[basuroy]

Originally Posted by abhinav.s

Basu, am late but nevertheless, congrats on the D390!!

With regards to the loss of air from the tyres, I would suggest you monitor the air pressure at home until the festival is over and the service center opens up. Get it checked at the service center itself! Reason - If it is a tyre issue, the dealer will no doubt get it done from a tyre shop nearby and it might cost you a few rupees extra, but if its a rim issue, it can be dealt with in that single visit rather than you going first to a tyre shop and then to the ASC again. And since you say that the workman ship in your place is not up to the mark, why risk it with a new bike?

Just my personal opinion but up to you to decide. Hope the issues are sorted out quickly and you get to enjoy your bike to the fullest!

Thank you Sir

I also plan to visit the SVC and let it be their head ache , for one if it is not a tire but rim/wall seal issue , they might lay blame on the 3rd party involvement . The dealership staff is not very confidence inspiring and can very well say that, the knowledge that I will be out of bareilly within 6 months was decisive .

[Sutripta]

Originally Posted by unk9ja

Check out the valve and its stem on the rim. If not properly fixed, then it can leak from that point.

+1.
Or the valve itself might be the culprit.

Regards
Sutripta

[ArizonaJim]

Those of you who are concerned about your Duke's cooling fan will be interested in this.

Like most all liquid cooled engines, the engine has a thermostat which control's the coolant temperature by opening to release water thru the radiator (heat exchanger for the technically inclined) or closing to force the coolant to circulate only around the cylinder and thru the cylinder head.

If the thermostat is operating correctly it will begin to open when the engines coolant reaches 88 degrees C (190.4 F). The thermostat should be fully open when the engine coolant temperature reaches 96 degrees C (204.8 F).

At this same 96 degrees C.(204.8 F), the fan turns on.
When the fan and/or riding the motorcycle has cooled the engine to 90 degrees C (194 F) the fan should turn off.
Notice that the engine temperature must drop 6 degrees C (42.8 F) below the "turn on" temperature before the fan will turn off.

While the engine is running, the metal parts are hotter than the coolant so although one can come to a stop and let the engine idle it takes some time for this extra residual heat to transfer to the coolant where it can be removed by the radiator.
That's a good part of the reason the temperature guage doesn't show a drop in temperature immediately.

When one shuts off the engine after a brisk ride this same residual heat will be transferred to the coolant but in this case, without the water pump circulating the coolant thru the radiator the cooling off time will take much longer even if the fan is still running.

With the engine off, the circulation thru the thermostat and radiator with the engine off will be dependent on the archaic thermo-syphon principal that depends on the density of hot and cold coolant temperatures. (This method went out of favor for vehicles about 100 years ago.)
The very slow thermo-syphon process can take a long time to move the coolant thru the radiator to remove the heat.

http://what-when-how.com/automobile/...em-automobile/


I found an interesting Adobe file link about the Duke 390 engine/lube/coolant that you all may be interested in:

https://www.dropbox.com/s/d4ld3kqno9...SSM_902_EN.pdf

[Cyrus_the_virus]

Originally Posted by ebonho

I have a question for owners of the newer 390s (later months this year).

Does the radiator fan still come on when you stop after a hard 15-20 minute city traffic ride? And does it stay on like in the older bikes (no matter how long you wait for it to go off at idle) or does it quickly go off once the temperature comes down (like in the 200s)?

Originally Posted by ebonho

That's really helpful (and depressing) bro.

mithunvijayan, once your bike is runin, and your first service and oil change is done, could you please check if the fan shuts off after some time.

Like added flavor, once jst to check, I actually sat near the idling bike for 15 minutes (burning my own fuel), and the fan still did not go off. After which I simply shut off the bike.

I cannot believe that almost 2 years later this is still happening ......

Originally Posted by ebonho

Simply put, the fan and radiator are incapable of cooling the bike down at standstill. They just about keep the temperature constant steady state. The 390 needs moving air for the cooling to work. I believe it needs a bigger radiator than the one it already has been given over the 200 .....

