Bajaj Dominar 400 Ownership Experience Thread

[kiran2508]

the past couple of yrs some of the services/repairs i've been diy with the help of my local mechanic(who usually does only activas), its been a learning experience for both of us! just getting the parts from the svc has been a pain!

Very true, finding a right SVC and mechanic is always a luck by chance. I've always allowed only one person to touch my bike, he alone rebuilt my entire engine taking his own sweet time with care and not doing it a rush hurriedly just to rip off money. He's always willing to allow me near the bike when in service(some SVC's dont even allow customer near service bay) and explains everything that's being done and how its done.

He knows my bike in and out what was done and how it was done, he's equally concerned and OCD as me on things needs immediate attention and what needs to be done in next service, I've his number on speed-dial.

We need people in the industry who work out of passion as mechanics rather than making money and rip off customers in SVC's.

[sanjeet286]

Very true, finding a right SVC and mechanic is always a luck by chance. I've always allowed only one person to touch my bike, he alone rebuilt my entire engine taking his own sweet time with care and not doing it a rush hurriedly just to rip off money. He's always willing to allow me near the bike when in service(some SVC's dont even allow customer near service bay) and explains everything that's being done and how its done.

He knows my bike in and out what was done and how it was done, he's equally concerned and OCD as me on things needs immediate attention and what needs to be done in next service, I've his number on speed-dial.

We need people in the industry who work out of passion as mechanics rather than making money and rip off customers in SVC's.

Name of the mechanic and place?

[arya809]

[QUOTE=s1d;n2229398]

make sure you drain the existing coolant, run some distilled water thru the radiator and drain it and fill with motul motocool expert. .

After reading your post, I started wondering, why only flush the radiator and container, shouldn't we start the engine for complete removal of old coolant? The website in this link suggest to run car's engine for 10 minutes for flushing coolant:

https://www.autozone.com/diy/antifreeze-coolant/how-to-flush-and-fill-coolant

Today I saw a youtube tutorial by MCGarage, even he flushed the radiator without starting the engine. So I guess it's a common practice, but I'm curious as to why not start the engine for proper flushing?

[s1d]

[QUOTE=arya809;n2229462]

After reading your post, I started wondering, why only flush the radiator and container, shouldn't we start the engine for complete removal of old coolant? The website in this link suggest to run car's engine for 10 minutes for flushing coolant:

https://www.autozone.com/diy/antifreeze-coolant/how-to-flush-and-fill-coolant

Today I saw a youtube tutorial by MCGarage, even he flushed the radiator without starting the engine. So I guess it's a common practice, but I'm curious as to why not start the engine for proper flushing?

this is a small motorcycle with hardly a liter of coolant. a normal drain will remove 95% of the coolant. and adding water and draining it will remove some left over traces of old coolant but leave a bit of the water(used to flush)
like you said, if time permits and if its been a long time since a last coolant change, it is recommended to start the engine and let the fan kick in (which means the thermostat opens and lets the water circulate throughout the cooling system).. and then wait for the engine to cool down and then drain the water.. and repeat this another time if required. this is also better in cases where there is suspected coolant contamination with engine oil. My bad i should have used the term 'Flush' in my earlier post.

but alas the svc doesnt have the time to do this routine and will simply only drain and refill. and remember whether you flush after running the engine or not, there will still be some traces of water or old coolant still inside respectively.
for example, when i switched from stock green coolant to motul motocool expert, i had the svc drain the old coolant then add water fully (they dint want to do it, but i made them do it due to the rapport i have with them), run the bike till the fan kicks in and then after the engine cooled down drained the water flush (which was light green to clear). Then filled up with the new motocool coolant. this was done because i was changing the brand and possibly the type of coolant and dint want a cocktail running in the bike.
The second time around after 3yrs on motocool expert, i simply drained the old motocool coolant (it was its usual color, no brown deposits or such) and filled up with fresh motocool coolant in both the radiator and the expansion tank. i could have flushed it, but felt it wasn't necessary. so it's just common sense and experience that tells you if a flush is really required.

[arya809]

[QUOTE=s1d;n2229469]

so it's just common sense and experience that tells you if a flush is really required.

Your post makes perfect sense, thanks for clarifying everything.

BTW my motorcycle's average will be 3000 kms per year, can you suggest which consumables to change as per timely basis, which should be changed irrespective of the kms run?

[s1d]

[QUOTE=arya809;n2229480]

Your post makes perfect sense, thanks for clarifying everything.

BTW my motorcycle's average will be 3000 kms per year, can you suggest which consumables to change as per timely basis, which should be changed irrespective of the kms run?

for usage of 3000km a year, i'd recommend you change the engine oil + oil filter and the fuel filter. The air filter can be inspected, cleaned with compressed air and reused (unless its badly clogged or damaged).. it is usually good for around 7k-10k km with one cleaning in between. and the spark plugs are easily good for around 15k km. keep the chain lubed to prevent premature wear and rusting.
the other fluids such as brake fluid,coolant, fork oil can be changed every 2 yrs.

