Bike cuts out under load?

[Lus7]

Hey guys, i have a fairly new bike (14,000 ks) and it rides great.
Recently I've noticed its randomly loosing power. Going up this hill, my bike starts choking till it stalls.
It feels like the bike just looses all power momentarily and jerks until it completely turns itself off.

Once it's turned off, I wont be able to start it again.
After 20 minutes i can turn it on and it runs fine.

This has happened twice.

The only adjustments I've made to my bike are 4 large holes in my baffle (which I did several months ago) and an oil change.


any advise?
cheers

[maggot]

What is it? Might help diagnosis.

[Lus7]

oh right, yamaha virago xv250

[blackdog]

Yeah I am psychic.

Start by cleaning yer air filter.

[Asher]

check fuel filters, blockages would starve the engine under load and it wont be able to start for a small while

[GSF]

One thing to consider, when it happens is your fuel level relatively low and have you been travelling inclines or taking corners?

My carbied Bandit cut out on me a couple of times for (seemingly) no reason after going up/down a hill or round a tight corner. When I did so with a low fuel level, the standpipe in the tank would be briefly exposed and suck a bit of air down into the carbs. So as I exited a corner it would die on me, then I'd have to sit on the side of the road with the fuel tap primed for a wee while to refill the bowls.

[98tls]

Possibly the coil,breaking down when hot.

[p.dath]

Hey guys, i have a fairly new bike (14,000 ks) and it rides great.
Recently I've noticed its randomly loosing power. Going up this hill, my bike starts choking till it stalls.
It feels like the bike just looses all power momentarily and jerks until it completely turns itself off.

Once it's turned off, I wont be able to start it again.
After 20 minutes i can turn it on and it runs fine.

This has happened twice.

The only adjustments I've made to my bike are 4 large holes in my baffle (which I did several months ago) and an oil change.


any advise?
cheers

I know this sounds obvious, but have you checked the oil and water levels?

[blackdog]

Oh FFS.

Someone go and chuck some sparkplugs at it this weekend.

[98tls]

Oh FFS.

Someone go and chuck some sparkplugs at it this weekend.

Why?a 14000km Virago wont need new plugs.

[blackdog]

Why?a 14000km Virago wont need new plugs.

We don't know the age of it. Remember I suggested looking at te airfilter first.

[Lus7]

I tried to check the air filter but couldn't unbolt the pod because i didn't have the tools.
it's a 2006 model, just hasn't been used much I guess.

Just took it for a ride, it was cutting out like you wouldn't believe.

Noticed it happened mostly on hills
the bike ran alright when the choke was half on (for a while)

and my gas tank is below half empty.

I've changed the oil recently. (first time i've ever done that). It stalled on me coming up a hill, so I thought I had too much in there so I drained it a little.
but no change.

[p.dath]

I've changed the oil recently. (first time i've ever done that). It stalled on me coming up a hill, so I thought I had too much in there so I drained it a little.
but no change.

Did you use proper motorbike oil when you changed the oil?

[blackdog]

I am in Wellington, but buy a box of piss and someone here will come 'round and drink it with you.

[98tls]

I tried to check the air filter but couldn't unbolt the pod because i didn't have the tools.
it's a 2006 model, just hasn't been used much I guess.

Just took it for a ride, it was cutting out like you wouldn't believe.

Noticed it happened mostly on hills
the bike ran alright when the choke was half on (for a while)

and my gas tank is below half empty.

I've changed the oil recently. (first time i've ever done that). It stalled on me coming up a hill, so I thought I had too much in there so I drained it a little.
but no change.

A 2006 Virago done blah blah wont need a plug change,forget the fuel level,does it have a dip stick or sight glass?how much oil did you put in it?Please dont say until it came out the top.

[Madness]

Possibly the coil,breaking down when hot.

There's more chance that this is the problem than oil having anything to do with it IMO.

[98tls]

We don't know the age of it. Remember I suggested looking at te airfilter first.

Ive recently started a Z650 motor after changing fluids but not plugs thats been left sitting since time began,plugs are fine.

[Lus7]

Did you use proper motorbike oil when you changed the oil?

nah, used regular 10w 40 oil. figured oil is oil and the more money i spend on oil, the less i can spend on my rego.
I sighted it, I filled it to just below the top line the first time, and now it's sitting about half way.

[blackdog]

You better make it a bottle of Jack.

[blackdog]

Did I mention STARTING with the airfilter?

[Madness]

Might want to get in a few grams of P too :facepalm:

[Lus7]

haha, how do i get into the airfilter? how do i know if i need to change it?

[98tls]

You better make it a bottle of Jack.

:laugh:Better grab me a glass eh....

[98tls]

nah, used regular 10w 40 oil. figured oil is oil and the more money i spend on oil, the less i can spend on my rego.
I sighted it, I filled it to just below the top line the first time, and now it's sitting about half way.

Why not just say "fuck the rego" and push the thing around...

[Lus7]

does the type of oil really make a difference?

[Lus7]

also, this has become a chronic problem after I decided to take a friend of mine on the back of my bike.

[blackdog]

does the type of oil really make a difference?

Not in so much as having the machine firing or running right in the short term, but over a period? Yes it is important.

[FJRider]

haha, how do i get into the airfilter? how do i know if i need to change it?

It runs badly ... often cuts out the engine ... :facepalm:




But the good news is ... car oil in a motorcycle engine usually just makes the clutch slip. Lots of rev's, but goes nowhere ... :lol:

[blackdog]

also, this has become a chronic problem after I decided to take a friend of mine on the back of my bike.

What does a case of whisky cost these days?

[GSF]

I'm no expert, but from what I understand:

Cars have engine oil and gearbox oil.

In your bike, your oil is lubricating the engine and the clutch/gearbox. Many car engine oils contain certain lubricating compunds that will cause clutch slipping (because these car oils are not intended to come into contact with clutch plates).

Oil is one thing you don't really want to cut corners on considering how vital it is.

Also, you'll know if your air filter is dirty because (I'm assuming it's a paper element) it'll look dirty. Like all grey 'n' shit, from drinking up soot and road gack all day.

