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All 650Fs Breaking up at 7k+ RPM

kylehondarider

2015
CBR650F
Aug 23, 2018
So problem I'm having is at wide open throttle the motorcycle runs like crap above 7000 RPM. I spoke with a mechanic and he suspected a fuel pressure issue so I've tried a few things I'll explain below but I believe it's a fuel map or something else. The behavior is very much ON/OFF dependent on throttle position, at 100% throttle it bogs and if I back off to ~80% throttle it runs great and accelerates. There's a definitive throttle position where it starts. There's no variable valve timing on this motor, right? Setup below-

2015 CBR650F, Akrapovic exhaust

Problem was present before and after I added the following:

Power commander V (tried tunes for Akra, 2 bros, Arrow)
K&N Air filter
Aftermarket fuel pump (returned to stock now since problem was still present)
New fuel pre & post pump filter
New fuel pressure regulator
Verified smooth operation of throttle position sensor in the power commander software
Checked one of the spark plugs and it didn't look like bike was running lean or rich
 
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kylehondarider

2015
CBR650F
Aug 23, 2018
Compared the plug to a photo chart and it was exactly where it needed to be. Bike has 4,000 miles. I'll need to see if I can get a pressure gauge or send it to a mechanic to check that.
 

baugustine

2014
CBR650F
Staff
May 21, 2016
Ventura, CA
A fuel pressure gauge will quickly tell you its fuel related. ”break-up” sounds more ignition related and these coil packs share cylinders that would amplify a problem.
 

kylehondarider

2015
CBR650F
Aug 23, 2018
I was just going to suggest this. A couple members have had poor running/misfire from cracked or failing coil packs and spark plug leads. May want to check there.
But wouldn't bad coil packs/plug leads cause problems throughout the RPM range? Intermittent behavior? The motorcycle runs good in all other conditions, only issue is WOT above 7000 RPM
 

baugustine

2014
CBR650F
Staff
May 21, 2016
Ventura, CA
But wouldn't bad coil packs/plug leads cause problems throughout the RPM range? Intermittent behavior? The motorcycle runs good in all other conditions, only issue is WOT above 7000 RPM
Not necessarily. Many ignition problems (primary or secondary) only reveal themselves under load. The condition you describe is a high-load (high cylinder pressure) scenario.
 

JRinKtown

2018
CB650F
Jun 30, 2019
Kelowna B.C. Canada
It sounds to me like a lean bog at full throttle. Symptomatic of that would be backing off the throttle causes it to accelerate. There could be a few reasons for this, but since you experienced it after installing the Akra system, it's likely related to the A/F mixture changes that brought about, even though it continued after you installed the PCV and various maps.

I've heard (from the PCV company) that some of the maps on the PCV site are for the restricted European model, and so would cause the unrestricted version to run quite lean. Your plugs may look good, but only a plug chop at full throttle would show the condition at the time of the issue.

Best action perhaps is get it checked out on a dyno. That would tell for certain if it's what I think, and they could manually set the PCV to deliver the proper amount.
 

miweber929

2014
CBR650F
650F Alumnus
Staff
Feb 13, 2015
Woodbury, MN
It sounds to me like a lean bog at full throttle. Symptomatic of that would be backing off the throttle causes it to accelerate. There could be a few reasons for this, but since you experienced it after installing the Akra system, it's likely related to the A/F mixture changes that brought about, even though it continued after you installed the PCV and various maps.

I've heard (from the PCV company) that some of the maps on the PCV site are for the restricted European model, and so would cause the unrestricted version to run quite lean. Your plugs may look good, but only a plug chop at full throttle would show the condition at the time of the issue.

Best action perhaps is get it checked out on a dyno. That would tell for certain if it's what I think, and they could manually set the PCV to deliver the proper amount.
Good thoughts but nothing in his post says this wasn't there before the Akra was installed (that I could see) and he also said that no matter what map he loaded, and before and after the PCV, it was there. A bad map can cause running issues, but unless it was a faulty unit it wouldn't "break up" running.

