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Discussion Starter · #1 ·
Need your thoughts on this one.

Recently raced the Hellas Rally Raid in Greece using my KTM500 EXC-F
MY20 with WP Xplor forks, uprated springs to my weight, all torque
settings and airgap etc to spec.

The issue experienced was this, in the morning the forks were ok but
after 3-4 hours of riding it felt like they just stopped performing,
almost like stiction, I guess due to the heat, constant pounding from
the terrain etc, the air and oil just could not cope any longer, (cavitation maybe??) so the
afternoons became a real battle to get any front end performance.
Interestingly when bleeding in the evening there was nothing, totally in
spec.

Looking at the 6500 cartridge upgrade, as i can't afford the full cone
valve 7448 option, do you think this would help this kind of riding or
is it more for MX track / Enduro? I also tour on the bike off road. Or
is it a false economy and I should save up for the 7448?

Any thoughts or options greatly appreciated,
 

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I have no experience of that type of riding myself, but used RSS after recommendation from Lee Walters and they did a great job on my forks and shock (FE 350) including adding a new low speed damping adjuster to underside of one of the forks, so a bit more than just springs and oil - and with shock bladder conversion and service the bill was still less than 50% of 6500 kit....

...However maybe for your demanding use splashing more cash is required - maybe call these guys and see what they recommend.
 

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Need your thoughts on this one.

Recently raced the Hellas Rally Raid in Greece using my KTM500 EXC-F
MY20 with WP Xplor forks, uprated springs to my weight, all torque
settings and airgap etc to spec.

The issue experienced was this, in the morning the forks were ok but
after 3-4 hours of riding it felt like they just stopped performing,
almost like stiction, I guess due to the heat, constant pounding from
the terrain etc, the air and oil just could not cope any longer, (cavitation maybe??) so the
afternoons became a real battle to get any front end performance.
Interestingly when bleeding in the evening there was nothing, totally in
spec.

Looking at the 6500 cartridge upgrade, as i can't afford the full cone
valve 7448 option, do you think this would help this kind of riding or
is it more for MX track / Enduro? I also tour on the bike off road. Or
is it a false economy and I should save up for the 7448?

Any thoughts or options greatly appreciated,
Cannot comment what "gave up" on the oem forks after hours of riding....
The 6500 are very similar to CV forks only have shims stack instead of cone valve...fitted some on mates exc and are very good. Probably the best option from value for £ point of view. (also extremely easy to move over to a new bike)
I cannot see why these wouldn't work on rally terrain.
Maybe, well worth to ask Desert Rose for advice?
 

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Discussion Starter · #6 ·
I have no experience of that type of riding myself, but used RSS
These guys? www.racesuspension.co.uk

Cannot comment what "gave up" on the oem forks after hours of riding....
The 6500 are very similar to CV forks only have shims stack instead of cone valve...fitted some on mates exc and are very good. Probably the best option from value for £ point of view. (also extremely easy to move over to a new bike)
I cannot see why these wouldn't work on rally terrain.
Maybe, well worth to ask Desert Rose for advice?
Thanks, yeah bang for buck the 6500 seems a good half way point, but i dont know anyone who has done it and got any opinion on them. basically about a grand vs 3,5 grand..
 

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My guess is rider getting tired as the day goes on so not hitting things as hard to make the suspension work, but thats just my opinion....chuck money at it that will fix it!
 

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RSS did my 6500’s. When I was chatting about doing it he explained some of the issues I had but also pointed out later in the day you can feel your starting to ride worse but actually the forks loose some of their performance later on due to cavitation and other things as you pointed out. The 6500’s help with this.
It’s the best thing I ever changed on my bike.
 

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Discussion Starter · #12 ·
My guess is rider getting tired as the day goes on so not hitting things as hard to make the suspension work, but thats just my opinion....chuck money at it that will fix it!
Feeling grumpy today mate. :ROFLMAO:

Yeah for sure it was some of that no doubt.
But even on the straights it felt terrible from day 2 when the ride got longer. First time I’ve really pushed the bike for that long that hard and it was like they just stopped working. Even after neutralisation they were ok again for a bit then felt like they seized up again. They just did not soak anything up.
 

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Any full cartridge fork can be made to work from anything from SX, MX, Enduro or rally. Any decent fork should look after you when tired or help reduce fatigue in the first place. If not then they are not set up right.

Xplor are limited in a number of ways. They are budget forks. Fine for certain things but they lack a number of components that better forks have inside. The plunger with a hole in it is 1950s technology. Not 21st century.

Buy 6500s and you can change them into each new bike if you stick with KTM. The external preload is very handy when changing from one venue/riding type to another or wet/dry, sand/hard pack. No bladder to pressurise like with Dal Soggio Sphere or WP CC as you have ics springs controlling things. This means zero loss of performance even if stood idle for ages.

Seals and bushes are the same dimensions across all WP forks. Quality changes though. I noted that Mannis cone valves at Erzberg appeared to have NOK (black seals). These are same as KYB. Mega quality, last longer and leak less than SKF in my experience but do need a couple hours initial use. NOK don’t seem to pack and swell with dirt from what I’ve found.

I’ll tell you now that once you open the suspension pandoras box it can get expensive unless you learn to do it/service it yourself.
 

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I am always grumpy! Just look at this above :rolleyes: first place to start is check the forks are in line, slacken pinch bolts on the bottom of the forks then push them up and down a few times then re tighten also be sure the yokes are not twisted/bent no matter how good your forks are if they are not in line they will never work but as ever people advise chucking money at it first.
 

