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My CBR300R wont start, even with jumper cables... PLEASE HELP

15190 Views 35 Replies 13 Participants Last post by  Painfulupchuck
So i was riding back from visiting my friend at his college when my bike started losing power slowly, i pulled over and it died. I tried starting it a few times and got it going, took an exit and it did the same thing, this time it wouldnt start back up so i called a towing company to get me home. the next day i went to check on her and it still wouldnt start, the lights came on but when i hit the starter it made this jitter sound. few days passed and i went to check on it again, i checked the air intake and everything was clean and not blocked. When i put the key in though, the lights were all so dim (dash,headlights etc) I pushed the starter and it wouldnt even make the jitter sound. few more days passed until i checked it again and when i turn the key, nothing, not lights, nothing. I tried to jumpstart it with my car (car off obv) all the connections were right because i got sparks, pos to pos and neg to my frame, every light turns on but when i hit the starter, NOTHING, It just turns everything off when i hit the starter. when i let go, everything comes back on.. idk what the poblem could be. When i serviced the bike they fixed the starter relay recall. PLEASE HELP ME. this weekend wether looks great and i cant miss out on riding.:devil::serious:
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Car needs to be running.


If your battery connections are fine then it may be a problem with charging.
Fuel injection needs a decent charge in the battery to start, the clicking noise you heard is due to flat battery or starter motor sticking, loose connection or a dodgy charging system, use a multi meter to test, it probably just wants a good charge. Check your battery leakege, it may have a short or be discharging, mine is 10 ma over the recommended, yes another minor fault, I keep it plugged in to a ctek charger. if it died while riding it could be a injector fault or pressure fault if at altitude.
If its new take it to the dealer.
You may be in possession of a faulty starter/igntion relay that was part of the recall?
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You may be in possession of a faulty starter/igntion relay that was part of the recall?
He says in his text that it was replaced when it was serviced.
@neema This may sound obvious but in my experience it is nearly always a flat or stuffed battery or the battery terminal connections. First place I'd start.
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He says in his text that it was replaced when it was serviced.

@neema This may sound obvious but in my experience it is nearly always a flat or stuffed battery or the battery terminal connections. First place I'd start.


I saw this to, does not mean you cant be unlucky. Assuming he got a decent bite on the battery terminals the bike should have started otherwise. In theory it should have started and ran regardless of whether the battery or stator were shagged.
The only other possibility is a bad connection between the battery and starter/power distribution point.
So i was riding back from visiting my friend at his college when my bike started losing power slowly, i pulled over and it died. I tried starting it a few times and got it going, took an exit and it did the same thing, this time it wouldnt start back up so i called a towing company to get me home. the next day i went to check on her and it still wouldnt start, the lights came on but when i hit the starter it made this jitter sound. few days passed and i went to check on it again, i checked the air intake and everything was clean and not blocked. When i put the key in though, the lights were all so dim (dash,headlights etc) I pushed the starter and it wouldnt even make the jitter sound. few more days passed until i checked it again and when i turn the key, nothing, not lights, nothing. I tried to jumpstart it with my car (car off obv) all the connections were right because i got sparks, pos to pos and neg to my frame, every light turns on but when i hit the starter, NOTHING, It just turns everything off when i hit the starter. when i let go, everything comes back on.. idk what the poblem could be. When i serviced the bike they fixed the starter relay recall. PLEASE HELP ME. this weekend wether looks great and i cant miss out on riding.:devil::serious:
Have you taken the battery out and put it on trickle charge overnight? I had this problem on my cb400-4 a couple of years ago. Put back in and started with a meter on it and found the rectifier was faulty & not charging the battery when the bike was running. Changed it for a new one and all was tickety boo. If the bike is still under warranty, get the dealer to sort it out.
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Have you taken the battery out and put it on trickle charge overnight? I had this problem on my cb400-4 a couple of years ago. Put back in and started with a meter on it and found the rectifier was faulty & not charging the battery when the bike was running. Changed it for a new one and all was tickety boo. If the bike is still under warranty, get the dealer to sort it out.
Exactly what my guess is. If it died while running it sounds like the rectifier isn't working properly. That would explain the slow death every time he went back to try starting it.
But first thing to do is check the battery connections. When the dealer installs the new relay they 'should' be unplugging the battery. Maybe they didn't tighten the ground wire all the way. But you have more symptoms than this simple solution
BTW the stock battery is garbage. Weighs more than a cinder block! I replaced mine with a feather light lithium
Exactly what my guess is. If it died while running it sounds like the rectifier isn't working properly. That would explain the slow death every time he went back to try starting it.
But first thing to do is check the battery connections. When the dealer installs the new relay they 'should' be unplugging the battery. Maybe they didn't tighten the ground wire all the way. But you have more symptoms than this simple solution
BTW the stock battery is garbage. Weighs more than a cinder block! I replaced mine with a feather light lithium
Mikal: You could always use the old battery as a wheel chock :)
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Ok, so i took out the battery to check the connections and what not and everything was good. I noticed a small bulge on the battery, so im guessing i should replace it? also since my bike is still under warranty so would the dealer replace it for free?

