fuelling problem??

[Steve H]

One thing you could try is check the flow of fuel to the carb. The float bowl should have a drain screw at the bottom and a pipe attached for the overflow. After it dies, open the drain screw to see if any fuel flows out.
Have you checked the breather in the tank filler cap ?. Open it after the bike has died, do you get a sound of air being sucked into the tank ?.

[guest27]

It still sounds like a fuel prob to me, but picking up on the above disabling the kill switch - not when you are riding it mind - to remove that possibility.

How did you clean through the jets? - I am not desperate to be right - but starting - running a bit and then dying sounds like a blockage getting into a jet - or possibly an air leak - not running off choke?  Dunno guessing.

As to buying a new carb.  IF it is the carb we should be able to get it running all be it roughly on a worn carb.  If we are then sure it is no the electrics cutting out - coil losing it when it gets warm?  I dunno.  If we can pin it down to the carb, then get a new un.  BUT if it is not the carb you are  out of pocket.

Does it start and tick over - chug chug chug, and then die when you open her up a bit?  Or is it all OK until = pop she stops? - Trying to get a feeling for when it happens.

Just as a side note - I have had the K4 carbs off and cleaned them through a couple of times over the last few days - stood and full of gunge.  keeps blocking up again as another little bit of gunge comes lose and jams in there - she is now taking throttle - and the slides are starting to jam but that is different.  I  know how you feel - if this is a carbie prob she is being a bugger.

More detail on what happens when she starts and then what occurs.

Best wishes - the Roger 14lb sledge does not work BTW

R

[cloggy]

Actually, following on from Steve , just take the petrol cap off and see if it runs. Have a spare spark plug ready and as soon as it stops see if there is a spark on the outside of the engine with the spare [not bothering to take off the one that's screwed in]
If the spark isn't there at once
The coil/condensor could be breaking down
Narrow the plug gap and try again
If the condensor is breaking down you will get a weak yellowish spark [or nothing]. It may spark and then break down as soon as it warms with the current, then it cools and uh there's a spark again!
Check the points aren't sticking open or arcing onto the cover.
If theres always a spark then see if someone has a carb you can try out, just to make sure it is the carb.
If you have a slide carb get the carb cleaned professionally  [£15 or so] to make sure the pilot circuit isn't blocked. I had that trouble and a clean fixed it.
PS Never use champion plugs, I've had duff brand new ones

[cloggy]

One more thing
I sold a nice PE 175 to a really solid bloke and started getting e's  about was the motor alright when I had it? The bike was cutting in and out and making no power
After some weeks the reason became apparent. the guy had taken off the tank cap rubber grommet thingermyjig whatsit and parked it under the seat over the airbox intake...and put the seat back on.
You haven't got a rag or anything blocking the air intake?

[boze]

Steve: the carb is definitely getting fuel, the bowl is full when i take it off. also the tank is breathing fine, no vacuum here.

Rog: when she dies it doesn't seem to have any correlation to what the throttle is doing, she has died when Ive been revving and when shes been idling.

i cant work on her till Monday as I'm gettin shafted at work but on Monday I'm going to have another bash at cleaning out the carb except this tI'me im going down to my mates work as theres a chem-clean there. basically is a barrel of kerosene with a filter and pump in it which pumps kerosene through a hose with a brush on the end and into a metal basin with a plug in it on top of the barrel. would it be worth getting one of these?: http://cgi.ebay.com/Yamaha-SR500-SR-500-2J4-2J2-carbureto-full-Kit_W0QQitemZ300098717363QQihZ020QQcategoryZ10490QQrdZ1QQssPageNameZWD2VQQcmdZViewItem just seeing as how its such an old carb, or should i clean it out first?

thank you so much for all your help!!! this is one hell of a community and i look forward to getting out on a run with ya all sometime!!

damo

[guest27]

MM - I would be a little careful of using a parts cleaner - do nto want to shift any grot out of the cleaner into the carb, but if it is fresh and new - OK - as for cleaning other parts, cases etc - great.

Champion plugs failing from new - have had the same with NGK and ND - it is not unknown on any make I understand.

