Cartrige emulators in a 650G, seeking advice

[Charlie G]

My forks are rebuilt and I'm ready to drop in Mike's emulators, springs and oil. The insturctions state to use the lowest preload setting (none) and the 650 dosen't have any preload adjustment. It has two springs. A long one which is uniformly wound and a shorter one, which seems to be progressive wound. If I don't shorten one spring I assume I will be increasing the preload. I thought of replacing the shorter spring with a PVC pipe spacer, shortened to allow for the thickness on the emulator(1/2"). Any advice would be welcome. I want to ride tomarrow. The Salmon river calls me........................!

Options I'm considering,

1-cut springs
2-install a shortened PVC spacer in place of short spring
3-stuff the standard springs in and call it good


Thanks



Charlie G

 

[posplayr]

Charlie,
Fork preload is set by measuring the sag. There is procedure in the link below for Ohlins but the same basics apply.

http://www.thegsresources.com/_forum/showpost.php?p=994640&postcount=7

Are you using the stock springs? they are probably be tired and you will want to stiffen them up by cutting them. That makes them stiffer . Figure is the spring is 30" long and you remove 3" then it will be 10% stiffer. People to 4-5 inches sometimes I guess without binding the spring. You idea a removing the small spring and using a PVC spacer is like cutting off the same amount.


You should be able to tell better when you stand after doing the sag measurements.

Basically other than spring rate (stiffness) you only have the preload adjustment. So you can either get the static sag correct on the loaded sag. but not both if the spring rate is wrong. Try to get both in a reasonable range using preload. If you cant get there make the spring stiffer..

Jim

 

[Charlie G]

Charlie,
Fork preload is set by measuring the sag. There is procedure in the link below for Ohlins but the same basics apply.

http://www.thegsresources.com/_forum/showpost.php?p=994640&postcount=7

Are you using the stock springs? they are probably be tired and you will want to stiffen them up by cutting them. That makes them stiffer . Figure is the spring is 30" long and you remove 3" then it will be 10% stiffer. People to 4-5 inches sometimes I guess without binding the spring. You idea a removing the small spring and using a PVC spacer is like cutting off the same amount.



You should be able to tell better when you stand after doing the sag measurements.

Basically other than spring rate (stiffness) you only have the preload adjustment. So you can either get the static sag correct on the loaded sag. but not both if the spring rate is wrong. Try to get both in a reasonable range using preload. If you cant get there make the spring stiffer..

Jim

I'm using the stock springs with emulators. Bear in mind I'm only 148 pounds and I don't generate much sag.

Thanks Jim.

cg

 

[Charlie G]

I cut the short spring .58"+ or - on the bottom end. Added 10lbs of air to the forks and went for a 190 mile run. Dive is gone but it's a tad stiff over bumps and rocks front to back. I have stock shocks on the rear and when I have some spare cash I'll replace them. I set the emulators at 2-1/2 turns. I plan on taking a run with no air added to the forks and see how it feels for comparison. I use to ride with 12psi with stock spring and did fine, although the forks would dive quite a bit in hard turns.

Still have a slight slow speed wobble when I have a loose grip in the handel bars. Anyone want to point me to a cause?

cg

 

[Chuck78]

Charlie can you help me out with the fork oil level or volume for a GS650G 1981? I am rebuilding them and installing the Mikes xs emulators as well, but I have only GS 750 and GS 550 manual to reference the fluid levels and they show about 15 different levels of fork oil depending on model!

 

[tkent02]

Don't cut anything until you try it.
Put it together and see how you like it.

 

[Chuck78]

Cut the springs more (7 to 11 coils total), run air spring pressure at 0psi, then test ride it - I think you will be happiest there. Maybe back emulator out to 2 turns if you want it a little softer on the dampening. 8 or 9 coils cut will be much much better for brake dive. that's where my GS750 springs are at, rate-wise. My '77 KZ1000 buddy who I gave the GS650G springs to chopped 10 coils out of them for his bike and said it totally transformed the way the bike rides. much more confidence, MUCH MUCH BETTER HANDLING, practically eliminated noticeable brake dive...

too many late late nights working on projects, running on empty and ready for a post-work nap, but the damper rods and drill press are calling me from the basement! Gotta finish the forks on the bench and yank my carbs off tonight, bolt the wheel and calipers up and test the brakes out to make sure the used Tokico Twinpot calipers (from a Ninja 600EX) are okay. Then move on to the carbs!