Thanks for the help
Ok, so i took out the battery to check the connections and what not and everything was good. I noticed a small bulge on the battery, so im guessing i should replace it? also since my bike is still under warranty so would the dealer replace it for free?

Thanks for the help
Maybe the bulge was always there, though I doubt it. A bulge can be a sign of overheating, but something pretty bad would have to be going on to create that much heat. It sounds like the battery has somehow been fried, so I would want to be sure there isn't an issue elsewhere before putting a new battery in there and possibly frying another one. One of the first things I'd be looking at is the new starter relay, simply because your troubles seemed to start around that time.

If you haven't already, give the dealer a call and explain that this started happening when the new relay was fitted. They might have some ideas. Then again, maybe they busted the battery somehow while swapping the relay, in which case they're unlikely to confess.
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Ok, so i took out the battery to check the connections and what not and everything was good. I noticed a small bulge on the battery, so im guessing i should replace it? also since my bike is still under warranty so would the dealer replace it for free?
I'm more of a mechanical guy than electrical but a bulging battery can be a sign of over heating as JNO said and generally this is caused by a faulty regulator letting too much current through to the battery.
I believe the CBR's have a rectifier/regulator in one, the output shouldn't read any higher than 14.5V volts or some where around there, I dont have a service manual to quote exact figure.
Do you have a multi meter so you can test the charge going into the battery?
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Sounds like your overcharging the battery so it boils and swells, check your charging voltage as kiwi says, its very easy to do, mine was 14.29v while idling, 14.31v at 1500rpm. Got a CBR250 Electrical Spec if it helps. It says charging voltage (C.V) 15.5v @5000rpm with high beam on, I would think its the same for a CBR300?, double check though.
Sounds like your overcharging the battery so it boils and swells, check your charging voltage as kiwi says, its very easy to do, mine was 14.29v while idling, 14.31v at 1500rpm. Got a CBR250 Electrical Spec if it helps. It says charging voltage (C.V) 15.5v @5000rpm with high beam on, I would think its the same for a CBR300?, double check though.
Yes Mark the 300 uses the same battery as the 250. I still recton that the Rectifier cooked the battery, back to dealer with this one.
Ok, so I finally the bike shop near me tested the battery in front of me and it read dead, before that we zapped it for 4 hours. so i bought a new batterry, i installed it and the HUD turns on and wand all lights and horn work. but it still wont start.. haha thanks for the help so far guys. I want to take it into the shop tomorrow and have them fix it since its under warranty. Is there a chance i could bump start it? The shop is 15 miles away from my house, could it make it?
......Is there a chance i could bump start it? The shop is 15 miles away from my house, could it make it?
If the engine is turning over strongly with the new battery, I doubt that bump starting will work. Worth a try though.

If you do get it started, bear in mind you still haven't fixed whatever fried the first battery, so you run the risk of buggering the new one, and possibly doing some damage elsewhere. If it is overcharging, there is the possibility that other components and connections are also overheating, with the consequent risk of damage, even fire.

Maybe strap a fire extinguisher to your back before setting off, eh? :devil:
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Ok, so I finally the bike shop near me tested the battery in front of me and it read dead, before that we zapped it for 4 hours. so i bought a new batterry, i installed it and the HUD turns on and wand all lights and horn work. but it still wont start.. haha thanks for the help so far guys. I want to take it into the shop tomorrow and have them fix it since its under warranty. Is there a chance i could bump start it? The shop is 15 miles away from my house, could it make it?
Is it turning over tho? If it's not turning over can you at least hear the starter relay clicking when you push the button or nothing at all?
I'm still suspicious of that new starter relay......
bumb starting didnt work. when i push the start button it makes one click sound and the HUD goes blank and all lights go out. Im not sure if the starter is the problem becuase ive been riding it for months with the new one (but i dont know much about mechanics so i could be wrong)
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