[98tls]

What does a case of whisky cost these days?

More than a Virago sadly.

[FJRider]

also, this has become a chronic problem after I decided to take a friend of mine on the back of my bike.

Good idea ... if you have problems with the way the bike is running ... take a passenger. (You have a full licence right ??) It's always nice to have somebody to help you push it ... :killingme

[Lus7]

I mean, are there visual cues that tell me it needs to be replaced? So far as I can tell, the engine cutting out could be anything from fuel line blockages to oil problems. It's not really that dumb a question haha

[FJRider]

More than a Virago sadly.

There's one in Auckland that you could probably get for a couple of Woody's ... now ... :shutup:

[blackdog]

More than a Virago sadly.

Must spread.

[FJRider]

I mean, are there visual cues that tell me it needs to be replaced? So far as I can tell, the engine cutting out could be anything from fuel line blockages to oil problems. It's not really that dumb a question haha

No visual clues if you can't see the air filter.

As to actual issue ... you start by checking the air filter. As it is usually the problem.

Then ... move on to the more difficult things.

With the baffles butchered ... does it still sound nice when you're pushing it ... ???

[Lus7]

just got the filter out, it's sitting in front of me.
it's just a sponge.
what am i looking for?

and the baffles just have holes in them, they sound nicer than the bike stock. but not quite how i'd like it to sound.
Pushing it makes it sound a little muddy, unless im going slow in a high gear

[ducatilover]

I mean, are there visual cues that tell me it needs to be replaced? So far as I can tell, the engine cutting out could be anything from fuel line blockages to oil problems. It's not really that dumb a question haha
The bike will feel strangled and be leaving sooty black deposits on the spark plugs with a blocked air filter, may also get harder to start.

I think you should also look at the small black vacuum line to the fuel tap on the tank (assuming it has one) and wiggle it when the engine is warm (it may be expanding with the heat and causing the diaphragm to close)

First things first, pull the park plugs and compare them with this here:
http://www.angelfire.com/fl4/pontiacdude428/Readplugs.html

Then pull your airfilter element out, it should look like:
http://images.wemoto.com/full/FILTER_AIR/10015483.jpg

If your air filter has sooty or dusty crap all over it or noticeable colouring differences, get a new one.

I'd then pull the fuel filter out and check that, yet again, anything that's in it that doesn't look like it should be, replace it.

[Lus7]

thanks man. yeah my filter has a big oil stain on the inside white rim. i'll get a new one tomorrow.

I'll check the fuel lines now, the Manuel says nothing about where my fuel filter is

[ducatilover]

You'll have a fuel filter inside the tank, you have to remove the fuel tap and it should be part of it, sadly that means you have to drain the tank :facepalm:

[blackdog]

You'll have a fuel filter inside the tank, you have to remove the fuel tap and it should be part of it, sadly that means you have to drain the tank :facepalm:

Good cunt. I don't have the patience.

[FJRider]

just got the filter out, it's sitting in front of me.
it's just a sponge.
what am i looking for?



Stick it to your mouth and hold your nose. Breathe through the filter. If you have trouble doing this ... your bike will too. Clean the filter. (Unless it's a paper filter) ... hot soapy water will do. But a bit of petrol will do. Wring the filter out and let it dry. THEN re-fit it and try starting/running it.

[FJRider]

Good cunt. I don't have the patience.

Will somebody tell the OP where the tank is ... ??? we may be here all night ...

[spanner spinner]

sounds like a fuel problem as per a couple of other replys. might be a blocked breather in the fuel cap as it fires up after a little while. check the fuel flow to the carb by taking the fuel line off and letting it run into a container, let at lest two liters run through the flow should be steady the whole time. Your bike has a vacume tap so to get it to flow you will need to locate the vacume line and suck on it to start the fuel flowing then block the line off by pinching it shut to keep the fuel flowing (or just keep sucking your choice). if the fuel stops or slows down first take the fuel cap off and see if this gets the fuel flowing again, if not its a tap or filter problem clean the filter as the earier reply or strip and clean the tap. While you have the vacume line off check it's condition as a cracked or leaking vacume line will cause the same running problems.

[ducatilover]

Good cunt. I don't have the patience.
Tank's going to drain either way :D

[JamesRoberts]

I had exactly this on my bandit 250, started under load up hills then eventually would die off the line unless you rev'd the shit out of it before letting the clutch out. Pulled the carbs and they were full of shit, a good clean of the carbs and new plugs and problem solved

[CookMySock]

might be a blocked breather in the fuel cap [excellent diagnosis and remedy trimmed]I agree with this.

Quick check for this - when the engine quits, quickly open the fuel filler and see if you get an inrush of air - you will hear it go foooosh.

[Lus7]

http://i.imgur.com/nnd0E.jpg

Ok so what do these do?
The big hole is my air intake i gather because when I block it the bike turns off.
the line i'm holding doesnt do anything when I block it, but its connected right to the carb so i'm guessing it's important.
the line hanging off isn't connected to anything, but it's connected to the air pod

What are they?

[Lus7]

ok, so I just put the filter back on and rode the bike to the gas station.

Everything seemed fine.

Put some gas in, started the bike. it had itself a little power fart but it was alright after that.
I'm still convinced something is wrong with it, seems to be burning a lot more gas than it has the entire time i've owned it as well.
hmm

[FJRider]

ok, so I just put the filter back on and rode the bike to the gas station.

Everything seemed fine.

Put some gas in, started the bike. it had itself a little power fart but it was alright after that.
I'm still convinced something is wrong with it, seems to be burning a lot more gas than it has the entire time i've owned it as well.
hmm

Did you clean the filter ?

[Lus7]

I cleaned it yeah, it decomposed a little when i soaked it in the soapy shit, so I've ordered a new one.
but it's going to be here on tuesday, so I dried and put the old one back on to see if the new spark plugs did anything.

ran it on idle briefly with no airfilter, then put it on and off to see if I could hear a difference in the engine sound. lol nothing.