We've had reports of high RPM mis-firing due to spark plugs, wires and coils.

kylehondarider @kylehondarider can you confirm if this was happening before or after the Akra? Did you use new exhaust gaskets? Anything else we should know about to help us?
 

kylehondarider

2015
CBR650F
Aug 23, 2018
I purchased the bike with 1200 miles and the Akra was already installed, apparently by a dealership. So I assume it was installed correctly. I've not ridden the bike with stock exhaust at all. I don't know if the problem has been there the whole time I've owned it or not. I noticed it first after about a year of ownership but it may have been present all along. There's no engine light on so I haven't considered checking codes, I can certainly do that. The Arrow map I've tried has enrichment from 2-5% in the upper rev range while the Akra map leans the map minus 2-4% in the rev and throttle range I'm having problems in. The Akra map (which is for the Euro model) seems to be a little better than the Arrow map in that area from what I can tell. I've also tried the 2 bros map with similar results. Side note- I have not done the PAIR valve mod. I do want to re-iterate that it's at a certain throttle position the problem begins and going past and under that specific position will begin and stop the problem.
 

baugustine

2014
CBR650F
Staff
May 21, 2016
Ventura, CA
Just for clarification, a 5% fuel swing in either direction will not cause your problem. Those symptoms sound like coil related. Fuel starvation will cause sluggish acceleration and over fueling will bog, which is not how your post reads.
 

miweber929

2014
CBR650F
650F Alumnus
Staff
Feb 13, 2015
Woodbury, MN
I purchased the bike with 1200 miles and the Akra was already installed, apparently by a dealership. So I assume it was installed correctly. I've not ridden the bike with stock exhaust at all. I don't know if the problem has been there the whole time I've owned it or not. I noticed it first after about a year of ownership but it may have been present all along. There's no engine light on so I haven't considered checking codes, I can certainly do that. The Arrow map I've tried has enrichment from 2-5% in the upper rev range while the Akra map leans the map minus 2-4% in the rev and throttle range I'm having problems in. The Akra map (which is for the Euro model) seems to be a little better than the Arrow map in that area from what I can tell. I've also tried the 2 bros map with similar results. Side note- I have not done the PAIR valve mod. I do want to re-iterate that it's at a certain throttle position the problem begins and going past and under that specific position will begin and stop the problem.
Thanks, that info helps a lot. baugustine @baugustine is right where my head is:


Just for clarification, a 5% fuel swing in either direction will not cause your problem. Those symptoms sound like coil related. Fuel starvation will cause sluggish acceleration and over fueling will bog, which is not how your post reads.
Without being there, working in the bike and hearing it through my own ears I’m heading towards a coil related issue. Someone or some people have had an issue with them (Don’t even get me started on why the hell Honda designed a new motor with coils and standard plugs Post 2005) so I’d start there.

Not sure how repair/tech savvy you are but start by seeing if the plugs are good and the plug caps are fully seated. I’d the tip the tank up and check your plug wire connections to the coils and caps, making sure they are tight and making good contact. If you were a gambling man I’d buy a used coil off eBay and swap it into the bike, new they are $50 each and apparently different between the two cylinder “pairs”:


It may be throttle position dependent so like a TPS or sensor thing but that’s hard to say since the revs rise at the same time, coils/caps are my thought at this point.
 
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kylehondarider

2015
CBR650F
Aug 23, 2018
Thanks- Yes, I've been doing all the work myself so far and have had the tank off and fuel pump out 5+ times. I may take a video for reference, not sure how well it will turn out with wind noise etc. I think it's supposed to rain the next few days however. I do have a set of new plugs I haven't installed because it looks like a serious PITA
 

miweber929

2014
CBR650F
650F Alumnus
Staff
Feb 13, 2015
Woodbury, MN
Another possibility justifying a looksee....in process of flipping the tank, check that the tank breather (vent) hose is free, clear, not kinked and does actually, fully VENT.

for partsbook reference...TUBE, FUEL TANK BREATHER 17580-MJE-D00
Another good suggestion and a good point. Venting is a HUGE thing for a motor and fuel system and if it’s plugged, wrong or pinched, that could cause issues under high vacuum.
 

JDude

2020
CB650R ABS
May 20, 2020
1979
It looks like all the big guns have replied with the usual suspects... I’ve learned to never assume anything with any engine! I received a Japanese gift from the gods via the Philippines and got a great one, l consider myself very lucky! I know my comments are completely unhelpful but it looks like you have to go down the rabbit hole... You purchased the mostly stock (exhaust) 2015 CBR 650 with 1600ml with issues and put on an additional 3,400ml and added mods. What I know (and its very little) @7000rpm the engine should spring to life and ride hard to 12,500 rpm. “Says the guy with an unmodified engine with 2000km/1250ml“ GOOD LUCK!!! I hope you find the culprit as I understand it can be a very frustrating experience!
 
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