fork tuning for enduros

mr le frog sir

taffy is correct 200 lbs it is , in birthday suit with throttle pinned to the stop .
[ and fingers crossed ] .

keep in mind i also had my rear shock serviced , preload correct .

this is the critical factor in the final result .

yes you are correct , the old girl cuts like a knife . :signcool:

been to 'full travel' just now and bought some 48s. i pleaded with DSdan to swop but he must be out or hates me!!!! i can't cope wiv it no more!!

anyway, i have the annual rugby club dinner tonight at which i shall get completely smashed. i'll be at swaffham testing ASAP. the police have said that i'm ok so that's good.

i'm so disappointed in kevin (harris) the nerw WP importer. he sells me standard KTM '05 shim stacks last summer, charges me an absolute fortune and then laughs when i say i want 48s.

"i only sell those to 17 stone blokes" he tells me.

i have to be so PC just to get them. "oh well. i'm sure to be making a mistake. on my own head be it...."

I phuqing hate that. anything that reminds me of being 17 (years of age) again rips my heart out. they laughed at everything you did, sold ya crap and took yer money. c>>>>>>>!

or as i once told bob 'they're not BW they're worse, they're FT'. that dear chaps is the ultimate english insult (old boy!). you don't wanna be called a FT! :lol: :lol:

anyway. we'll see.

regards

Taffy

Bobzilla said:

Nick I see you went with stiffer springs. I used to weigh just a bit less than you but probably ride the open stuff a bit faster also. What about the forks did you not like. I thought they were very good with only firm bottoming on big landings or g outs. Seemed to work good in the rocks as we got lots of them mixed with the sand here. Did you have your valve stack changed too? How is the back. for me that was the problem area to get it to g out well but not rebound too much then and still have it supple in the rocks. hard to get both. Now on my 05 I think I may try the 48's but the forks work pretty good now and I havent gone through all the clickers yet, let alone fork oil levels and weight.
Its always good to try new stuf and find out just what works good for YOU

Click to expand...

Well what happened is that I redesigned the MX-Tech.com Web site and part of the deal was a suspension tune up by the master Jeremy Wilkey himself so I sent the shock assembly and the forks to his shop in Bourbonnais, IL and it came back with a PDS8 in the rear, his brand new needle, and .48 in the front, the entire thing being revalved and refreshed.

By the way it really needed to be redone, the oil was starting to get funky in there, but that's my responsability, so don't get annoyed, the bike had miles on it and I knew it.

Yes, indeed, the rear was not set up to handle G Outs properly for my weight and according the Jeremy, this is part of why I flew over the bar, along with a basic riding mistake (sitting while going at 40mph and not looking ahead).

Below is the dyno chart for my rear shock, compared to a stock 2006 250 SX-F shock. Looks a lot smoother huh.

This also refers to the latest PDS articles posted by Jeremy on mx-tech.com lately.

He is trying hard to make this technology work, apparently.

well i went and tested at swaffham again today. i rolled off the comp clicks 10 and the bike nearly bottomed out leaving just 5mm of travel unused.

the forks had .46 springs fitted with 15mm of packing of which 6mm is preload. so i fitted the .48s and didn't fit any packing whatsoever. this has dropped the front end 9mm on it's own in theory so that the bike rests purely on the top of the springs.

(FOOTNOTE: the springs have a 15mm gap to the cap so they were 6mm shorter than the 46s. that meant the forks were sitting 6mm lower overall with 48s).

in testing, with the zip-ties pushed back up the leg of course-i again had full travel and 5mm left. the springs felt very similar to the 46s. i could feel slightly better steering geometry (for me. i have the KTM 14mm offset triples fitted), i could feel a little bit more of the light stuff and the rebound will need strengthening as she reared her head a bit.

she fairly hopped across the top of the rutted stuff. i need more time in the saddle.

talk to you after next sunday's race.

regards

Taffy

well, i raced today on a very rough circuit, orchards, green fields and crops etc but would you believe it? hard pack small whoops and ruts that tested the suspension to the limit.

i didn't try the PDS4, i know, i know, i let you all down...i'm a BW! 8O 8O

but i did give those .48s a good run out!

the forks didn't rock and roll the bike and in the bumpy corners i was flying! the bike never ever lost it's shape, for some reason the handling and balance of the bike is now even better than it's ever been.

i'm starting to pull back two stroke 'expert' riders in the woods! awesome!

the valving is 'as was' for the .46s and i could feel the stutter bumps hammering up through the heels of my hands just like it used to. but after a session i took 8 clicks off the compresssion front to go along with some advice from a mate that the rear needed to sink a bit more: so another 6 clicks off the rear.

