Bike Cutting Out - Help
Discussion
Good Afternoon,
I bought a Brixton BX125 EFI as a project bike, this is my first venture into bikes - although I used to be a car mechanic.
I've been working my way through all the little niggles with the bike, although there is one problem I can't get my head around. When riding the bike, if you pull the clutch in coming towards a junction the engine will cut out - it doesn't splutter or suddenly cut out (I thought it could be a side stand switch issue, but it is no where near as aggressive when cutting out as if you engage the side stand.) The revs just seem to lower all the way to 0 - if I know it is going to do it I can bump the bike whilst riding at it starts up again. Although if I have to start it again on the button it can take a bit of doing to get it going.
The issue used to be a lot worse than it is now, before it would cut out unannounced at idle, where as it can now idle fine (I can rev it aswell in neutral and suddenly drop the revs and it doesn't cut out - it just seems to be when moving/under load.) Also the bike idles at the factory recommended RPM normally which is around 1800.
I don't think it is compression or valve adjustment related - as it will still have plenty (for a 125cc) torque and will pull itself along with me on it and the clutch released and no throttle.
The parts so far replaced are:
Fuel Filter
02 Sensor (this was a logged fault when I purchased the bike)
MAF Sensor (2nd hand)
Idle Control Valve (2nd hand)
Thottle Position Sensor (2nd hand)
Throttle plastic spacer (This was cracked causing an air leak) but all seems okay now it has been replaced.
Air Filter
Spark Plug
I've also checked battery voltage, other rubbers for cracks/air leaks, spark plug looks good as well - although I've only done around 5 miles on it so it might be too early to tell.
Just seeing if anyone else has experienced anything like this or has any suggestions as to what to check next? the bike seems to run well through the rev range. And I know there is still parts to check/replace (carbon cannister, coil, fuel tank ventilation (the vent looks clear although it is very tricky to see if it is blocked.) Once the tank is empty I will take the tank off and fuel pump out to see if there is anything obvious.)
Any suggestions would be appreciated,
Kind Regards
Ed
I bought a Brixton BX125 EFI as a project bike, this is my first venture into bikes - although I used to be a car mechanic.
I've been working my way through all the little niggles with the bike, although there is one problem I can't get my head around. When riding the bike, if you pull the clutch in coming towards a junction the engine will cut out - it doesn't splutter or suddenly cut out (I thought it could be a side stand switch issue, but it is no where near as aggressive when cutting out as if you engage the side stand.) The revs just seem to lower all the way to 0 - if I know it is going to do it I can bump the bike whilst riding at it starts up again. Although if I have to start it again on the button it can take a bit of doing to get it going.
The issue used to be a lot worse than it is now, before it would cut out unannounced at idle, where as it can now idle fine (I can rev it aswell in neutral and suddenly drop the revs and it doesn't cut out - it just seems to be when moving/under load.) Also the bike idles at the factory recommended RPM normally which is around 1800.
I don't think it is compression or valve adjustment related - as it will still have plenty (for a 125cc) torque and will pull itself along with me on it and the clutch released and no throttle.
The parts so far replaced are:
Fuel Filter
02 Sensor (this was a logged fault when I purchased the bike)
MAF Sensor (2nd hand)
Idle Control Valve (2nd hand)
Thottle Position Sensor (2nd hand)
Throttle plastic spacer (This was cracked causing an air leak) but all seems okay now it has been replaced.
Air Filter
Spark Plug
I've also checked battery voltage, other rubbers for cracks/air leaks, spark plug looks good as well - although I've only done around 5 miles on it so it might be too early to tell.
Just seeing if anyone else has experienced anything like this or has any suggestions as to what to check next? the bike seems to run well through the rev range. And I know there is still parts to check/replace (carbon cannister, coil, fuel tank ventilation (the vent looks clear although it is very tricky to see if it is blocked.) Once the tank is empty I will take the tank off and fuel pump out to see if there is anything obvious.)