[Lus7]

so sitting at idle, if i rev it really hard/suddenly it makes a pop and doesn't rev.

happens once every 20 revs

[FJRider]

so sitting at idle, if i rev it really hard/suddenly it makes a pop and doesn't rev.

happens once every 20 revs

From the tank there should be two lines running to (different places on) the carb One is a fuel line, the other the vaccum line which opens the fuel tap when the engine is started. If the vaccum line is not connected ... it wont run well.

[FJRider]

I cleaned it yeah, it decomposed a little when i soaked it in the soapy shit, so I've ordered a new one.
but it's going to be here on tuesday, so I dried and put the old one back on to see if the new spark plugs did anything.

ran it on idle briefly with no airfilter, then put it on and off to see if I could hear a difference in the engine sound. lol nothing.

Take it for a short run with no filter on it. See if there is any improvement. If it was the filter blocked ... it will run better. But it Will need a filter soon as you can ...

I doubt you will notice any difference in sound at idle with no filter (apart from intake noise ... thats the air getting sucked in)

[ducatilover]

Try it with the fuel tap on reserve or if it has a prime position too.

[FJRider]

Ok so what do these do?
The big hole is my air intake i gather because when I block it the bike turns off.

The line i'm holding doesnt do anything when I block it, but its connected right to the carb so i'm guessing it's important.

Most likely the overflow from the carb.


The line hanging off isn't connected to anything, but it's connected to the air pod.

It is most likely the breather hose from the crankcase to the filter pod. They can block the filter as the fumes can be oily ... most likely your problem. (the filter blocked, not the line doing it's job)

[ducatilover]

Most likely the overflow from the carb.



It's the vacuum/pressure reference for the bowls.
It needs to be in still air (under the tank should be fine) if it's getting proper airflow to it it will pressurise the carb bowls and it'll flood, if it's pinched or blocked the bowl pressure will be too low and it'll lean out and die.


It pays to triple check the fuel and vacuum line to the fuel tap, while you're there replace the vacuum line, it'll cost sweet FA and it won't hurt.

[FJRider]

It's the vacuum/pressure reference for the bowls.
It needs to be in still air (under the tank should be fine) if it's getting proper airflow to it it will pressurise the carb bowls and it'll flood, if it's pinched or blocked the bowl pressure will be too low and it'll lean out and die.


I stand corrected ... :yes:

[Lus7]

So i took my bike out for a ride and it's riding fine now
I changed the spark plugs and the engine sounds a little different

i'll update if something happens, but seems all good

i'll still clean out the carb and replace the lines

[Lus7]

Cut out this morning on the highway. pulled over and it wouldn't start again for 20minutes, almostshatmyself when the truck behind me flew passed
it's been a few weeks since I changed the spark plugs, not sure what's wrong.

When the throttle cable is too tight (or loose, I can't remember), it does this:
http://www.youtube.com/watch?v=obXYvH0UhHc
if that means anything


also, the last time this happened I let my tank run low. I filled up and the issue seemed to subside (although my bike feels a little underpowered)
I've let my bike run low again and this happened. I checked to see if it's the gas cap, but it doesn't hiss when I open it before/after it has cut out.

another thing, when the bike is cold, I can start it without the choke on but if I move the choke to the on position it will cut out, my mate's bike doesn't do that.

[Lus7]

reading on the internet "Alright so my mechanic checked my bike out and he found that one of the lines to the fuel tank was plugged. He unplugged it but a new line on. He also mentioned a fuel valve or something that recycles unused fuel back into the engine was gone or not functioning right. He said when he was checking it out the fuel was coming out slowly and then barely at all. (not sure where this was happening but he started mentioning things about how the carbs didnt have enough fuel in them and what not. Anyway he told me to ride it around for a week and see if I still have issues with it. So far it run's A LOT better. To me it's almost like a new bike. Runs smoother, sounds better, and maxes out at around 106mph, previously it was around 90.

Sorry this description sucks but hopefully it gives you an idea of what was wrong."


I found a tube that was wet on one end and that hangs down the bottom of my bike just chilling not connected to anything under the seat.

[nzspokes]

Get some clear plastic hose, under the carb there should be a drain and a screw to undo it. Put the hose on the pipe and hold the pipe up. Undo the drain screw. Fuel will flow into it to the height of where it sits in the carb. If it goes above float bowl height thats your issue. Sounds like your float valve is rooted or blocked in the carb.

[Lus7]

Get some clear plastic hose, under the carb there should be a drain and a screw to undo it. Put the hose on the pipe and hold the pipe up. Undo the drain screw. Fuel will flow into it to the height of where it sits in the carb. If it goes above float bowl height thats your issue. Sounds like your float valve is rooted or blocked in the carb.

thanks, i'll do that when i get home. what gives you that impression?

[nzspokes]

thanks, i'll do that when i get home. what gives you that impression?

Sounds like she is over rich, and thats the most likely cause.

[Lus7]

It also sounded like it was reving pretty hard on the highway, even though it's only got 5 gears it sounded way over the top
reakon drilling holes in my exhaust is making my bike run rich? doesn't it usually make it run lean?

[mossy1200]

Sounds like the vacuum hose onto the fuel tap was this issue.If the mechanic has fixed it then stop playing with the bike before you break something.

[Lus7]

Sounds like the vacuum hose onto the fuel tap was this issue.If the mechanic has fixed it then stop playing with the bike before you break something.

Never took it to a mechanic, just changed the spark plugs and it seemed to fix it.
May end up taking it to a mechanic if I have to, but I'd be rather keen to learn to fix it myself

[ducatilover]

First things first.
Replace the small vacuum line between the fuel tap/intake.

If that doesn't work:
Pull the spark plugs out and check them against this:
http://www.angelfire.com/fl4/pontiacdude428/Readplugs.html
Then:
Do what NZspokes has said.
Then: if the float level is higher than your owners manual (assuming you have one, if not, get one) specifies, adjust it.
Clean the carbs while you're there.

[Lus7]

So i'm trying stuff out, I just noticed I hadn't put the battery in properly at all. It was sitting loosely on top of it's strap and the battery breather hose wasn't connected.

