sag - are you getting it right?

john

i have 104mm sag which is right on the border line of what the '02s should have (85-100mm) i uysed to run 90mm but when the shocks aren't right which bit do you blame first?

i have a lot to do. so we'll see...

regards

Taffy

well i practiced today for the first time since the 'john banks' in november and really enjoyed my new focus of 'suspension'.

you'll agree that this has been overlooked by me but for a lot of good reasons over these last four seasons.

but focus i did today.

i rode with my usual set up and all the standard husey clicks, gladly knowing that i would twiddle away at them as i went.

i had to back the fork comp off 5 then a further 3 clicks.

on the rear i was being launched so i put the rebound in 3 and then did a sag test.

i'll tell you all now that i usually measure from above the wheel nut to the split in the seat pan around behind the number plate area and into a little 'V'.

610-575-500. so it was 110 race sag and 35 sag.

the front felt like a rubber ball storing energy as i hit each bump so i wound the fork comp a further 3 for a total of 11 out. sheeeesh!

i was unable to use all the front end travel regardless of the comp backing off and every ride the zip-tie measured 50mm of unused travel.

i forgot to take a syringe and pipe with me so i was stuck with 'as was' settings there.

wound the rear spring in (71-90 260) from 245 to 241mm = 2 turns and the sag was now:

610-587-511. that's 99mm and 23mm.

it turned so much easier into the corners that i wondered what i'd been doing all my life! this bike likes the rear jacked up and unfortunately it's the wrong spring that's in. but at least i know what i need now.

regards

Taffy

ok, i'm out again this sunday testing the sussies at yet again - swaffham!

this is what i'll test:

the forks have had 4 or 5 jobs done at once which i stotally against my usual style.

this is what i've done:
i did the 17-18cm drill hole mod (anti bilge)
polished the cartridge rods to gleaming finish
turned the rebound taps down - the same as the OEM ones from '03 onwards.
drilled the bottoming cones

i left the rebound valves as was because tom on katoom talk hasn't identified the EXACT dimensions.

so the above 4 changes represent the first test.

the second test and more will come about as a knock-on from the above and i'll check whether the bottoming cones are part of or the cause of the forks not bottoming.

then i shall modify the air gap from it's present 128mm through to 140 i suspect. 16ML is 10mm of travel so i may be taking out a wee dram or two! long, long tube and the hydraulic clutch syringe should do the job.

i shall also try a ride height of 85-95mm. the test last week showed 99mm to be far better than the 105mm i had. i had a little headshake but this week my re-greased headraces have settled so that shouldn't happen again.

finally, i should collect tomorrow, and therefore test, a PDS-2 spring from dave clarke racing. he is kindly loaning this to me.

that should be enough for one day!

regards

Taffy

Firstly
I think its good that most of you are discussing your suspension and developing opinions. Setting sag is subjective and should ultimately reflect each riders personal preference.
Figures quoted by factories and tuners should be considered as guidlines or a base point from where you guage the initial performance and adjust from there. The important thing to realize is that when you set your sag you are in fact determining the final geometry of the motorcycle. Riding styles vary as do the demands each rider places on the motorcyle. Faster riders will experience greater amounts of G-forces being generated under acceleration, cornering, braking etc. This will have to be accounted for. Someone who sits down all the time places more weight over the rear compared to the front. Smooth tracks favour less sag for added drive and better starts, while rough tracks favour more sag for better compliance under acceleration and greater stability whilst braking. Set your sag at a nominal figure and ride over a familiar piece of track. Adjust the sag by 5mm and ride again. If the ride felt worse than go the other way. If it got better then adjust by another 5mm in the same direction. You will soon work out where the best position for your requirements is. Most people look to forums for easy answers. Ultimately you can only gather ideas. The answers will come when you dedicate the time to your own testing and evaluation.
Terry Hay

cheers terry for that. i wish i'd focused more than i did until recently but the suspension has never held my interest like tuning. i've finished the tuning for now and this seemed the place to focus.

swaffham, soft mud, loamy damp soil that has luckily few single track ruts due to the track attendees being just 15 riders most times.

forks
today i found the bike was plusher on what i thought were going to be nasty spikes that i braced myself for. i take this to be having machined back the rebound taps so that the 4 x 24 midvalve shims could arch their backs. i've gone straight to an immitation of ZP3s taps.