 

[Chuck78]

It occurred to me that with the emulators the oil level may not be quite as critical, more of a baseline spec. In the xs emulator instructions it says to install the factory oil amount and then verify that the emulators are submerged in the oil

 

[posplayr]

It occurred to me that with the emulators the oil level may not be quite as critical, more of a baseline spec. In the xs emulator instructions it says to install the factory oil amount and then verify that the emulators are submerged in the oil

I have removed the springs, dropped the emulators in and push the forks up to full compression and measure the oil height as per factory settings.

 

[Charlie G]

Charlie can you help me out with the fork oil level or volume for a GS650G 1981? I am rebuilding them and installing the Mikes xs emulators as well, but I have only GS 750 and GS 550 manual to reference the fluid levels and they show about 15 different levels of fork oil depending on model!

The Suzuki factory manual states to use 210ml of 15 w fork oil and with the springs out of the froks it should be 6.5" from the top of the frok tube. To achieve 6.5" I had to add a bit more oil.

cg

 

[salty_monk]

I would have left out the small spring & replace with spacer allowing for the extra height of the emulator. This will give you a straight weight spring which is best for emulators.

Worked fine when I did it that way on a 550....

If you've cut the spring I would suspect you to need to cut off at least 2" - maybe as much as 4". Remember you can always cut more off.
It's always better to get the sag right with the spring rate (by cutting or replacing) rather than just adding preload, the less preload the better as it's really a "crutch". You want about 30mm of sag (put a jack under it & measure to a known point with fork on full extension then sit on it with it down on the ground get someone to measure to the same point) with full gear on.

I would run 10w oil with the emulators. Stock oil height & run the emulators at 2 turns (that's what I have on the 1000 right now). You'll be way overdamped on compression at the moment with both 15w oil & 2.5 turns - that's why it feels so stiff over bumps. The 10w will also help with the rebound. Using 15w is another "crutch" to work with the original non adjustable setup.
You shouldn't need any air.

Your low speed wobble is likely to be:

1. Head bearing adjustment
2. Swingarm bearings worn out

I doubt it is anything to do with the forks if it is stable at high speed.

Dan

 

[posplayr]

I would have left out the small spring & replace with spacer allowing for the extra height of the emulator. This will give you a straight weight spring which is best for emulators.

Worked fine when I did it that way on a 550....

If you've cut the spring I would suspect you to need to cut off at least 2" - maybe as much as 4". Remember you can always cut more off.
It's always better to get the sag right with the spring rate (by cutting or replacing) rather than just adding preload, the less preload the better as it's really a "crutch". You want about 30mm of sag (put a jack under it & measure to a known point with fork on full extension then sit on it with it down on the ground get someone to measure to the same point) with full gear on.

I would run 10w oil with the emulators. Stock oil height & run the emulators at 2 turns (that's what I have on the 1000 right now). You'll be way overdamped on compression at the moment with both 15w oil & 2.5 turns - that's why it feels so stiff over bumps. The 10w will also help with the rebound. Using 15w is another "crutch" to work with the original non adjustable setup.
You shouldn't need any air.

Your low speed wobble is likely to be:

1. Head bearing adjustment
2. Swingarm bearings worn out

I doubt it is anything to do with the forks if it is stable at high speed.

Dan

i have to check what I have on the shelf but I'm pretty sure it is 15w and I either went 2 1/4 or 2 1/2 as recommended by race tech for my 1100ed with 88 GSXR 1100 forks. I weigh a little more at 210 lbs and think some of the other guys were setting up similar. Of course you two are both lighter so the 10w with fewer turns is probably more appropriate.

 

[posplayr]

I would have left out the small spring & replace with spacer allowing for the extra height of the emulator. This will give you a straight weight spring which is best for emulators.

Worked fine when I did it that way on a 550....

If you've cut the spring I would suspect you to need to cut off at least 2" - maybe as much as 4". Remember you can always cut more off.
It's always better to get the sag right with the spring rate (by cutting or replacing) rather than just adding preload, the less preload the better as it's really a "crutch". You want about 30mm of sag (put a jack under it & measure to a known point with fork on full extension then sit on it with it down on the ground get someone to measure to the same point) with full gear on.

I would run 10w oil with the emulators. Stock oil height & run the emulators at 2 turns (that's what I have on the 1000 right now). You'll be way overdamped on compression at the moment with both 15w oil & 2.5 turns - that's why it feels so stiff over bumps. The 10w will also help with the rebound. Using 15w is another "crutch" to work with the original non adjustable setup.
You shouldn't need any air.

