Stalling and stuttering at motorway speeds.

[Wardy]

Stalling and stuttering at motorway speeds.
Hi All.
No not a Z, but a Kawasaki KLE 500.
Yes its crap but up to now 30K miles relatively trouble free and important bike to me as it’s my sole means of daily transport to work.

It’s got a problem best described by going to this thread here.
https://www.bikechatforums.com/viewtopic.php?t=272730
(I have copied the hyperlink but this site don’t like it, please cut and paste into your browser.)

The guy has the same problem as I, however the thread was never completed so no one knows if he found a solution or not, I hate that.

I’ve followed pretty much everything he has done, but still the problem remains. If I can add anything to the picture is that it seems to happen when my bike is warm and on a steady throttle 50mph or above. I don’t want to colour your judgement but it really feels like fuel starvation, but I may be totally wrong.

You are a brainy bunch so hoping someone can suggest what the problem may be or at least other options to try.

Thanks for any input good or stupid.
Wardy

[Pigford]

If it get worse as it gets hotter - could be electrical, if fuel starvation is defo ruled out (such as fuel cap blocked breather, etc).

More heat = More resistance, such as coil breaking down? New sparkplug? Valve clearances? HT lead okay?

Can't be arsed to read link

Have you run on dual carriageway & soon as it plays up turn off fuel tap, cut ignition & then check fuel level in carb - just drain into container to compare amount when it is full,

[z1bman]

most common problem with the 2 cylinder 500 is the ignition coils fail & spark plug cap suffers bad corrosion due to water not draining from the spark plug hole also have you bypassed the side stand switch?

[Wardy]

Thanks Pigford. Will give it a spin later and try and check the fuel level in the carbs.

I`m sure its not electrical, sometimes when it plays up i pull over and just keep tickling the throttle and after a minute or two its running fine again, until i hit the next fast long stretch of road. Sometimes it just dies and i have to wait a while and then when starting it acts like it hasn't been started in ages and gradually fuel gets through. Ive also tried running it with the fuel tap on prime which makes no difference at all

Ralph Ferrand has put on new coils, HT leads, caps, plugs and done numerous other electrical testing and all checks out OK.If you can be arsed to read the link its actually quite interesting and thorough, will definitely test your grey matter.
Z1B man. I never thought of the side stand switch. Will bypass it this weekend.

Thanks Guys

[Pigford]

No oil leaks around the head?
The head could have hairline crack internally?

[Wardy]

Hi Pigford.

No - no oil leaks around head, no air leaks around carbs or inlets and no exhaust leaks.

Update.
Took bike for a spin. After about 10 miles on an A road ran it up a long fast hill top gear full throttle. Crested the hill and still giving it some, all was ok.
Less than 1 mile later I had to slow down for a roundabout and it started to stall and splutter again.
Killed the engine ASAP and pulled over to check if there was fuel in the float bowls. Yes there was!!
(I could only check right hand carb as left one is inaccessible with tank / bodywork on)
Tried starting the bike and it ticked over raggedly – exactly as if starting a laid up bike on dry carbs before you give it enough time for the fuel to properly get to the carbs.
Then ran fine at sub 50mph the 10 miles home.
So assuming you have read the thread in my original message, and I do have fuel to the carbs – what else could it be!

PS. I will disconnect the side stand switch this weekend but I am sure it not that, I’ve been through some pretty deep streams and it’s never played up

Really driving me nuts

[oldzed]

I know that you say not electrical but I had a similar problem when my alternator windings were giving up.
Under load at dual carrageway speeds the alternator output could not supply enough amps to run the coils.
Never had a problem getting it to start ,or rev at rest, but would not hold 70 for any time .
Ended up running a cheap voltmeter to the battery and going for a run. at higher speeds voltage sagged enough to cause misfires.