however, the front still feels a little like a rubber ball and i pulled in and removed 28cc of oil. from each leg. this gave me another 15mm or so of travel but i could have done with taking more out. i still have 40mm of leg left.

the comp was wound off all the way to zero so this week i will make my first attempts at a BV stack. and reduce that oil height. i may even change the MV first and leave the BV until the day.

shock
i also fitted a rear spring halfway through the afternoon. for the record: 200lb rider with PDS7 spring - 76/95 265? long. i wish i'd measured it's free length to be 265mm for sure because it went to just 254mm long for the sag figures of 98mm and 40mm.

i didn't notice much difference on the soft soils but i detected slightly less spike on mild stuff. minimal.

the next spring up is a PDS8 - 8.1/9.95 265mm long and averages '9' where as i've gone from a PDS1 260mm (7.1/9.0 averaging 8.05) long crushed to 245mm and now a PDS7 265?mm (7.6/9.5 averaging 8.5) long crushed to 254mm. so i think if i were to find a PDS8 averaging 9 i might have a spring with a very light preload.

all the comp is off and the rebound (oddly given that the spring weight went up) is out as well to 20.

the forks have been beating the shyte out of me for 4-years and i'm determined that i should at the age of nearly 45, get a plusher and less exhausting ride!

i'll post the numbers i've gone for this week.

regards

Taffy

with the bike and shock cold i measured the sag at 99/29. the 99 is better than anything over 100 for turning but there seems little point in winding it up further at this point.

so this evening i went over to the NEW white power importers house at bury st. edmunds and had my shock leak sorted. i also bought a new PDS8 spring whilst i was there.

it's an 8.1-9.95. from what i can tell, i need a 9.2 straight so this should have a good progressive rate. that will be tried this sunday and also how much difference losing that thimble of oil out of the shock had cost me.

i will then try the bike with sag numbers of LESS than 100mm towards the 85mm mark.

regards

Taffy

I also am not done fiddling with my rear spring either. In a quest to try and cure my bottoming out problem, I am fitting a Factory Connection "big boy" progressive spring. It is, I believe the dealer told me, a 9.2/11.5. This spring is available through any Parts Unlimited dealer. I have proper sag numbers with a 8.8, but it just goes through the travel too fast on big hits. Adjusting the compression in does not help.

On the front, the 46's I bought are proving too soft still also. Think I'll throw some 48's in and call it good. Overall, I am happy with the overall suspension, I don't really want to screw up the overall action with a revalve, so I am trying to address it with springs. We'll see.

MMMMMM! interesting!

last week i was talking to chris hocky who races in the WEC and runs a suspension company fore his living. he told me that over recent years the tuners have gone strong on the right spring and soft on the valving.

brilliant...

you're on the money fella!

regards

Taffy

back to swaffham again today. i arrived 2-hours after the gate opened and as planned the track was drying nicely.

here again is a chart of springs

PDS0-250 6.5 - 8.3 7.4 average
PDS1-250 7.1 - 9 8 average
PDS2-250 7.5 - 9.7 use .44 fork springs 8.6 average
PDS3-250 8 - 10.3 9.15 average
PDS4-250 8.5 - 11 9.75 average
PDS5-265 6.6 - 8.6 7.6 average
PDS6-265 7.15 - 9.05 8.1 average
PDS7-265 7.6 - 9.5 use .44 fork springs 8.55 average
PDS8-265 8.1 - 9.95 9 average

i have been using the PDS7 for the last 3 weekends and the preload was 253-254mm. it was a lot better than the PDS1 i got with the bike but today i fitted the new PDS8 which will need bedding in and the preload/ride height checking.

the sag of 99mm was 116mm today with the mud etc so i pulled the PDS7 and fitted the PDS8 and set it to exactly the same sag. the 7 was on 254mm and therefore a preload of 6mm whilst the 8 has a preload of 1.5mm and is at 258-259mm. what a difference this made! instead of sinking into the bottom of each whoop it now rides the top of them.

there was a nice little jump on the course and as i landed both ends sank very little, sank together and the time saved in opening the throttle is palpable. the comp is completely out and the rebound is completely out.

this week i'll check the sag again and will test it next week to see how that 99mm sag goes at 95mm and maybe even less!

regards

Taffy