Only running on 2 cylinders

My 650 is only running on 2 cylinders. Numbers 3 and 4 so it is not a coil issue. Im thinking i need to do a really good carb cleaning when i get my carb kits in. Would that be the issue or could it be something in the cylinders them selves?

 

Carbs, and sufficient spark (coils, plugs, maybe pick up coil?) If everything good internally.

Since the gas in the first two carbs isn't burning it could have made its way into the crankcase. FYI

How's the compression in 1 and 2?

 

I checked before i did the valve job and i had spark on all 4 but the was in september or somethibg like that

 

Check for pinholes in the diaphragms in your carby's as well.
I have a similar problem at the moment as well.

 

A good thing to check for, I don't know exactly how much that has to do with this specific problem, at idle atleast.

I'de switch the coils just in case and see if that changes the problem cylinders.

Make sure your battery is fully charged.

Spark plugs good/gapped correctly?

Carbs are a possibility if the mixture is crazy off.

A compression test would tell you whether or not something is wrong internaly.

How do you know those 2 aren't firing? Cold pipes?

 

Well i have the means to do a compression test while im waiting on those carb kits. I guess it would only work on the 2 cylinders that are running? I had my carbs apart once to clean them. Im gonna re do them, like i said, cuz they sat for a while and they weren't church of clean clean. My battery is completely dead but im using a booster. Could that be the problem? I havn't checked the gaps on the spark plugs either so i guess that would be the first thing to do as it is the easiest. Would i have to take the coils off to switch them or would i be able to just swap the wires?

 

Oh and I guess i just smell the oil to see if there is gas in the crank eh?

 

If you switch the wires they could fire at the wrong time. You'd basically have to swap the connectors going to the coils.

Check the plugs for fouling or incorrect gap first. It's the easiest and probably a more common reason for random dead cylinders.

Then ide switch the coils. If it changes the actual wires or boots could be the culprit too, check the resistance in the boots. If they're good suspect the coil.

Then check the Compression if everything else looks good so far. You can check all of them for the hell of it, doesn't hurt to know the condition of the innards.

As far as your battery, I'de get it fully charged and tested before going down that list, then see if the problem persists.

And yeah, just smell the oil, it probably won't have leaked enough to overfill it.

 

When you switch the coils you need to switch the plug wires too I think, if it backfires or acts funny something needs to be switched around. Just remember how it all goes back together.