most small bumps. Now start taking that bike on beat up roads and the forks/shock will quickly blow through the stroke and bottom out if you weigh over 160 lbs. If you’ve ever bottomed the suspension, you know it is neither pleasant nor safe. Even if you don’t bottom all the way, the last 20mm of travel are rather “firm”, since there is an oil lock piece in the bottom of the fork tube that quickly increases the resistance to travel. It’s like pulling your parachute in a free fall (it’s better than hitting a wall). I’ve bottomed out the stock suspension (preload maxed out) on just beat-up “maintained” roads and potholes, using all 135mm of compression travel.

So the typical thing to do is install stiffer springs (30% higher rate than stock in my case) and heavier fork oil, and maybe emulators (I did all the above). Now the suspension is less likely to bottom out, which is good. Those same roads that used 135mm of compression travel, now only use 120mm of travel and we are almost out of the dreaded oil lock territory. However, we now have to deal with less compliance (i.e., plushness) over all the smaller impacts. Simply put, the suspension now moves less and the chassis moves more. Not a great compromise for comfort or traction, but better than stock in most people’s opinions (mine included).

With the 40mm increase in travel, I was able to lower the spring rate by 10-20% because there is more travel in the suspension before it will bottom out. Yes, it will still eventually bottom out, but all the impacts up until bottoming cause less chassis movement and better tire contact with the surface, resulting in better comfort and traction. Those same roads that used 135mm of travel with the stock springs and 120mm with the stiffer setup, now use 130mm of travel (the spring rate is 10% stiffer than stock in my case). Another big difference compared to the stock suspension is my bike stays out of the oil lock territory longer, so even the bigger impacts are nicely absorbed by the suspension (no parachute effect).
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Old 04-23-2011, 02:18 PM   #2
OhioPT OP
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Continued...

Why not raise it even higher?

Center of gravity: let’s face it, raising the bike any amount will raise the COG. Consider the Law of Diminishing Returns: a bike that is too top heavy is going to be difficult to handle when the going gets tough, and will offset the benefits of increased ground clearance and suspension travel. About one inch taller than stock is a great compromise, IMO.
Control: Being able to flatfoot a street bike is important to me for safety reasons, such as controlling the bike at a stoplight. It also provides confidence when trying to maneuver a 500lb bike on less than perfect surfaces. I can comfortably flatfoot my Strom with these suspension changes AND my taller seat. I would not recommend these modifications if you have trouble flat-footing your Strom with the stock suspension and seat.


Fork tube overlap:
using a longer damper rod decreases the overlap between the upper (inner) and lower (outer) fork tubes. There comes a point where this will be detrimental to the strength of the forks. With the 40mm longer damper rods, the overlap only decreases about 15% once the additional rider sag is dialed in. This seems reasonable to me. Those who have done the DR/DL fork mods (which uses a damper rod about 40mm longer) have had no complaints about fork strength.

Limits of the rear suspension: you have to raise the rear of the bike by an equal amount to how much you raise the front, in order to retain its handling characteristics. Raising the rear too much will make the chain ride on the front swingarm guide, increasing its wear. Folks who have raised the rear more than 1.5” have reported this problem.
Brake line length: at some point the front end raise will require longer brake lines. This is not an issue with my setup, even with my modest bar risers, but my bike doesn’t have ABS.

Things to be aware of:
The side stand is too short with these modifications and will cause the bike to lean way over (it’s already a bit short with stock suspension). I cut the side stand and welded in a 45mm long section of 5/8” diameter solid rod. The lift from this was about equivalent to using a 1.25” thick object under the stand (the stand is at an angle, so a 45mm increase in stand length is not the same as using a 45mm thick object under the stand). I still wanted the bike a little more upright so I carved out a ¾” thick block of wood and attached it to the stand foot with a couple screws. The nice thing about this setup is I won’t have to cut and reweld the stand if I decide to lower the bike back down to stock height: easily removing the wood block should allow the modified stand to work.

