airhead problem need help please

upsman · 07-05-2004, 02:12 PM

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

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

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.

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.

07-05-2004, 02:12 PM	#1
upsman ^OP Gnarly Adventurer Joined: Jun 2002 Location: michigan Oddometer: 234	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 thanks greg

07-05-2004, 02:48 PM	#2
Rubber Cow GS Dork Joined: Jul 2001 Location: Aloha... yes, Aloha, Oregon Oddometer: 5,299	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 __________________ "He had that rare weird electricity about him--that extremely wild and heavy presence that you only see in a person who has abandoned all hope of ever behaving"normally"." HST-RIP "Woof, woof woof woof ...woof woof!!!!!!!!!" Cricket the Dog-RIP

07-05-2004, 03:04 PM	#3
upsman ^OP Gnarly Adventurer Joined: Jun 2002 Location: michigan Oddometer: 234	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

07-05-2004, 08:40 PM	#4
Chopperman I am dead Joined: Sep 2001 Oddometer: 27,033	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. __________________ dead

07-08-2004, 11:38 PM	#6
Cpt. Ron aka Birdkilla Joined: Jul 2001 Location: Sacramento, CA Oddometer: 2,351	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.... __________________ Cpt. Ron Sack-O-Tomato, CA '05.5 950 Adventure S "Bad Mutha F@&ker" '04 R1150RTP "cop motor, cop suspension.." '00 XR650R Dual Sport "Lil' Mule" '75 RL250 '01 TTR90 '01 PW50 Conti TKC80 tire swing "I don't know what you do, but I know what I do, and I don't do that." --Uncle Doug, R.I.P. "Without the possibility of death, adventure is not possible"--Reinhold Messner

07-05-2004, 10:09 PM	#5
RockyRaccoon Found:Gideon's Bible Joined: Jul 2001 Location: Collapsed in the Corner Oddometer: 53,669	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.

07-09-2004, 02:49 AM	#7
Possu de-nOObed! Joined: Jan 2004 Location: Oxford, UK Oddometer: 5,050	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.

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