Would that do anything?

Also, I pulled out the spark plug and it's pretty black so my bike seems to be running real lean. i'm gonna try that clear hose thing, as soon as I figure out which hose to pull.

And What hose is on the fuel tap

[ducatilover]

So i'm trying stuff out, I just noticed I hadn't put the battery in properly at all. It was sitting loosely on top of it's strap and the battery breather hose wasn't connected.

Would that do anything?
I doubt it


Also, I pulled out the spark plug and it's pretty black so my bike seems to be running real lean. i'm gonna try that clear hose thing, as soon as I figure out which hose to pull.
Black = rich.


And What hose is on the fuel tap

There will be two hoses, one fat one (fuel) and one small one (vacuum) replace the small one, if the other is soft or perished looking, replace it too

[Lus7]

Get some clear plastic hose, under the carb there should be a drain and a screw to undo it. Put the hose on the pipe and hold the pipe up. Undo the drain screw. Fuel will flow into it to the height of where it sits in the carb. If it goes above float bowl height thats your issue. Sounds like your float valve is rooted or blocked in the carb.

lol arm covered in gas

[Lus7]

Black = rich

right, because soot = not enough oxygen in burn

http://i.imgur.com/uAfcn.jpg <- spark plug
http://i.imgur.com/NpxtL.jpg <- clear hose coming out of the carb. does this mean anything?

(sorry about the insane fisheye. These were taken on a GoPro

[ducatilover]

My eyes aren't good enough for them pics sorry :facepalm:
I can see that the plug is rich looking, but the plug temp is okay.

Will have to wait 'till someone else looks at the first pic :shutup:

[Lus7]

http://i.imgur.com/N0xYH.jpg <-- better picture

[Lus7]

http://i.imgur.com/eta8u.jpg

that's the fuel tap right? which one is the vacume line?

[nzspokes]

http://i.imgur.com/N0xYH.jpg <-- better picture

Turn the switch on to PRI and leave it for 5 min, see if the level stays at the same height. Is the height the same as the top of the float bowl.

[ducatilover]

The fuel line will go to the carb/s, vac line will go to the intake betweent he carb and cylinder head, probably on the front cylinder.

How high was it in relation to the carb? I would say it should be around 11-13mm below the top of the float bowl, if the level keeps getting higher, then you have a leaking needle/seat in the carb, if the level is too low, your floats are set wrong.

It's a bit hard to see over teh interwebs :sweatdrop

[Fast Eddie]

261993 <--- Better picture

[Lus7]

Lol so where is the float bowl? I'm not sure how high it needs to be

[Fast Eddie]

Lol so where is the float bowl? I'm not sure how high it needs to be

iraq.. think its code name for a WMD

[Fast Eddie]

2 joints should get it high enough..

[nzspokes]

Did it change when you turned it to PRI?

[Lus7]

Did it change when you turned it to PRI?

Closed it off and took the hose off, it's been sitting for about 3 min and the level hasn't changed

I tightened the bolt back up and tried to start it, it wouldn't start

http://youtu.be/en8lsdpJxpc

[Lus7]

hasn't moved in pri, it's been 7 min

[Lus7]

should my bike be on when i test out the float level?

[nzspokes]

The level wont change if youve turned the drain off.

Sounds flooded now. Open the throttle wide open and dont use the choke. Be ready to close the throttle as it will rev hard.

Then try what I said again. Leave the drain open and turn on to PRI. Leave it and see if it rises.

[Lus7]

Cool, got my bike outside, got it running, turned it off, got it inside, put the hose on the carb, drained it, sucked on the hose to get it going, let it sit for 2 min, then switched it to pri and let it sit for about 5 min and it hasn't moved

[mellowyellow]

float bowl issues would be seen when starting the bike and while its running. the float bowl would flood over night and cause issues for early morning starts, i would have thought. a flooded floatbowl while running would cause issues while hes riding anytime, not just under load. a flooded bowl should still start with the throttle fully open, unless its just dumping fuel in the intake.

it's low on power, black plugs, guzzling more gas than usual and cuts out after loading the engine with an uphill run where a 20min wait will allow it to restart. replacing the plugs helped and choke doesnt work. dont worry about the choke, different engines need different amount of choke, maybe yours only needs it when FROZEN. :cold:

i only know of one thing that would cause all these issues, spark issues.
i'd be pointing towards the coils, bad leads, magneto (or pick up sensor) or control box.
coil, pick up or control box could be over heating due to the highier rpm your doing while going up a hill.
might have a lose wire or connection
since its not starting all all for 20min, i'd forget about the coil or leads having issues, for now. it should pretend to start on 1 cylinder.
id test for spark the next time it dies. take a old plug with you. as soon as it dies, unplug a lead, plug in the old spark plug, hold it agianst some bare metal (like the engine) with some pliers (so you dont get shocked) and check to see if there is spark. do the same for the other cylinder.

my 2c

[ducatilover]

That's a fair point, but why is the plug temp still in range if it's weak spark?
The chokes could be stuck or leaking anyway, I've had split rubbers in my chokes, fuckin' annoying :bash:

[Lus7]

20min wait will allow it to restart

sort of, letting it sit allows me to ride again but only for a brief period of time.
Like this morning on the highway, I had just gotten to the top of a hill at 100 when it cut out. I sat there for 20min, started it and rode down the hill. at the bottom it died. let it sit and repeated the process till i got home. - but it tends to die on hills mostly.