This problem is a cycling thing - runs Ok and then dies (sorry thinking out loud here) but when it is running you seem to be well made up with the bike - so we know it is a problem that can be cured - bike runs fine sometimes - and you want it cured - you like the bike when she is going.

It dies when it has been running for a bit - whether it is ticking over or being revved - suggesting carb picking up dirt - would cause the engine to run rough on the jet that is blocking or stop, but would not overly affect jetting away from this - ie if it is a blocking pilot jet, revving it up on to the needle or main would loose the problem.  If the engine is just dying and not revving itself up then dying this suggests that it is not fuel starvation - the bike wil pick up revs and run quite well as the float bowl empties and the bike runs lean.

It is occurring when the engine warms up, this has got me leaning towards electrics now - but I would still give that carb another clean -

Please wait until others have confirmed this.  Looking at the wiring diags on the following web site, your bike runs a CDI with spark info coming from the AC generator (alternator) so there must be the ign circ coil and a pulser coil or the like in there.  The CDI is fed 12V DC through the B/W wire, the B wire is the earth and the O wire is the low tension to the coil.  We can exclude a lot of the electrics from any test (this is the bit that needs confirmed before we cook your CDI) by chopping in a wire from the battery +ve to the B/W wire to the CDI - Thus if the vibration or what ever are causing the ign switch to cut out, kill switch etc, this will cut them out.  Of course you will not be able to stop the engine once it has started unless you pull the wire from the +ve pole. - Personally I do not think the problem is in any of the switches - but I am often wrong.  There are then three potential culprits.  The CDI, the coil and the ign trigger in the alternator.  I would start looking at the one one most liable to fail - the coil.  Can you lay your hands on a CDI suited coil?  Does not have to be the right one for the bike, so long as it is from a bike (car ones tend to be too big and hungery) - jury rig it to the CDI LT output a good solid earth and the plug.  - You do not want to be touching it when it is up and running just in case.  See if the engine will run up and if it does will it stop running again.  If it is now fine - the issue is your coil, if it is not you may have two duff coils or the bike may not like the one you are using.

Jumping about a bit here... On the web site below it has the test resistance for the charging coil and the pulser coil, if you have a test meter you could check these when the bike is cold and again just after it has failed - there should be some difference between the two sets of readings - resistance changes with temp - but the magnitude of change should be pretty much the same for all elements - if not  - if you get an open circuit, or even total resistance - this would / could be the issue.  Ditto the same for the coil if you cannot lay your hands on an alternative.

Probably late to the ball but have been looking at this http://www.slash5.net/sr500.html

Oh I would look to check resistances etc first - before I start poking wires in trying to short out the ignition switch etc - I mullered a Renault EMU by connecting up the wrong wire - right colour, wrong wire...

Hope some ideas help - kinda difficult being here in South Wales...

[boze]

did i mention also that when i hear her beginning to fade if i rev her she sometimes picks up and sometimes just dies quicker?

[GB500nz]

It obviously isn't fuel, so it's electrical. It works fine till it gets hot, so it's coil insulation. Two coils that make the bike run are the ignition coil and the spark sensor down by the flywheel.

[boze]

ok i was at it for a short while today, put my new indicators on...gotta make myself feel like im makin progress...

i disconnected the kill switch and it still does it so i can rule that out.

ive never really had any experience with bike electronics as ive never had any problems with them. please excuse my ignorance but Rog: The CDI is the black boxy thing mounted under the tank on the frame yeah? what are the coil and the ignition trigger?

GB500nz: what are the ignition coil and spark sensors? what do they look like and where is the igniton coil?

Ill hopefully get the carb cleaned again tonight and ill try and make a start on the electrics but i really am quite crap with electrics so ill probably fry something and make it worse.....

damo

[boze]

Right, its only been 20mins or so since my last post but ive been thinking about this.

I need transport to get to work and im honestly thinking about selling her. I cant spare the time to fix her,  the train fares are killing me and i often start work before the first train in the morning so my missus has had to run me into work, this is not feasible to continue as she has uni and work herself etc and its an hour drive to work.

