At this point, I would be curious on how well the piston rings are sealing with a leak down test just to be sure. Is the compression stroke allowing fuel into the sump? When was the last time you did a valve adjustment?
Help about motorcycle
- Thread starter Johnny25
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Yes, it is!
Feels weird as hell, but I'll post a pic this weekend.
It's a Bajaj Pulsar NS125 FI, 2018 model.
I have replaced all parts with OEM ones, as the OEM are dirt cheap!
Compression seems fine.
My bet still relies on too much fuel being injected and it can't be burned, so it travels downwards to the sump... Bit by bit
Valves have been adjusted on the 2nd service (5000km).
I am getting them adjusted In the near future.
Although this problem came on one day and stayed.
When you mentioned that the idle changes when you sprayed brake cleaner, what is your assessment on this discovery? Did you spray in the rubber intake manifold boot area after the throttle body but before the engine head?
Not motorcycle related but I just changed my Toyota‘s intake manifold gasket as there’s a well documented issue for intake leak causing a lean code with this car. The computer then compensates and adds more fuel and thus my mileage dropped a good 10% when I ignored the trouble code for months. My point is a leak was my root cause. If you verified through your testing that there’s an intake leak and maybe that’s why your ECU is sending too much fuel. How confident are you with all the seals, gaskets, o-rings, clamps, and manifold etc., between the TB and intake head?
I sprayed brake cleaner basically in the entire throttle body:
Where map sensor is attached;
Where the rubber boot meets the throttle body;
Where the injector is attached;
And on the idle solenoid.
Last weekend I disassembled the throttle body and reinstalled everything checking every hose, seal and orings.
Even where the rubber hoses connect to the throttle body, I used some gasket maker to be sure they would deal.
This weekend I will be sure of what is what
You have a vacuum leak. The fuel is rich because the fuel injection is going to full output to try and compensate.
I hope it's solved when I try it again this weekend.
It has been drying the gasket silicone I put it almost every seal.
Did you replace the seals?
Every last one of them...
Then hopefully that will cure your issue. Good Luck and please let us know.
*Update*
Took the motorcycle to a dealership I know.
They asked all about my problems and were very unsure of what could it be.
They said that if I spray brake cleaner, or propane before the throttle body and it destabilises idle, its not very problematic. It would be more serious if it happened after the map sensor.
The thing that they suggested about one of the probable causes was the calatytic converter.
They had very rare occasions that a cat would melt, clog the exhaust air flow and that would make the bike behave as mine seems to behave.
Carburated bikes wouldn't even run.
The solution they gave me was very simple: remove the cat.
As it's a 125cc motorcycle, it's not yearly inspected.
Performance could even increase on the low end on the revs.
I didn't test that option as I have no tools for testing.
I did spray air on my exhaust through the lambda port (with a 24L compressor) and didn't felt much of it coming out from the exit... Hmmm...
Took the motorcycle to a dealership I know.
They asked all about my problems and were very unsure of what could it be.
They said that if I spray brake cleaner, or propane before the throttle body and it destabilises idle, its not very problematic. It would be more serious if it happened after the map sensor.
The thing that they suggested about one of the probable causes was the calatytic converter.
They had very rare occasions that a cat would melt, clog the exhaust air flow and that would make the bike behave as mine seems to behave.
Carburated bikes wouldn't even run.
The solution they gave me was very simple: remove the cat.
As it's a 125cc motorcycle, it's not yearly inspected.
Performance could even increase on the low end on the revs.
I didn't test that option as I have no tools for testing.
I did spray air on my exhaust through the lambda port (with a 24L compressor) and didn't felt much of it coming out from the exit... Hmmm...
*Update*
Just came from mechanic.
Valves were tuned.
Various shenanigans checked, they found no problems whatsoever.
One thought occured me:
Could it be that their guess about the catalytic converter be right?
On my way home (after picking up the motorcycle) I went another way where I can find a not very steep hill.
Middle way through it, it seemed the bike was losing power, like getting out of breath.
Could it be the catalytic converter?
I know that one of the symptoms is that going uphill becomes harder.
Just came from mechanic.
Valves were tuned.
Various shenanigans checked, they found no problems whatsoever.
One thought occured me:
Could it be that their guess about the catalytic converter be right?
On my way home (after picking up the motorcycle) I went another way where I can find a not very steep hill.
Middle way through it, it seemed the bike was losing power, like getting out of breath.
Could it be the catalytic converter?
I know that one of the symptoms is that going uphill becomes harder.
I don’t think so. A clogged cat is clogged from the get-go. It doesn’t take it half of a hill to fill up with pressure and bog down. That sounds to me like it’s more a function of temperature. Pre-ignition? Timing too advanced? Mixture too lean under high load? Head temps too hot?
A partially clogged cat might only impact the engine under more load because it can't flow the higher exhaust flow. At low engine loads, a partially clogged cat may not show up nearly as much.
Correct…. Let me see if I can explain that better. lets say the hill is a straight incline, like he hits 90% throttle by the first 100 yards. It will be bogging then. It won’t make it half a mile up the same slope and Then start bogging, like it had to fill a balloon to max capacity as pressure builds up… a clogged cat will start to bog as soon as the throttle demand is commanded. Does that make better sense?
I think it might be possible to have a slightly delayed reaction because the engine may not start running bad until the space/volume in the exhaust system between the head and the cat becomes somewhat pressurized. It would be the back pressure in the exhaust system that causes the engine to react, and it might not react until that back pressure builds up some.
@meep
You are making every sense, but the problems I'm facing seem like nonsense; as I can't find any plausible solution for them.
The only thing that made me try to remove the catalytic converter is this:
The bike seems to be out of breath as the revs go up and the heat/pressure builds up.
Once you start to climb the revs, you feel that it lacks the pickup to climb them.
Even downhill the rev pickup seems slower/harder.
The only plausible explanation is: as pressure builds up in the exhaust, as the revs go up, it reaches a point where it almost becomes a constant pressure output, if I'm getting the words right.
I will weld the exhaust together and the weekend should tell me everything I need to know.
This is the last step before I'm forced to trad the bike
You are making every sense, but the problems I'm facing seem like nonsense; as I can't find any plausible solution for them.
The only thing that made me try to remove the catalytic converter is this:
The bike seems to be out of breath as the revs go up and the heat/pressure builds up.
Once you start to climb the revs, you feel that it lacks the pickup to climb them.
Even downhill the rev pickup seems slower/harder.
The only plausible explanation is: as pressure builds up in the exhaust, as the revs go up, it reaches a point where it almost becomes a constant pressure output, if I'm getting the words right.
I will weld the exhaust together and the weekend should tell me everything I need to know.
This is the last step before I'm forced to trad the bike
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