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-   -   airhead problem need help please (http://www.advrider.com/forums/showthread.php?t=46219)

upsman 07-05-2004 02:12 PM

airhead problem need help please
 
long story short, riding my 78 R80/7 yesterday when it went down to one cylinder without warning. i have checked all the usual things , spark, fuel, timing, compression they all check out good but i still cant get it to run on the right hand cylinder, it backfires out the carb on this cylinder and wont clean out, the bike has a dyna 3 electric ignition and is otherwise stock.

any help or advice appreciated :hair thanks greg

Rubber Cow 07-05-2004 02:48 PM

Have you checked the carb main jet for debris or inspected the carb diaphragm for tears?
Dyna coils have been know to fail but I haven't heard of their ignition module/booster failing for this vintage BMW.
Hope this helps.
Jorge

upsman 07-05-2004 03:04 PM

airhead problem
 
yes we checked the carb and put on one from another bike and still nothing, thanks for the input thats what im looking for, we have tried everything and nothing made a bit of difference so far. thanks again greg

Chopperman 07-05-2004 08:40 PM

Couple things

Dynas have been known to blow a channel resulting in one side barfing like that. But also check the ring on the cam where the points used to be. That ring will sometimes slip and the timing will get fuxored.

RockyRaccoon 07-05-2004 10:09 PM

Have you determined whether it's getting spark? Take out the plug and hook it back up to the wire, make sure it's grounded and then turn it over and see if you can see a spark. Sometimes the spark plug wires and caps go bad. :dunno

Cpt. Ron 07-08-2004 11:38 PM

Take the left plug wire and put in the right side, and vice-versa. See if the problem changes sides. If it doesn't, it's a fuel or compression issue. If it does, it's an ignition issue.

Fuel/compression problems: blocked main jet, torn diaphragm, broken throttle cable....

Ignition: worn out spark plug caps, old spark plugs, broken coil, bad connections....

Possu 07-09-2004 02:49 AM

Remove right plug, tip a little fuel down the plug hole, re-fit the pug & cap etc & see if it fires up briefly on both cylinders.

If it does, then it may well be a carb blockage as mentioned previously.

If not, then probably ignition related.

Worth trying as there's no cost except 5 minutes of time.

storymitchell 07-10-2004 03:41 PM

Quote:

Originally Posted by Steve Pickford
Remove right plug, tip a little fuel down the plug hole, re-fit the pug & cap etc & see if it fires up briefly on both cylinders.

If it does, then it may well be a carb blockage as mentioned previously.

If not, then probably ignition related.

Worth trying as there's no cost except 5 minutes of time.

Lazy turd that I am, I simply shoot a bit of ether into the carb in question whilst cranking the starter. Same outcome, though, I suppose.


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