My bike has no temp gauges so i don't really know what's up.
The control box is under the seat, i'll give it a check for loose cables tomorrow.

i'll take it for a ride tomorrow and test the sparks out

[mellowyellow]

That's a fair point, but why is the plug temp still in range if it's weak spark?
The chokes could be stuck or leaking anyway, I've had split rubbers in my chokes, fuckin' annoying :bash:for new plugs, they seem to be a litttle dark around the edges. i know that can be cuased due to many things, but the state of the plugs cant rule out a spark issue, imo. dont forget i'm suggesting intermitent spark fault, not consistant (overheating pick up vs cracked coil). though cracked leads probably could cause the coil to overheat, i guess.


sort of, letting it sit allows me to ride again but only for a brief period of time.
Like this morning on the highway, I had just gotten to the top of a hill at 100 when it cut out. I sat there for 20min, started it and rode down the hill. at the bottom it died. let it sit and repeated the process till i got home. - but it tends to die on hills mostly. that makes sense, it would take mre time for something to overheat from dead cold, from that point on, it would be a much shorter time period for when the problem returns.
heres a senario the old ford LTD's use to have - car would run well for the first 10 min, next 10min the car might loose power. about 20-40min of driving from cold, the engine would die. wait 15min and the car would start and you'd have 2-5 min to drive to saefty (no way you'd wanna push one of these home :wacko:), wait another 15min to get another 2-5min of driving. the cause is due to a little piece of electronics on the side of the dissy over heating and preventing the pick up in the dissy from working. good news for the ford driver, the fix was to remove the electronic device, renew the thermal grease and reattach the device.

now im not saying this is your problem or fix, but your issues do fit in with that (and many other senarios i have come across) same type of issue.
loose wire causing overheating in the connector or at the grounding
faulty CDI unit
faulty magneto pickup
overheating electronics
overheating coil/s
cracked or faulty leads
faulty kill switch (handle bars OR side stand)
hairline crack in a fuse
just a few ideas of what could be the cause IF you have no to low spark when the fault arises.

another idea...... when you are testing for spark, if you find you have a good spark, pull out the existing plugs, straight after your test (during the fault, on the side of the road) and see if they are "wet" with fuel.
Just getting back to basics here. checking for spark and fuel while the fault exists

[Lus7]

Awesome, i'll try to get it to fail and test the sparks.
won't it damage the engine if I try to start it without the sparkplugs in?

Also, as far as the choke is concerned. If I cold start the bike it will start with no choke, but if I slide the choke across then it will die. If I start the bike cold with the choke on full, then it will start up and rev hard. When warm i can move the choke across while the engine is on and it won't die. Why's that?

Also, going back to the dirty carb issue. Under the throttle I have a little screw cable extender. When it's screwed so that the cable is as long as possible, the throttle sticks like it did in that youtube video I posted earlier. Does that mean the carb is dirty, or that the cable has too much tension or something?

[Lus7]

lol went to try start my bike with the spark plug out. held it with plyers against the engine. Got shocked as haha, i'll try that again with gloves on or something

[Lus7]

not sure how much electricity should be jumping when the spark plug fires, but there doesn't seem to be a lot jumping the gap. The bike hasn't failed, i'm just testing it in sitting at home

[Lus7]

Alright, so I plugged the holes I made in the exhaust with some cut up bits of cork. Took my bike out round the block.
on the final stretch (which is also the biggest hill), I chucked it in 5th gear and strained it (which i've done up this hill before without problem) half way up no matter how much throttle I gave it, it wouldn't get any faster. I dropped a gear and power seemed to return briefly, 3/4s up the bike started to loose all power. I dropped a gear and gave it gas, nothing happened. Dropped another gear, full throttle, nothing. Bike dies.

I pull over, try to start it. dead, she wont start. cool, recreated the problem successfully. I pull out my tools, take off one spark plug and put it against the engine block. I start the bike and the plug seems to fire fine. same with the other plug. interesting.

She's been sitting for about 5 minutes now. I try to start her, nothing. I turn the choke to full and start her, she starts. I turn the choke off and ride home (15m away)

dafauq is going on?

I'm going to fill her up on gas, last time I did that the problem seemed to subside.
The only reason I didn't want to was because I'm not sure how to stop the tank from leaking everywhere if I take it off to try clean the carb


The spark was firing probably 1/3d as powerful as this one and the electrical bolts were all over the place.
http://www.youtube.com/watch?v=W8V0ULlWBrM&feature=related

If that matters, it seemed to be the same as when the bike was sitting at idle at home before it failed


p.s. it's my birthday today, so i got the day off work to try fix my bike

[ducatilover]

I'm going to say it again :D
Get owners manual;
Set floats/clean carbs
Check the cokes (will have a guide in the owners manual)
Check the coils.
Check operation of the fuel tap.
Replace fuel filter.

[Lus7]

will do, just some more info. I filled up the tank with gas and it hasn't cut out on me since.
Would that have anything to do with anything?

[ducatilover]

How far have you ridden?
There will be some sort of tank venting under or incorporated in the fuel cap, if you can figure out how it works, clean it.

[Lus7]

3 times the distance it took me to get the bike to fail last time

if it's the gas cap, should it run fine after it fails with the gas cap open?

[ducatilover]

3 times the distance it took me to get the bike to fail last time

if it's the gas cap, should it run fine after it fails with the gas cap open?

It'll run fine with the cap part open or fully open, but with the engine shut off, you have to switch to the prime/reserve on the fuel tap because fuel won't flow without the engine running (that's what the vacuum line is for)
If you can run it with the cap just cracked open and the bike doesn't cut out, there's your problem.
If it runs on reserve/prime and doesn't cut out, your fuel tap, or vacuum line is at fault.
If it does it even after this, I'd be then going with leaking float needles, or still possibly the fuel tap.
I had an issue years ago exactly the same, my VT250 shat the fuel tap (there's a rubber diaphragm with a spring to cut fuel when the engine is not running) and it had a hole in said diaphragm.
Chased my tail for ages on that one, then replaced the fuel tap and I never had an issue again

[Madness]

Hey guys, i have a fairly new bike (14,000 ks) and it rides great.
Recently I've noticed its randomly loosing power. Going up this hill, my bike starts choking till it stalls.
It feels like the bike just looses all power momentarily and jerks until it completely turns itself off.

You have tried changing down gears when going up this hill, aye?

