1/2 an engine

[Rick Earle]

My first post and new to CBX. I got a '79 several months ago (it looked better in the pictures from 3,000 miles away!!) It hadn't run in about 8 years and the carbs were a significant mess. With the help of Mike Nixon's book I cleaned them (didn't separate) and reinstalled them, the bike runs, but only on cylinders 1,2,3; I have separated the two banks thinking the fuel pipe beween them may be gunked up but they're clean. (hoping to avoid separating the individual carbs)
Any thoughts or experience with this problem??

[alimey4u2]

Welcome to the site Rick... Can't help you I'm afraid as I'm rubbish on Keihins. Hold on though, help is on it's way...

[Tom Neimeyer]

Just a few questions, I know they will sound dumb but they are necessary. When you had the carbs off, did you watch the blades open inside each carb as you worked the linkage? Same for the choke, the linkage between each side is easy to get unhooked and it will then drive the choke blades closed. Do you get gas at each float bowl on 4,5,6? Is gas getting to the plugs on 4,5,6? Are the plugs wet?

Depending on answers, we can continue the troubleshooting.

Cheers, Tom

[Rick Earle]

Thanks Tom, When I drained the bowls 4,5,&6 didn't have any gas in them; 1,2,&3 did. All the blades, on the throttle side and choke side worked together. The air passages in the carbs were really difficult to clear and I had to use chemicals that the supplier made me read the cautions on, in front of him, before he sold it to me (just an indication of the level of gunk in them); that's why I was convinced that the gas supply tube between 3 and 4 must be clogged, but it wasn't!

[Tom Neimeyer]

OK, if the tube ain't plugged we need to make sure fuel is getting to that tube. How did you check the fuel passage? Carbs on bike now? I know this sounds dumb because you have already tried it. If carbs are off turn them upside down and pull 4 or 5 or 6 bowl and the float/float valve and blow air backwards and verify it comes out the fuel inlet.

Did you replace any of the float needle valves? Can you verify that they are coming open on 4,5,6? With bowls off, when held right side up, you should be able to see the float needle drop down and go back up when you pick up on the float.

Cheers, Tom

[Rick Earle]

Good tests Tom,
I took 4,5 &6 bowls off (#6 was slightly wet) and injected air in the beginning of the fuel tube, all 3 floats fluttered and when I turned them right side up the air flowed freely.
I blew air into the main feed tube between #1 & 2 and the air flowed well out of the end of the main connecting tube.
What are the odds of it being three floats, in a row, all stuck in the "up" (off) position?? How could they get stuck??
When I first discovered that 4,5&6 weren't firing I thought it might be an ignition problem but the individual coils feeding two plugs (1-6),etc. made it seem impossible to be three cylinders in a row not firing; now I'm not so sure (but then why were the bowls empty?)
I'm muttering!!! ......It has to be stuck floats!!? Put the carbs back on and try again??? thoughts?

[Tom Neimeyer]

Great work so far, I'm guessing the carbs are still off the bike. Also sounds like they are split, 1,2,3 and 4,5,6. For gas to flow, there has to be a vent in the system. I assume you blew through all the vents during the cleaning.

Your question about how could it be three floats is why I ask about replaced float valves, possibly some too long.

If you have good air flow through all the fuel pipes, I would put the carbs back together and do a flow test prior to putting them on the bike. I would use the actual fuel tank and the petcock on it. You may want to do a flow test just on the petcock and make sure it gives a full stream of gas. I would not put the carbs back on the bike until you can get gas to 4,5,6.

Once you get gas to 4,5,6 and it still won't run we will start troubleshooting the ignition.

Cheers, Tom

[alimey4u2]

May I also suggest by opening the drain screws sequentially, one can determine what carb is getting (or not getting) an ample supply of fuel ?

[Rick Pope]

Please don't laugh, but are the floats right-side up? I know sometimes you can install floats up-side down, with similar results. Don't ask.........

[Rick Earle]

Rick: I didn't laugh I ran ('er walked smartly) to the garage and checked all 6 with the pictures in Mike Nixon's book; they're all on correctly (definetly not beyond me to make that mistake!).

I did have a lot of trouble with the air vents/passages but ultimately they cleared through the magic of chemicals. I have been using an auxiliary fuel tank (it's like a hospital IV bottle) so fuel from the tank isn't an issue. As suggested I'll put them back together and test them before putting back on the bike. I'll do the sequential drain screws test and let you know the results. At this point, I'm not going to be able to get back to the bike until Tuesday evening; I'll let you know the results.
Thanks for all the help!!

[daves79x]

Rick:
Make sure someone didn't put a solid connection between #4 and #5 cqrb's bowl vents. That's where the vent 'T' is supposed to go and most guys just let them bare, but I've seen a set that someone put solid hose between them (just like the correct hose between #5 and #6). This would allow no venting of the bowls. Also take the float valve seats out and make sure the little plastic screens aren't plugged.

I'd make sure you had good fuel flow starting at the petcock also. Sounds like a venting problem if no obstruction can be found.

Dave

[Rick Earle]

There IS a solid connection between #4 & #5; I just got home from work and it's late but I'll go through the other tests that have been suggested and then cut out the solid connection and do them again. I've checked the little screens in the float valves and they appear ok.
I'll post how it goes tomorrow!!

[Rick Earle]

Got it all back together and after years!!; it's running; more than a little smoke but that's ok!! Thank-you for all your help!

[Rick Pope]

I don't know what it is, but when you get on a properly running CBX it's just magic.

My yellow '79 had been running poorly for quite some time. After the weekend when Jan, Dave McMunn and I worked on the Dawg and I got a chance to ride it, I fell in love again. I set about getting 'Ole Yeller sorted, and with the help of Jim Zemanek, found the problems and now, I'm on a cloud every time I thumb the starter.

I can't wait to get the Tilley bike up and going. I just got home from bead blasting the motor mounts for painting. Hopefully, tomorrow I can paint them and touch up the engine, pull the polished covers for a proper polishing, and start the assembly process.