I had this issue last year, the bike would bog/cut out randomly, it would never stall out though. It seemed to happen when it was hot, after maybe ten minutes of riding, and usually after landing off a jump. I was using T4+ at the time and after doing some research, found other people were having similar problems using that fuel and it was causing damage to fuel pumps. I stopped using the T4+ and went back to VPR but still had the issue. So this winter I put a new OEM Honda fuel pump from motosport in it.
It has been perfect so far this year but again the bike is randomly bogging/cutting out, popping on decel., and has even stalled a couple times. It doesn’t seem to matter if the bike is cold or hot, and it seems completely random. I’m thinking of putting an injector in it but in all honesty it’s just a guess at this point. With it being so random I don’t know how I’d ever find the issue without some trial and error.
I really like this bike but I have pretty much lost faith in it. This sport is dangerous enough without having to worry about your bike randomly cutting out over a jump. The red light on the kill switch lights up solid after starting, but goes right out and does not flash, so I don’t think there’s any fault the ecu is detecting. With a basically new fuel pump, I would think an injector would be the next logical thing to replace. Anyone been through something similar, or have any advice?
How does the plug look?
Thinking it could be electrical or something disrupting the EFI (temp sensor?)
Maybe do a fuel pump pressure test to rule that out?
Haven’t touched it yet but certainly will check the plug. I would imagine any kind of electrical issue related to a sensor would cause it to flash a code, but I honestly don’t know. As far as checking fuel pressure, it happens intermittently so I’d have to somehow T- in a gauge and go ride it, not impossible I guess but it would suck lol
If pressure is within spec with the bike warm, then I'd probably rule out the fuel system, not necessary to ride it with the gauge attached.
If it's low in the spec or inconsisten pressure then that might be worth the effort.
VP fuel usage seems to be consistent with some of these issues.
No fault codes. Check.
Fuel pump replacement. Check.
I recommend pulling the injectors, and cleaning them and seeing if that solves for the bogging. If not the next step would be to replace them.
You indicate you are using VPR which is a leaded fuel that was originally intended for two strokes. Have you tried using a non leaded fuel? Are you running a high octane/race fuel map that requires oxygenated fuel?
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Yeah when this started happening again I was actually using an ETS fuel that is unleaded. No ECU or mapping done, I just don’t ride a ton so using a good quality fuel doesn’t break the bank, it’s certainly overkill and not necessary but it’s what I do. I will probably replace the injector and see what happens. In the back of my mind I’m thinking these Hondas do not like these “race fuels” and it just does bad things to the fuel system.
I hear you on stable fuel.
Keep in mind oxygenated fuel runs leaner if you are not compensating for it with mapping.
But back to bogging...
You could do a few things that are no cost: Run some regular fuel through and see if the issue persists. If no, then you know it's the fuel.
If the issue persists, then pull and clean the injectors. If that solves for it then it was a fuel metering issue from debris. If the issue continues, the injectors could be clogged or damaged.
From there on you are replacing parts.
I think I’ll just replace the injector, there’s only one on this bike. At least if I do that I’ll be able to say for sure it’s not the injector if the issue persists. I have to say I’m not a fan of this whole situation… I have lost all confidence in this bike and don’t even want to jump it, unfortunately I only ride moto so that’s a huge problem lol.
So far you've focused solely on fuel but this could be an electrical issue. Make sure you check your battery connections and trace the positive and ground and make sure they are clean and solid. Unfortunately, a bad battery can present these symptoms if it has a slight/intermittent open internally somewhere.
I did look into that last time I was having this issue. Worked my way from the battery and wiggled every connector/harness I could access with the bike running to see if I could get it to act up, as well as inspected connectors for water/pin issues. I will go through it again though.
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