need help 2cyl.droping out

[shchuck]

I need help when the bike is runing down the road it will drop 2 cyl and stay that way if you dont do any thing. But if I turn the Ig. off then back on it will pick up the 2 cyl. for some time then it will do it again. what do you pepole think? I need help please

Thanks Chuck

[hammerhead]

Bet it is one of your coils that has a loose connection or a wire leading to the coil. Each of the 2 coils sends spark to 2 cylinders, so it would seem that this would be the case.

Sure you will hear from some of the more knowledgable experts in this forum.

Bob

[mitch]

Wires

Or it could be your pick up coil wires, a fix is on the site in the maintence or repair section.......MITCH

[skids]

Re: need help 2cyl.droping out

If 1 and 4 or 2 and 3 are dropping out as pairs, it is either a pick-up coil wire problem or high voltage coil problem. If the problem can exist long enough for the two head pipes to cool a little, you can spray water on them (or use wetted finger tips QUICKLY) to find out if this is the case.

High voltage coil can be spot-checked by disconnecting the plug wires and checking resistance from cap to cap for the problem pair (ign off). You should get 15,000 ohms plus the resistance of each cap (varies from brand to brand).

The pick-ups can be spot checked (sometimes) by unplugging the vacuum hose from the No 2 carb, plug off the nipple on the carb, and see if it cylinders drop out again. This will reduce the efficiency of combustion, especially when you goose it, but the cylinders should still fire if the pick-up wires are not failing at idle. If it runs like this at speed, the pick-ups are suspect. Then you can remove the ignition case cover (left side), run the bike (maybe have someone hold the throttle at 3000 rpms or so), and manually twist the pick-up plate to flex the wires and see if she dies at a position. If so, shut if off, and gently pull the wires and check for hour-glassing of the insulation and check for bare wires.

If on the other hand, head pipes 1 and 2, or 3 and 4, are cooler in that initial test, you likely have a fuel delivery problem. Maybe a clogged inline fuel filter or a clogged filter tower in the tank, or maybe the automatic petcock function for that petcock is not working because of a vacuum leak in that hose to the manifold (standards models only). But, I wouldn't suspect that to be the case because the float bowls would remain low and simply turning on the engine again would not immediately show a temporary improvement...

I hope my garble made some sense! :-/

Originally posted by shchuck
I need help when the bike is runing down the road it will drop 2 cyl and stay that way if you dont do any thing. But if I turn the Ig. off then back on it will pick up the 2 cyl. for some time then it will do it again. what do you pepole think? I need help please

Thanks Chuck

[randy]

Chuck,

If the prblem was coil related, I'd think that the coil in trouble would need some cool-down time before the trouble cleared.

From what you said about turning the ignition off then on and trouble goes away, it sounds to me like your TCI box has issues. I'd bet some of the solder joints inside are weak and are going intermittent.

Try this. With the seat off and the engine running, when the trouble occurs, give the TCI a couple of raps with the butt of a screwdriver. Let us know what you get.

If the cylinders come back with the rapping, you're welcome to send me your TCI for repair. Or, if you're handy with soldering, you can do it yourself.

HTH

Randy

[scalded dog]

My '79 was doing similar cut outs, If I idled it all the way down, then opened the throttle back up, it would run for a little while, found the pick up coils was the problem. Later 'Dog

[xssiveone]

Classic pickup coil symptoms. Check the wiring for breaks and repair.