rear cylinder won't fire
06-13-2012, 03:51 PM
#1
Junior Member
Squid
Thread Starter
Join Date: Jan 2012
Posts: 15
rear cylinder won't fire
last week i did a compression test (165) both cylinders and then syncd my carbs. all is well....then i put it all back together and blam...no fire in the rear cylinder...so then i cleaned the carbs...replaced slow jet to a 48 replaced plugs...blew in the vacuum on the petcock and it flowed,,,bled float bowls lots of fuel....spray a little carb cleaner in the rear carb boom fires no carb cleaner no fire???
anyone???
anyone???
06-13-2012, 06:41 PM
#5
99 superhawk
Superstock
Join Date: Jun 2011
Location: jasper Ga.
Posts: 256
+ 1 if it fires on spraying a mist in then its most likely a weak coil or wiring (due to the fact that a mist will fire on a weaker spark than liquid fuel).
06-13-2012, 10:19 PM
#6
Slacker
Superstock
Superstock
Join Date: Jun 2005
Location: San Antonio, TX
Posts: 489
Possibly a bad connection between the spark plug boot and wire.
Pull boot off plug, turn boot clockwise on the wire so that it bites better (the boot simply threads into the copper wire) , then reconnect to plug and try again.
The coil end of the plug wire could also cause the same problem.
Pull boot off plug, turn boot clockwise on the wire so that it bites better (the boot simply threads into the copper wire) , then reconnect to plug and try again.
The coil end of the plug wire could also cause the same problem.
06-14-2012, 05:42 AM
#7
Administrator
MotoGP
Join Date: Apr 2006
Location: Kempner, TX
Posts: 4,402
If you suspect a coil or ignition wiring issue, scrap the whole lot and do a COP swap..
Rid your self a possible source of trouble, some wiring and bulk, and get to "MOD" at the same time WIN / WIN
Rid your self a possible source of trouble, some wiring and bulk, and get to "MOD" at the same time WIN / WIN
06-14-2012, 11:57 AM
#8
Junior Member
Squid
Join Date: Jun 2012
Location: Alberta, Canada
Posts: 6
Seems like the plug/coil is a known weak spot according to everyone on here. I had a similar issue and have ordered a new set it's only $200 and even for a ham fisted twit like me, isn't too big a job!
06-14-2012, 04:08 PM
#9
Seasoned tech
SuperSport
Join Date: Apr 2012
Location: Issaquah, WA
Posts: 576
It's possible that it could be a plug or coil but usually if it will fire when you spray some sort of starting fluid in the carbs but won't otherwies that's telling you it's not getting any fuel. I'd make sure the carb is getting a full constant supply of fuel and that all the jets are installed properly and none have come loose/fallen out or become plugged. Also make sure the float and float valve are operating properly.
06-14-2012, 06:50 PM
#10
Junior Member
Squid
Thread Starter
Join Date: Jan 2012
Posts: 15
06-15-2012, 04:05 AM
#11
Former Superchicken Owner
SuperBike
Join Date: Sep 2008
Location: Ft. Worth, TX
Posts: 1,607
06-15-2012, 06:10 AM
#13
Slacker
Superstock
Superstock
Join Date: Jun 2005
Location: San Antonio, TX
Posts: 489
The coil on plug, or coil on cap, could be a good choice if you have confirmed that the problem is indeed electrical. If the problem lies elsewhere, then you are simply doing it because you have money to burn. Isolate the problem first before throwing money at it.
Try switching the coils that are already installed and see if the problem migrates to the front cylinder. If the rear still will not fire, then look to fueling or an air leak.
I can't tell you how many times I have reassembled things and then found a new problem, only to later find that I put some part together wrong, forgot to connect a hose, or made an incorrect adjustment. Retrace your steps and double check everything.
Try switching the coils that are already installed and see if the problem migrates to the front cylinder. If the rear still will not fire, then look to fueling or an air leak.
I can't tell you how many times I have reassembled things and then found a new problem, only to later find that I put some part together wrong, forgot to connect a hose, or made an incorrect adjustment. Retrace your steps and double check everything.
06-15-2012, 09:14 AM
#14
Administrator
MotoGP
Join Date: Apr 2006
Location: Kempner, TX
Posts: 4,402
The coil on plug, or coil on cap, could be a good choice if you have confirmed that the problem is indeed electrical. If the problem lies elsewhere, then you are simply doing it because you have money to burn. Isolate the problem first before throwing money at it.
Try switching the coils that are already installed and see if the problem migrates to the front cylinder. If the rear still will not fire, then look to fueling or an air leak.
I can't tell you how many times I have reassembled things and then found a new problem, only to later find that I put some part together wrong, forgot to connect a hose, or made an incorrect adjustment. Retrace your steps and double check everything.
Try switching the coils that are already installed and see if the problem migrates to the front cylinder. If the rear still will not fire, then look to fueling or an air leak.
I can't tell you how many times I have reassembled things and then found a new problem, only to later find that I put some part together wrong, forgot to connect a hose, or made an incorrect adjustment. Retrace your steps and double check everything.
It's a WIN / WIN, even if it does not fix his issue.
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