Your low speed wobble is likely to be:

1. Head bearing adjustment
2. Swingarm bearings worn out

I doubt it is anything to do with the forks if it is stable at high speed.

Dan

i have to check what I have on the shelf but I'm pretty sure it is 15w and I either went 2 1/4(eased of a bit) or 2 1/2 as recommended by race tech for my 1100ed with 88 GSXR 1100 forks

 

[salty_monk]

Charlie's bike is lighter as is Charlie. He's controlling a lighter spring.
I am using the same emulators he has.
There's no way he needs heavier oil than I have fitted.

15w oils is usually used to up the damping rates on a stock fork.

when you have the adjustment for compression that emulators provide you don't need to go that heavy.

 

[Charlie G]

I would have left out the small spring & replace with spacer allowing for the extra height of the emulator. This will give you a straight weight spring which is best for emulators.

Worked fine when I did it that way on a 550....

If you've cut the spring I would suspect you to need to cut off at least 2" - maybe as much as 4". Remember you can always cut more off.
It's always better to get the sag right with the spring rate (by cutting or replacing) rather than just adding preload, the less preload the better as it's really a "crutch". You want about 30mm of sag (put a jack under it & measure to a known point with fork on full extension then sit on it with it down on the ground get someone to measure to the same point) with full gear on.

I would run 10w oil with the emulators. Stock oil height & run the emulators at 2 turns (that's what I have on the 1000 right now). You'll be way overdamped on compression at the moment with both 15w oil & 2.5 turns - that's why it feels so stiff over bumps. The 10w will also help with the rebound. Using 15w is another "crutch" to work with the original non adjustable setup.
You shouldn't need any air.

Your low speed wobble is likely to be:

1. Head bearing adjustment
2. Swingarm bearings worn out

I doubt it is anything to do with the forks if it is stable at high speed.

Dan

I will change the oil to 10w and pull the emulators out and set them a 2 turns and see what happens. I'll also check the sag. I didn't bother as I only cut the thickness of the emulators out of the top springs. I was unsure as what to do and as you say I can always cut more later. The springs, before and after I cut them, stuck out of the tubes a quarter of an inch. I didn't think this would much of a preload. This is the first time for this type of work for me, so I really don't know what I'm doing. I was somewhat unhappy with the stiff ride and was afraid I had sacrficed some comfort I'll need going to rallies. I did enjoy the confidence and lack of dive going into corners, although I didn't push to hard as I haven't got my riding skills up to speed from a winter off the road.

Thanks for the comments Dan and Jim I'd be running blind without some advice.

I suspected head stock for the wobble. It's happens at about 25-35 mph, in a straight line mostly when I have a light grip on the bars. I'll look up the adjustment procedure. Swing arm bushings....another item on the list. Brake lines were the next priority, but I need to get this finished right.

Yes I'm light. About 148 with my work clothes/boots on and the bike I think is about 465 lbs.


Thanks guys!

 

[Wizard]

Head Shake

Head Shake

"Head Shake" can also occur from a Front Tire worn Flat in the middle.
More pronounced on roads with pavement worn into 2 tracks by heavy trucks.
Though the roads around your area are more likely to wear your tire sides.
Check Tire Pressure too.

 

[salty_monk]

The ride will be much more compliant with lighter oil & emulator adjusted etc.

If you want to leave the oil for now I would try the emulators with 1.5 turns instead of 2.

You now have 2 separate damping circuits instead of one piston trying to do both (not particularly well).
You can now adjust oil weight to adjust rebound damping and adjust the emulator to adjust compression damping (remembering that you need to adjust the emulator to compensate for a different oil weight if you want the same level of compression damping you had before you changed the oil... )

The harshness is likely too much compression damping (hence the reason you can change oil & emulator adjustment or just adjust the emulator).

By the way there is usually 2 or 3 springs in a GS fork. The bottom short ones are top out damping springs. Then there is usually either a long progressive wound long spring or 2 shorter straight rate springs stacked one on top of the other. In the latter setup the lighter spring is usually about 4" long & you'll notice the wire will be lighter (smaller dia) and the coils will probably be closer together.

Good comparison of progressive versus dual rate on this link: http://www.baggersmag.com/tech/1006..._progressive_suspension_upgrade/photo_13.html

Dual rate springs