News

DIY: Serviced the chain & changed coolant on my Duke 390

29th January 2024, 14:28 by Ananth Iyer

I've been reading on how gear oil is a good lube for chains, even ones with o-rings. Heck, even the KTM service center had an advisory on their board asking patrons to use SAE 90W gear oil on their chains every 500 km.

BHPian SunnyBoi recently shared this with other enthusiasts.

The chain links were completely rusted when I first got the bike, all the links just looked like a consistent rust orange color. On that moment, I had bought a can of Motul C2 chain lube and very liberally applied it. In the coming days, I kept adding more C2 lube on the chain after every 500 KMs.

I had noticed that the chain links were very stiff when I had taken the rear sprocket off to do the brakes. If I bent the links at say 90*, it would just stay at that shape - which I read was not a good thing. I did not have enough bandwidth to do up the chain as well as brakes together that day and earmarked chain clean for another day. Lately, the chain had become quite loud with a constant tick noise cosign from around the front sprocket. I had just returned from a 400KM ride so it was time to clean the chain before lubing it.

To begin, this is how the chain looked, there was sizeable debris stuck to it

Took the front sprocket cover off and I found why I was getting the additional noise

The chain slider had broken off and rubbing on the chain causing the extra noise. This meant I had to go back to the KTM service center for a new chain slider. Ugh, I had been there just yesterday for a new fuel hose and other small things.

I did not take much pictures of the chain cleaning process - I first lightly sprayed some kerosene on the links. Let them soak for about 20 minutes then used an old toothbrush to rub both outer links, inner links then upper and lower surfaces with rollers. I dried off the chain with rags.

I only had a tad less than 100ml of kerosene left with me. Getting more kerosene here isn't easy hence I was very conservative on how much I used. There was still some muck on inner faces of the links and rollers, which would have come off with a liberal spray. I'll keep that for next time. Right now, the outer faces and the rollers were adequately clean so I let it be.

The metal chain guard around the front sprocket was loose and shaking around. I had to take off the sprocket to access the screws to tighten them back in. This was literally the last frontier when it came to cleaning my bike - I had pretty much disassembled and cleaned all surfaces, bar the area behind the front sprocket. I took this chance to go ahead and clean everything.

So, on to removing the front sprocket. I took off the 2 screws on the sprocket and took off the lock. The sprocket wouldn't come off - the chain did not have enough slack. The obvious next step had to be loosening the chain to take off the sprocket. I had bad memories from the last time I had adjusted the chain slack and ended up exploding the sprocket bearing - hard pass.

I then had an idea and fashioned a puller to pull out the sprocket using the chain lock, few M6 bolts, a nut and a wide washer.

Did it work? oh yeah it did! Front sprocket was off!

Area behind the sprocket was given a deep clean.

Now, on to replacing the chain slider. This required taking off the foot rest which I despised doing. I looked around and it was possible to change the slider witht he front sprocket off, so I let the sprocket be for now till I change over the slider.

At the KTM service center, they did not have stock of the chain slider for my model, instead they only had the chain slider for the 2017+ duke 390s. I asked their resident mechanic and they said the newer slider will fit the old swaingarm. I bought the newer slider and went my way home.

My handle bar had a slight bend - it was a bit irritating but I let it be. Since the bike was down anyway, I took off the handle and gave it to the local hydraulic press. He straightened the handle for me while I collected parts from the KTM service center

Back home, the sliders were very different. This is a photo of the top - old slider above and new one below. The new slider was made of rubber while the old one felt it was made of plastic.

There is also the issue of the vertical bolt holding the chain cover on it, the old slider had a bolt with 7mm width and a M5 thread on top. Taking off teh nut on top was always a pain in the rear, I had to put in a 9mm spanner to hold in the bolt while I loosened the nut on top. Putting the spanner in place was very frustrating thanks to lack of space.

New slider only has a 5mm hole. Instead of using a standard M5 bolt, I put in a M6x25 bolt and threaded it all the way through. Now it has enough thread on top to put in a screw and is securely held with the rubber. No more faffing with a spanner to take it off! Yay!

Even though mounting locations are different, the old swingarm had a mounting point which matched the new slider. However, it was full of dirt, sand and old chain lube. It took me close to an hour to dig out all the dirt from the hole, run a thread chaser to clean the threads. What you see below is the end result, which took me close to an hour. At this point I was wondering this could have gone lot faster if I had access to compressed air. Sigh.

The red marked hole is where the old chain slider mounted to, blue marked hole is where the new slider fits

Great, the top is done. I then try to bolt in the bottom aaand it doesn't match. Again, there is a threaded hole on the swingarm but as usual, it's caked with dirt sand and old lube. JFC GIMME A BREAK.

After another hour of cursing, the new slider was finally on.

The chain guard was fitted back. The screws holding the chain guard were given an application of loctite so they don't work themselves loose again. Time to put the front sprocket back on and surprise! It wont go back in!

Ugh. So I had to loosen the chain, get some slack. And I wasted 15 minutes coming up with this brilliant idea of making a puller. FML.

This time, I made marks on the bolts and swingarm to make sure I adjust it back to how it was before.

Finally the front sprocket goes back on. I used new allen bolts to hold the sprocket in place, one of the old bolt heads slipped when loosening and I did not want to reuse them again.

I've been reading on how gear oil is a good lube for chains, even ones with o-rings. Heck, even the KTM service center had an advisory on their board asking patrons to use SAE 90W gear oil on their chains every 500KMs. SO why not try it out? I got a bottle of cheap 140W oil, instead of 90W I also read thicker is better and wanted to try the thickest one out there.

While rotating the wheel with one hand, I added in a line of oil on the center rollers, the one each on the edges. I then wetted an old clean toothbrush with gear oil then used it to spread and simultaneously take off the excess from the edges and later the rollers. This left behind a wet looking chain, I hope it won't sling much but we'll see.

The restored handle bar was painted silver again. I re did the [paint on the holder as well, this time I pre heated the part with a heat gun prior to shooting it with paint. This working and I finally have a nice consistent paint finish on it.