Any suggestions would be appreciated,
Kind Regards
Ed
I have thought this as a potential option, although not sure if this would cause the issue only to happen when riding and pulling the clutch in. As the issue isn't present when you put it through the gears and then try and replicate it with the back wheel lifted with no load on it. The battery and normal charging seems very good on the bike as well (the battery has never gone flat) and doesn't seem to drain. Also on the OBD reader the ECU voltage always seems good (but again don't know if this is a good indicator to showing if a stator is good.
So just to clarify, if you're riding on the flat on a straight road, and you pull the clutch in, the revs slowly drop? And this is repeatable and consistent?
And, does this happen at any time during a ride of any length - I'm trying to find out if, over a long ride, the battery is getting a good charge and doesn;t cut out as much.
Have you tried taking the battery off the bike and giving it a good charge, see if that reduces the symptoms?
And, does this happen at any time during a ride of any length - I'm trying to find out if, over a long ride, the battery is getting a good charge and doesn;t cut out as much.
Have you tried taking the battery off the bike and giving it a good charge, see if that reduces the symptoms?
Hello Again
If I'm riding on a flat and straight road, and slowing the bike down (junction, letting a car go etc), then pull the clutch in - so the revs dropping would be part of the engine braking (before pulling the clutch in), and also my hands would be off the accelerator. If I was to pull the clutch in whilst still holding the throttle open, then the revs wouldn't decrease.
It is fairly repeatable and consistent - it won't happen 100% of the time, but probably 70% of the time. I haven't taken the battery off the bike to charge as I don't have a charger (although I can get one), the bike has been an ongoing project since October but has never failed to start or go flat when running it at idle in my garage on and off - it seems to always have the symptoms of a strong battery at least, but has only been on the road for the past few weekends but mainly very local just to test it. I have been letting it get warmed up as well just to see if it is an issue when the engine is cold.
Also I forgot to mention, when the problem was alot worse (before fixing the air leak), and fiddling around - it used to cut out after about 30 seconds or so (once it switched to a leaner mixture I believe.) From what I can see as it is fuel injected you can't manually raise the idle speed either - if I tighten the cable then it interferes and tightens too much when turning the bike.)
If I'm riding on a flat and straight road, and slowing the bike down (junction, letting a car go etc), then pull the clutch in - so the revs dropping would be part of the engine braking (before pulling the clutch in), and also my hands would be off the accelerator. If I was to pull the clutch in whilst still holding the throttle open, then the revs wouldn't decrease.
It is fairly repeatable and consistent - it won't happen 100% of the time, but probably 70% of the time. I haven't taken the battery off the bike to charge as I don't have a charger (although I can get one), the bike has been an ongoing project since October but has never failed to start or go flat when running it at idle in my garage on and off - it seems to always have the symptoms of a strong battery at least, but has only been on the road for the past few weekends but mainly very local just to test it. I have been letting it get warmed up as well just to see if it is an issue when the engine is cold.
Also I forgot to mention, when the problem was alot worse (before fixing the air leak), and fiddling around - it used to cut out after about 30 seconds or so (once it switched to a leaner mixture I believe.) From what I can see as it is fuel injected you can't manually raise the idle speed either - if I tighten the cable then it interferes and tightens too much when turning the bike.)
Mk3Ed said:
I will get the battery fully charged - would this rule out a potential bad stator if the battery is charged enough? ...
'Hopefully' it would temporarily eliminate the problem until the symptoms slowly re-emerge again. Then you could be fairly sure the stator isn't charging as well as it should be.But if after a really good charge, the symptoms are immediately apparent then the problem will probably be elsewhere. I'm no electrician or anything btw, these are just guesses.
I haven't been out for longer than 5 or 10 min around the estate, I did think it could be something that would clear and also maybe some fresh fuel aswell, it had pretty much a fresh tank a while ago but it was E10 I was also thinking of brimming with E5 and seeing if that helps it, if it is dry tommorrow I will give it a go and plan my route where I can stretch the legs on it a little
It doesn't take much for a slightly dragging wet clutch and a slightly clogged injector to stop a small bike engine ticking over properly.
