Great explanation! I have done decarb for my car using water spray, as you said in very little quantity and by pulling the throttle cable to keep the rpm high. I made sure to use spray bottle, which helps the water entering the chamber to be almost in mist condition, so that the chances of hydrolock is nill. The results were amazing. I used tiny endoscope camera through sprak plug hole to see before and after effects of decarb which surprised me. Service center charges upwards of 1.5K for decarb sessions which is a simple DIY job. Unfortunately I don't have any pictures saved.

I was curious if anyone has actually tried it on D390? TB cleaner really helped me to keep the rpm stable couple of times and also instantly reduced vibrations. I also had to get the TB cleaned at service center once, to get the idle rpm fixed which was erratic.

I poked the camera through D390 spark plug hole and I already see some carbon deposit on the piston head, though not much which should make one worry. However, my 19.5K run D390 has more carbon deposit than 98K run car which confused me. Due to high compression, the deposit should have been actually low. I can only imaging how is the deposit on intake valve when the piston head itself have some deposit.I recently changed the spark plug to NKG which should help reduce the build up. Due to high compression ratio of D390, is it safe to use water spray Or is it better not to fix which is not broken?

do run it in for a few 100km to break in the new rings.
get the official diag tool connected and checked at the svc for the right info on error codes and fix accordingly.
i am guessing either the tps or idle control stepper motor might be causing the idling issue.
if possible compare the values from the official diag tool, with readings from another 390 of same model yr.

Welcome back Raju. I'll try to be as brief as possible, starting with the valve clearances. They are perfect, nothing to fiddle with. Secondly, I did go through the entire video of the diag, and it seems everything's as it should be. The fan kicks in rightly at 96 degrees and turns off at 90 odd, so your cooling system is working as it's should be. Rest of the readings are sensitive to throttle inputs, as they vary according to the RPM.

Coming to the temperature values, those values are absolutely fine, nothing to worry about. You have more reading on the cylinder surface, even more higher on the exhaust bend pipe and fluctuating readings on the radiator once the fan kicks. With an IR thermo, you can practically see the radiator cooling as the fan kicks in, so again you're perfect on the temperature part.

Rings, like piston do need to bed in, but not as how a piston is bedded in, you can rev the engine freely, hit top whack. Make sure the engine isn't highly revved where the ECM kicks in to cut the RPM. Yes, mild leaks in the piston where the air bled off during the bench test, and your lovely piston skirt test with ratios confirms it. My advice would have been to have replaced the piston along with the rings, considering the bore inner diameter was within spec.


Did you check the compression ratio before and after the rings were installed? Ideal compression ratio should definitely be above 190 psi which would mean 13 to 14 kg/cm2. Near 100 or lesser than 100 psi would mean, we have blowby loss, which is attributed to the worn piston rings and a piston skirt that's values are off by a good margin, which would mean replacement of either the rings or piston with rings, it's usually the latter that's the best course of action.

I'd suggest you to check your compression, that's first, both warm and cold.
Secondly, was your throttle body and injector considered an overhaul for cleaning.

Lovely work as always.

Here's a link for you.

Where I've answered query on a similar line.



Hope it helps!

Keep your observations posted.

Cheers!
VJ

Thanks for checking the video and confirming Vijay sir. Went for a long ride last Sunday and the temps were all OK.Except for starting issue the bike felt good. No more vibrations on the foot pegs. I also did a compression test(warm and cold) and I got a value of 30 psi. Will a bike even start with 30 psi compression? I tried it with the throttle open and the air filter out but still only 30 psi. I'm confused here. I went through the thread and looks like 5.5 bars(79psi) is the accepted value for the duke with decompression lever. I always get around 2 bars(30psi). Didn't do a wet test.

I also cleaned the throttle body and injector(battery and spray method) completely. Removed all the sensors and cleaned all the ports.

You are right about the piston though. I should've replaced it while I had the chance. This is a project for next month if things don't improve.

replaced finally after 14800 kms ,
service centre didn't care to replace.
finally after odd 2 hours.
got it done with tool kit

Great that you've replaced your fuel filter after such a long interval. What I'd suggest is, KTM sells the service kit that includes, oil filter with O ring, air filter and inline fuel filter, costs 550~ rupees approximately, which I'd have recommended at this juncture. Nevertheless, I'd recommend you to replace your air filter, spark plug and clean your throttle body if feasible.

Cheers!
VJ

replaced finally after 14800 kms ,
service centre didn't care to replace.
finally after odd 2 hours.
got it done with tool kit[ATTACH]248902[/ATTACH]

The recommended interval is 15k only.

replaced finally after 14800 kms ,
service centre didn't care to replace.
finally after odd 2 hours.
got it done with tool kit

hi, i've been reading some of the posts in here, but i never posted one before...

i was wondering, is there any possible or anyone in here who sold the parts online? a recommended seller maybe?

ps. just got my brembo attached, feels nice when you hit the lever... but still need some small adjustment on the bolts placement...

So while coming back from work today I hit a pothole. Must be riding at a speed of 40-50 but because it was a nasty one I got home and checked the rims and found them to be bent from two different regions on either side of the tyre.

Is this a quality issue? Has anyone faced a similar situation? What other damage I should be wary of? Solutions? Please help.

I'm afraid, our members don't sell anything specifically high end components for the Duke, apart from radiator guards, crash bars and nitty-gritty. You have a wide variety of offerings abroad and from international sellers. Coming to your Brembo caliper, is that a genuine caliper or are these the first copy ones? I haven't come across such a design. What was the cost and which pads are you using stock or upgraded, do post some details on the pad setup and the rotor setup.



It isn't a quality issue per se, these things happen on almost all Dukes, given the wrong circumstances unfortunately. These things happen due to the extremely low sidewall thickness of the tire. Mild bends can be tinkered with, but I don't recommend them as hammering can lead to poor structural integrity of alloy even more. You can get them mended at a tire walla, albeit with the pain of losing some paint, as some heat and hammer, and some just hammer it out.

There shouldn't be any other damage apart from this. Do check your steering freeplay just in case, sometimes they can damage the steering bearings and induce a grabby feeling, but that's worse case scenario. Get it checked at your SVC as a precautionary measure. Keep your observations posted.

Cheers!
VJ

Hi VJ, yes you're right, as for the high end parts, i can find it online, but i'm looking for an OEM parts, i live in Indonesia, there is so much dealers in here, but for some of the parts, they still hard to find...

For the brembo's caliper, they are genuine, 100 mm pitch caliper, ex. ducati to be exact, with stock pads, right now, i'm still waiting from my friends to let me borrow his Brembo M4 and M50, i hope i can use the same bracket with different kind of calipers...

As for the front rotor disc, i'm using a 320 mm chinesium that i found on aliexpress...