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Yamaha xs500 won’t run

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bikenut
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PostPosted: 11:22 - 12 Nov 2018    Post subject: xs500 Reply with quote

You could just rig up a hot wire direct to the coils suitably switched and fused and run engine on that but the charging system must be plumed in and should be checked it works ok as soon as the engine is running.


ASs said earlier you can hot wire the coils from the battery but make it fused for safety. This eliminates the bike wiring from the circuit apart form lt from the coils to the points.


hopefully jay has the knowledge not to leave the ign permanently on, but yes, you never know.......

Go down the red noen plug cap route first, but you will probably have to make an adaptor for your plug caps ( the red neons plug into these via an adaptor ) , money and time well spent as you can see, or not see, the ht and its relative strength in real world engine cranking and running conditions.

If all ok, then move onto fuel, but to stop hair pulling, either rule out or rule in an ign problem.

Just to clarify please post a cmsnl exploded view of the cb points for your exact bike......and the correct wiring diagram......

cmsnl shows cb points for a 1977 europe spec bike.....

just had a quick look in the manuals section on here, no xs500 listed so presume the wiring is the same as an xs250, 360 and 400....conventional ish, so no ballast resistor.
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bikenut
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PostPosted: 11:56 - 13 Nov 2018    Post subject: caps Reply with quote

If the red neon plug caps have not arrived yet, its a good time to think of the adaptor needed.

The plug end is no problem, simply screw on tight ( Murphies laws ) a "nipple" supplied with plugs to simply plug on the red plug cap, but what about the lead end of the plug cap that has the nipple permanently attached?

Your ht lead plug cap has the push on threaded end attachment?

A short length of old style wire inner ht lead with the nipple connection end for the plug, and a modified oe lead end, a threaded end to push into the oe plug cap.

You could use some copper pipe and form an end for the nipple, and using a suitable lenght brass machine screw with the head cut off for the oe plug cap end. You could crush the copper pipe and clamp the threaded rod that way, or since its brass solder it to the copper pipe.

A small bore copper pipe would be more suitable......

You could use a scrap clutch cable or similar cable "outer"......

You will have to make an adaptor to use the red neon plug caps, as a diagnostic tool, rather than a cool plug cpa that flashes......

Once you have made the adaptor and used the neons indicators, do not loan them to anyone !!

I am still waiting the return of one "set", its been about 7 years so far, the robbing bastard!!!
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bikenut
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PostPosted: 11:48 - 23 Nov 2018    Post subject: xs Reply with quote

Hi jay, how you getting on ?
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Jay2903
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PostPosted: 01:12 - 28 Nov 2018    Post subject: Re: xs Reply with quote

bikenut wrote:
Hi jay, how you getting on ?


Hey mate
I’ve been putting it of for a bit because I’ve spent so long on it and got literally nowhere.
I’m gonna take another look at it this week
Neon plugs due on Thursday
Cheers
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bikenut
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PostPosted: 11:18 - 01 Dec 2018    Post subject: Reply with quote

Once you have made the converter so the red neon plug caps fit, for testing, you will see much more.

Well worth the cost of purchase and the hassle of making the converter, dont loan them out !!
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Ed Case
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PostPosted: 20:30 - 01 Dec 2018    Post subject: Reply with quote

I know it sounds stupidly insane but you are turning both fuel taps on aren't you. I've posted this because a bloke I used to work with had an XS 500 and was moaning that it was gutless and only running on one cylinder.......he didn't know that the carbs were fed independently from the taps and there was no 'crossover' link. He sold it shortly after coz it frightened him on full power
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Jay2903
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PostPosted: 22:45 - 03 Dec 2018    Post subject: Reply with quote

Ed Case wrote:
I know it sounds stupidly insane but you are turning both fuel taps on aren't you. I've posted this because a bloke I used to work with had an XS 500 and was moaning that it was gutless and only running on one cylinder.......he didn't know that the carbs were fed independently from the taps and there was no 'crossover' link. He sold it shortly after coz it frightened him on full power


Cheers mate. At the moment I’m using an auxiliary tank so I don’t have to keep taking the tank on and off. And the fuel lines are transparent so I can see it’s getting fuel.
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Jay2903
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PostPosted: 22:57 - 03 Dec 2018    Post subject: Reply with quote

bikenut wrote:
Once you have made the converter so the red neon plug caps fit, for testing, you will see much more.

Well worth the cost of purchase and the hassle of making the converter, dont loan them out !!


I bought the wrong ones the oringinal plug caps are long so they can reach down to the plugs these ones were standard 90 degree but fit for threaded plugs. But nonetheless I made one functioning one out of the two.

I couldn’t start it. I put the neon cap on the right then the left. The thing flashed whilst on both sides.

long story short , there’s spark on the right side, neon plug cap flashes and I can see spark from the plug. When I moved the plug cap and plug to the left side it still flashes but less so and there’s also spark at the plug but seems to be much weaker.
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Jay2903
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PostPosted: 22:57 - 05 Dec 2018    Post subject: Reply with quote

So
I replaced the the ht lead on the left side and put the standard plug caps on and out to new working iridium plugs in. Spark good on bith sides. I put the plugs in and tried to start it. It stated on one cylinder (right). I turned it off and pulled the plugs. The one on the left no longer sparking. I switched them around to confirm it was the plug at fault.