this greatly improved things and i then hit a nasty run of 'chops' and the bike was worse than before so i removed 6 clicks of rebound. the next time out the bike was better still.

i feel i need to soften the valving somewhere on compression but i'm not sure where? certainly the sore heels to my hands went in the afternoon.

i can't see me going back to .46s but i can see me trying a 46 and 48 combo to make .47 average!

the handling is now quiet superb!

regards

Taffy

this is what i put on to try with the new .48 springs:

24, 20, 24, 24, 22, 19, 15, 13, 11, [email protected]

had become:

24, 18, 24, 24, 22, 19, 15, 11, [email protected]

i'm getting closer with this, it felt lovely. the sag by the way was 35 and 75 making an absolute mockery of race sag numbers, they are quite frankly all over the show. this number (75) was actually 90 but i have a 15mm gap between the top of the spring and the underside of the cap. this will be a problem if i ever launch off a table top (when i'll hear a TWANG) but it's giving me superb handling at present and the bike is 'dipping' nicely under braking etc. i feel i can put some packing back in soon so that there is no gap twixt underside of cap and top of spring.

i feel i want to make one more adjustment, i want to take either a 24 out or make the 18 smaller?

Per
can you tell me again what the 18 is doing? you once said a 16 or the 18? correct?

i also feel that the MV should be a straight tapered stack so:23, 23, 18, 15 or 13 and then the ZP3 post which is 10mm anyway.

regards

Taffy

Taffy
that 18 shim is there to aide in the breakaway if you run straight stack
against the piston the fork tends to be rather harsh and roll the rocks as
you are riding over them with a breakaway you tend to ride over them
which gives better traction
you are flirting with disaster by only having two 24x.10 shims against MV
they tends to get sucked through !!
sounds like your spring rate is too stiff for riding style and aggressiveness
you can accomplice the same with lighter spring and higher oil level then
fine tune the fork by relocating tubes in triple clamp (tight woods tubes up
higher speeds tubes down)

so long Per

VIKING said:

Taffy
that 18 shim is there to aide in the breakaway if you run straight stack
against the piston the fork tends to be rather harsh and roll the rocks as
you are riding over them with a breakaway you tend to ride over them
which gives better traction
you are flirting with disaster by only having two 24x.10 shims against MV
they tends to get sucked through !!
sounds like your spring rate is too stiff for riding style and aggressiveness
you can accomplice the same with lighter spring and higher oil level then
fine tune the fork by relocating tubes in triple clamp (tight woods tubes up
higher speeds tubes down)

so long Per

Click to expand...

i don't quote people too often but you are always the exception Per!! :wink:

i will continue with the 18 and maybe try a 16 next time. i may still pull out one more 24 for 24, 16, 24 and in the mid valve, well i have a large float which must help, i have the ZP3 mod to the tap, and the softer the BV the more of the 'burden' it shares.

however your point is well made and as usual i will push my luck too far!

regards

Taffy

raced at lt hadham today and it had everything: fast straights, woods, stutter bumps, roots.

the rear shock with the 85/111 260 was georgous! like velvet!

the forks were a little spikey so i undid the comp 6 clicks and it was a lot better. i noticed a straight track with grass on it where you would feel the occasional solid bump but it didn't feel a TALL bump but as though the forks couldn't move quick enough. also on one part of the track on some rollers and going down into a pit i still got a hit which i thought with my weight on the front wouldn't happen - again reasonably quick in third?

i think i need just one more shim out for now and that may be a 24 i think. the third 24? all bar 15mm travel used so the oil level is spot on!

i'm sorry folks but these 48s are really, really good! the bike is very stable and i'm getting great results presently. the big change is the suspension of late. the rest has pretty much been the same for a little while.

regards

Taffy

Taf,
are you still at 1.55 mm of free play for the Mid Valve shims? Do you use a wire coil spring to hold them down to the valve body or do they float around as they will?
Regards

smorgy

i use those conical springs and the '02 came with the hard ones i believe. at my first costly rebuild i had them changed to the softer ones. i still keep them fitted and wouldn't let them just flop around.

nobody at k-talk lets them float as i'm aware although there are a few that prefer the harder spring.

my freeplay is still 1.55mm. i don't know if you're aware but Per is concerned about my MV reaching an armagheddon and i need to keep those fragile little things from breaking up - i'm sure the springs help.

have you removed them? are you tempted too?

this is my latest BV to try:

was: 24, 18, 24, 24, 22, 19, 15, 11, [email protected]
is 2b:24, 16, 24, 22, 20, 18, 15, 11, [email protected]

as the forks get slightly softer i'm getting more travel use, as i ride at faster and harder packed stuff in the summer i also use more travel. i haven't touched the oil level for 2 months now and yet i've gone from 40mm unused to just 20mm left. it was 155mm air gap but i injected 30cc/ml of oil (look back for a record of it). when i next rebuild the forks i will rebuild them exactly the same:155 air gap, squirt in 30cc of oil and then re-measure!