[mellowyellow]

sweet, so no issues with spark. it may be weak but its there. i'm starting to wonder if you have a collection of issues.
choke on full cleared the fault an allowed the bike to start, i would think this was pointing towards a faulty tap too. choke on full would increase the vacuum to the tap and allow more fuel to flow.
if you released the accelerator to drop the gear, you would have had a burst of vacuum to the tap, throttle open and you would have lost the vacuum (guessing normally not an issue on a functioning tap) and float bowls emptied out.
if it were a tank breather issue, one would think it would be worse with a full tank.

ducatilover has had the problem, find out how much a replacement tap is and swap it out if you can afford it. check the vacuum line for cracks.

as for the engine running rich and the darker colour around the outside of the new plugs (and weak spark)
are the plugs the correct type and gapped correctly? you have spark so its not a huge issue.
you could be running rich due to the other hoses flapping about, it has already been suggested one of the hoses could be causing issues with your float bowl level.
the running rich issue could be why people are pointing towards a leaky needle, but a leaky needle isnt fixed with choke on full, not that i know of anyway.

[Lus7]

I'm going to take the hoses connecting everything on the bike off and replace them with brand new fuel hoses from supercheap (or where-ever is cheap)

In the owners manual under carborator it says "Adjusting the carborator is compicated, take it to a yamaha dealers if you have issues"
All I want to know is which line is the vacume line and what the parts do.

I'm going to check the internet for a more comprehensive manual

[Lus7]

a new petrol tap is 30nzd on ebay. can't be far off that at the store

so full tank of gas, just went up that hill 4 times, no cut outs. however every now and then the bike seems to choke/stutter

[mellowyellow]

been doing some reading, your fuel tap has three positions, correct?
"on" "pri" "res"
"on" is reliant on the vacuum pipe and diaphram (apparently)
"pri" is for the primary tank, fuel should flow no matter what the vacuum is doing
"res" is for the reserve tank.

from a pic i have seen, "pri" is between "on" and "res". switch it to "pri" and go for a test ride. this has been suggested before though.

edit: is your fuel pump run with vacuum or electric?
are all the carby and intake mounting bolts tight?

[ducatilover]

from a pic i have seen, "pri" is between "on" and "res". switch it to "pri" and go for a test ride. this has been suggested before though.

edit: is your fuel pump run with vacuum or electric?


My thoughts exactly.

To my knowledge they didn't have a fuel pump, just gravity feed, so I'd rule that out (going to laugh and cry if it does have a pump though...)

[Lus7]

My thoughts exactly.

To my knowledge they didn't have a fuel pump, just gravity feed, so I'd rule that out (going to laugh and cry if it does have a pump though...)

http://i.imgur.com/Budda.png
It's got a fuel pump. You'll be laughing because it makes it easier to fix.. right? :sweatdrop

[Harry the Barstard]

Best thread in ages.... some funny shit!

Hope you get it working mate, well after a few more pages anyway.

[ducatilover]

Yay, another spanner in the works!

In that case, I am going to assume there's no vacuum line to the tap and it has a vacuum operated pump?
I'll go to google and look in a second.

Now, it shouldn't need a vac pump unless the fuel pick up in the tank is sitting lower than the carb float/bowl.
You should be able to bypass it.

First things first, check the condition of all the hoses to the pump, if you find an electrical plug I shall yet again laugh and cry.

[Lus7]

The diagram that I linked from the service manual says that there is a vacume line connected to the fuel tap
No electrical cables on the fuel pump, but there are a few plugged into the carb. checking the state of the fuel lines atm.

reakon it would be worth just replacing all the lines tomorrow with some standard fuel lines?

[ducatilover]

I'd expect there to be an overflow or return line from the carbs.
Replace the lines, but I wouldn't be surprised if you had a shagged pump

[Lus7]

i see, know of any way I can test to see if that's the issue?

[ducatilover]

Carry that little clear tube around.
When the bike cuts out, jump off (well, stop first) and check how much fuel comes out the carb bowl like you did before.
If it's significantly less, or much more, than it's a fuel pump issue.
Alternatively, you may be able to get a tee fitting and bypass the fuel pump and ride it.

[Lus7]

lol seems a little weird to have a fuel pump if you can bypass it.

I'm curious as to how this pump works, it's got no cables running to it so i'm not sure what actually powers the pump

[Lelitu]

then it's vaccuum powered

there will be at least 3 hoses going from it, one to the tank, one to the carb bowls, one to either an inlet manifold, or elsewhere on the carb

that last one is a vaccuum line, it works because it's airtight, and when the engine is running, the intake manifold/carb sucks the air out of the line, that powers the pump.

[Lus7]

Ok, so after reading the service manual's instructions on how to test if the fuel pump is working, I have determined it's ALL GOOD.
Got the fuel pump -> carb hose connected it to a jar. turned the bike on and fuel flowed out which suggests that the fuel pump is fine

damn, what next?

[Lus7]

So If the fuel pump relies on the vacuum tube to work and the fuel pump works, then the vacuum tube must be fine right. right? :brick:

[ducatilover]

When it cuts out, check the fuel level with your hose.
What I'd do is;
Make a mark on the bottom of the tank and hold the clear hose to that mark, take note of the fuel level.
Then do the same thing when the bike cuts out, this way you can see if the fuel level is dropping or raising.
If it's lower then there's a fuel restriction, if it's higher, your carb float needles are sad.
If it's no different?
Then we're back to step one and I'd still say clean carbs and replace fuel filter.
Then we'll look for electrical gremlins.

[ducatilover]

So If the fuel pump relies on the vacuum tube to work and the fuel pump works, then the vacuum tube must be fine right. right? :brick:

The vacuum tube could be fine.
It may still work, but not flow as much as the engine needs if it's split.
If it's soft, it'll close up and stop vacuum supply to the pump.
So, replace it just for peace of mind

[mellowyellow]

No electrical cables on the fuel pump, but there are a few plugged into the carb.

they wouldn't have fitted anti-desiling solinoids would they? surely not:eek5:
that would be funny.
those are a bastard to diagnose without replaceing and would be controled by the CDI unit. check the electrical conectors for dirt and moisture

[ducatilover]

they wouldn't have fitted anti-desiling solinoids would they? surely not:eek5:
that would be funny.
those are a bastard to diagnose without replaceing and would be controled by the CDI unit. check the electrical conectors for dirt and moisture

Oh God, you just ruined my night.