What could be causing the plugs to keep dying like this ?? It’s probably the tenth plug I’ve put in this bike quite literally. Some were standard some were iridium some bought online some from a local store all but one now don’t work.
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Riejufixing
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PostPosted: 00:00 - 06 Dec 2018    Post subject: Reply with quote

Jay2903 wrote:
What could be causing the plugs to keep dying like this ?? It’s probably the tenth plug I’ve put in this bike quite literally. Some were standard some were iridium some bought online some from a local store all but one now don’t work.


Are you cleaning them with anything? What/how if so?
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Jay2903
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PostPosted: 02:02 - 06 Dec 2018    Post subject: Reply with quote

Riejufixing wrote:


Are you cleaning them with anything? What/how if so?


Nope they didn’t touch anything at all
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Nobby the Bastard
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PostPosted: 20:16 - 06 Dec 2018    Post subject: Reply with quote

Have you replaced the condensers?
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Jay2903
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PostPosted: 22:02 - 06 Dec 2018    Post subject: Reply with quote

Nobby the Bastard wrote:
Have you replaced the condensers?


Yes
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Riejufixing
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PostPosted: 00:44 - 07 Dec 2018    Post subject: Reply with quote

Jay2903 wrote:
Riejufixing wrote:
Are you cleaning them with anything? What/how if so?

Nope they didn’t touch anything at all

Hm, you didn't say anything about "they" before. Who is "them", a bike shop? What have they been doing?
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Jay2903
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PostPosted: 10:43 - 07 Dec 2018    Post subject: Reply with quote

Riejufixing wrote:

Hm, you didn't say anything about "they" before. Who is "them", a bike shop? What have they been doing?


I meant the plugs didn’t touch anything
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bikenut
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PostPosted: 11:00 - 07 Dec 2018    Post subject: neon Reply with quote

2 neon plug caps plumed in ( for ign testing/comparison ) would be the ideal, as the neon "flash" can be compared side for side, cylinder for cylinder, individual ign system to individual system, one for each cylinder., in cranking and running conditions, even on a road test.

The only common factor for each ign system ( apart from earths ) is the Y junction of battery voltage just before the coils., and the bike wiring thru the kill and ign switch before the coils.

So, do both coils get battery voltage when the ign is switched on. Check this with both sets of points disconnected from the coils.

back in abit.....

using the red neon plug caps avoids checking the ht by removing the plugs, resting the plugs on a dodgy earth and cranking the engine, with the ign on. This method only checks ht "in open air", rather than "under pressure" which is what the plug is experiencing in real world engine cranking and running conditions. When the engine is cranking, compression is taking place that the ign must force a ht pulse thru....the system may display ht in open air, but , under pressure, fail.

If you are resting the removed plugs on the engine and cranking it with the ign on you should see a spark at the plug electrodes, if not may be a dodgy earth, as the plug is "resting" on the engine, earth.

Red neon plug caps remove this problem.

If you are testing for ht with the plugs out and cranking with the ign on, the plug bodies, the metal part with the thread on, must be earthed.

back in a bit

back in a bit
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bikenut
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PostPosted: 11:22 - 07 Dec 2018    Post subject: neon Reply with quote

New plugs failing?

Are you damaging the plugs when they are being fitted??

Have 2 clean plugs ( clean the end of the plugs where they fit inside the engine, the working end of the plug where the spark happens. They can be cleaned with a soft wire brush and some solvent, like some carb or brake cleaner aerosol, even some petrol ) ready for fitting.

Make sure the gap is correct, adjusting the "bent earth electrode" welded to the periphery of the plug body at the end of the plug thread, NOT THE CENTRE ELECTRODE !!!

Fit 2 clean and gapped plugs into the engine.

Fit the 2 neon plug caps so that they can be seen easily when the engine is cranked/running.

Make sure that the 2 carbs have clean fuel and start engine.

both neons flash as bright as each other?

Both neon flashes "grow" with slight increase of revs, growing brighter with more revs ? They should grow brighter with revs cos with revs the charging system produces more output, until regulation takes place at about 14.5 volts across the battery.

When the engine has warmed up, allow to run out of fuel and cool. Remove plugs and check colour of the electrodes.

You can rig a multimeter to the Y junction before the coils to check voltage there whilst the engine is running. You can look at the contact breaker points and see "excessive" arcing. Expect some light arcing, which the condenser is bale to manage, but never entirely elimiantes.

Dirty plugs do not allow good ht, they incourage incorrect ht down the centre electrode insulater rather than across the "air gap" between the centre electrode and earth electrode.
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Riejufixing
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PostPosted: 14:39 - 07 Dec 2018    Post subject: Re: neon Reply with quote

bikenut wrote:
(Sparking-plugs) can be cleaned with a soft wire brush and some solvent


I dn't like doing that, since it is possible to smear metal onto the insulator. YMMV.
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bikenut
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PostPosted: 11:18 - 08 Dec 2018    Post subject: xs Reply with quote

How about a nylon soft wire brush, to agitate the solvent.

Is ngk goofy juice still available?
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