i have got plenty of 'dip' going into corners and the head angle is OK. i need someone around to help me check with rider sag and then i might jack the rear slkighty as i'm running 109mm race sag at the moment and to jack it up would help the front even more on slow corner entry.

the '02s are meant to be 85-100mm BTW.

when i get that sorted i will look at adding the correct packing to the forks to have zero preload. i estimate about 8-10mm. i haven't found out with these springs yet, all i wanted to do was fit 'em and run 'em with the front as low as possible and no MX flying for that 'knocking' inside.

hope all this helps? do come back to me.

regards

Taffy

Taffy,

Isn't it that bad to the bone root at high speed that is the greatest risk for your Mid Valve shim rather than the MX take offs and landings? Or anything else that would compress the springs and then immediately subject your shims to the the full force of them as soon as that bad root is behind the now in midst air wheel. After a fullish compression MX flight landing much of the spring force will be used up to rise the now lowrider bike with its weight and mass and then add a Taffy or so atop of it, taking much of the pressure off the rebound stack and thus off the Mid shim.

I'm not really tempted to remove the Mid Valve wire spring by anything else but for the sake of simplicity. Think I'll leave them alone.

Are you going to undo the rebound adjusters a little to compensate for the weaker to be BV?

Best regards

the MV shims do the most flexing when they go from sitting flat toi being bowed back against the inside post seat.

as you've seen perhaps in the doc and front suspension: i have a ZP3 post in mine. it limits how far back the shim can go and the taper of the inner seat allows the load to be spread throughout the shim.

so that i'm happy with. the next thing is when does it stop being a check valve (like a 1mm washer with no flex) and become a flexible MV?

well i'm not too sure? i know that if it slammed open all the time it would be stressful on the face shim (a 23mm in my case).

the rebound? i will change that on the clickers if i need too but so far i haven't had to touch the clickers more than 2-3 turns.

regards

Taffy

Taffy said:

well i'm not too sure? i know that if it slammed open all the time it would be stressful on the face shim (a 23mm in my case).

Click to expand...

umm... I was thinking,...
that the slamming shut was the stressful thing...

Taffy said:

the rebound? i will change that on the clickers if i need too

Click to expand...

In case the front rides lower (harsher?) in rough sections with the new shimming?

Regards

smorgy

i don't always follow you?

the rebound has been fine after i changed the shimming and then ended up putting it back to 'as was'.

the shims during rebound?
they slam shut but they slam flat on the back of the piston so they aren't stressed i don't think whereas, when the forks go into compression the shims 'arch' and that's where the stress is.

the ZP3 post limits the stress IMHO.

essentially people like viking (per) have told me that the MV i'm running is at the limit of what the shims can safely cope with before they fracture and break. i feel that the shimming is just about there just at the moment that realise some think the shims will break.

BUT by doing the ZP3 mod i feel i've gained a little more 'safety'. even if it's 5% more, it means i may run this shim stack in safety i hope. (P.S. touch wood!)

as for the rebound, well it's staying high at present and on really deep fast hits i get almost a slight jump from the bike on the rebound BUT and again i say BUT!!!!! if you watch a MX race the top guys have too little rebound and live with it.

i also have too little rebound on the rear to sit much. this is why i now have to stand more. I'VE MADE MYSELF STAND. if i was to sit i would be launched off the top of each roller BUT if i had more rear rebound, sat down and it was ok then when i stood the rear wheel would not come down in time for it to contact the track and grip as i lean over. i came to this dilemma at the tail of last year and in jan/feb this year. so i made the decision i mention above. it's far quicker but i'll have to be fitter and stronger.

that's why i always watch MX and enduro action at international level very, very, closely and try and guess which way to go with compromises. i also believe if you study the top enduro riders that they are running heavy springs which they describe as MX suspension but is infact heavy springs and light valving. that isn't the same thing.

there's a good chance that these quality twin air chamber forks may change my mind but we'll see.

regards

Taffy

raced at hawkedon at the weekend and it's the toughest test for forks i meet. the track was hardpack farmers field with tons of chop and stutters at the corners. a real test!

my forks showed recently that they like the slow speed stuff and even the chop but it really is desperate stuff over perfectly small but hard bumps at speed. i feel the whole impact.

so what does that make them? a HS bump - but shallow or a LS bump but fast? MMMM?

the forks are now due a service and i have a chance to change the rebound or the MV as well as the usual BV settings.

