[vernonbc]

Fork oil levels (air gap height) is normally measured with the spring out. Your discrepancy was probably mostly due to oil clinging to the springs when you pulled them out. And any leakage you might have had.

I do not disagree with you here as that is the common way of measuring airgap BUT, my gap was measured 25mm shy with the spring and its retainer still installed. The retainer also is partially submerged in oil, so a lot of oil is being displaced.
I have drained the oil over night and will fill with the recommended 660ml and see where that takes me with the spring removed. Thanks.

 

[vernonbc]

Sir,
I changed springs in my 2015 sdr when it had 300 miles on it. Note that both forks were nearly 100ml shy of the recommended level by the service manual. Not a very good quality control process from KTM. If you own one of these bikes that difference in what you have and what you think you have can be substantial.

100ml is fair amount of oil. When I removed my springs to check airgap the oil was well beyond the 110mm measurement.
As in my previous post, I will fill with 660ml and see where that takes me with the spring out. I will report my findings.

 

[shield9]

100ml is fair amount of oil. When I removed my springs to check airgap the oil was well beyond the 110mm measurement.
As in my previous post, I will fill with 660ml and see where that takes me with the spring out. I will report my findings.

Sir,
I called a suspension shop that I deal with often and was told that it is common for KTMs to be low on fork oil from the factory. He made it sound as if they were trying to save money. I recorded the amount as 625ml, I checked after i wrote the reply so i exaggerated the amount.

 

[vernonbc]

Unfortunately I am still not sure as to whether or not the airgap is measured with spring in or spring out. I know that the normal is with spring out.
I just poured 660ml oil in my 2014 and after pumping and priming etc i measured the gap at approx 125mm (spring out) and after sitting overnight it will just get larger by a bit if any. I wonder if this is why they changed the capacity to 680 in the 2nd gen bikes.

 

[jim620scot]

Unfortunately I am still not sure as to whether or not the airgap is measured with spring in or spring out. I know that the normal is with spring out.
I just poured 660ml oil in my 2014 and after pumping and priming etc i measured the gap at approx 125mm (spring out) and after sitting overnight it will just get larger by a bit if any. I wonder if this is why they changed the capacity to 680 in the 2nd gen bikes.

Spring in according to manual 👍

 

[vernonbc]

I took a look at the service manual again and according to the pictures, the oil is being added after the spring and retainer are installed. Once my oil has settled, I will measure the gap with no spring installed and then try to measure the gap with the spring installed. This may prove difficult as the spring will be in the way.

 

[vernonbc]

Spring in according to manual 👍 View attachment 106020

Damn....you beat me to it. The challenge as i mentioned previously may be measuring the gap with the spring installed.

 

[jim620scot]

Damn....you beat me to it. The challenge as i mentioned previously may be measuring the gap with the spring installed.

You might find some useful info in the attached fork setting document (see second page for English translation) 👍

 

[vernonbc]

Thanks for the document. I installed the spring and retainer and measured once again. The air gap has not really changed much. The gap was measured at approx 125mm, looks like the spring stays above the oil so no displacement. So with adding the recommended amount of oil the gap is still out of spec from the document in previous post. The document states 660ml and 80 - 120 gap. I wonder if I add 20ml, will it take me within spec or maybe just add oil to take me to 110mm which of course means adding more oil than recommended.

 

[jim620scot]

Thanks for the document. I installed the spring and retainer and measured once again. The air gap has not really changed much. The gap was measured at approx 125mm, looks like the spring stays above the oil so no displacement. So with adding the recommended amount of oil the gap is still out of spec from the document in previous post. The document states 660ml and 80 - 120 gap. I wonder if I add 20ml, will it take me within spec or maybe just add oil to take me to 110mm which of course means adding more oil than recommended.

I reckon the correct air gap is more important than the quantity of oil

 

[vernonbc]

I reckon the correct air gap is more important than the quantity of oil

I decided to check an online fiche and compare the 2014 to the 2017. They both have same part numbers and graphics for the front forks, in other words they are the same forks. KTM may have increased 660 to 680ml fork oil to meet the air gap.
I am just going to add oil till I get 110mm gap. Since I have 660 in there, I will add 20ml more and see what happens. I'm betting I will get my 110mm gap.
Thanks everybody for all your help. I will let you all know if 680 is the magic number for the 2014. There is actually room to put my motionpro oil gap gauge between the spring and the outer tube.

 

[vernonbc]

After rebuilding the second fork and adding oil, it looks like approx 700ml will take the gap to about 110mm.