Off to google again...

[Lus7]

The vacuum tube could be fine.
It may still work, but not flow as much as the engine needs if it's split.
If it's soft, it'll close up and stop vacuum supply to the pump.

yeah, i'll replace it.
But even still, that doesn't really account for why the issue only happens when the tank's below half

[ducatilover]

they wouldn't have fitted anti-desiling solinoids would they? surely not:eek5:
that would be funny.
those are a bastard to diagnose without replaceing and would be controled by the CDI unit. check the electrical conectors for dirt and moisture
Seems to have Mikuni BDS26s fitted to it, I'm not sure if they had an anti run-on solenoid?

yeah, i'll replace it.
But even still, that doesn't really account for why the issue only happens when the tank's below half

Unless the weight of the fuel in the tank is enough to push past the diaphragm in the pump
In which case, the spring behind the diaphragm may be weak.

[mellowyellow]

is the following correct?
Your bike is a 2006 yamaha VX250 which has only done 14,000 km's
all you have done (or has been done) to the bike is
* change the plugs
*oil change
*drilled some holes into the muffler
*the air box is removed and a pod filter installed, this has left a couple of hoses to flap about without a home.

things to check so far...... correct oil level, correct plugs, reinstall the air box so the hoses have a home for now.

so, bike runs okay (though lacks power) until its running high revs up a hill. when fault happens, engine wont start unless full choke is applied and turned off once started.
are you sure the oil level is correct? (Make sure that the motorcycle is positioned straight up when checking the oil level. A slight tilt to the side can result in a false reading)

firstly, this is a V twin with single carb, applying full choke to the makuni bypasses the throttle piston, draws lots of fuel from the float bowl and dumps the atomised fuel behind the throttle piston. this could be an important fact to note. full choke applies vacuum to the float bowl. (dont worry about the choke not being needed when you cold start, its not really a choke, just a fuel enrichment system, doesn't "choke" the engine).
so, it seems your float bowl is empty at the time of the fault, hence the reason why full choke remedies the fault.
what causes the float bowl to become empty? starting from the carby....
*sticky float (wont drop to let in fuel)
*sticky needle valve
*pressureised float bowl (vent plugged where it shouldnt be or not attached)
*no fuel getting to carby

so lets look at the no fuel geting to carby possibility
starting from the tank.
*the tank needs to have fuel in it :)
*the fuel tube in the tank needs to be clear, no crap floating in the tank, just waiting for its time to block the tube
*the fuel tap apparently filters the fuel, find out how to clean it
*the fuel tap has three settings, one of which is vacuum opperated "on", set it to "primary" incase the diaphram is needing to be replaced.
is the tap leaking? is it leaking fuel out the vacuum hose? does the hose have a hole in it?
*next is the vacuum operated fuel pump, this too could have diaphram issues or loss of vacuum due to clogged lines or cracks in hoses.
*lastly is the path to the carby. there will be a fuel filter canister somewhere, check its condition. more than likely there will be a second filter just inside the carby.
the whole fuel delivery system relies on vacuum, without it, it may take 20min for the fuel to trickle down from the tank and fill the float bowl. applying full choke would "suck" the fuel into the float bowl.



first thing (after rechecking oil level and reinstalling the airbox) i suggest is to inspect the float bowl breather. is there crap in the hose, could crap have gone into the hose and into the float bowl? if so, have the carbi serviced.
second thing, clean the tank, really shake it about with some fuel in it and make sure nothing is floating around in there.
third, create the fault and carefully disconnect the fuel hose where it goes into the carby. allow about 500ml of fuel to drain into a CLEAN 1 litre container this is to see how fast it runs out with bike off. i would expect it to rush out at first (as the pipes empty), then trickle out.
with hose still in the bottle, hit the starter, how fast is the fuel pumping out? is it pumping out? if so, then you have no issues with fuel delivery. reconnect the fuel hose to the carbi and try to restart the bike, still nothing? choke it, still nothing? choke and half throttle.

if the fuel delivery test fine, the carby could be full of sludge, have the carby serviced

[ducatilover]

I forgot about the pod.
Put the airbox back on :yes:

[Lus7]

So far this morning I have learnt how to take the tank off, access the carb, understand how everything connects/works together and replaced a whole bunch of tubes.
Here's a video:
http://youtu.be/TT0Bux-nQfQ


I forgot about the pod.
Put the airbox back on

haha nah I never got round to putting a pod on it, just replaced the air filter with a stock one

What I've done so far:
* changed the plugs
* oil change - 10w 40 car oil
* drilled some holes into the muffler - plugged them up with bits of cork
* changed the air filter with another stock sponge one
* Replaced all the tubes but the two going from the tank to the tap with fuel line hoses from supercheap

I'm a little concerned about the tube connecting to the fuel pump. at 0:18 of that video, the tube seems to be bent a little too much, worried it could restrict vacuum flow - but it doesn't seem to

Also my engine seems to be knocking a little, is that normal? You can kind of hear it in the video, it's done that for ages and i've just ignored it.


I just took my bike for a ride (full tank/changed tubes) and it seemed to ride smoother. Not entirely sure though.
Syphoned 5L (out of 15) of the tank into a gas can and took it for another spin, rides a little better than I was expecting. Seemed to do mini chokes every now and then but i'm not sure if that's just placebo or bumps on the road.

Gonna ride it round till the tank runs low today in an attempt to get the bike to break down again. will report back.

[p.dath]

Hold on - you used car oil?

[GSF]

* oil change - 10w 40 car oil

If you start noticing the clutch slipping a bit, this might be why.

Also, it'd be interesting if the bits of cork you stuffed into your muffler get hot enough to start burning.

