cdi box XL500S 80- Engine cuts off clean above idle

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Tundra Man
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cdi box XL500S 80- Engine cuts off clean above idle

Beitrag von Tundra Man »

Hi all !i own an XL500S 80- since 30 years now and never had a serious problem with it but when i started it up for the first time this spring something was wrong. It starts perfect but when increasing rpm a bit over idle it cuts clean off ,im pretty sure its ignition related ,its rpm not trottle setting that triggers the cut off ,i,ve tested an other coil and measured components as decribed in the Clymer workchop book ,but they dont specify any readings for the Cdi box .changed the plug to by the way ,has anyone out there had the same problem ,engine cutoff when rpm goes a bit over idle?Anyone knowing how to test the Cdi box ? Its supposed to be the box to the left under the gastank ,but what about the box to the right ,that one is not mentioned in the Clymer book .As the boxes are filled with epoxi theres not mutch to do about them i guess, maybe i can get an used one from a bike scrap yard but i would be wery greatful to hear any ideas and whatever similar problems you might have had . Hope its ok for me writing in english my German is not that good.

Greetings from Ted,Junsele Sweden,,
Zuletzt geändert von Tundra Man am 11. Juni 2011, 09:51, insgesamt 3-mal geändert.
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Gunnar_HH
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Beitrag von Gunnar_HH »

Hey Ted,
I think you have a XL-S Modell and so I am not very well experienced in this modell.
But at first I would check all cables and plugs to CDI and right ground connection. No corrosion, no cable breaks.
The second thing I would check is the ignition control under the right cover of the engine block, does it work.
The third thing could be false air between the carburetor and the cylinder. Spraying a little bit of brake-cleaner will help you to find leaks.

If you have the opportunity try another CDI, maybe a friend of you has one. Normally the CDI is fault-free.

Heydo
Gunnar

PS: in three weeks also in sweden, bohuslän and smalland.
XL500R / Bj 82
Moto 6.5 / Bj 96
Die besten Kapitäne stehen an Land!
WAFI: Wind assisted freaking idiot
Tundra Man
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Beitrag von Tundra Man »

But at first I would check all cables and plugs to CDI and right ground connection. No corrosion, no cable breaks.
The second thing I would check is the ignition control under the right cover of the engine block, does it work.
The third thing could be false air between the carburetor and the cylinder.



PS: in three weeks also in sweden, bohuslän and smalland.[/quote]

Hi Gunnar ! Thanks for the answer ,yep i have cleaned all connections for corrosion and measured the resistans for the pulse generator under the right cover the ohm reading was ok . Im 99% its ignition related since it cuts of distinct at a specific rpm a bit over idle regardless of trottle setting .You say that cdi box failure is almost unheard of ?

Great forum ,,the XLs must have been a success in Germany ,so many members of this forum when the bikes are up to 30 years old !!

Welcome to Sweden Gunnar , if you ever go farther north by the way of Junsele you are welcome to stay by at my little farm,,
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tommot
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Beitrag von tommot »

Hi Ted
I think if the ohm readings for the pick up coil are ok you still have to make sure that the ignition timing advance unit works ok. You need to take of the right casing off to check that.
Another idea to make absolutly clear that it is/ or not an ignition problem is to cut the sparkplug cable a couple of centimeters before the spark plug.
Than find a piece of transparent hose which fits tight over the cable.
push the cable from both sides into that hose so that there is a gap between them.
Now when you start the engine you can watch the sparks.
When you look at the sparks in the gap while you open the throttle
you can see if the spark dissapears when it cuts out.
If there are still a few sparks after it cuts out you have a carburetor problem.
May be that helps
Good luck Ted.
Markus
" You never know how fast you can go -`til you fall down ! " Dave Aldana
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Ford_Prefect
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Beitrag von Ford_Prefect »

Hi Markus,

very nice trick withe the transparent hose. Never heard of that,
but it sounds very reasonable !

@ Ted: I recommend to do this check to be sure :)

Regards
Frank
XL 250 K0 motosport
CB 250 RS
omagott
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Beitrag von omagott »

Hy there,
feel free to massage the cable that leads form the coil to the CDI, you may have a broken cable that cuts out from time to time. Second, shorten the cable to the spark plug by 1cm and put a new connector on it, they rot and loose contact due to oxides on the cables core. Third, try to wiggle the connectors while the engine is running just to see what is going on, if it spits your problem lies here. The 4 prong connectors can be disassembled with a fine screwdriver, the connector has a small spring that claws into the connector housing. Depress it and push from front towards the back. And make a plan before you take it apart!. Even connectors that look good may not conduct. Best thing is to disassemble the CDI from the bike and do the work on a well lit table.
You can also hit the CDI box with the back of a screwdriver while the motor is running to simulate vibration, if yu have a problem here the motor cuts out in the rythmn of your hits. In case your CDI is shot feel free to grind down the epoxy and resolder the joints on the PCB. A lot of CDI boxes fail due to cold solder joints and mechanical strain. The electronics are still perfectly healthy.
In case you feel the need to order a new CDI box PN me, I think I have a new old stock one somewhere in the basement that I´m willing t part with at a reasonable price. Hope this helps.

Cheers,
die Oma
Hammer: Werkzeug, das sich aus einer primitiven Schlagwaffe entwickelt hat. Der Hammer wird als wünschelrutenähnliches Gerät genutzt, um das teuerste Teil zu finden das in der Umgebung des Teils liegt welches man eigentlich treffen wollte.
Tundra Man
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Re: cdi box XL500S 80- Engine cuts off clean above idle

Beitrag von Tundra Man »

I,m making a new effort to get my XL 500S -80 going..Ignition problem where the engine starts fine but at 2000-2500 rpm it misfires heavily and rews no higher..Have now substituted the cdi box with another used one ,,the pulsergenerator/impulsegeber with a new one,,new ignitioncoil..And the obvious plug,,plugcap,,HT cord,,connetions is new/checked.. Only the generator/lima left ..according to my Clymer workshop manual it should have 200-500 ohms at the excitercoil/ladespule cdi,, it has 345 ohms..I have measured the voltage at the red/black wire from this coil its 65 volts at idle and 92 volts when at 2000-2500 misfiring,, steady readings no fluctuations..I would be very thankful for ideas from you that have any experience from working with the excitercoil,,the voltage readings are made with an ordinary multimeter not a peak volt meter..Anyone now what those readings should be..

Gruss Ted..
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