Doc, few points to put things in perspective:

The job of the radiator and the fan is to simply prevent "overheating". it is not to cool the engine to ambient temperature. Infact, on the 390, for the best performance, the engine temp is supposed to be 2 bars shy of the top segment. (4 bars shy of full). This is the 'normal' temperature.

Having said that, it is true that the cooling system was not a fully thought out process by KTM which was evident in the afterthought changes they made. However, you should not really worry so much because shutting the engine off is really dependent on the scenario. Let me explain:

When you come to a stop, almost always the fan will kick in, this normally happens when the bar in the middle segment reaches the second last bar(4th bar from top in total). This is to obviously stop the engine from heating up further and it works. No matter how long you run the fan, the max it will do is go one bar down. The function doesn't cool, it prevents overheating.

So, you have to make a choice weather to turn off or not depending on the situation. If you are going to be parked for more than 20mins or less than 2mins, the go ahead and turn the engine off right away, no harm done. This is because 2mins is too less for the engine to soak in the heat to overheat and on riding again will bring it to normal. More than 20mins is enough for the engine to soak heat and cool back to normal operating temperature through ambient heat exchange. However, if you have already hit the top segment (last 2 bars) and the fan is already running, only turn off if you are stopping for more than 20mins. Even if the stop is less than a minute in this case, it will overheat, so keep the engine running till it comes back to the middle segment.

The reverse fan operation was a non conclusive fix by KTM because this fixed the issue of heat onto the riders legs but it brought into the picture another concerning issue,i.e when stopped, the reverse flow of the air is only pulling in the hot air over the engine and putting it to the radiator. This is why the temperature never really goes down when the fan is running when you are stopped, the air thrown into the radiator it is just a few degrees cooler than the temp in the radiator because of where it is pulling in the air from.

All in all, the current system does "satisfactorily" do it's job except in certain conditions like stop and go traffic. This is not just KTM specific scenario, even my tiny 135LS used to heat up like crazy and quite literally burn my skin in stop and go traffic thanks to it's high compression ratio. So, unless your everyday commute includes more than 15mins of stop go traffic, you should be golden.

My thoughts are that adding a second similar fan would help the bike by leaps and bounds but then there is problem of electrical load. Remember, it runs of a puny battery. Another high amp fan would literally kill the battery in no time or add extra engine load for power generation. So, it is compromise of sorts.

Originally Posted by sandeepmohan

I find the trigger for the radiator fan a little too aggressive. You stop at a long traffic light. I keep the engine idling. Fan starts up and keeps running. Traffic light turns green, I start moving at a speed of no more than 20-30kmph considering I am in the thick of traffic inching slowly to cross the signal. In this short time I have started to move, the radiator fan turns off, possibly instruction from the ecu that the bike has started moving and natural air flow can take care of cooling. Not good. Its taking place too soon. Temperature starts rising, fan restarts.

This is due to the reverse flow logic they added, where from stop to 18kmph it rotates the opposite way(air flow back to front) and if it heats up above that speed, it pushes air front to back. This is why the cutoff happens. If it was one single direction, it would have kept running till it was normalized.

Originally Posted by basuroy

I have few queries btw ,
The bike after starting (as in cool engine ) is extremely jerky , no I don't mean mild snatching that are present in even hot engine below 4k rpm but severe snatches and they are present even after 4/5 bars on temp gauge in first 3 gears ( 1st gear is insufferable , 2nd too and 3rd is just about tolerable and coming from a CI bullet , a regular bike guy will probably brand it defective the way it is right now ) . Fuel is premium indian oil(91 RON) from a company owned and run pump , has a good reputation so chances of adulterated fuel is very low . Bike is just 140km on Odo , I assume it will get smoother with passage of miles and is the cold engine behavior normal ? I should mention I keep the bike below 5k rpm , tried 2nd today at 6/7k rpm and it was still jerky for the rpm .

