Bogging/poor low RPM throttle response
 

Hi everyone,

Introduction of me:
I am a new member of this forum and also a brand new rider. I'm 21 years old and I dont easily let mechnical or electrical things scare me off cause im dedicated to what I buy.
Maybe because I study electrical engineering, it helps me keep moving when electrical issues happen, anywho.

Preliminary information:
I bought my first new bike 2 months ago from a mechanic, yet he was a bit odd. I bought a CBR600F4(PC35) EU version and bought a digital user/maintanance manual. It has about 67K KM on the odometer and has traces of fall damage as the tank also has a dent in it.
When I bought the bike, I test drove it and ran fine (cold run). I didn't run it for too long.
I drove it all the way home and everything ran fine. I had a buddy who is a mechanic clean out the whole carbs, let him fine tune the thing, replaced the sparks, oiled up the chain, replaced the air filter and test drove it for me.
He said that it ran like butter and was perfect. After I got it back, I put on brand new Oxford heatgrips pro 2.0. They have a built in LED that blinks when the battery falls below 13.3V.
So, I start my bike, use the choke let it warm up etc. I start driving. When the motor is cold everything is fine, good response etc. After 5 minuted of driving and standing still at a red light and wanting to leave at green. I notice that the motorcycle struggles a lot to go without stalling.
I use a lot of gas to make sure it doesn't stall. First I thought, maybe I'm wrong. So i go to a industry park to test my skills, just to find out that after standing still, the motorcycle falls shorter and shorter in RPM's and the dies on its own.
I replace the RR for a new one, bridged the + and - of the RR straight to the battery and bingo RPM drop fixed. YET I STILL HAVE POOR REPSONSE AT LOW RPM. The battery works fine now, 13.6V at idle and 14 to 14.2 at 5K RPM.

MAIN PROBLEM:
After doing all the electrical work (RR replaced, stator wires straight soldered and instant connection RR to battery (30A fuse in positive line)), I still get bogging when I want to leave red lights or driving at low RPM's. These symptoms of poor response and bogging always happen when the motorcycle is warm and at low RPM (under 4K RPM). My last hope is that replacing the fuel cut off relay will solve it as the previous owner used a jumper cable to bridge pin 1 and 3. This bridge overrides the use of the fuel pump transfer relay but I dont know if thats an issue. If that doesnt fix it, i'll be at lost and might sell the bike as I've spent more time repairing the thing than riding it. If anyone knows anything, PLEASE HELP, I just want to enjoy my newly bought bike. If people want an audio file of this bogging, Ill do my best to catch the sound without to much wind.

Things checked off (EDIT)
-Brand new RR from ultimate rectifier (Part number: UR-R-110-194)
-Stator wire connector removed and wires soldered
-New + and - cable from RR to battery (30 A fuse in the + line)
-Brand new LifePo4 battery installed ---> (https://www.123accu.nl/Landport-LFP1...O4-i36734.html)
-Carbs fully cleaned and tuned by experienced mechanic
-Oxidated connectors cleaned with baking soda
-Sparks replaced
-Air filter replaced
-Checked for vacuum leak with carb cleaner (none found)
-Fuel pump works, keeps clicking, when carbs full it clicks in intervals of 3 to 4 seconds due to jumper cable.

~Breadboiiy

If you look at the sequence of events as described, it appears that something went south while in the care of your friend.
Just by what you said, it sounds like something with the carbs isn't correct. I'm not knocking your friends' abilities, but it does take some extra care and knowledge when working on multi-carb engines. There are sixteen individual fuel circuits that have to be mutinously inspected and cleaned. Those sixteen then need to be properly adjust so they function as one. It's not an overly difficult practice, but it is a very tedious one.

Once I install my fuel pump cutoff relay I will test it again and if it persists I will go back to him. I also drove with my tank open in the hope of a vacuum leak but none the less, no vacuum leak. Kinda lost for sauce.

As a silly question, do you know how strong the stators are for these bikes, anecdotally I believe I have seen people critique performance if the bike has the fan running and the full headlights on. Could the heated grips be drawing alot?
please excuse the completely naive question.

No you're fine, it's about sharing knowledge not withholding it. Short awnser, no. The grips use little current and are parallel hooked to the battery. And the symptoms I'm having also happen when the grips are off so they are not the root cause of this issue.
The stators are fine, I've measured them at idle and 5K RPM and I'm getting correct voltages. 15VAC @idle and 60VAC @5K

Hi sorry to hijack the thread a bit @BreadBoiiy but my f4 is doing exactly the same. Runs nice til warm then bogs down from the traffic lights and then eventually dies. Everything pointed to the regulator/ rectifier as it doesn’t charge the battery when the symptoms occur. I’ve put a scope on it from stator, both sides of the loom to the RR but still no difference and I’ve replaced it twice! Really scratching my head now and getting a bit frustrated. Any help on this much appreciated. P.

The next time it does this, pop open your fuel cap and see if that causes a change. If it does, you have a clogged or pinched vent tube.

Possible solution
 

Hi everyone, so it has been a while now and I got my CBR running almost perfectly again. After removing the air box above the carbs, I inspected ALL the tubes and found that one of the vacuum tubes is splitting from the end. After properly installing it back it fixed the bogging COMPLETELY.
No more stalling at idles, no more hesitation when leaving stop signs or lights. Nice, smooth pulls without issues. The CBR still has unstable idle RPM's because my fuel cut off relay is missing (it's on its way).
I will be fixing the tube soon so I will be adding a picture of the tube that I mean.
I also had my fuel pump fail on me due to poor connectors from the aftermarket fuel pump. I cut the connector and replaced it with wago clips to make sure that it never disconnects, while still leaving the option to replace the thing.
So I am very happy, as I said, I will be posting a photo of the tube and some other stuff that I fixed to make sure it runs like butter.

Nice one! Congratulations on the fix. I will have a look as well at those on my bike now also. There are some vaccum tubes on my bike that connect to blank plastic outlets on the carb body but one has broken off and the tube just has a bolt jammed in it. I presume after your answer this may not be optimal 🤣

Thank you. I did try that once it started playing up but it didn't do anything sadly.