[arya809]

Great, Bajaj has started showing its inferior quality!

Today while on a highway ride, engine stalled without any reason. It's a D400 bought in Dec 2019, 2nd free service was done 2 weeks back, total odo reading is 22xx kms. Since the engine running-in was over, I was riding at full throttle on the highway, keeping it between 7k to 9k rpm's. The auxiliary LED light (30 watts) was on since it was late evening.

Tyres fully inflated, cleaned and lubed chain myself 2 days back, Battery was fully charged, spark was generating, half tank fuel, all fuses okay, starter motor kept cranking then stopped on its own after few seconds BUT engine never started. Called a friend to tow it with his car. I planned to try to start it in gear at higher speeds while towing. Engine reluctantly started working in 2nd gear and 40 kmph speed.

Engine kept stalling at lower rpm's (like when a carburetor bike runs out of petrol), I had to rev it constantly to keep it above 5000 rpm else engine stalled within a blink. Rode it at high rpm's constantly and took it to the SVC, apparently they were closed for the past 3 days so they decided to work full time today. The mechanic attached the ECU diagnostic tool and it was showing an ECU malfunction (as told by them). They reset the ECU or cleared the malfunction, I am not sure. But immediately after that, the engine started behaving normally (somewhat normal). They told me to bring it again tomorrow morning for full workup.

My queries:
1. What happened to the ECU all of a sudden? I am seriously starting to mistrust it, do they use the same brand/model ECU in KTM's as well? What needs to be done to make my motorcycle trustworthy enough for long highway rides?

2. The engine is still far from normal. After keeping it off for a few minutes, it stalls at idle then I have to start it again and rev it a few times, then it holds idle and runs normally.

3. Since this issue, I am noticing a tik-tik noise coming from the left engine side. It is a constant ticking noise which can be heard across entire rev range. If it's the valve clearance (tappet gap) then how did it occur all of a sudden?

[kiran2508]

Great, Bajaj has started showing its inferior quality!

Today while on a highway ride, engine stalled without any reason. It's a D400 bought in Dec 2019, 2nd free service was done 2 weeks back, total odo reading is 22xx kms. Since the engine running-in was over, I was riding at full throttle on the highway, keeping it between 7k to 9k rpm's. The auxiliary LED light (30 watts) was on since it was late evening.

Tyres fully inflated, cleaned and lubed chain myself 2 days back, Battery was fully charged, spark was generating, half tank fuel, all fuses okay, starter motor kept cranking then stopped on its own after few seconds BUT engine never started. Called a friend to tow it with his car. I planned to try to start it in gear at higher speeds while towing. Engine reluctantly started working in 2nd gear and 40 kmph speed.

Engine kept stalling at lower rpm's (like when a carburetor bike runs out of petrol), I had to rev it constantly to keep it above 5000 rpm else engine stalled within a blink. Rode it at high rpm's constantly and took it to the SVC, apparently they were closed for the past 3 days so they decided to work full time today. The mechanic attached the ECU diagnostic tool and it was showing an ECU malfunction (as told by them). They reset the ECU or cleared the malfunction, I am not sure. But immediately after that, the engine started behaving normally (somewhat normal). They told me to bring it again tomorrow morning for full workup.

My queries:
1. What happened to the ECU all of a sudden? I am seriously starting to mistrust it, do they use the same brand/model ECU in KTM's as well? What needs to be done to make my motorcycle trustworthy enough for long highway rides?

2. The engine is still far from normal. After keeping it off for a few minutes, it stalls at idle then I have to start it again and rev it a few times, then it holds idle and runs normally.

3. Since this issue, I am noticing a tik-tik noise coming from the left engine side. It is a constant ticking noise which can be heard across entire rev range. If it's the valve clearance (tappet gap) then how did it occur all of a sudden?

Only one answer from my side: Bad/Adulterated fuel which you topped up on the highway, either contaminated with water/kerosene or bottom of the barrel fuel collected with sludge, dirt, mud

1. Engine has a knock sensor built-in, sensors detected a knock due to bad fuel, hence ECU started adjusting on-the-fly the Fuel ratio to prevent the knock. Hence bike went to "limp mode". Reset of ECU cleared the knock warning, and everything is happy and normal again

2. Again, drain all the old fuel, clean fuel filter, clean spark plug head, and check for any mud/sludge/water contamination.

3. That's normal tappet noise, after break-in period and when engine is fully open, valve clearances do expand and contract need re-adjustment with correct shim sizes in some cases. Nothing worrying, you can run on it till next service and ask for "Stethoscope sound inspection"

[arya809]

@kiran2508

Good explanation, but that depends upon the assumption that I filled adulterated fuel. I was on the highway for only 80 kms round trip, got the tank full in the city from my regular BP petrol pump, plain petrol.

