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2018 KTM 85 odd sag recommenation

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I just picked up a 2018 85SX for my son this weekend. He loved the bike and even though he is small for it. I am not sure how much he will want to ride his 65 now. He was jumping everything that he does on the 65 in a couple of laps on the bike so he was definitely comfortable.

It seems to have a little bit of a kick in breaking bumps and acceleration bumps, otherwise looks good.

My question is around sag setting and spring selection. Stock is a 4.0 spring and the manual says it is good for 99-121 lbs. And 3.5 for less than 99lbs. Geared up weight.

He is 11 and weighs 65 lbs with no gear so I figure 75 with gear(need to weigh his gear) So I put on a 3.0. I also have a 3.5 to try.  

KTM recommends 120 sag and 30 free. This seems odd for 305mm travel (I would expect more like 101-102). Last year they recommended 100mm for 300mm travel which seems to make sense. For '18 they have 10mm more front travel, 5mm more rear travel and the shock is laid down 3 degrees, steering angle is the same so I would expect same or less sag recommended. They also have HS compression settings backwards in the manual, so maybe a typo, 120 vs 102.

With the 3.0 and 120 sag we had 45 free which would indicate he needs a lighter spring. I had the forks set at the lowest pressure 58psi (stock is 73psi) Air fork on the 85 this year.

I took it for a spin and it felt way soft in the rear compared to the front. I am way too heavy, but thought it would feel soft but balanced, maybe my height put me toward the back. 

Thinking to try the 3.0 at 102 sag and see if that gives 30 free and then choose up or down on the spring rate based on normal more free-ligher spring, less free-heavier spring.  

As usual for me this is way long, so my question is...

Does anyone have any technical reason they would recommend so much sag?

Thanks,
Jason

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I think it's a typo

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Ball park starting static sag is 10%, race sag is 25%. So 300MM travel is 30mm static and 75+mm race. Then you adjust/change to suit the rider. some like the numbers flopped all about. I suggest keeping an eye on the shock and see if he bottoms, if he does, try the 3.5. I'd keep static at the 10% area and adjust the race to suit.

 

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My Wp spec sheet says 120mm with 30 static, that's from the factory.

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Thanks for the replies, they seem to align with what I was thinking.  

 

Karlace, that is what my manual says too, it just seems way out from everything else I have seen and experienced.  120 mm puts the sag at ~40% and there isn't anything else about the chassis that I can find that would suggest such an extreme setting.

 

Jason

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I've seen ktm recommend 90mm of sag on a big bike, they are sometimes a tad crazy

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With that much sag, it sounds like stiffer springs are needed. It is more then likely they could be "off" by 1-2 spring rates rather then the 120mm being wrong. PDS on big bikes is around 112-116.

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On 7/4/2017 at 10:22 AM, Jasons said:

Thanks for the replies, they seem to align with what I was thinking.  

 

Karlace, that is what my manual says too, it just seems way out from everything else I have seen and experienced.  120 mm puts the sag at ~40% and there isn't anything else about the chassis that I can find that would suggest such an extreme setting.

 

Jason

Did you ever sort this out on the bike?

The sag measurement seem way off with 120mm rider sag. The bike does not feel balanced

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Just picked a 50SX 2018 for the little one and KTM recommends 80mm of SAG so the same 43% of travel...I don't know what was recommended in 17 (same chassis) but it seems to be a lot. Looks like a new engineer figured out something different...or made a mistake !

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We are running 120mm.  He was complaining the bike was twitchy and got headshake with less sag.  I talked with a guy from KTM at a WORCS race that does the training for service and asked if it was a misprint and he said it wasn't and that they do a lot of testing to come up with the settings.  

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14 hours ago, Jasons said:

We are running 120mm.  He was complaining the bike was twitchy and got headshake with less sag.  I talked with a guy from KTM at a WORCS race that does the training for service and asked if it was a misprint and he said it wasn't and that they do a lot of testing to come up with the settings.  

Thanks for that we'll aim for 30mm and 120mm.

 

Just one more question the manual has the high speed compression as softer the further it is wound in, I've not seen this before as it's normally the other way round.

Did you find this to be accurate?

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It seems to have the comfort, sport and standard settings backwards.   It also states turn in for more damping and out for less.  I would start with the standard setting and try in and out and see if he likes it better.

 

Jason

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