Firstly, Indian oil premium is only just normal fuel with additives. It is not true 91RON. The only premium correct RON petrol you can get is speed petrol.

Secondly, the jerking is not due to heat or fuel. It is due to the gear ratio. Understand that the 390 produces so much torque that the larger gears are invariably going to be jerky at lower speeds because they are meant to pull as quickly as they can, smaller gear notches will be less jerkier but the pull is going to take forever when you give gas.

It will take practice and learning to know how to ride smoothest way possible on the 390 with gas and clutch usage simultaneously. It's a balance you will eventually find.

Originally Posted by basuroy

Twice now the gear indicator has malfunctioned during shifting to neutral in standstill , it shows 0 but stall on letting off clutch . Should I be concerned or such occurrence are typical ? It doesn't really bother me but at the same time I don't wish a complication later on .

This is called false clutch. Initially it can happen. But over time, it will improve. You will need to know the feel of when you are in neutral than looking at the display. Learn the feel of how the gear normally slots into neutral. Normally I go to 2 and come to neutral. 1 to neutral doesn't always work for me.

Originally Posted by basuroy

Tonight during a short acceleration burst ( almost WOT ) , the front wobbled slightly (nothing scary but noticeable , road is good ) . Is that normal , excuse the question if it comes across as newbie/vague but I am not used to this type of acceleration hence really have no idea at all what is normal and what is not .

Rigid hands. loosen up. Also, not sure which was your previous bike, but the 390 behaves completely different from anything below it. Acceleration can make the front end really light and any winds or bumpiness can make the front wobble unless otherwise there is a mechanical problem with the front end.

[sandeepmohan]

Originally Posted by Cyrus_the_virus

This is due to the reverse flow logic they added, where from stop to 18kmph it rotates the opposite way

Oh Yeah. I remember this one. I still wish the change took a little time cause you know how it is when you get off a busy traffic light.

All said and done, I don't think the Duke over heats. In the said conditions, just about any motorcycle will run super hot.

I am sure most of us have thrashed this motorcycle on the highway and the engine is well within safe limits of temperature.

[mithunvvijayan]

I just read that Bajaj has launched Kawasaki Z250 for 2.99 Lakhs. I just don't understand, why would people prefer a bike with a puny output of 32 bhp and a kerbweight of 167 kg for Duke 390??? other than for 17 litres tank it offers

[ebonho]

Originally Posted by ArizonaJim

When one shuts off the engine after a brisk ride this same residual heat will be transferred to the coolant but in this case, without the water pump circulating the coolant thru the radiator the cooling off time will take much longer even if the fan is still running.

Unlike in my SUV, the fan on the 390 does not work unless the engine is running. So if you shut off the engine, it force shuts off the fan even if its still running. Which is actually what I started this discussion with. The fan never stops. It goes on and on. Which means as per your explanation, it is incapable of bridging that 8 degree difference with the bike at rest and without moving air to assist it.

Originally Posted by Cyrus_the_virus

Doc, few points to put things in perspective:

The job of the radiator and the fan is to simply prevent "overheating". it is not to cool the engine to ambient temperature.

Ambient temperature would be 30-40 degree Celsius. We are talking about the fan cooling the engine to the late 80s (88 deg C), for the fan to shut off. Which it does in the 200. Which it does in all cars/SUVs. Which it does not in the 390.

Infact, on the 390, for the best performance, the engine temp is supposed to be 2 bars shy of the top segment. (4 bars shy of full). This is the 'normal' temperature.

The moment the bike stops, and the moving frontal air is taken out of the equation, the temperature rises to 9 bars (from 8) and the fan gets activated. But the fan is not able to get it back down to 8 bars - as in the 200. Ergo, either the radiator is deficient, or the fan is, or the combination of both is.

However, you should not really worry so much because shutting the engine off

This is to obviously stop the engine from heating up further and it works.

Agree. It prevents the bike from going on to 10 bars or the last High Coolant Temperature zone.