I am not sure, but isn't "limp mode" exactly opposite of my case? As far as I know, in cars and bikes, "limp mode" means the engine runs smoothly and perfectly, starts easily and holds idle rpm but the max rpm is limited to a lower level like 3000, 4000 rpm's etc. In my case, the engine was rough, refuses to start, doesn't hold idle and can only be run at higher rpm's.

I took it to SVC today morning. I bluntly told them that I will sell this junk as I can't trust it anymore, the SVC manager voluntarily agreed to get the head assembly changed under warranty. They have placed the order and it will be done once the parts arrive.

They made this decision based on the horrible ticking noises from the engine head. Today morning when I started the bike, there was a loud ticking/clicking noise for 10 seconds. After 10 seconds, the noise was slightly lower but constant and easily audible, there is considerable loss of power and no refinement whatsoever.

I am more irritated by the fact that I will have to follow engine running-in procedure for 2000 kms after the head replacement. And still bewildered as to what could be the reason for the valve or cam assembly going kaput like this.

[B7ACKTHORN]

Chances are you have issues sinister than what a bad fuel can be summed upon. First off, the Dominar doesn't come with any knock sensor, all it does have are a couple of sensors generic to an FI unit and an oil pressure sensor switch on the head. Many chances of Dominar failing have been to three reasons, primarily, engine coolant vanishing without a trace, secondly faulty valve train and thirdly some batches plagued with faulty ECMs and failed stator coils. As you've summed up right, limp mode basically restricts the free revving RPM to a preset RPM level enough to move the vehicle on its own for a proper diagnoses.

As a goodwill that they agreed upon to change the entire head assembly, I would also insist you replace your timing chain, chain tensioner and completely new parts for the valve train. Make sure your valve clearances are triple checked and the right size shims are used; if required make sure the SVC manager assistance is obliged upon to make sure you are completely satisfied with the work carried. I'd also strongly recommend you to inspect your fuel pump pressure to make sure it's maintaining and supplying the right pressure to the injection system.

The Dominar is a great one at that, but definitely not the best out there in terms of reliability and pestering issues. Good luck on your saga, and keep your observations posted.

Cheers!
VJ

[arya809]

The Dominar is a great one at that, but definitely not the best out there in terms of reliability and pestering issues. Good luck on your saga, and keep your observations posted.

Cheers!
VJ

Glad to hear from an expert.

1) I already asked the head mechanic about chain tensioner but he said it's not a problem, no need to change. Should I visit again to force them to change it? They will need to order the parts in advance if not in stock.

2) I don't know all the detailed parts in cam & valve assembly, kindly elaborate "completely new parts for the valve train". When they change the complete head assembly, doesn't it include all new parts of a valve train?

3) I had previous suspicions about the valve clearance, I was noticing clear and loud tappet noise since 3 months now, that too while accelerating quickly FROM 6000 rpm (I mean I don't accelerate hard from lower rpm's which causes knocking). But mechanics kept telling me it's insignificant and doesn't need tappet adjustment so early.

4) I am paranoid about losing compression when these local mechanics replace the head, how can I make sure that they replace head assembly with precision, please tell me the exact points like using torque wrench, diagonally tightening nut/bolts, decarbonizing piston, order of putting parts/gaskets etc etc.

[B7ACKTHORN]

Glad to hear from an expert.

1) I already asked the head mechanic about chain tensioner but he said it's not a problem, no need to change. Should I visit again to force them to change it? They will need to order the parts in advance if not in stock.

2) I don't know all the detailed parts in cam & valve assembly, kindly elaborate "completely new parts for the valve train". When they change the complete head assembly, doesn't it include all new parts of a valve train?

3) I had previous suspicions about the valve clearance, I was noticing clear and loud tappet noise since 3 months now, that too while accelerating quickly FROM 6000 rpm (I mean I don't accelerate hard from lower rpm's which causes knocking). But mechanics kept telling me it's insignificant and doesn't need tappet adjustment so early.

4) I am paranoid about losing compression when these local mechanics replace the head, how can I make sure that they replace head assembly with precision, please tell me the exact points like using torque wrench, diagonally tightening nut/bolts, decarbonizing piston, order of putting parts/gaskets etc etc.

Thank you for the kind words Arya, please I am no expert. Sharing what I have seen and observed. In their order.

1. Parts sometimes fail sooner, whether the mechanic justifies it or not, when they fail, they fail and it's absolutely no point for a guess work when half the engine is being stripped. Insist on replacing the chain, tensioner and if possible the cam shaft too.