In all seriousness how much do people think id get for her? Does anyone want to make me an offer?

having had the engine apart, the cylinder, piston and valves are in excellent condition, the bike has only done 46000 kilometres, new gaskets, air filter, oil filter, fork seals+oil, indicators, spark plug. The tyres have an excellent amount of tread on them and she also has 11months tax and MOT.

She is a beautiful bike but i just cant spare the time to troubleshoot the problem and if i can fix her im going to sell her anyway as i am looking to buy a 600 or a 650.

This is breaking my heart but i need to be able to get to work.

Im going to have one last try to sort her out tonight but in the meantime please let me know what you think.

regards

Damien

[guest27]

Hi Damo

Two thoughts - chasing after a problem can be soul destroying and maybe getting shot of her would be the best - but she will probably be worth 2X as much running than as she is.

Two - you may get the same or another problem with another bike. (May not mind, just know I hever have a car that does not go wrong)

OK - When you fiollow the HT lead back from the spark plug it comes to a (usually) black palstic encased thing bolted to the frame, this not only has the HT lead running into it but one or two standard sized wires too.  This is the 'coil'.  This has a low tension side (12V) and a HT side (20,000+ volts)  When the 12 V power is switched off suddenly the induction causes a suddern burst of KV from the other - which passes to earth as the spark across the plug - can also be done with a suddern burst on the LT side - like from a CDI unit.  As this coil gets hotter - with use - the insulation on either the LT (12V) or HT side can break down - usually the HT side as it has a bigger job holding in the KV (kilovolts).  If you follow the normal sized wire back you will come to a black box thingy under the tank - this usually has two bundle of wire going to it, one side is the output to the coil - switches the 12V side oat the right time to make the spark, there will also be a 12V feed - this is what is killed by the kill switch (usually). The other bundle of wires head off into the cover on one side of the crank cases - to the alternator.  The CDI gathers electricity from here and also information as to where in the cycle the piston is.  This is done by a small coil - often sat outside the alternator, but sometimes in the alternator and a small magnet set on the alternator rotor, each time the magnet passes the little coil a small induction charge (burst of electricity) is sent to the CDI - the magic in the CDI then decides when to make the spark plug fire.  The little coil triggered by this small magnet is the trigger coil or pulser coil.

The think about electrics - and I am not the best sparky person by far - is that they are logical.  They are pretty basic physics.  They just frighten because you cannot see what is happening, they can hurt if you grab the wrong bit, and they can be annoying because there is so much of them all tangled together in the wiring loom.

Hope this helps.

You say that you can get the bike back when she starts to die if youo rev her hard - does this get her back for a time or just whilst you are revving?

R

[boze]

"You say that you can get the bike back when she starts to die if youo rev her hard - does this get her back for a time or just whilst you are revving?"


it doesnt always get her back...sometimes it seems to have no effect, sometimes it feels similar to when shes really cold and you open the throttle only for her to die.

im gonna go try not to electrocute myself.

Damo

[guest27]

Arrrrrgrgggg - just want to stand there with the bike and give you a hand rather than all this.  I think you are saying that she never comes back fully on song when you rev her just as she is dying. Mmmm - is sounding electrical - but was sounding carb, mind it could be both.

R

[boze]

yeah, basically if shes dying theres not a lot you can do to stop her, revving will occasionally rescue her but not for long.


im way too tired now, mentally and physically to tackle it.

im toying with the idea of taking her to a garage to sort out but that would go against my "no garages" rule....plus it would have to be a last resort as im so ridiculously tight on cash.

*sigh*

damo

[themoudie]

Aye damo,

Garage will spend a lot of time going over where you've already been and cost you.

May I suggest you start with the ignition coil under tank with thick black wire to plug. Check that the thin wire going into your coil from the loom hasn't broken the insulation where it enters the coil body. Sally had, and would short out for no apparent reason. Cleaned up the wires and surrounding areas with brake cleaner, then sealed the whole lot with Araldite. No more shorts!

Replace your ignition coil  with an ignition coil off known runner and see how you go.

Other bits are more expensive or involve diving into the 'guts' of the old ****!!!!!&& cantankerous one. I understand the frustration (Ducati single electrics!), you aren't the first and won't be the last. AAAAAaaaaaahhhhhhhh!

Get a good nights kip, Bill