Cylinders 2 & 3 not firing!

Hey all,

So the bike started running terribly one day-- not that it has been run ever run perfectly yet. Still have yet to do a carb sync and proper ignition timing. But it was losing power, constantly had to give it gas to stay alive, and when riding it would sputter and suddenly lose/gain power at any RPM.

I cleaned the carbs, got B7ES plugs instead of my old B8ES, and new better pods.

Now, it idles great, actually too good-- with the idle screw all the way out it sits at 3K! Must have an air leak somewhere, have to buy more carb cleaner to spray and check. The carb boots are brand new. But it does the same thing when riding, just loses power and suddenly regains it. Felt the pipes and 2 & 3 were cold. Pulled the plugs and 1 & 4 looked great, 2 had literally no indication that it was used on a running motorcycle, and 3 was basically the same. My coils are new as of last summer (cheap OEM eBay coils).

One thing I need to check: To see if there is spark on 2 & 3 plugs.

Can anyone think of anything else? I put on new points over the winter and gave them a pretty rough timing, but no static timing test or timing light. Could it be related to that? Or does it have to be the coil and/or it's connections?

Also, another random question, when I reassembled the carbs I noticed my 3 & 4 needles were getting stuck in the closed position, and when I open the throttle you can hear them unsticking themselves. I have never removed the needles, perhaps they got bent? Do I need new needles?

Thanks!
-Stephen

Seems to me you are answering all your own questions! LOL.

Rough timing with ignition would give the same results all the time... carbs that have stuck, bad needle and seats or their alignment, will just over flow and "could" flood the cylinder or if allow no fuel, shut it down.
etc...

missionkz wrote: Seems to me you are answering all your own questions! LOL.

Rough timing with ignition would give the same results all the time... carbs that have stuck, bad needle and seats or their alignment, will just over flow and "could" flood the cylinder or if allow no fuel, shut it down.
etc...

Haha I was afraid I might already have the answers!

But really, would rough timing cause cylinders 2 & 3 to not fire at all? Seems plausible

Well, the needles haven't caused any flooding-- yet. But maybe it's a good idea to replace the needle and seat next time I take the carbs off!

Thanks!

It would be a good idea to insure that the 2/3 coil is getting full battery voltage. If so, the coil may be defective,. If not, then the wiring, points and condenser need careful scrutiny .

TexasKZ wrote: It would be a good idea to insure that the 2/3 coil is getting full battery voltage. If so, the coil may be defective,. If not, then the wiring, points and condenser need careful scrutiny .

How exactly do I make sure they are getting full battery voltage? It very well might say in the FSM, I just don't have it handy right now.

I'm sure the wiring connections could use a clean up too.. The points are new, but the condenser is not. I will look into it!

Thanks!!

Set your multimeter to VAC. If it has a low range like 0-20, that will be ideal. Attach the - lead of the multimeter to the - post of the battery. Attach the + lead of the meter to the + post of the battery. Notice the reading on the meter. If you are concerned that you might forget the reading, scribble it someplace handy. Unhook the + lead from the battery and connect it to the power line to the 2/3 coil. It is often connected to the + post of the coil. Turn the ignition key on. Note the reading. If the reading is within .5 VAC of the previous reading, then that part of the system is probably ok.

TexasKZ wrote: Set your multimeter to VAC. If it has a low range like 0-20, that will be ideal. Attach the - lead of the multimeter to the - post of the battery. Attach the + lead of the meter to the + post of the battery. Notice the reading on the meter. If you are concerned that you might forget the reading, scribble it someplace handy. Unhook the + lead from the battery and connect it to the power line to the 2/3 coil. It is often connected to the + post of the coil. Turn the ignition key on. Note the reading. If the reading is within .5 VAC of the previous reading, then that part of the system is probably ok.

I think you mean VDC don't you?

If the points are sparking you need new condensers.
Steve

so are they getting spark outside of compression? and when you take out the plugs can you smell gas on them at all?

Yes, missionkz, I meant VDC. Good catch. :blush:

You could always swap the coils and see if the problem follows. If it stays with 2/3, check points/wiring. If it moves to 1/4, check coil/caps.
Why did you go to a hotter plug?

TexasKZ wrote: Yes, missionkz, I meant VDC. Good catch. :blush:

Although, if he did detect AC at the coil, we'd have a much more intriguing problem to discuss :whistle: