SuperMoto Junkie banner
1 - 5 of 5 Posts

·
Registered
Joined
·
2,153 Posts
My best guess is the blackness is being cause by the wrong oil and now it is causing the o-rings to deteriorate. Start all over with a slave kit and master cyl. kit. and the proper oil.
 

·
Registered
Joined
·
149 Posts
I've noticed that in the last month, when I drop it in 1st gear from N, it's definitely not going in smooth as it used to. I purchased this bike second hand about 2 months ago and it would shift fine from N. Now it banging in.

Thought about bleeding the hydraulic clutch but when I opened up the reservoir, the oil is black and smells like used motor oil. No, I didn't check this when I was inspecting the bike at the time of purchase :/

Fluid level isn't low in the reservoir, its normal. It's just black and smells like motor oil.

Have two questions:

1) Should I take the slave off and drain all the oil and refill with the hydraulic fluid 75? Will I need new gaskets and O rings if I do?

2) Just bleed until it the black oil is clear with fluid 75?


If the poor shifting isn't caused by horrible old oil in your transmission (unlikely), it sounds like your slave cylinder is starting to leak a bit, so it draws in a bit of oil from the engine and turns black. this can happen to a 690 as there's a plastic part in the slave that wears out. It happened to me. The piston seal area starts to leak a little. First symptoms are notchy gear shifts. Try flushing and topping up with fresh fluid, believe that its mineral oil but check on the reservoir cover.

Yes, bleed it until clear, use a bit of hose and a catch can, top up the master, and just take your time to not get any air in things. The new fluid will make it shift better, but it'll likely continue to leak for another month and then things go downhill very fast, like instantly. You don't want the slave to fail on you, as if it goes, its totally gone. Mine went at 90km/h while going over a bridge; trying to get the bike stopped wasn't easy without a working clutch.

While you can get a replacement stock one, I suggest you look at this Oberon one, from the UK, better leverage and higher quality than stock. I put one in mine, instant fix, and smoother clutch lever action than stock, bolts right up.

http://www.oberon-performance.co.uk/acatalog/KTM-LC4-Models.html

I suggest that you bleed your current one and monitor the colour over a week or two; if it turns black again, you should really think about ordering the Oberon asap so you're not stuck waiting a few weeks for parts in the mail during riding season...
 

·
Registered
Joined
·
18 Posts
Discussion Starter · #4 ·
Appreciate your input. I would definitely hate for it to go as in your scenario. For $150 for the Oberon, might as well just get it.

If I remove the slave cylinder, do I need to drain the engine oil or tilt the bike over on its side like working on the clutch?
 

·
Premium Member
Joined
·
6,598 Posts
'08 still uses an older style magura clutch that doesn't suffer from the same issues like the current magura that uses brake fluid (bad seal on the slave, known to rip and cause a leak so the system loses pressure). check your cap on the master cylinder. if it says mineral oil you can use ATF, 5wt fork oil or the correct magura blood fluid (harder to come by and more expensive).

honestly I flush my clutch fluid just as much as my brake fluid, sometimes even more. the clutch gets worked a lot and I always noticed more discoloration in the clutch fluid compared to the brake.

if it becomes that contaminated it can plug up passages and you can loose the clutch all together. begin with flushing it so it has clear fluid in there and make sure no air is in the system. that's the first thing you should try if the clutch hasn't been serviced in a long time.
 
1 - 5 of 5 Posts
Top