Yamaha R6 Forum: YZF-R6 Forums banner
1 - 14 of 14 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter · #1 ·
Hey,

since a few weeks I have the following problem with my R6 RJ15 which has 18000 km: After a cold start the bike has hardly any power, stutters extremely and sounds like it is choking. Wenn i give it gas several times or let it warm up a bit longer, it runs normal again. I thought it might be the spark plugs or ignition coils, which I then replaced, but this did nothing at all. The battery was also recently replaced and I don't know what else it could be. Does anyone have an idea?

here is the video showcasing the problem:
 

·
Registered
Joined
·
3,664 Posts
Is that a 2015 model? Low RPM, high load engine miss is typically spark related; whether that be spark plugs and/or ignition coils. People have been known to pickup bad replacement coils. Check air/fuel ratios and enrich if necessary.
 

·
Registered
Joined
·
148 Posts
Hi there,

Guess this wont be much help,

But my bike was doing kinda the same 4-5 days ago, it was more obvious when cold, but she also did it when warm, to a less extend, barely noticable.

Sympthomps were just like yours, exact same rpm/ and sound, (and probably feel).

But in my case, it was indeed a spark plug, i changed them yday and she stopped that.

I find it weird that new plugs/coils did not fix that, were both items new ?

and all 4 plugs and all 4 coils changed ?

were the coils used? like the user above me mentioned?

Exaust filter PCV/flash?

Im intressed.

Have a nice day !
 
  • Like
Reactions: NaoTaymoon

·
Registered
Joined
·
8 Posts
Discussion Starter · #4 ·
Is that a 2015 model? Low RPM, high load engine miss is typically spark related; whether that be spark plugs and/or ignition coils. People have been known to pickup bad replacement coils. Check air/fuel ratios and enrich if necessary.

2013 model. Would be terrible luck if I got a brandnew defective spark plug or coil... I thought about the motorcycle being too lean since I installed the air fitler, but I am not sure if this would be enough to make it stutter that badly.

377287


My spark plugs looked like the one in the middle, but I only installed the bmc air filter over a month ago, so I don't know if they would have looked differently, if I had the bmc filter from the start. I also have the cat and the db-killer installed.

Any tips on how I can verify the fuel/air ratio? Do i need to buy a measurement tool or should I get it checked by someone who does dyno tuning?

I have a few things I can try:

1) diagnose mode
2) use fuel cleaner
3) check airfilter an hoses
4) clean fuel filter
5) verify throttle body sync (don't have the tools)

(the new coils are from tour max, the spark plugs are iridium and from ngk)
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #5 ·
Hi there,

Guess this wont be much help,

But my bike was doing kinda the same 4-5 days ago, it was more obvious when cold, but she also did it when warm, to a less extend, barely noticable.

Sympthomps were just like yours, exact same rpm/ and sound, (and probably feel).

But in my case, it was indeed a spark plug, i changed them yday and she stopped that.

I find it weird that new plugs/coils did not fix that, were both items new ?

and all 4 plugs and all 4 coils changed ?

were the coils used? like the user above me mentioned?

Exaust filter PCV/flash?

Im intressed.

Have a nice day !



Yes the spark plugs looked normal, but I replaced all of them with brandnew iridium spark plugs. I didn' t have tools to test the ignition coils, I replaced them with four brand new ignition coils.
The problem was already present before I switched from the akra slip-on to the leovince full exhaust system, so I can rule out that it has something to do with the exhaust. I didn't flash the ecu since I waited for my new leovince system, but the problem appeared like 2 weeks after I installed the new bmc air filter (might be coincidence). And I am not sure if I should flash the ECU while something is not working properly. It it's a fuel/air ratio problem, remapping would solve it, otherwise it might only do more damage :(
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #7 ·
I bought it recently and I can only guess that it isn't tuned. The only thing the person before me changed was the exhaust.
Thanks for your ideas, I will try to solve it and report back when I succeed.
 

·
Registered
Joined
·
148 Posts
I bought it recently and I can only guess that it isn't tuned. The only thing the person before me changed was the exhaust.
Thanks for your ideas, I will try to solve it and report back when I succeed.

I´ve heard, the r6 doenst like the iridium plugs that much, and it´s actually better to stick to OEM plugs,

But i am not sure "why" i read that , but i remember i did a wihile ago.

Could also be a defective coil , i´ve never used NON OEM coils on my bikes, so idk the resistances/etc.. of those

But you can test them with a multimeter , you just try to look for consistency on the readings.


Even tho last owner only changed the exhaust, he could still have tune/flash it ,

But listen,

I ran my bike for 1.5 years with LV full exhaust ( no-db killer) + KN filter and no tune, she was running lean but fine lol - Lil flat spot low rpm , specially on 4-6k RPM , apart from that , no other damages were done to my bike during that 1.5 year, even the plugs lasted that long, they were fine everytime i pulled them out, and i think i did 3-4x during that time .. i was not able to get a tune done at the time, and the bike just had to suck it up, and she did just fine.

Let us know if you find something.
 