anyway, this ride...
BV was : 24, 18, 24, 24, 22, 19, 15, 11, [email protected]
BV became: 24, 16, 24, 22, 20, 18, 15, 11, [email protected]

i had a slight leak on the right leg whilst in transit.

after a 30 minute session i took 5 off the comp and this was better - less harsh. i then later took another 4 off the comp and also 6 off the rebound. didn't notice this second change so much. comp has gone from 14 to 23 out. 30mm unused.

i think i'm going to rebuild with a MV change
is: 23, 23, 13, 20, 15
will be: 23, 23, 18, 14, 10 - is the post

may reduce the 22 to a 20 and 18 to a 16, 15 to 14 on the BV.

the rest is really good, just that stupid small but hard stuff.

regards

Taffy

well it's taken 6 months of hard testing but i'm just about there now!

the result? SUBLIME!!!!

i changed the MV to that proposed by ZP3 from k-talk and that was as follows: 23, 23, 18, 13, 10-post seat. ZP3 post.

i kept the BV the same so that i could clearly define the changes made and their effect.

BV: 24, 16, 24, 22, 20, 18, 15, 11, [email protected]

i altered the float from 1.5 to a conservative 1.25mm by taking out the three home made shim spacers from each leg (read previous posts) fresh oil and then i set the level to 155cc and added the 30cc i'd found improved the bottoming out (i.e. stopped it!). i scotchbrited out alloy from the bushes as the shop is closed at the moment that is near me. one of the bigger bushes has a chunk out of it and i expected to see the fork seal also damaged - but it wasn't!

everything was set equally and then rebuilt.

as said. 155mm air gap then add 30cc and measure. this equaled 135mm when checked.

the forks didn't leak during this the most viscious of courses!
butts quarry IS A *******!!!! it had jagged rocks, one foot tall were the norm, bolders - big *******s!!!!

the straights were slow and very, very rough. there were 3 motocross jumps and a drop over a 4' (yes 4' wall!) which had a 'facial' landing to a halt and turn left!

the forks absorbed everything faultlessly! i couldn't fault them on this terrain - fantastic! i need to thank ZP3 and all the crew at k-talk as well as viking here for their help. it's been hard work but it's been worth it.

i bottomed out twice when i got it slightly heavy on the front when landing so this wouldn't normally happen in an enduro. however this was a SLOW enduro and as i've learnt before, the faster you go the more suspension you use so i may have to alter it all a bit again. maybe some more oil taking the air gap to 125mm?

the rebound seems fine but again i may reflect on the difference between a slow track and a fast one.

one other thing. whilst the forks were split and on the bench i rebuilt them so far as getting the spring free length gap to the underside of the cap correct (see photo in the forks section of 'the doc'). the gap is 15mm with these .48s so i can either put 15mm of packing over them OR i can put longer top out springs in. by 'packing' them i raise the bike and slow the steering. by putting longer 'top-out' springs in i lower the front end and remove any slack when in mid-air.

the husey has 22mm top out springs but KTM have 37mm (i believe) which will virtualliy eliminate any slack.

so this will be the next thing i may try.

do later huseys have the same as katooms? around 35-37mm long?

regards

Taffy

Taffy
The top outs could very well be 37mm as they are not 22mm. I'll measure them next time I tear them apart but I don't know when that'll be.

Taffy said:

the shims during rebound?
they slam shut but they slam flat on the back of the piston so they aren't stressed i don't think whereas, when the forks go into compression the shims 'arch' and that's where the stress is.
Taffy

Click to expand...

I'm running 4 off Ø24 0.1 thick as MV or CP at 1.4mm spring loaded freeplay. This is what was in there when I got the bike and might even be the stock setup. When taking them out only the one next to the valve body is deformed, looking like the side of a cars tyre. I'd like to belive that if it was pressure blowing the shims like an umbrella in storm, they would all be deformed more or less one like the other. Or possibly that the one next to the nut would be more deformed than the others. But it is the other way around. It is the one next to the valve that is deformed. Just as if it bulged under the suction from the ports. That's why I think that the wake of that root or rock is worse to the MV shim than the rebound after a MX landing or indeed the landing itself. Of course I could be wrong, but the shims seem to tell the tale. Another thing, the inner edges of the MV ports are telling the same tale. There doesn't seem to be any other port of any valve in the system that are subjected to edge pressures like these ports.

VIKING said:

you are flirting with disaster by only having two 24x.10 shims against MV
they tends to get sucked through !!

Click to expand...

Viking warned you! But I don't know, after having seen that only the shim next to the valve is getting deformed, perhaps it just doesn't matter, maybe your setup is just as safe as ANY other MV setup?

BTW does anyone know what the latest 14mm rod stock FE shimming is? Or EXC?