[Mr Bump]

I know that you say not electrical but I had a similar problem when my alternator windings were giving up.
Under load at dual carrageway speeds the alternator output could not supply enough amps to run the coils.
Never had a problem getting it to start ,or rev at rest, but would not hold 70 for any time .
Ended up running a cheap voltmeter to the battery and going for a run. at higher speeds voltage sagged enough to cause misfires.

Simple way to check for that would be to try turning the lights on/off and see if it has any effect?

If it had points on it I'd swear that was the condenser breaking down.

Stating the bleeding obvious, but are you sure the fuel isn't contaminated (there might be a bit of diesel in there perhaps? The petrol floats on the diesel when its laid up then the two mix up when you start moving... can give really wierd confusing symptoms) and that the tap or float strainers in the carbs (assuming it had them) isn't partially blocked. That might fox you because by the time you've parked up and got at the float bowl its partially refilled?

Olly

[Wardy]

Thanks OldZed.
Will have a go at rigging up a cheap voltmeter and see what happens.

Mr Bump. unfortunately the lights come on automatically, cant run without them and 100% sure i haven't put in diesel and also it has a fuel nozzle restriction under the fuel cap.
I also refuel very regularly, sometimes supermarket fuel, sometimes proper garage fuel and in the tank now is shell V power. Bike keeps breaking down no matter what its drinking.

Gary

[Wardy]

Hi OldZed & Mr Bump....and anyone.
Update.
As suggested I attached a cheap voltmeter and went for a ride in the hope the bike will fail whilst showing the voltage was all over the place, indicating an alternator / magneto /rotor problem when the bike gets hot.

Bike stuttered and stalled as usual but the voltmeter reading was a stable 14.5 volts both before during – and after breakdown. Dismayed I carried on with the petcock on prime and the tank cap open, just in case it was a fuel / vacuum problem………but the bike broke down just the same.

To date:
New plugs (x3) – New HT leads – New coils (x2) – New Reg/rec (x2) – Replacement 2nd hand ICU (known to be good). Carbs ultrasonically cleaned and checked - Air filter clean - New carb rubbers – No leaks from airbox to cylinder - Inlet / exhaust valves checked.
I have gone over every wiring connector at least twice to check for loose connections – all looks good.

Ralph Ferrand has done numerous electrical ignition and other circuit test and all checks out good whilst stationary.
I haven’t replaced the key / ignition switch, nor the handlebar kill switch as the bike only breaks down when hot and I can’t see how these would be affected.

The bike starts, ticks over and runs very well otherwise. But always after about 20 mins on a steady open road, she stutters and stalls. Same time period but with city riding…no problems at all.

Really at my wits end…………Has anyone any idea as to what I have missed. I am hoping someone will come up with a solution that’s so simple it will be embarrassing for me.

Any help seriously welcome.

Gary

[Pigford]

Double check valve clearances - sounds like symptoms if gaps too tight?

Did you check volts at coils input (low tension) side whilst running?

[wilsonsjw11]

It wouldn't take much to carry out the Wired George modification to guarantee 14volts on the coils LV terminals.
Regards
Steve.

[Pigford]

It wouldn't take much to carry out the Wired George modification to guarantee 14volts on the coils LV terminals.
Regards
Steve.

True, or for a quick test, start the bike then whilst running, run a wire direct from battery +ve to the live coil terminal then go for a ride.

The ignition barrel could still be a weak area so next time if stops test feed in/out with meter without touching anything - also kill switch.

Have you eliminated clutch/kisckstand switches, best to get rid of them completely.

[Steve Cooke]

Have you cleaned out the tank? has it been lined? if any of that comes adrift it can restrict fuel to the tap when running steady but not necessarily when moving around town as it can get moved around with the bike, same if something has sucked into the air filter, a bit obvious I know but a possibility all the same.

[oldzed]

Had a quick look at the wiring diagram for this model.
It shows a crank sensor.
I know this is probably the coil pickup
I work on cars and crank sensors are common for failing when hot.