If there is no fast idle control, you may have to crack the throttle ever so slightly for it to tick over until it's fairly warmed up.
Ticking over without your hand on the throttle is not always to be taken for granted with some bikes.
If it didn't go at all, sidestand switch is traditional suspect.
Some new clean fuel is a good idea. As is a new spark plug.
When my bike hasn't been used for a while, I put some expensive petrol and some injector cleaner in it and it will get smoother after a tank or two.
When it's cut out, you could whip the plug out, if it's wet with fuel, that suggests ignition.
One problem I have seen with small EFI bikes is the in-tank pump over heating with too much slow running and not much fuel in the tank.
Heat from the engine builds up if the bike isn't moving.
I doubt that's what you're seeing though.
May be worth checking fuel line pressure and perhaps getting the injector professionally cleaned. Strobe the ignition maybe, but TBH the electronics usually just work unless there's a bad connector.
If there is no fast idle control, you may have to crack the throttle ever so slightly for it to tick over until it's fairly warmed up.
Ticking over without your hand on the throttle is not always to be taken for granted with some bikes.
If it didn't go at all, sidestand switch is traditional suspect.
Some new clean fuel is a good idea. As is a new spark plug.
When my bike hasn't been used for a while, I put some expensive petrol and some injector cleaner in it and it will get smoother after a tank or two.
When it's cut out, you could whip the plug out, if it's wet with fuel, that suggests ignition.
One problem I have seen with small EFI bikes is the in-tank pump over heating with too much slow running and not much fuel in the tank.
Heat from the engine builds up if the bike isn't moving.
I doubt that's what you're seeing though.
May be worth checking fuel line pressure and perhaps getting the injector professionally cleaned. Strobe the ignition maybe, but TBH the electronics usually just work unless there's a bad connector.
Been out on the bike today, for 25 min or so, mixture of urban riding and slightly faster roads. The bike now has a full tank of fresh fuel - and although the problem does improve once the bike is warm - it is still present. It is controllable - if when cruising to a stop I refrain from pulling the clutch until the engine is around 2,500 rpm it seems to be fine. It is when the clutch is dipped at anything higher than this. It is almost like it can't keep up if the revs drop too much.
Also it seems less of a problem (this could just be a coincidence) if the bike is in second gear. I haven't fully ruled out it being clutch related either. As a few things point this way, I've also disconnected the clutch level switch to see if this has any change (not sure how it would, but wanted to check) and it doesn't. What I should of checked is if the problem occurs if placed in neutral when slowing to a stop - which I will get checked when I can next get out on it.
I've also got a spare injector which I will put in the bike as well, the bike has been standing I suspect for quite some time before I purchased it. So it could be related to it not being used.
I will also have a look at the carbon cannister and just make sure there is nothing obviously wrong with this as well.
Thank you all for all your replies.
Also it seems less of a problem (this could just be a coincidence) if the bike is in second gear. I haven't fully ruled out it being clutch related either. As a few things point this way, I've also disconnected the clutch level switch to see if this has any change (not sure how it would, but wanted to check) and it doesn't. What I should of checked is if the problem occurs if placed in neutral when slowing to a stop - which I will get checked when I can next get out on it.
I've also got a spare injector which I will put in the bike as well, the bike has been standing I suspect for quite some time before I purchased it. So it could be related to it not being used.
I will also have a look at the carbon cannister and just make sure there is nothing obviously wrong with this as well.
Thank you all for all your replies.
If the bike is in gear it won't turn over when trying to start, without the clutch pulled in. Neutral it will start with with the clutch out. If I disconnect the clutch switch though it doesn't make a difference though. Next job I think is to take the fuel pump out and clean the tank and check for any rust etc in the tank and also check the carbon cannister. I will run it though for the remainder of the tank and just see if it does get better over time. When the issue was worse it would improve if I reset the ECU (apparently switching the ignition on and off 5 times does this on the bike) so it might also be the ECU learning?
