Suspension setting and sag

G

gex

Registered
Hi,

Yesterday i began to ajust my rear "sag",,,when doing this a question came in mind,,,,,is it better to have gaz tank full, half or empty to do the setting? i tried to find the answer but found nothing,,,maybe it is not important but if possible would like to know your opinion.

Too, i am interested to try the below setting(I weight 185), it is supposed to be a good one or a good start...

The question i have about that setting is,,,,does the air pressure in tire important,,,,,,does the setting have been done with let say 32 in both tires and if i run 36-38 should i check(or change) something in the recommanded setting???

Front  
Preload 2.5 lines showing  
Compression Out 2 clicks  
Rebound Out 2 clicks  
Rear  
Preload 1.25inches of sag  
Compression Out 5 clicks  
Rebound Out 7 clicks  

At this moment, i cannot push as hard as i would like my Busa because suspension seems to be too soft(original hard setting) and would like to fine tune as best as i can...

All infos greatly appreciated

Thanks
 
(gex @ Aug. 29 2007,06:56) Hi,

Yesterday i began to ajust my rear "sag",,,when doing this a question came in mind,,,,,is it better to have gaz tank full, half or empty to do the setting? i tried to find the answer but found nothing,,,maybe it is not important but if possible would like to know your opinion.

Too, i am interested to try the below setting(I weight 185), it is supposed to be a good one or a good start...

The question i have about that setting is,,,,does the air pressure in tire important,,,,,,does the setting have been done with let say 32 in both tires and if i run 36-38 should i check(or change) something in the recommanded setting???

Front  
Preload 2.5 lines showing  
Compression Out 2 clicks  
Rebound Out 2 clicks  
Rear  
Preload 1.25inches of sag  
Compression Out 5 clicks  
Rebound Out 7 clicks  

At this moment, i cannot push as hard as i would like my Busa because suspension seems to be too soft(original hard setting) and would like to fine tune as best as i can...

All infos greatly appreciated

Thanks
Click to expand...
do a search on "jinksters suspension setting" very helpfull

you need to sit on the bike to measure sag
 
Air pressure in tires has no effect on setting sag. Anything on wheels and tires is unrelated because it is unsprung weight (not supported by suspension)

Gas tank *shrug* won't have much affect on the static sag settings... there isn't a lot of difference, but I would have the tank 1/2 full to have the best compromise between empty and full...
 
I went with what Sport Rider published a couple of years back. Works well - street or track. Stock suspension.
 
(SpeedGeek @ Aug. 29 2007,10:45) Air pressure in tires has no effect on setting sag.  Anything on wheels and tires is unrelated because it is unsprung weight (not supported by suspension)

Gas tank *shrug* won't have much affect on the static sag settings... there isn't a lot of difference, but I would have the tank 1/2 full to have the best compromise between empty and full...
Click to expand...
+1 good compromise
 
(ozz @ Aug. 29 2007,07:22) do a search on "jinksters suspension setting"   very helpfull    

you need to sit on the bike to measure sag
Click to expand...
+1 on Jinksters settings. They're very good as a starting point to get where you (personally) want to go  
beerchug.gif
 
Thanks guys for your reply.....

Dr and Ozz,,,,the link you provided were excellent infos

SpeedGeek,,,yes i understand that tire pressure does not influence SAG but with the setting i want to try do you think the setting for rebound and compression can be differrent on bike with tires at 32 compare to another bike with 36-38

Now, about setting the rear sag,,,,i did not have too much problem but today i try the front and i think there is something i am not sure........please correct me,,,i should be wrong somewhere......

For the rear, i used the GP method,,,extend the shock completely, sit on the bike and push the rear for 1 inch and finally rise the rear for one inch ,,,and at this moment the rear is at 32mm but will be fine tune when the front will be done...

