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???

If you crack the float bowl drain on the rear carb does fuel come out? If not then you've got a fuel supply problem. Did you make sure to turn the fuel petcock all the way on?

yea man bled the bowl and the petcock is on all the way

Check the plug for the coil,it might have come undone or loose.
It's in the loom under the seat.check all the wiring for the coil.

+ 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).

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.

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

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!

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.

tell me more about that swap...


thanks

Search for coil on cap mod.

https://www.superhawkforum.com/forum...cap-mod-23004/

Well you could just click on the link in my signature titled "Coil on CAP MOD"

:D

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.

Good points mostly, though it is a MOD in it self just to do in any case, loose some weight, clean up the are where the old coils are, and bring at least part of the bike in to something that is both modern, simple, proven and easy to do.

It's a WIN / WIN, even if it does not fix his issue.