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Author Topic: KTM 690 HARSH SUSPENSION FIX - THIS IS HOW I FIXED MINE  (Read 359 times)

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Offline AlanDoyle

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KTM 690 HARSH SUSPENSION FIX - THIS IS HOW I FIXED MINE
« on: July 18, 2019, 09:18:52 am »
The earlier 690's came with WAY WAY too much rebound damping in the back shock, the back shock causes the front to feel harsh and get those bouncing wheels entering a corner while under braking, so instead of having a new chromed shaft and damping rod made to allow more oil flow, I chose to drill one 1.5mm hole (easy to close up if you want to) through the piston to increase the oil flow and sort out the over damped problem permanently!!!. You cannot believe the difference. A lovely comfy ride like never before with a smile on my face all the way!  :ricky: A lot of people think more damping is better, it's not, it makes for a harsh ride, you only need just enough damping to stop the seat from hitting you in the ass, because there is no damping at all. So it's just to control the suspension slightly, not ridiculous solid feel like the 690's.

Well, after a lot of thinking about whether to or not share this info, I decided to give the info to you all as it would benefit those of us who have this problem. (harsh suspension) keeping in mind that my 690 Enduro is a 2008 model and I am not sure which models were affected later on as the 690's were developed. Just be careful when working on these super high pressure back shock (10 Bar of Nitrogen pressure) so here goes..................

Firstly, remove the rear shock from the bike, then wash the unit super clean. Blow dry or air dry as you wish. Release the gas pressure completely and remove the air valve inside the air nipple. Then loosen off the spring tension and remove the spring. Unscrew the oil filler/drain bolt on top of the shock. 5mm allen key, drain all the oil inside, help this by pumping gently on the chrome shaft to help dispense the oil until empty. Remove the dust cap carefully and do not damage the chrome shaft. Then push the seal collar down a little so as to reach the retaining circlip. remove the circlip. Slide the chrome shaft out of the housing, now you have the shock valving in your hands. Clamp the bottom shock mount in a vice with protection so as not to leave marks on the mount. carefully loosen the 17mm nut on the top and take the top set of valves out NB do not mix the valving plates up, ALSO note which way the piston goes in, these is a top and bottom, then remove piston and the the bottom set of valve shims. I use a cable tie to keep them all in order.

Now, you only need your piston, remove the teflon ring on the outside but not the "O" ring!!! Then get a 1.5mm drill bit. You will see 2 dimples on the piston. Using a drill press, choose 1 dimple ONLY and drill carefully the 1.5mm hole right through the piston. NB. Dont be nervous as this hole can easily be sealed off again if necessary. Wash the piston and blow dry, and put all together again. Bleed oil circuit and regas to 10 bar if Nitrogen and 8 bar if air. Air expands much more when hot than Nitrogen.

I run my settings as follows: Front Forks, Zero compression and Zero rebound, Zero air. (All settings all the way out)

                                         Rear is std comfy compression settings on the compression and around 15 to 20 clicks out on the rebound setting or as you prefer

In the bottom pic you can see the hole drilled in the centre of the dimple indent on the piston. You can see the damping hole in the centre of the shaft which is too small and adjustable.

Top pic shows it from the other side of the piston.
You can see the hole I drilled and it does not interfere with the valve plates at all.


PLEASE GIVE ME FEEDBACK GUYS!!!

« Last Edit: July 22, 2019, 08:07:38 am by AlanDoyle »
 

Offline AlanDoyle

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Re: KTM 690 HARSH SUSPENSION FIX - THIS IS HOW I FIXED MINE
« Reply #1 on: July 22, 2019, 07:57:51 am »
Please ask question if you need, I dont mind helping....................
 

Offline adamktm

Re: KTM 690 HARSH SUSPENSION FIX - THIS IS HOW I FIXED MINE
« Reply #2 on: July 31, 2019, 05:43:29 pm »
Thanks for posting. Do you know if the 2011 forks are the same? My rebound adjusters are on the back of the fork foot and my mates 2010ís are on the bottom.

@AlanDoyle
2018 KTM 250 6 Days TPI
2011 690 Enduro

When I bleed, I bleed orange!
 

Offline geopat

Re: KTM 690 HARSH SUSPENSION FIX - THIS IS HOW I FIXED MINE
« Reply #3 on: July 31, 2019, 07:44:14 pm »
I have recently taken my suspension in for a service and "upgrade" but all they did was change the shims now I haven't had a chance to test it yet but do you recon that would do the job?
 

Offline AlanDoyle

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Re: KTM 690 HARSH SUSPENSION FIX - THIS IS HOW I FIXED MINE
« Reply #4 on: August 01, 2019, 07:17:16 am »
I am not sure if they are the same, but try the settings and see if they help get the suspension plusher. There is one thing that a lot of people get wrong, and that is that you need more damping, wrong, you need less. The more damping you apply the harder the ride and if you go far enough on the rebound damping you get packing, that is when you hit a bump and then the suspension tries to return to its normal ride height but gets hit by another bump before it reaches its normal riding position and ends up holding the suspension in a loaded position and makes for a very hard ride.

I have found that my rear suspension was causing the front to feel harsh too, so I adjusted the front to soft and did not help, it was the rear all the time causing the problem.
« Last Edit: August 01, 2019, 07:24:55 am by AlanDoyle »
 

Offline AlanDoyle

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Re: KTM 690 HARSH SUSPENSION FIX - THIS IS HOW I FIXED MINE
« Reply #5 on: August 01, 2019, 07:31:58 am »
I have recently taken my suspension in for a service and "upgrade" but all they did was change the shims now I haven't had a chance to test it yet but do you recon that would do the job?

Hi Geopat, I reckon it might help a bit but the one big problem remains no matter what shimming you do. And that is that the rear shock has way too much damping.
Normally one would have to change the rear shock shaft and the damping adjuster rod inside to fix this problem, that's why I though out the MUCH cheaper method of drilling the hole in the piston to increase the flow of oil and smooth out the shock, I really love the bike now, before I did not enjoy it off road at all. Felt like a motard bike to me.
« Last Edit: August 01, 2019, 07:33:26 am by AlanDoyle »
 

Offline geopat

Re: KTM 690 HARSH SUSPENSION FIX - THIS IS HOW I FIXED MINE
« Reply #6 on: August 09, 2019, 07:07:08 am »
Thanks for the reply I will do some playing with the settings when I get home