FJ1100 Won't run on all Four Cylinders

[Spudman]

So I picked this bike up a few weeks ago from a barn. So far I have:
Cleaned the carburetors
Changed the plugs
Fixed a coil grounding issue
and looked for a few missing parts.
Now at this point I'm sitting with a bike that will 1. turn over 2. fire on two cylinders (I've tried them all independently) The two that fire are marked 2 and 3.
It will idle with the choke on full, very roughly, but will only rev slightly and the other two cylinders never join in on the fun. One thing I am missing is the airbox, I know this will affect the overall performance and cause it to run rougher but would it prevent two cylinders from firing on these bikes?
Also the petcock has two nipples sticking out, one on each side of the main fuel outlet, that I assume these are for vacuum. I've found that one connects to the second carb boot but I don't know which side nipple to use (hehe) and also I have no idea where the other one is supposed to connect?

Any ideas? I'm fairly stumped on this one. 

[PaulG]

Ignition and/or cam timing?  Faulty ignitor unit?

What year?  By the sounds of it a pre fuel pump model?

Only issues I've ever had similar to this were a shorted spark plug cable or a bad plug.

[Pat Conlon]

A clue could be the numbers on the cylinders that fire... #2 and #3
Those cylinders 2/3 share the same coil (right side)
Cylinders #1 and #4 share the left side coil.

[4everFJ]

A clue could be the numbers on the cylinders that fire... #2 and #3
Those cylinders 2/3 share the same coil (right side)
Cylinders #1 and #4 share the left side coil.

^This^

[Spudman]

The bike is an 85 and definitely pre-fuel pump. See I thought that the coil might be it but I still have spark and if I squirt some gas into the cylinders it will fire. I'm thinking it is not getting the gas it needs so maybe a combination between a few areas I missed cleaning and the wrong petcock? I have been looking them up and only see petcocks with one vacuum nipple on it, is that the correct one? The one that came with the bike has two and I think that may be causing some starvation.

[FJmonkey]

The bike is an 85 and definitely pre-fuel pump. See I thought that the coil might be it but I still have spark and if I squirt some gas into the cylinders it will fire. I'm thinking it is not getting the gas it needs so maybe a combination between a few areas I missed cleaning and the wrong petcock? I have been looking them up and only see petcocks with one vacuum nipple on it, is that the correct one? The one that came with the bike has two and I think that may be causing some starvation.

You need a 10MM fuel barb and a 4 or 5MM vacuum port. The 10MM is routed over and around the #3 carb top and splits to feed carbs 1&2 and 3&4. The vacuum line is connected to the #2 intake carb manifold. The petcock will have two positions. "ON" and "PRI. "ON" allows fuel to flow when engine vacuum is present and shuts off fuel with engine off, "PRI" will free flow fuel till the tank is empty.

[Pat Conlon]

....The 10MM is routed over and around the #3 carb top and splits to feed carbs 1&2 and 3&4....

Fuel line routing is important on the gravity flow bikes.
So....Just to be clear: the single fuel line that leaves the petcock runs *under* the 2 branch lines that feed the carbs.
It is counter intuitive until you see how low the petcock outlet is when the tank is bolted down.

If you don't run the fuel line this way, you will pinch either of the two branch lines, or the main line itself.

Don't ask me how I know.

[Spudman]

So from what I'm gathering is my fuel line was definitely cut short as there isn't much before the tee. I'll have to pick up some more.

....The 10MM is routed over and around the #3 carb top and splits to feed carbs 1&2 and 3&4....

Fuel line routing is important on the gravity flow bikes.
So....Just to be clear: the single fuel line that leaves the petcock runs *under* the 2 branch lines that feed the carbs.
It is counter intuitive until you see how low the petcock outlet is when the tank is bolted down.

If you don't run the fuel line this way, you will pinch either of the two branch lines, or the main line itself.

Don't ask me how I know.

[Spudman]

I'll see if I can get a picture for verification tomorrow but I'm almost certain I have the incorrect petcock.... Looks like the part may cost almost as much as the bike did... 

The bike is an 85 and definitely pre-fuel pump. See I thought that the coil might be it but I still have spark and if I squirt some gas into the cylinders it will fire. I'm thinking it is not getting the gas it needs so maybe a combination between a few areas I missed cleaning and the wrong petcock? I have been looking them up and only see petcocks with one vacuum nipple on it, is that the correct one? The one that came with the bike has two and I think that may be causing some starvation.

You need a 10MM fuel barb and a 4 or 5MM vacuum port. The 10MM is routed over and around the #3 carb top and splits to feed carbs 1&2 and 3&4. The vacuum line is connected to the #2 intake carb manifold. The petcock will have two positions. "ON" and "PRI. "ON" allows fuel to flow when engine vacuum is present and shuts off fuel with engine off, "PRI" will free flow fuel till the tank is empty.

[Pat Conlon]

$120 is chump change. Less than the cost of a new tire.
http://rpmracingca.com/proddetail.asp?prod=M%2FC%3A36Y-24500-01

....and it's already safety wired for you.

[Tuneforkfreak]

A wet paper towel on the header is a good way to see which cylinder is hot or cold. If you got one that's cold or in your case you already know which ones are dead, drain the float bowl and see if you have any gas in that carb.  That's how I did it and after setting my floats to spec I found that one of the carbs didn't really like that measurement and had the gas shut off. I can honestly say that I have pinched my fuel line off on my 90 model when the line fell out of the holder on the tank. 

[Spudman]

Update so far, carbs are getting a thorough soak with all the jets pulled and soaking independently. I've looked into the new petcock and will have it ordered soon. Should I separate the carbs off of the rack on this for any reason? I'm not sure if the plastic in between them will get soft or damaged?

Thanks for all the help and suggestions so far everyone.

[Tuneforkfreak]

Update so far, carbs are getting a thorough soak with all the jets pulled and soaking independently. I've looked into the new petcock and will have it ordered soon. Should I separate the carbs off of the rack on this for any reason? I'm not sure if the plastic in between them will get soft or damaged?

Thanks for all the help and suggestions so far everyone.

If I was in your position I would break down all the carbs and run each one through a sonic bath of vinegar solution then put new O rings on all the supply lines. They're probably hard and they're cheap to boot.Dont try and cut any corners in this area or you'll fight the gremlins on some back country road.  I picked up an ultra sonic cleaner to do mine  http://www.harborfreight.com/25-liter-ultrasonic-cleaner-95563.html . It worked really well and the smallest of ports get scrubbed out which is why the pro's use them.

[Tuneforkfreak]

Make sure you remove the emulsion tubes as well and soak and clean them. When I took mine out they where full of nasty schmuck. I had a problem getting two of mine out and ended up having to replace them.

[Spudman]

Well it is a little late but here are a few pictures of that old petcock. Do you think it came off of one with a fuel pump? It does have the on/prime/on options but the two nipples throw me off.