2. They do and they do not; partly because a mechanic can salvage parts deemed necessary for him, refer to the first point (when parts fail, they fail, they don't ask for a mechanic's consent ) though a mechanic may still say a part is great. Making sure everything is replaced in the head, removes guess work out of the equation and definitely doesn't warrant future unnecessary follow-ups.

3. Please refer part 2.

4. This is a totally different chapter altogether. There are those who do things with and without a torque wrench. I have known people who can put a torque wrench to shame primarily because of the finesse and the dexterity at which they do their job, and knowing when and what tool to use for a given project on hand. Then there those who have them but still do a fidgety job which eventually leads to shoddy work. Don't worry about the torque specs, what matters here are new parts, correctly installed and the rest will follow naturally.

5. My personal suggestion to you would be, be present at the garage when they assemble your motorcycle. Trust me, you will spot many things they don't. z

Good luck.

Keep us posted.

Cheers!
VJ

[kiran2508]

4) I am paranoid about losing compression when these local mechanics replace the head, how can I make sure that they replace head assembly with precision, please tell me the exact points like using torque wrench, diagonally tightening nut/bolts, decarbonizing piston, order of putting parts/gaskets etc etc.

As VJ mentioned in previous post, there is no one size fits all.
To give you an analogy, Maggi is sold all over the country coming out of same factory, yet no two hotels/houses cook the Maggi same way. All have their minor variations in their cooking process. Even though clear instructions is printed on the back of the packet.

Same way the parts come straight form assembly line of Bajaj, parts which would have gone on to one of the production bikes to be assembled and sold in showroom.
If done right and parts are assembled properly (like my engine which was shattered to pieces inside the head), it should be as good as new bike if not on par better than brand new.
Expertise of the mechanic and number of engines rebuilt by him till now, makes a difference. Someone who either follows the book or who follows his skill.

Try to ask for someone who has a "Certification to work on Dominar and trained by Bajaj training camp", not some Discover, Platina mechanics.

Principles of putting together a ICE engine is same for all 2 wheelers, cars, be it single cylinder or twin or inline 4 or V6 or V8.

Piston goes in the cylinder connected to crank, head goes which is faced(if needed), add the head gasket, valves lapped to clearances with new oil stem seal, valve clearances checked to specs with correct shims/screw setting, cams and timing chain adjusted to TDC and BDC marks, cover with came guide cover, put some gasket maker and cover up the valve cover. Tighten everything up. Voila. You've a fully rebuilt top-end.

For all the spec numbers, ask for Domniar service manual from you SVC, you'll find all torque specs, valve clearances, piston ring clearances etc etc.

[arya809]

For all the spec numbers, ask for Domniar service manual from you SVC, you'll find all torque specs, valve clearances, piston ring clearances etc etc.

By the way, I was searching for the terms "dominar + engine + head", found few videos on Youtube in which owners of D400 2019 had similar engine head problems. Few of them got the Head assembly replaced, for others the mechanics simply replaced and adjusted new cam and valve set. It seems to me that quite a lot of Dominar 2019 are plagued by this issue. My SVC had already ordered 1 head assembly for another D400 2019, then ordered another for me.

I have a basic knowledge. I can't IMAGINE the reasons for such loud tapping noises in my motorcycle. My GUESS is that since it's DOHC so there's no rockers, hence it shouldn't make such noises which is common with SOHC rockers?
I am imagining the worst that somehow the camshaft etc are misaligned, timing is way off or some parts moved from its place. I mean how else can there be a loud ticking noise in a DOHC engine?

Again, all that is wild speculation, I watched a few Youtube videos of DOHC engines and imagined the rest, please explain the actual facts.

[kiran2508]

I can't IMAGINE the reasons for such loud tapping noises in my motorcycle. My GUESS is that since it's DOHC so there's no rockers, hence it shouldn't make such noises which is common with SOHC rockers?
I am imagining the worst that somehow the camshaft etc are misaligned, timing is way off or some parts moved from its place. I mean how else can there be a loud ticking noise in a DOHC engine?

Again, all that is wild speculation, I watched a few Youtube videos of DOHC engines and imagined the rest, please explain the actual facts.

DOHC engine of Dominar doesn't have a convectional rocker arm but they have a finger follower type rocker arm which make a tick tick tick sound at high temperature.
There are chances of faulty manufacturing defects timing chains where it's expanded beyond the actual tolerances, hence the cam is running out of sync, hence the wired sounds.

Fun Fact: Mahindra is recalling brand new Thar's around 1500+ cars due to faulty camshafts in their diesel engines.
https://www.timesnownews.com/auto/ca...n-india/715881

So no manufacturer is immune to manufacturing defects, as companies source parts from 3rd party vendors. Even a minor imperfection or improper Heat treatment will lead to faulty component.
Since your bike Service center has already to replace things under warranty, nothing to worry.