Today when i tried to do the same with the front,,,,,i turn the preload until 2.5 lines,,,,like the setting i want to try and mentionned above but for me with GP method it does not work but with Jinkster it seems i am closer to the goal to achieve(i am surely wrong somewhere)...i think both don't use exactly the same method.....GP push on the fork and rise them with rider on the bike,,,,,,and Jinkster take a measurement with only the weight of the bike on the suspension and after that a measurement with a rider on the bike.........it is my understanding!

my result with GP method

full extended:                                 127 mm or 5 inches

with the rider on bike
and push on suspension:               70 mm or 2.76 inches

with the rider on bike
and rise the suspension:               80 mm  or 3.15 inches

75 mm is my number  and 127-75 = 52cm or 2.05 inches
so it is still not ok with GP method because i look for 30-35 mm

With Jinkster, i think the result is 39 mm front sag....not sure, i am confudedtrying to undertand both method

Yes i need help....

Does my method of measurement is ok?

I thought after reading a lot that setting the preload at 2.5 should be stiffer,,,,do you think it is normal to have 52 mm of front sag with that setting?

If not, do you think the springs could have been change by the other owner for softer spring for drag race.....

I know i should change the spring even if they are original but at this moment it is difficult and we are supposed to set something good with the original(if they are the original for sure)

If someone can direct me to my mistake,,,it would be appreciated

Thank you
 
you probably won't get the numbers you're looking for.the stock springs are too weak.check this sight out,go to spring calculator www.racetech.com   your weight at 185 the spring rate is .95 kilo for street.and 1.0 kilo for race
The stock busa spring is .85 kilo.
 
Proud Dad is right.... you won't get the optimum number with the stock springs. You will need to get .95 springs to get your "ideal" sag.

However, you should be able to get to a noticeable difference and VERY rideable by following Jinksters setup. I weigh 210 and before I got new springs I made the best of the stockers... I went to only 1 line showing on my front preload.

The Busa also seems to have less travel in the forks than most road bikes.... if you get the "ideal" number, it will likely be VERY stiff for normal riding. Plan on compromising.
 
Thanks for the information

Yesterday evening, for a test, i crank all the preload and mesure,,,,,i got something better .....

Now, my last 2 important questions because i want to wait until next year to change the springs because the riding season is almost over.....and would like to get some improvement with the busa before the end......

1- Is there a reason to not let the preload ajustment at the maximum or i really should turn back half turn or two turn?

2- I read almost everything about setting suspension and some recommand :

28 to 32 mm for rear and 32 to 36 mm for front or
25 to 30 mm for rear and 30 to 35 mm for front or
30 mm front and rear.......

So, now i know i cannot obtain the right front sag,,,,,knowing that my front is at 40mm,,,,should i set the rear at 30 mm like several articles propose or i should set the rear to 35 mm or even more to have a more soft suspension but probably more well balanced,,,,,,,,for me 30 mm rear and 40 mm front is a big differrence when some article mention to have 30 front and rear!!!

Thanks a lot
 
the way I do the front sag is to be on the bike (geared, tank 3/4 full, etc)
friend pushes down on the front and slowly lets it rise back up x3.. record measurement.
same thing but now friend lifts front up and slowly lets it sink back down x3... record measurement.

take thee two measurements divide by 2 and that is the sag number I get.

make adjustments to pre-load and measure again again...

the reason I do this is to get the average. If you just sit on the bike and take the measurement it'll be different each time you do it. The reason I take the average is to compensate for the fork friction.

hope this helps... or did I just muddy things up for ya'?
 
Hi Commuta_Busa,

Thanks but i know how to set the sag but with the result of my stock front springs i ask two questions to help me finish the setting because i won't change the spring this year........
 
Is there someone who have an idea about my 2 questions,

I have read a lot but did not found those info....

Can you recommend a reading???

Thanks and have a good day
 
(gex @ Sep. 01 2007,03:39) NX,

The link does not work!!!
Click to expand...
my link?? if so i just sold my car that i had on the KA-T.org board it was 1 of 10 car on the site that had a page by it self. my car made 486WRHP 468 TQ. and it was a 4-bangger..
biggrin.gif
 
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