[mellowyellow]

the wires going to the carby are probably nothing more than a carby heater to help atomise the fuel when cold, some bs like that anyway.
failing that, they could be just grounding wires. either way, nothing to worry about.

so, back to the oil, definitly not over filled? that would cause you to loose power too, as well as a whole lot of other bad stuff. using car oil aint too good for the bike. i dont know enough about bike clutches to know if car oil additives slowly soak into the plates and screw em over for good or not. might be something worth finding out.
i know oil on a car clutch is bad, no matter the grade or type :)

edit; i may be wrong, but.....your fuel tap should be horizontal, not vertical, to select primary. if the fault occurs, switch it to primary

[Lus7]

Cool so that fixed nothing.

Tried riding with the cap on, off pri etc. even after replacing the lines it's still stalling. ghey as bro

[Lus7]

On the plus, it seems to last longer and breakdown for shorter periods of time. Don't know if that has anything to do with anything though

[ducatilover]

Did you try the clear tube/carb bowl when it cuts out?
What a cunt of a problem.

[Lus7]

Did you try the clear tube/carb bowl when it cuts out?
What a cunt of a problem.

Nah, forgot it at home.
I'll try that tomorrow, maybe the bike is fine, i just need to keep the tank above 1/2 full.

Know if the biker meet ups are still going on in albany on weds?

[ducatilover]

Nah, forgot it at home.
I'll try that tomorrow, maybe the bike is fine, i just need to keep the tank above 1/2 full.

Know if the biker meet ups are still going on in albany on weds?

Does it do it when it's on the reserve or prime position? (sorry if I have a weak memory, Kawasaki ownership does odd things to a man)

No idea about Albany, I'm about 5-600km south of that...

[mellowyellow]

Cool so that fixed nothing.

Tried riding with the cap on, off pri etc. even after replacing the lines it's still stalling. ghey as bro

yeah ducatilover, he has tried prime. hard to keep up with what has and hasn't been done with this one :)
try the clear hose, be interesting to see if the carby has fuel in it when it stalls out.
replacing the hose is good, atleast it removes that from the list of possabilities.

not really much more you can do until you find out if theres fuel in the float bowl when it stalls and if the fuel is pumping after it stalls.
trying the above with a 1/4 full tank is probably best. i'm thinking the weight of the fuel in a full tank is the only thing reducing the stall rate and down time.

[Lus7]

http://youtu.be/-ELP-yTcY1M
does the throttle sticking like that mean my carb is dirty?


also, when checking the level in the carb, do I suck on the other end of the hose to draw fuel out?

I forgot to mention that hardly anything comes out unless I do

[mellowyellow]

http://youtu.be/-ELP-yTcY1M
does the throttle sticking like that mean my carb is dirty?


also, when checking the level in the carb, do I suck on the other end of the hose to draw fuel out?

I forgot to mention that hardly anything comes out unless I do

throttle will stick when you adjust the cable too tight, basically the same as turning the throttle yourself.

when checking the level, you will need to fit the clear tube to the carby drain, just as you have already done. if the fuel wont run out freely, try starting the bike. does the fuel pump out now?

[ducatilover]

The fuel should run freely from the carb drain, you shouldn't need to siphon it

[Lus7]

The fuel should run freely from the carb drain, you shouldn't need to siphon it

When I hook the hose up and unscrew the bolt a bit of fuel will trickle into the hose, but it wont really level off or anything. it just sits there, I have to suck on the hose till the level rises then let it rest and it will drain back down to the float level.

I'll video what I mean when I get home from work

[Lelitu]

well, that sounds like a possible fuel supply problem right there..

[mellowyellow]

When I hook the hose up and unscrew the bolt a bit of fuel will trickle into the hose, but it wont really level off or anything. it just sits there, I have to suck on the hose till the level rises then let it rest and it will drain back down to the float level.

I'll video what I mean when I get home from workcould be clogged breather, jets or no fuel being pumped into carby. dont worry about the video, drain the tank to 1/4, create the fault, fit the clear tube (which wont allow fuel to flow without syphoning) and hit the starter. does fuel come out now?
the fact you can suck on it to get fuel and then it will drain back into the carby tells me the float bowl is empty. just prove fuel is getting to the carby when the fault occurs. after that, its 90% a carby issue.

[Lus7]

http://www.youtube.com/watch?v=FwxQvTMGcvc&feature=youtu.be

does this look right to you?

[mellowyellow]

http://www.youtube.com/watch?v=FwxQvTMGcvc&feature=youtu.be

does this look right to you?nice video, but you need to prove you have fuel in the carby when the fault occurs.
again, create the fault with a 1/4 full tank, attach the clear tube like you did in the video (NO syphoning!!) and see if any fuel runs into the tube.
*if it doesn't, you are one step closer to finding the problem. check to see if the fuel pump is working.
*if it does, hit the starter and see if more fuel is pumped into the clear tube. make sure the end of the clear tube is below the carbi and able to drain into a bottle/container.

[Flip]

Are you sure the bike is not running onto reserve?

Failing that it is either the tank breather, the fuel filter or fuel tap.

[Lus7]

nice video, but you need to prove you have fuel in the carby when the fault occurs.
again, create the fault with a 1/4 full tank, attach the clear tube like you did in the video (NO syphoning!!) and see if any fuel runs into the tube.
*if it doesn't, you are one step closer to finding the problem. check to see if the fuel pump is working.
*if it does, hit the starter and see if more fuel is pumped into the clear tube. make sure the end of the clear tube is below the carbi and able to drain into a bottle/container.


OK, will do that this evening. Is the fuel supposed to continuously flow free out of the carb when unscrewed? or does it just drain till empty?
Considering how a float works, it should consistently flow right?

[Lus7]

I have been unable to recreate the issue. hmmm

[mellowyellow]

OK, will do that this evening. Is the fuel supposed to continuously flow free out of the carb when unscrewed? or does it just drain till empty?
Considering how a float works, it should consistently flow right?

engine off, the small amount of fuel you had in the video was just what was in the float bowl. it doesnt suprise me that fuel wont flow unless you suck on the hose. the pump will be slowing the flow rate to a tiny trickle, until you either atempt to start the bike or suck on the hose.
of course i could be wrong :)

just remember to try the test when the fault does happen.
read my last post for my suggested test to make sure the float bowl has fuel at the time of the fault.

good luck