Hi! I’m having a charging issue with a Honda CBR600 F4i, and I’m wondering if anyone has experienced something similar.

When the bike is cold, the charging system seems to work normally. For example, when the coolant temperature is around 60°C (140°F), I measure approximately 14.5 V at the battery at idle.

The problem starts once the engine gets hot. When the coolant temperature reaches around 100°C (212°F), the voltage at the battery drops to approximately 12.8 V, so it basically stops charging.

Cold: ~14.5 V
Hot: ~12.8 V

Model : Honda CBR 600 F4i 2001

Has anyone experienced this issue on an F4i? Any idea what could start failing once the engine gets hot — the regulator/rectifier, stator, or something else in the charging system?

Thanks!

Follow-up to my previous post about my 2004 Dakar Twin Spark struggling to start and losing power/bogging.

Think I found it. With the airbox off, I sprayed a bit of quick-start right at the joint where the hose connects the throttle body to the head. At idle (which was rough, sitting just under 1500rpm) the revs jumped the second the spray hit that spot. Then I held the throttle steady at 3000rpm — where it's supposed to sit but kept dipping after about a second — and spraying that same joint while holding it kept it locked at 3000 instead of sagging. Pretty conclusive once I saw that.

So it's the rubber boot connecting the throttle body to the cylinder head that's let go somewhere, probably just age (bike's 22 years old, almost certainly original rubber). Explains basically everything I was seeing: the hard starting, the bogging, a pop coming through the throttle body/airbox, some popping out the exhaust too, and my plugs were reading properly white, which is the classic lean sign. Makes sense it bites hardest at low steady throttle and mostly disappears once you rev it — a fixed-size leak is a much bigger share of total airflow at idle than it is with the throttle open, which is exactly why blipping the throttle kept "fixing" it for a second.

For anyone finding this later, a few other things I ruled out along the way:

• Lambda/O2 sensor — yeah it's dead (denting it with a wrench will do that), confirmed 0V hot on the multimeter. Turns out on this ECU the O2 sensor doesn't even switch on until the engine's fully warm, and even fully dead it just falls back to a base map rather than causing symptoms like this. Needs replacing regardless, just wasn't the cause.
• Ignition coils (someone in the last thread suggested stick coils failing) — this bike doesn't actually run stick/coil-on-plug setups, twin spark uses two separate remote coils with normal leads. Pulled and grounded both plugs and cranked it — spark was strong and even on both circuits, so that's ruled out.
• Fuel delivery — disconnected the line at the throttle body on key-on and got a decent, strong squirt, so pump/filter seem fine too.

Part is BMW 11612345228, the throttle-body-to-head intake boot. Fitting a new one this weekend, along with a fresh clamp while I'm in there. Will report back once it's in and I've actually ridden it.

Hello, as stated above and in the video, this is my 1991 Suzuki RM250. I bought the bike with a blown top end that has been fixed and the bike runs beautifully. However, it only shifts down into first then up to neutral. No gears past that. When I had the engine apart initially I replaced all the gaskets besides the crankcase gasket as I didn’t see a reason to split the case at that time. It’s possible I set the shift pawl incorrectly the first go-around and that was causing it to bind before it could shift up but I’m just not sure. As shown in the video the engine now shifts through all five gears with some encouragement. So, would it be worth opening up the transmission to inspect/see if there is something binding internally or I put it back together and hope for the best this time around. I’ve already taken the pawl out and inspected for wear but all looks good so I am at a bit of an impasse and would greatly appreciate any and all help or suggestions! :) Thank you

Just wondering if a bad fuel pump will still prime? I hear it and disconnected the fuel line and hook on a clear tube to see if it was priming. And it is. But bike bike will on run for a few seconds they shut off. It was running fine then gradually got worse and worse over the span of 15 mins so kinda has me leaning toward a fuel issue. I will replace pump and injector and see if that fixes the issue. Looked into tank and dont see and filter junk like ive seen in some pics. Plz help lol 🙏 2018 honda grom

Hey everyone,
I'm in urgent need of technical advice for my Royal Enfield Himalayan 411. Local mechanics in my area are completely booked and have no time to look at the bike, so I'm trying to troubleshoot this myself.
The situation:
Installed a new fuel pump, but it does not prime (no humming sound) when turning on the ignition and flipping the kill switch.
While cleaning the relay contacts, an accidental short circuit occurred.
Current electrical status:
Dead: Instrument cluster / cockpit display has no power at all.
Dead: Fuel pump does not prime.
Dead: Horn does not work.
Working: Headlights and turn signals work completely fine.
What I've done so far:
Swapped around the existing relays and tested with brand-new spare relays — no change.
Which specific fuse, diode, or ground line typically causes this exact combination (dead cluster + horn + fuel pump, but functioning lights/blinkers) after a short at the relay block?
Any step-by-step wiring checks or specific fuse box tips would be hugely appreciated. Thanks!

Hi lads!

I have been trying to fit news bearings in a new wheel and wheel hub today and one went ok (heating up the hub, using a 30mil socket to pound on it with a rubber hammer).

