Monster 620 Forks

[Research Monkey]

So I searched for fork/forks/dive/braking etc. etc. but couldnt find anything.

I picked up on 05 620 yesterday and one thing i've noticed is that they dive under "heavy" braking.  I assumed before purchasing that the forks were adjustable and figured i'd just stiffen them up a tad.  Well yeah... they aren't adjustable.  I'm wondering if they are completely shot or if they just need the oil replaced.  The bike only has 3600 miles on it...

Thanks in advance~

[mstevens]

I had my front forks tuned by my trusted dealer. They replaced the springs with ones of a different rate and changed the oil weight. I am of a non-Italian-teenager build, so this made a big difference in handling.

[A.duc.H.duc.]

As mentioned earlier, the monsters are setup for your average male "italian teenager", meaning they are set up for a rider with a weight of about 160-165. Us americans are a wee bit fatter on average, so some springs, and oil are generally in order to get them much better.

[Buckethead]

Forks are probably fine for what they were designed for, which is someone who weighs aprox. 160 lbs. Anything more than about 180 and they're gonna feel really soft.

Option a) New springs/oil. Figure $250-400 or so, less if you do it yourself. Won't make the forks adjustable, but having springs that are meant to take your body weight and riding style will keep the suspension from feeling like its made of marshmallow.

Option b) SBK fork swap. $250-500 for basic forks, more for higher end, plus cost of any machining/shimming/spacers needed. Possibly another $250-400 for different spring rates, as well, but then you'll have adjustable forks with the right spring rate. Any of the **8 forks _should_ fit the triples, as long as they're 50mm diameter. **9 forks are 53mm dia. top and 49mm bottom and will require machining/shimming to work. Its also generally agreed that stock spring rates for SBK forks are unnecessarily stiff for most Monster riders. May require spacers for the brake disks as the calipers will likely be mounted slightly further out. Someone who's done this want to chime in? Also, SBK forks are about an inch longer than stock Monster forks so to keep the front end geometry the same you'll need to plan accordingly. Could cause clearance issues if you use a handlebar, but this can be solved by switching to clipons.

Option c) Other bike fork swap. Lots of other bikes use a 50mm fork. You may have to use a Suzuki front wheel, or a good shop should be able to swap fork bottoms, or those forks may fit your Monster wheel. Too many variables to say for certain. It is doable and the results can be quite good. Same clearance issue will probably apply as the stock handlebar will be right on top of your preload adjusters. Again, clipons solve this.

Option d) Say screw it, take out a home equity loan, take the bike to the dealer and have them swap in some Ohlins. Mega $$$

Option e) Starvation diet and boot camp style workout regiment until you, too, weigh 160lbs.

[fasterblkduc]

So I searched for fork/forks/dive/braking etc. etc. but couldnt find anything.

I picked up on 05 620 yesterday and one thing i've noticed is that they dive under "heavy" braking. 

Good news... that means that they work.

Before anyone can suggest throwing lots of $ at it, more info is needed. Have you checked the sag? Are you bottoming the forks on braking?
 

[Research Monkey]

Great info guys! Thanks for so many responses!

Good news... that means that they work.

Before anyone can suggest throwing lots of $ at it, more info is needed. Have you checked the sag? Are you bottoming the forks on braking?

I'll be putting a zip tie on the forks tonight to actually measure how far they are traveling.  When i say diving, i mean that they arent stiff at all.  All they do is dive.... for instance, i can be going 160 down the front straight @ California Speedway and slam on the front brakes to make turn 1 and they don't dive like the monsters forks do grabbing the brakes at 30mph.

[fasterblkduc]

Gotcha. Do you know if the previous owner changed the springs? How much do you weigh? How much did the previous owner weigh?
 They are obviously non adjustable but you can set them up pretty good. Racetech has springs and you can adjust the preload by the length of the spacer in the bottom. Plus your compression and rebound are affected by the weight of oil. You're going to check for bottoming but also check your sag and try to figure out what springs you have in it. You can take the cap off, and get to the spring easily. It's not hard to see what the spring rate is because it will be stamped into the top of the spring.

[Research Monkey]

Gotcha. Do you know if the previous owner changed the springs? How much do you weigh? How much did the previous owner weigh?
 They are obviously non adjustable but you can set them up pretty good. Racetech has springs and you can adjust the preload by the length of the spacer in the bottom. Plus your compression and rebound are affected by the weight of oil. You're going to check for bottoming but also check your sag and try to figure out what springs you have in it. You can take the cap off, and get to the spring easily. It's not hard to see what the spring rate is because it will be stamped into the top of the spring.

Thanks for the info.  I weigh about 185 and the previous owner didnt really have it long enough and was pretty new to riding. I'll be checking the spring rate, but i'm pretty sure everything is OEM.  I might end up going to my local suspension shop to have the forks done. 

[clubhousemotorsports]

Springs are marked some times from the manufacturer, often after they have been used you would be hard pressed to read anything.
As the fork moves so does the spring and markings tend to wear off quickly.

Springs will fix your problem.

I believe that I actually did Mstevens  forks and I would bet that he will tell you it is a noticable difference.
The forks you have are limited in what you can do to them but just adding springs will make a  big change for the better.
Good luck

[Hyperion]

Forks are probably fine for what they were designed for, which is someone who weighs aprox. 160 lbs. Anything more than about 180 and they're gonna feel really soft.