Modified Sidestand


The center stand is too short. You can use a 3/4” thick piece of wood under the center stand feet to get the rear wheel off the ground, or weld in extensions for a permanent solution. Or, remove the stand and sell it like I did. Some skid plates allow you to use them to jack up the bike. This is the easiest way to work on the forks anyways.
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Old 04-23-2011, 03:52 PM   #3
SlipChip
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Nice work PT!
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Old 04-23-2011, 05:10 PM   #4
sailah
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Haha Mark I read the title and thought our last meeting convinced you to stuff a gsxr 750 motor in your bike....

Looks good. We'll get in a ride soon when I finish my bike
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Old 04-24-2011, 05:19 AM   #5
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Thanks! Hope to catch a ride with you guys soon.
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Old 04-24-2011, 08:20 AM   #6
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Great project.
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Old 04-24-2011, 11:41 AM   #7
Jud
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Nice work and a great write up.
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Old 04-24-2011, 01:33 PM   #8
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Quote:
Originally Posted by Jud View Post
Nice work and a great write up.
Thanks Jud, you definately inspired me with your DR/DL fork conversion.
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Old 04-28-2011, 06:03 AM   #9
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great write up. cheers !!!!
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Old 04-28-2011, 06:05 AM   #10
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Who exactly did you speak to at Cogent as I think I am going to order the exactly same shock that you did. Shipping is kinda not relevant as I'm on the other side of the world anyhow.
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Old 04-28-2011, 06:22 AM   #11
OhioPT OP
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Quote:
Originally Posted by tileman View Post
Who exactly did you speak to at Cogent as I think I am going to order the exactly same shock that you did. Shipping is kinda not relevant as I'm on the other side of the world anyhow.
They are a "mom and pop" operation so it's really just Joyce and Rick. Ask to speak to Rick. Everything should be fresh in his head since he just built my shock a week ago. Ask him what spring rate he recommends for your weight. I went with a 600 lb/inch spring, which is perfect for my 225 lb weight. I set it with a tad more preload (12mm from free length) so I was on the lower end of recommended sag- 56mm, which is 30% of the 190mm total wheel travel. That way I don't have to adjust the preload when I add some gear for a camping trip, etc. If I ride 2-up I will add 6-8mm more preload. I also ordered an $8 Ohlins spanner wrench to turn the preload collars.

You don't want to go too stiff on the spring rate. The shock spring has to have at least 8mm of preload on it for it to perform properly. If you go too stiff you might find that you can only preload the shock like 4mm to keep the rider sag in the recommend 30-33% range for riding solo. That would not be good.
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OhioPT screwed with this post 04-28-2011 at 06:31 AM
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Old 04-28-2011, 09:40 AM   #12
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Thanks.
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Old 05-01-2011, 07:10 PM   #13
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Looking good!

Do you know what the overall length of the shock is without the "shortening spacer" installed? Im looking at mine and I think I want about a 360mm overall length.
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Old 05-01-2011, 07:56 PM   #14
OhioPT OP
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Originally Posted by NADZ View Post
Looking good!

Do you know what the overall length of the shock is without the "shortening spacer" installed? Im looking at mine and I think I want about a 360mm overall length.
Rick told me he made the shaft "a few millimeters longer" so I would guess it could be as long as 358-360mm with the spacer removed. He can make it as long as you want (well, up to a point anyways). 360mm would be more than plenty to play with. Like I mentioned earlier, any taller and you will likely run into issues with clearance (between the chain and swingarm, and also between the lower shock clevis and the swingarm).
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Old 07-22-2011, 09:50 AM   #15
Weekend_warrior
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I Bought a replacement shock from Rick a few years back on my V-strom. Works great. They are good folks and do a hell ofa job.

Mine does not have a remote resevore on it though on it. Yours looks a bit more adjustable. The preload on mine is still easy to adjust. I believe it has rebound, but compression is internally valved. The setup is great on the rear of the bike. I didn't want to mess with the ride height on mine, but it works well for what I use it for. I have been to lazy to tweek with the forks much more. They are a bit on the stiff side now, but atleast there is no dive.....
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