But it reaches a steady state, on the brink of the warning zone. It arrests further escalation. It fails to bring the bike back from the brink. It leaves the bike too close for comfort to the danger zone. It removes any leeway or flex in case anything goes wrong in this delicate equilibrium (coolant levels low, fan malfunctions, battery low, bimetallic strip of thermostat malfunctions, etc.)

No matter how long you run the fan, the max it will do is go one bar down.

That is EXACTLY it! In the 390 it does NOT bring the bike one bar down. I have checked this on the old test bike as well on some of the newer production bikes.

The function doesn't cool, it prevents overheating.

Correct. Too close to the brink. Its a machine. Anything can go wrong. Some give must be built in.

The reverse fan operation was a non conclusive fix by KTM because this fixed the issue of heat onto the riders legs but it brought into the picture another concerning issue,i.e when stopped, the reverse flow of the air is only pulling in the hot air over the engine and putting it to the radiator. This is why the temperature never really goes down when the fan is running when you are stopped, the air thrown into the radiator it is just a few degrees cooler than the temp in the radiator because of where it is pulling in the air from.

In my opinion, it was a stupid fix for a problem that was never a problem in the first place. Like what they did when they remapped the 200 to take care of initial jerkiness in the throttle response. And killed the bike's character. Now they try to pander to soft puppies whose delicate skin is getting toasted ......

Such puppies should not be riding bikes. They should move from their cycles directly into their daddy's climate controlled air-conditioned SUVs or cars.

[Cyrus_the_virus]

Originally Posted by ebonho

In my opinion, it was a stupid fix for a problem that was never a problem in the first place. Like what they did when they remapped the 200 to take care of initial jerkiness in the throttle response. And killed the bike's character. Now they try to pander to soft puppies whose delicate skin is getting toasted ......

Such puppies should not be riding bikes. They should move from their cycles directly into their daddy's climate controlled air-conditioned SUVs or cars.

Well, I think it might have actually prevented a serious health hazard. An engine can be replaced, but a leg can't be

The way the cooling works now works at the edge but ok for my riding patterns. But yes, there are those days where I have to go into the old city to get that one thing which you only get inside gullies jam packed with traffic and people, yes those days the cooling can be a bia**h but otherwise, my normal routes are free from stop go traffic and at times i have been able to adjust accordingly, like going low revs when the engine starts to exceed heat limits.
But I can't complain, because I know for a fact that the Duke390 is not made as a city traffic commuter, so if I am not giving enough space for the bike to stretch it's legs, I am the one not doing justice to the 390 and cannot blame it for getting hot and angry. It's like blaming an angry bull for running over people in a crowded market. The owner that let it loose should be the one to blame. it just did one thing it does

[basuroy]

250km clocked so far , enjoying the bike A LOT now as getting hang of the control . Sometimes I feel I may be a little too confident on the saddle but hard to control oneself all the time

The engine braking is hard but I find it very good for controlling speed , low rpm performance leaves a lot to be desired but then I have so far avoided any prolonged first gear crawl so no issues . The left side heat at this time of the year is at worst a minor botheration but I guess it will be a lot more in summer , the culprit being the exhaust bend pipe . Braking is good , coming from an CI enfield , it is a whole other universe and allows one to ride aggressively (within reason of course) .

ONE QUERY - the rear brake is very weak in my opinion , it is hard to quantify but I feel that "front only" can stop the bike in half the distance if not less than "rear only" application takes . I am aware of sports bike brake distribution but is such a gap in braking prowess normal or should I get it checked ? I should mention the rear pad is more or less brand new as I rarely use it , does it gets better with use ?

And , how accurate is the on board mileage calculator and the fuel indicator(bike being held upright of course) ?

Is it OK to wash the bike with garden hose (no pressurized jet ) or does it demands special care where to and not to spray water ? For example I feel water might seep into the battery compartment while washing the seats, can that potentially harm the bike in any manner ?

