rear cylinder not firing 1984 vt 700C

[cruiser_rider]

I was able to start my bike after recent rebuilding work. and now the rear cylinder doesn't fire. the front works well. Now i am getting good spark (not tested with meter) but recently replaced the coil because the resistance was higher than spec. I am getting gas (plug wet) and I have compression blowing out the exhaust. My friend and I are thinking we didn't set the valves correctly when putting the engine back together. Could this be the root cause or has anyone now something else to check? one more note.. I am not getting any air sucking in from this cylinder through the carb. btw the carb were also rebuilt.

[tubes_rock]

First off, welcome to the group!

Second, how is the spark plug getting wet if you have nothing moving through the carb for that cylinder? Something isn't adding up...

--Justin

[SHADOW 1100T]

Take a spark plug and put it in the wire that's not firing and put it to the head to see if you getting spark, could be the wire isn't getting a good contact, Honda coils don't go bad very often in fact it's more like never.

[cruiser_rider]

I am getting good spark. from that coil/cylinder

[cruiser_rider]

justin, I have gas going to that cylinder but no air movement from the carb.

[SHADOW 1100T]

One or two of the valves is open, clearence could be off or worse you could be a tooth or more off on the cam, if you are you can change it without takeing everything apart, push the tensioner back and lift the chain, make sure the cam is in a position that it can be adjusted and won't snap from spring tension.

[tubes_rock]

Originally Posted by cruiser_rider

justin, I have gas going to that cylinder but no air movement from the carb.

You must have some air movement. Air is what carries fuel to the cylinder. If you don't have air, you can't get fuel in the cylinder.

Also, anything blowing out the exhaust indicates you have airflow. You can't blow something out the exhaust that you didn't suck in through the carb!

Compression means that you have airflow as well. The compression stroke squeezes the air that was drawn through the carb. Since you have compression, you must have air flow.

How did you determine that you didn't have air moving through the carb?

--Justin

[cruiser_rider]

i placed a clean rag over the air intakes on the carbs

[tubes_rock]

Throttle fully open or not? Before testing for airflow, be sure you hold the throttle open. If it's a matter of carb sync, holding the throttle open will eliminate that as a possible cause.

If your carbs are our of sync, it's possible to have one throttle butterfly completely closed, while having the other one open enough to fire the cylinder. The effect is drastically reduced the farther you open the throttle.

--Justin

[SHADOW 1100T]

All of Justins responses are right on BUT keep one thing in mind, a engine is a engine is a engine, IF there's gas in the carbs and IF the pistons are in good shape and IF the valves are closing at the right time and IF your getting spark you gonna get a BANG, forget no air going into one cylinder, all that indicates is something is wrong with the engine so go back and check everything you did and find what you did wrong because you did do something wrong, the place that is the easiest to go wrong is the valves so check your valve timing, if a valve is open when it should be closed all that piston can do is go up and down, it can't suck in air and it can't compress the mixture, you have a choice, either go back and find what's wrong or let the bike set and wonder why it ain't working.