ReverendCounter said:
Which is why I think you should take it out and thrash it for 30mins, as in red line every gear and keep the revs high when you're in top gear - just in case there's a possibility you could wake the ECU up.
If you do that and it doesn't seize, it's probably not a lean-running issue.....How much 'learning' does the ECU in one of these things actually ever do?
The EFI bikes I've looked at in any depth have been older, pretty much open loop.
Don't know if it is of any help but I had a Kawasaki GT550 a few years ago and it would bog down and stall every morning at roughly the same point in the journey, which was about 5 minutes in. It only did it once, wouldn't start for a few seconds and then would fire right up and be fine the rest of the day. Next day, same thing. I got quite good at timing my journey so I would coast to a halt at a bus stop and wait it out.
I retro-fitting a timing light to the fork leg so I could see whether it was electrical or not, fully expecting to see the timing lamp stop flashing when it bogged down. Instead when it died, the light came on and stayed on. As soon as it went out, I could start the bike. Ended up being the CDI unit, bought a second hand one from eBay and fitted it and it never happened again.
I retro-fitting a timing light to the fork leg so I could see whether it was electrical or not, fully expecting to see the timing lamp stop flashing when it bogged down. Instead when it died, the light came on and stayed on. As soon as it went out, I could start the bike. Ended up being the CDI unit, bought a second hand one from eBay and fitted it and it never happened again.
Mk3Ed said:
Been out on the bike today, for 25 min or so, mixture of urban riding and slightly faster roads. The bike now has a full tank of fresh fuel - and although the problem does improve once the bike is warm - it is still present. It is controllable - if when cruising to a stop I refrain from pulling the clutch until the engine is around 2,500 rpm it seems to be fine. It is when the clutch is dipped at anything higher than this. It is almost like it can't keep up if the revs drop too much.
Also it seems less of a problem (this could just be a coincidence) if the bike is in second gear. I haven't fully ruled out it being clutch related either. As a few things point this way, I've also disconnected the clutch level switch to see if this has any change (not sure how it would, but wanted to check) and it doesn't. What I should of checked is if the problem occurs if placed in neutral when slowing to a stop - which I will get checked when I can next get out on it.
I've also got a spare injector which I will put in the bike as well, the bike has been standing I suspect for quite some time before I purchased it. So it could be related to it not being used.
I will also have a look at the carbon cannister and just make sure there is nothing obviously wrong with this as well.
Thank you all for all your replies.
Please don't be offended by this, but I'm questioning whether the bike doesn't like your riding style!Also it seems less of a problem (this could just be a coincidence) if the bike is in second gear. I haven't fully ruled out it being clutch related either. As a few things point this way, I've also disconnected the clutch level switch to see if this has any change (not sure how it would, but wanted to check) and it doesn't. What I should of checked is if the problem occurs if placed in neutral when slowing to a stop - which I will get checked when I can next get out on it.
I've also got a spare injector which I will put in the bike as well, the bike has been standing I suspect for quite some time before I purchased it. So it could be related to it not being used.
I will also have a look at the carbon cannister and just make sure there is nothing obviously wrong with this as well.
Thank you all for all your replies.
I'm reading it that you're pulling the clutch in while the revs are still moderate and coasting to a halt.
I've known engines which shut the fuel off completely while the ECU thinks 'engine braking' is happening.
Maybe change down more when decelerating? Or leave the clutch out until the revs are nearly down to the point where it would be rough?
What happens if you pull the clutch to around the biting point instead of right in?
A combination of that and a little bit of fouling of the injector might explain everything.
Apologies if I'm reading stuff between the lines and talking rubbish!
If the bike's been sat idle, fuel can gunge up quite soon, if it doesn't improve with a few gallons through it, I'd talk to injectortune.
I assume the 'carbon canister' is there to absorb vapour in the breather and won't have any influence unless it's totally blocked?
Mind how you go, I know this kind of niggle can get out of hand if you find yourself going downhill on a bad surface.
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