Option a) New springs/oil. Figure $250-400 or so, less if you do it yourself. Won't make the forks adjustable, but having springs that are meant to take your body weight and riding style will keep the suspension from feeling like its made of marshmallow.

Option b) SBK fork swap. $250-500 for basic forks, more for higher end, plus cost of any machining/shimming/spacers needed. Possibly another $250-400 for different spring rates, as well, but then you'll have adjustable forks with the right spring rate. Any of the **8 forks _should_ fit the triples, as long as they're 50mm diameter. **9 forks are 53mm dia. top and 49mm bottom and will require machining/shimming to work. Its also generally agreed that stock spring rates for SBK forks are unnecessarily stiff for most Monster riders. May require spacers for the brake disks as the calipers will likely be mounted slightly further out. Someone who's done this want to chime in? Also, SBK forks are about an inch longer than stock Monster forks so to keep the front end geometry the same you'll need to plan accordingly. Could cause clearance issues if you use a handlebar, but this can be solved by switching to clipons.

Option c) Other bike fork swap. Lots of other bikes use a 50mm fork. You may have to use a Suzuki front wheel, or a good shop should be able to swap fork bottoms, or those forks may fit your Monster wheel. Too many variables to say for certain. It is doable and the results can be quite good. Same clearance issue will probably apply as the stock handlebar will be right on top of your preload adjusters. Again, clipons solve this.

Option d) Say screw it, take out a home equity loan, take the bike to the dealer and have them swap in some Ohlins. Mega $$$

Option e) Starvation diet and boot camp style workout regiment until you, too, weigh 160lbs.

So for option B you cannot use S2r 1000 forks in the 620? What about 695? There was a thread a few days ago with someone asking about 695 fork upgrades but i cant find it and I think he ended up just buying springs and diff weight oil.

[mmakay]

So for option B you cannot use S2r 1000 forks in the 620? What about 695? There was a thread a few days ago with someone asking about 695 fork upgrades but i cant find it and I think he ended up just buying springs and diff weight oil.

I think the 695 uses the same forks as the 620.  If they aren't the same, they are no better.  I'm about 200lbs, and my 695 is very dive prone when braking, too.

[clubhousemotorsports]

Depending on the year of 620 the 695 forks may even be worse.
As already stated by others the two best options are
1. springs and oil and get it much better for little money.
2. fork conversion, this will cost much more but you are buying forks that have more adjustability built into them.

[speedevil]

The 620 and 695 forks are roughly the same - same outer diameters, same lack of external adjustability.  Of course, you can adjust the preload/sag by replacing the springs with ones of the proper rate and then set the sag by altering the spacer length.  Not terribly convenient, but it works.  Compression and rebound dampening can only be adjusted by using different weight fork oil - thicker oil = more dampening - lighter oil = less dampening.

On my 695, I am replacing the forks with forks from an 05-06 GSXR1000.  I have new .85 kg/mm springs from Traxxion ready to go in and the spacers are being made so I can use the Duc wheel, brake rotors, and fender.  I will rebuild the forks before installing the new springs.  When I'm done, I will have external adjustments for preload, compression dampening, and rebound dampening.  I'm not an expert at dialing in suspension, so trial and error will have to do.  What a shame that I'll have to ride a lot to be sure the setup is right for me.

EDIT: I've installed risers so the adjustable fork caps will have no clearance issues with the stock bar.  Clipons would solve the clearance problem too.

I'm not sure what to do about the rear shock/spring.  I'll cross that bridge when the forks are swapped.

Any suggestions on the rear shock?

[brad black]

there's a couple of issues with the marzocchi forks, not sure if they're similar to the showa or not.  i haven't had many late non adj sjowa apart to remember.

1/ springs are more dual rate than progressive, so they give a lot of sag and initial movement and then go to the heavier rate, which is about 0.85 from my calcs.

2/ the compression damping valving gives no damping in about the first 2/3 of travel.  then in the last 1/3 it has damping.  no idea why they did it like that.  they have rebound all thru the stroke.

so the net effect of soft spring rate in the inital travel, plus no compression damping, is lots of dive under braking.  even low speed stuff would have my bike diving like mad, and i've almost fallen off a couple of times at no speed running thru traffic because of the sudden "didn't see that car - brake" manouver with the bars turned, etc.  really annoyed me.  i replaced my std springs with 0.85 a couple of months ago, and while the sag and dive is better, it's still a bit annoying.  the early marzocchi - up to '00 or so - are not revalveable, the cartridges do not come out.  dunno about the later stuff.  all the showa you can revalve.

also, all the adjustable damping in the world is no use if the basic damping settings are off for the bike or style of riding.  and, if the adjusters are the usual bleed valve style, all they are doing is letting oil bypass the shim stack, which is the basic advantage of cartridge suspension anyway - to get away from oil just flowing thru round holes.  with a good shim stack you should be able to run the adjusters fully closed or very close too.

altho some systems do load the shim stack - the marzocchi duo shock in my 851 has a load of opposed conical shims (like a bellows) on the rebound adjuster rod that compress and load the shim stack.  of course, out of the 60 or so clicks of adjustment, it's only on the last 7 or 8 that you can actually feel any difference.  and it's crap anyway.

[clubhousemotorsports]

The 620 and 695 forks are roughly the same - same outer diameters, same lack of external adjustability.  True externally but there is a newer damper cartridge being used that is far worse than what the early forks used. You  an tell if you have this version by the size of the damper rod shaft.