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How many hours on the forks?

This is a wild guess but perhaps if the teflon bushes have worn badly then maybe a load of heat increases the friction between the bushes and the tubes...

Other than that, the only thing that heat (because that's what we're talking about I guess) would affect is the air pressure so there's a slim chance that could have increased significantly.

Cavitation is normally causes of a lack of damping control rather than the forks going stiff.

For once, I'm with grumpy Lee on this and it is likely to be a maintenance/adjustment issue unless something inside is broken.

Sure the 6500 insert will be a massive improvement but that doesn't mean you need them to solve this issue.
 

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Bushes that have the small metal flakes stuck in them form internal wear get sticky. On a WP fork (not cones) it can be surprising the mount of metal flecks in the bush surface after 20 hours. Change them or go roque and clean them up gently with scotch brite and forks feel mega again. I’ve never noticed a such performance change with new seals compared to bushes. Bushes are much cheaper than seals. Seals can be easily cleaned.
 

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Discussion Starter · #17 ·
I am always grumpy! Just look at this above :rolleyes: first place to start is check the forks are in line, slacken pinch bolts on the bottom of the forks then push them up and down a few times then re tighten also be sure the yokes are not twisted/bent no matter how good your forks are if they are not in line they will never work but as ever people advise chucking money at it first.
Don't worry Lee we have swapped enough chats over the years, I get it. Really don't want to throw any money at it, would rather keep it for more rally's but there is f'all point in spending on that if I have the same problem. hence the question. So now I need to think about not doing one to pay for this, which sucks.

Ok per original post 100% in spec, everything, pinch bolt torque, airgap, alignment, spring weight, static sag, rider sag (as much as you can with forks), oil weight, not twisted etc etc. been building and working on motorbikes for 35 years, not an engineer but know my way around a tool box and a workshop manual. 100% it is NOT shit setup or anything out of alignment. Was so pissed at the end of the day double tripple checked everything, started questioning riding position, putting more effort into it but the timing was almost the same every day. (Even taking the mousse out to check it to make sure it wasn't shot to shit.)

@Al_Orange Good point, however serviced both forks before, as blew the seals on a previous ride, mostly crud build-up over a 3 day training ride, so new bushings, seals, fresh oil etc, forks had 120 hours so nothing. No signs of abnormal wear, pitting on the legs, everything put back correctly no twisting all to factory spec. Did a 5 hour mix ride to break in and 3 hours on the MX track (stopping and starting) for training after the change.

The combination of the heat, hours, pounding they got the performance just dropped to nothing. So either shit happens, man up buttercup or spend some dough to mitigate the issue.
 

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My guess is cavitation as you have already pointed out.
The 6500s are brilliant, I have fitted a few now and because they run the same springs as the stock forks it makes things easier/more cost-effective.
message me if you want me to get you a price on a set :)
 

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I never forget a day on the Hellas or could have been the serres I had been lost a few times had a few offs, banging headache cut up trail I was all over the place felt like I was hitting every bump twice, thinking this bike is shit, this track is shit, suspension is shit blaming everything except myself, just wanted to get to the Bivouac asap had enough. Then another rider I know in the same team came past clearly he had been lost even more than I had, shouted "come on lee" I latched on to the back of him, It was like I had flicked a switch went from looking like someone had stolen my stabilisers to someone who had a clue how to ride a bike, we were flying along and having great fun, proves nothing wrong with the bike all in the riders head.

Once you let these messers get inside your head you might as well just keep on writing out blank cheques. I know Exactly what goes on at these "suspension tuners" they talk the talk and get a decent rider to make out (for financial gain) it is the suspension that makes the differance, plenty out there gulliable enough to fall for it.

Wilso122 what other road book rallys you got planned? you done any in the desert? I am a bit out of touch with road book rallys seems to have been taken over by facebook trendy wendys (like everything these days!) but really should go do another before age makes it not possible.
 

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If the suspension quality made no difference then surely every race team would save cash and fit cheap stuff, and world championships would be won with XPLOR.

Of course lots of riders will throw money at a bike as they believe they are way more talented than they are, and some folk in the business will happily take their money, but I think most will give good advice and deliver an improvement and it ain't their fault if the rider is shit.

The argument that it is only the rider does not stack up, sure any MotoGP rider would beat me if you put us on the same bikes and drained all the oil out of his forks and shock and let his tyres down.

Does that mean it is pointless having oil in forks and air in the tyres?
Would he not go faster with the forks in tip top condition and tyres blown up?

Or are you saying people like me with less talent would not be able to tell the difference between the good bike with perfect tyres and suspension and the other one?

You are bang on about peoples heads though, but some folk will go better if in their head the bike has the best of everything, and maybe considerably better, whereas some folk like you Lee seem able to make the best of what you have and not really care too much if you are on a far from perfect bike.

I sit half way between the two, I know how I like a bike to feel, if it feels nice I ride more confidently and better for it, but it has nothing to do with how much I have spent, just how it feels.

When I rode the RSS bike back-to-back with mine it immediately felt nicer and soaked up bumps better. If racing I doubt the money spent would of resulted in much different lap times, but it feels better and I ride better for it, and definitely less tiring as it no longer hammers my forearms as much.

More skill / extra talent would all bring me more speed and comfort, but I cannot find anyone selling that!
 
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