·
Registered
Joined
·
3,664 Posts
Stock copper plugs have a comparably MASSIVE amount of surface area for the spark to jump the gap. These are "anti-fowl" designs for NGK. The iridium plugs have a very tiny conductive surface area... they fowl quick if the ratios are off. NGK has no anti-fowl designs for iridium. When I changed my COILS, I had to use newer ones which have much higher resistances versus the original OEM spec. So that meant that an already short re-gap interval, would be even more frequent. To offset I did go Iridium. The manual specifies either a 10 or 9 for the heat range. To make the iridium work, I had to go two steps colder with the NGK iridium, so a heat range of 8, while blocking off part of the radiator to allow it to get to thermostat temp faster and even run above it depending on ambient conditions.

Only time I've had any preignition was towing another bike at high-temp and low-RPM. Fortunately I didn't have to make any stops while towing so I could stay out of low-RPM and lower the engine temp. I'm also boosting octane.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #10 ·
I´ve heard, the r6 doenst like the iridium plugs that much, and it´s actually better to stick to OEM plugs,

But i am not sure "why" i read that , but i remember i did a wihile ago.

Could also be a defective coil , i´ve never used NON OEM coils on my bikes, so idk the resistances/etc.. of those

But you can test them with a multimeter , you just try to look for consistency on the readings.


Even tho last owner only changed the exhaust, he could still have tune/flash it ,

But listen,

I ran my bike for 1.5 years with LV full exhaust ( no-db killer) + KN filter and no tune, she was running lean but fine lol - Lil flat spot low rpm , specially on 4-6k RPM , apart from that , no other damages were done to my bike during that 1.5 year, even the plugs lasted that long, they were fine everytime i pulled them out, and i think i did 3-4x during that time .. i was not able to get a tune done at the time, and the bike just had to suck it up, and she did just fine.

Let us know if you find something.

I will have to do some troubleshooting this weekend and test a few things out, like diagnostic mode, injection cleaner, check air filter, throttle bodies, checking temperature of exhaust manifold and so on. If nothing works, i might have to visit a workshop until i have a multimeter and a carburetor synchronizer tool. And I somehow doubt that changing to a sport air filter made the bike stutter after cold starts, unfortunately i also don't have means to measure the fuel/air ratio..

Thanks for your suggestions and I will report back when it's fixed.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #11 ·
Stock copper plugs have a comparably MASSIVE amount of surface area for the spark to jump the gap. These are "anti-fowl" designs for NGK. The iridium plugs have a very tiny conductive surface area... they fowl quick if the ratios are off. NGK has no anti-fowl designs for iridium. When I changed my COILS, I had to use newer ones which have much higher resistances versus the original OEM spec. So that meant that an already short re-gap interval, would be even more frequent. To offset I did go Iridium. The manual specifies either a 10 or 9 for the heat range. To make the iridium work, I had to go two steps colder with the NGK iridium, so a heat range of 8, while blocking off part of the radiator to allow it to get to thermostat temp faster and even run above it depending on ambient conditions.

Only time I've had any preignition was towing another bike at high-temp and low-RPM. Fortunately I didn't have to make any stops while towing so I could stay out of low-RPM and lower the engine temp. I'm also boosting octane.

Thanks a lot for this valuable information. So i might still have a problem with spark plugs or coils. I will recheck the temperature of the exhaust manifold and see if something stands out. Unfortunately I don't have a garage where I can work on my bike, changing plugs and coils outside on the parking lot was a pain in the ass..

Sooner or later I will have to invest in those measuring tools, but until then I will try with what i have.

Since you seem to have great knowledge about mechanical stuff, could you maybe explain to me what the sparks and coils do when i turn my motorcycle on and why I have troubles only when cold, but none when I rev a few times or let it warm up for half a minute. Maybe you can provide me a scientific explanation on how temperature affects coils and plugs?

I really appreciate your detailed explanation from before :)
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #12 ·
Hello,

I had tried a few solutions this weekend, however the problem still persists.

1. the diagnostic mode ran without errors
2. with the engine / injection cleaner, the bike seems to run a little smoother in idle.
3. the air filter looks super clean and the cables from the tank all look ok
4. i didn't notice anything completely out of sync with the throttle body. The video of it here:
5. I started the bike and checked the temperatures of each tube. The result:
377312



(The left pipe was always colder and that was also the case before replacing the ignition coils/spark plugs.)

The only thing I could have done is to check the fuel filter.

My idle RPMs are:
377311


What I find strange is that I start the bike in the morning and it initially stutters and loses power until I play with the throttle. Then after 4 hours I start the bike again and since it should be cold again, I expect the same symptoms. However, the motorcycle starts properly, it does not stutter and I immediately have my normal performance.

Could the problem be engine oil, fuel, injectors?

In the coming week I will try to flash my ECU and if the problem persists, then I will have to visit the workshop.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #13 ·
Hello,

Unfortunately, after so long I do not have good news. The motorcycle was at the workshop since October until mid-May. A lot has been tested and replaced (spark plugs, ignition coils, ecu flash, electronic parts, wires, valves, throttlebody, all kinds of filters and sensors etc.), but the problem has remained. In the meantime, 2 other R6s with less miles were there and they supposedly had the same problem, just not as pronounced. So the mechanic has come to the conclusion that no part really needs to be repaired and that the problem occurs normally with time....
 

·
Registered
Joined
·
3,664 Posts
Since you seem to have great knowledge about mechanical stuff, could you maybe explain to me what the sparks and coils do when i turn my motorcycle on and why I have troubles only when cold, but none when I rev a few times or let it warm up for half a minute. Maybe you can provide me a scientific explanation on how temperature affects coils and plugs?

 
1 - 14 of 14 Posts
Top