Do brake pads require any maintenance in the form of washing ? If so can I use car shampoo allowing enough time for the pads to dry under the sun ?

On the topic of the ongoing radiator/fan discussion -
Maybe the engine oil pump is not powerful enough for the bike ? end of the day this is from outside same engine as a 125cc and 200c bike and maybe the design in some form didn't allow for a pump powerful enough for 375cc hence resulting in less than desirable oil circulation .

[Cyrus_the_virus]

Originally Posted by basuroy

ONE QUERY - the rear brake is very weak in my opinion , it is hard to quantify but I feel that "front only" can stop the bike....

Rear feels ineffective coz of the forward speeds the bike is able to do, however, you should learn how to balance between front and rear. Rear brakes need just a tap, not a hard foot, infact, if you test and slow down just with the rear brakes, you will get to know that they are pretty effective. It's just that the front is much more powerful with the obvious larger braking surface area. Besides, rear brakes need to be less stubborn and only aid, else would result in lockups but thanks to ABS, that doesn't happen on this bike but still the rear can get light under hard braking conditions.

Originally Posted by basuroy

And , how accurate is the on board mileage calculator and the fuel indicator(bike being held upright of course) ?

Pretty accurate as long as you are not idling for too long.

Originally Posted by basuroy

Is it OK to wash the bike with garden hose (no pressurized jet ) or does it demands special care where to and not to spray water ? For example I feel water might seep into the battery compartment while washing the seats, can that potentially harm the bike in any manner ?

Do brake pads require any maintenance in the form of washing ? If so can I use car shampoo allowing enough time for the pads to dry under the sun ?

Just don't wash the engine area. besides, it doesn't get that dirty there. Do not do anything with the break pads unless there is oil spilled on it.. they are clean as it is already thanks to how brakes work.

Originally Posted by basuroy

On the topic of the ongoing radiator/fan discussion -
Maybe the engine oil pump is not powerful enough for the bike ? end of the day this is from outside same engine as a 125cc and 200c bike and maybe the design in some form didn't allow for a pump powerful enough for 375cc hence resulting in less than desirable oil circulation .

If it was an oil circulation issue, mechanical failure would have happened within the first 500kms. The honest truth is that this bike was not made to be driven on traffic choked roads, it does perfectly fine in almost all other circumstances.

[mithunvvijayan]

Originally Posted by basuroy

And , how accurate is the on board mileage calculator and the fuel indicator(bike being held upright of course) ?

The only way to know, if the mileage shown in the onboard display is accurate, is to use the full tank method.

Fill the fuel untill the fuel reaches the brink of the tank opening. Ride for say 100kms in your normal riding style( you have to watch the odometer) . Note the mileage figure in the onboard display. Go to the fuel pump and fill it to the brim. But this time measure the quantity of fuel needed to fill up to the brim. Suppose it is say 4 litres. Then you got a mileage of 25 kmpl. If it's same as that shown in the onboard display, then the display is accurate.

I guess you already know the process.

The fuel guage in most economic vehicles, are exponential. They tend to show the fuel consumption at a faster rate, initially. It is due to the float design used in the fuel gauge, in most economic vehicles.

Originally Posted by basuroy

Is it OK to wash the bike with garden hose (no pressurized jet ) or does it demands special care where to and not to spray water ? For example I feel water might seep into the battery compartment while washing the seats, can that potentially harm the bike in any manner ?

However you do it, please do not pressure wash the radiator. The fins are so flimsy that they will bend and restrict the passage of air. And also be careful in the sensor areas. Sensors are costlier.

[shan_ned]

Originally Posted by Cyrus_the_virus

Having said that, it is true that the cooling system was not a fully thought out process by KTM which was evident in the afterthought changes they made. However, you should not really worry so much because shutting the engine off is really dependent on the scenario. Let me explain:

So, you have to make a choice weather to turn off or not depending on the situation. If you are going to be parked for more than 20mins or less than 2mins, the go ahead and turn the engine off right away, no harm done. This is because 2mins is too less for the engine to soak in the heat to overheat and on riding again will bring it to normal. More than 20mins is enough for the engine to soak heat and cool back to normal operating temperature through ambient heat exchange. However, if you have already hit the top segment (last 2 bars) and the fan is already running, only turn off if you are stopping for more than 20mins. Even if the stop is less than a minute in this case, it will overheat, so keep the engine running till it comes back to the middle segment.

