mid range miss

[steelcat]

I am having a mid-range miss. It starts in at about 4250rpm. It only is happening while under a load. It does not happen when the bike is in nutral. I've syn'c. the carbs. I am wondering about whether the needle jet needs to adjusted - if so how do you get to the little clip?

[TopCatGr58]

Hey there Steelcat,

Welcome to the FORUM!! If your bike has been running well before, then the first thing that comes to mind is the Pickup Coil wires, for your 79XS. Those wires wear out, and can get a short in them, and then with the rotation of the timing advance plate at the higher revs the wires can flex and get pulled apart to where they are not making good contact, and your ignition will cut out=miss! Check the tech tips on pick up coil wires, as well as some searches on the subject, you'll find plenty of threads!!

Next would be to check your fuel flow, carbs, etc.. Tell us a bit about your bike, newly acquired, or had it a while, any mods, etc!?

T.C.

[ratbyk]

Mid Range Miss

Do not be to quick too blame the carburetors.
Doing diagnosis from long range is difficult. Give us more info. Are you under acceleration? Are you cruising or does the miss occur as you roll on the throttle?
Could be something as simple as a dirty spark plug or a plug boot that is shorting to ground. More info would help a lot. Otherwise we are just making a bunch of wild guesses. Any of which may be correct there are dozens of things that could cause your symptoms as described.
Ken/Sooke
78E Ratbyk
82 FT500"lilRat"

[steelcat]

A couple more things to add. I've had the bike for a while, but have never gotten it to run quit right. It was orginally in Louiiana (near sea level), I purchased it up here & have not ridden much. My elevation is about 5,000ft. in the valley - so I may have to re-jet.

[mitch]

Pick up wires

I would start with the pick up wires , thats what it sounds like. But that is just a starting point i say the odds are about 60% that is the trouble.......MITCH

[desert1]

altitude

Altitude wouldnt be the problem, more than likely it is your pick up wires.....check to see if there is some stretch in the sheathing of the wires, its a sure sign there coming apart if theres some stretch .....is the missing you describe a heavy miss, complete power loss for an instant or just a slight miss? Major loss of power could be a sign of a short in wiring.

Bruce

[desert1]

plug caps

Heres a source of hi-speed misses that I did'nt mention before, I discovered thru frustration more than anything else that two of my plug boots contained small resistors embeded in the elbow of the boot, problem was they were old and water had gotten in there over the years and left plenty of oxididation on the thing, need I say more I bought 4 new plug boots and one less problem......also check your ballast resistor up under the tank, make sure the wires are'nt "fraid" and there not touching each other or close to grounding on the frame or tank. All for now

Bruce Doucette
78 XS1100 Alpha
79 XS1100 Special

[young nip]

mid range miss

Steel cat, hi from ontario, Yikes minus 20 celcius today.
I had the miss last year myself. Went over evrything ,carbs, advance plugs, wires, redid everything as the guys have mentioned. Turns out my miss was a sticky advance mechanism.Dah! Just a little dryness on the mechanism will make a diffrence. Mechanism is behind vacumn advance.
Good luck
Steve