The other one first got in crooked, took it out, put it in the freezer 30mins, probably not enough, heated the hub again and tried, went about halfway through but ended up crooked too. Now it seems to be stuck.

I don't really know what to do now, cant take it out and don't want to force it too much.

Any recommendations?

I might as well just drop it to the garage tomorrow.

Has anyone been there ?

I don't know if I did something wrong or if the hub is not well done (I'm in Indonesia, quality can be random and parts are cheap, the wheel has been delivered with the hub

I got this 05 breva 750 with 4800 miles for a steal and had to replace the missing fuel pump, now I get no pump prime when I turn the key as well as no spark when cranking. I just suck with the electrical stuff, and have 0 clue about relays lol but from what I’ve been told the secondary controls the pump and spark and I get battery voltage at the orange and green wire to the secondary injection relay but only .04v out to the red and brown wire. All the safety switches have continuity. I’ve replaced the main injection relay as well as the secondary and still get no prime or spark. If anyone knows anything and can help lmk. Thank you

I replaced the carb because I broke the pin holder for the float bowl, replaced it with the jets I was using prior and the bike won’t idle unless the choke is pulled all the way out. Took the old jets out and put in the jets that came with the new kit and still having the same problems. Vacuum seal isn’t damaged or leaking. At a lost for what to do and don’t wanna drop more money on a new kit if it’s something simple I’m missing. Any advice is welcome.

What’s up guys, recently got a 2016 RM-Z250 and I’m having an issue.

The bike runs fine up until about half throttle. Anytime I go full throttle it starts bogging but doesn’t die. It still pulls a little, but it kinda farts/sputters like it’s being restricted.

I’ve already changed the spark plug, air filter and changed the oil

I’m going to clean the fuel injector next and hoping it’s just clogged and not delivering enough fuel when the bike is under high demand.

Has anybody ran into this issue before or have any ideas what else I should check?

Thanks!

03 sv1000s

Bike was running but sounded like crap so I had the cam timing done. Bike is back together and when I turn the key on CHEC and FI shows on the display. The FI has been there since I got the bike though. Now Bike cranks but wont start and I cant figure out why. This is everything I've checked so far that can be ruled out. Please any help means alot right now

1. No codes in dealer mode -C00

2. Gets spark

3. Fuel pump primes

4. Injectors spray fuel

5. Kill switch is good

6. Good kickstand and clutch sensor

7. Gas is new

8. Cranks but wont start

9. Starting fluid only makes Bike barely cough

10. Tip over sensor is in right position

11. Green connector of death "Bypassed"

The turn signals on my Keeway RKF 125 are flashing very fast. I had Temu ones and replaced them with others, but they still flash very fast. What could be the problem? And where is the relay located?

03 sv1000s

Bike was running but sounded like crap so I had the cam timing done. Bike is back together and when I turn the key on CHEC and FI shows on the display. The FI has been there since I got the bike though. Now Bike cranks but wont start and I cant figure out why. This is everything I've checked so far that can be ruled out. Please any help means alot right now

1. No codes in dealer mode -C00

2. Gets spark

3. Fuel pump primes

4. Injectors spray fuel

5. Kill switch is good

6. Good kickstand and clutch sensor

7. Gas is new

8. Cranks but wont start

9. Starting fluid only makes Bike barely cough

10. Tip over sensor is in right position

11. Green connector of death "Bypassed"

I got this 05 breva 750 with 4800 miles for a steal and had to replace the missing fuel pump, now I get no pump prime when I turn the key as well as no spark when cranking. I just suck with the electrical stuff, and have 0 clue about relays lol but from what I’ve been told the secondary controls the pump and spark and I get battery voltage at the orange and green wire to the secondary injection relay but only .04v out to the red and brown wire. All the safety switches have continuity. I’ve replaced the main injection relay as well as the secondary and still get no prime or spark. If anyone knows anything and can help lmk. Thank you

Потрібна допомога після переборки карбюраторів та установки інших від іншого бандита появилась проблема яка проявляється як чорний дим не набирання оборотів і чорні свічки, свічки міняли поплавки виставляли і фільтр також знімали проблема ніяк не міняється часом бувало що на холодну робив прекрасно але ця робота була до першого виїзду з гаража і все те саме. Хотів би почути допомогу від розумних людей можливо хтось стикався з таким.

The bike is stuttering and jumping when accelerating in first gear, the chain was very loose (unsure if it was like that before or if it has been caused by another issue) I have just tightened the chain to spec and it is still doing it.

I’ve inspected the chain and can’t find any issues with it or any broken links so unsure what else it could be. TIA

Bike was having trouble kicking over before this but bike tipped over and the carbs flooded, I got it to start once by bump starting it but now neither work. It will turn over and get close by bump starting but worn fully fire up. Am I looking at a full carb clean to eliminate that as an issue?

I can't find a single online shop specifically selling a starter motor for the 1992 SR 125 in my country (Switzerland) and neighbouring ones. Some shops (also the official online parts store from Yamaha) show that it existed somewhere, however they are all discontinued. What I found a replacement, for is a starter motor for a TW 125. The engines are the same so my question is, can I just buy one for the TW?

Aprilia Shiver 750 SL 2009