My thoughts are that adding a second similar fan would help the bike by leaps and bounds but then there is problem of electrical load. Remember, it runs of a puny battery. Another high amp fan would literally kill the battery in no time or add extra engine load for power generation. So, it is compromise of sorts.

Good to hear your points in addressing some of the concerns raised on the engine overheating. You are suggesting few precautionary measures about when to switch off and when not to that in case of engine overheating. To keep things simple, can we arrive at a set of golden thumb rules on preventing such sudden overshoot of engine temperature ?. One of the posts was mentioning about a superbike (which had a temp indication in it's console) which showed an abrupt increase in engine temp due to it's sudden engine switch off. You have already summarized a few in your post, but if there are any other measures to be taken while riding, then collating those points in this thread will definitely help all the 390 owners.

In another forum, there was a guy who simply replaced his stock fan with an aftermarket fan and he found the solution to be more effective in controlling the engine heat, but I am not sure if that is well accepted.

Originally Posted by ebonho

Unlike in my SUV, the fan on the 390 does not work unless the engine is running. So if you shut off the engine, it force shuts off the fan even if its still running. Which is actually what I started this discussion with. The fan never stops. It goes on and on. Which means as per your explanation, it is incapable of bridging that 8 degree difference with the bike at rest and without moving air to assist it.

More on a tangential note - On the contrary, I heard few Hayabusa owners complaining about the radiator fan not getting switched off even after shutting down the engine and the fan keeps on running unless the ignition key is turned off. Their concern was about the fan draining the battery .

[VW2010]

Such puppies should not be riding bikes. They should move from their cycles directly into their daddy's climate controlled air-conditioned SUVs or cars.

haha..

Dr...i wish some of them took a long ride on those old 500s for i actually felt a slightly higher temperature with 390 but was anyway used to the warmth of the engine

Those early morning rides at 4Am and the warmth these engines provide is such a boon for me or for some.

If its too hot, a great time to take those tea or coconut water breaks

[ebonho]

Originally Posted by VW2010

haha..

Dr...i wish some of them took a long ride on those old 500s for i actually felt a slightly higher temperature with 390 but was anyway used to the warmth of the engine

Those early morning rides at 4Am and the warmth these engines provide is such a boon for me or for some.

If its too hot, a great time to take those tea or coconut water breaks

It pisses me off no end when a company starts reacting to kids and their inflated sense of biker wisdom and technical knowledge, and messes up a good product by trying to re-engineer (with Indian jugaad) what has been designed by a world beating cutting edge bike maker with more trophies to its name than can be counted in motor sport across the globe.

My largely unsolicited advise to Bajaj on this one. Observe. Learn. Internalize. Ride piggyback and take giant steps. Short circuit the long arduous very expensive learning curve. But for God's sake, do not overreach .....

[gharika]

Thanks to the friendly and informative people on this forum, I went ahead with the purchase of the Duke 390 and got it under me today . This is my fourth bike but this time it was after a gap of 10 years. My last one was a CBZ (1999 make).
This is the second time that the forum has helped me in making my buying decision and I have the confidence in the people here to get me out of any machine trouble. So much so that the first time I rode the Duke was after I purchased it.
The recent discussion on the cooling system of the Duke was fresh on my mind during the ride out of the showroom and I experienced it first hand. I am still in doubt what to do on the traffic stops, the only time I have to stop actually and the speeds come down below 40. The stops range between 30 seconds to 110 seconds. So should I switch it off? Let it idle? Cyrus_the_virus provided good tips, I will follow them in the meantime.