miss and backfire

[agabus]

WooHoo!
I've bought a 1978 XS1100E and I am in the process of resurrecting it from the dead. It has sat up for awhile. I've changed the plugs and plug wires, adjusted the cam chain, changed the oil and filter, cleaned the carbs, changed all the other fluids, cleaned the gas tank, and generally tried to tweak and test everything I could. It will fire right off and run with the choke out, but it idles badly with alot of sputtering and backfires. I suspect it has something to do with the carbs...is this something I can fix or do I need to have it synched and adjusted by a pro? Yes, I've checked and inspected the fuses and fusebox. Any suggestions or tips? I can't stand it much longer...I want to ride NOW.
Thanks,
Agabus

[skids]

Re: miss and backfire

Try using some Techron total fuel system cleaner. You might just get lucky enough and it might clean your pilot circuit. A lot of people use this stuff. If you have a completely plugged pilot jet or a pilot pinhole (little pinholes in the top of the carb ventouri by the throttle plate), then the techron might not work.

Originally posted by agabus
WooHoo!
I've bought a 1978 XS1100E and I am in the process of resurrecting it from the dead. It has sat up for awhile. I've changed the plugs and plug wires, adjusted the cam chain, changed the oil and filter, cleaned the carbs, changed all the other fluids, cleaned the gas tank, and generally tried to tweak and test everything I could. It will fire right off and run with the choke out, but it idles badly with alot of sputtering and backfires. I suspect it has something to do with the carbs...is this something I can fix or do I need to have it synched and adjusted by a pro? Yes, I've checked and inspected the fuses and fusebox. Any suggestions or tips? I can't stand it much longer...I want to ride NOW.
Thanks,
Agabus

[TopCatGr58]

Hey there Agabus,

Congrats. Sounds like you have already done some reading of the tech tips on this site!! So...you know that you have cleaned your carbs once, only have 2 more cleanings to go!!

But seriously, HOW did you clean your carbs? Did you take them apart, or just spray some cleaner in the throat? The Pilot/idle circuits are easily clogged, and they will control it's behavior when not on the throttle as well as at least 1/4 into it!!

Did you inspect the rubber diaphragms on the slide tops for holes? The choke enrichens the mixture,hence running better with it since the idle circuit is probably clogged, and without the choke, it's not getting enough or properly mixed gas. The Carbs can be cleaned yourself, and a basic bread stick tie synch can be sufficient to get it running smoothly. If your careful when taking the carbs off, you don't have to remove them from the bracket, and so you won't have to disturb the synch to really thoroughly clean them!

And like Skids says, using Techroline or even SeaFoam to clean out the passages might help, but will take some time and miles to get it done!!! Good Luck.
T.C.

[Redbaron]

Spit & Backfire

Many things, start with carb sync and adjust, but also search this site for coil pickup fix. Then just for fun clean all your electrical connections and hang in there you are getting close to riding the last motorcycle you'll ever want.

[POOLBOY]

Mine did that too.

My 81 Special ran like crap the first time I ran it too.Here is what I found out.
1-Clean the brass insert's that the diaphram needles go into.There are a lot of names for them,(emulsion tubes??) If you take off the top of the carb's, you will find a spring, and a diaphram with a plunger on it.The plunger had a pin that stick's into a brass jet assembly.Clean all of them.(dont clean the rubber diaphram's with carb, or brake cleaner!!!)
2-Add new spark plug's. I tried to run it with the old plug's in it. New plug's made a big difference.
3- Buy fresh 92 octane gas.Thing's have changed since 1979 in the gas department.
4-You need to have the air box on, and an air filter in it, for these carb's to function properly.
5-Dont worry so much about some poping and banging.Mine sounded like it had a bunch of problem's, but it run's smooth as silk under load(out on the road).
6-As far as "tripple cleaning" go's,do it right one time, then clean the tank, the petcock's, the fuel lines, everything gas touches.
7-Do the bench sync (bread wire tie)as accurately as you can.
8-Check your rubber manifolds for crack's.Dont be fooled, as I was, into thinking that if they showed some crack's, they were bad. Most dont crack completely through. Just some surface cracking.
9-Please dont buy the K&L carb kit's unless you really need, or want to. You will spend a lot of unneeded money.Buy float needle and seat set's from your local YAMAHA dealer.Clean all the original jet's with anything but steel or iron wire.I bought the K&L kit's, and after inspecting them very closely, I used only the needle and seat's, and the gasket.The jet's weren't even close.Original carb part's are still available(at least here in Illinois).
My 2cent's worth.I have been there all winter.Mine run's like a dream.
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