No 3 & No 6 cylinder not working

[Littleeagle28]

Ordered mike nixons carb booklet and cleaned the carbs as engine not firing on all cylinders (I know the feeling).

Started her today, after finding some wires not connected it fired up. Unfortunately I have the exact same issue that made me clean the carbs I. E No 3 & 6 cylinder not firing.

Checked spark plugs for spark both ok.
Swapped plugs for the known good ones anyway, just in case.
Both plugs are wet.
Compression in both cylinders, No 3 has approx90psi, and No 6 ha around 70psi.

I noticed at one time they both seemed to work at one point then failed again.

Anybody experienced this before, can you hep?

[cross]

How did this problem start? Was bike sitting for long time?
When you say wet spark plugs, do they smell like fuel or oil?
I would do a leak down test which should pin point leak of compression.
In either case, head will have to come off.
You could have stuck valve but most likely burned exhaust valves.
Just my $0.5

[Littleeagle28]

How did this problem start? Was bike sitting for long time?
When you say wet spark plugs, do they smell like fuel or oil?
I would do a leak down test which should pin point leak of compression.
In either case, head will have to come off.
You could have stuck valve but most likely burned exhaust valves.
Just my $0.5

Sasha after carb clean, 5 cylinders operate, only No. 6 not doing so.

Will take another look at fuel delivery.

Sorry for late reply, not always been on site.

[Littleeagle28]

How did this problem start? Was bike sitting for long time?
When you say wet spark plugs, do they smell like fuel or oil?
I would do a leak down test which should pin point leak of compression.
In either case, head will have to come off.
You could have stuck valve but most likely burned exhaust valves.
Just my $0.5

Sasha after carb clean, 5 cylinders operate, only No. 6 not doing so.

Will take another look at fuel delivery.

Sorry for late reply, not always been on site.

Bike was sitting for some years in Germany I believe, PO wanted to custom it.

You tube link here when firing on 3 or 4 cylinders.

http://m.youtube.com/watch?v=3mHErBa4EhY

Bike appears to get fuel, plug wet. No 6 has same compression as No1 cylinder.
Swapped plugs ( which are all new btw) from 1to 6. No difference.

Plug is getting spark.

Also do not know how to set idle speed, as when running, I have to hold the throttle open or engine will eventually die otherwise.

[cbx6ss]

I'm going to guess idle passages still not clear in carbs (found this to be very important part of carb overhall). OR, carb sync required; another very important task in carb overhall. When you get past this you will enjoy!
/r
Brad

[Larry Zimmer]

Is it only at idle that 3 and/or 6 don't seem to fire? Or, at any speed? If only idle, yes, I'd get into the idle circuit(s) of the carbs. If it's any speed, you might try some new/different plug wires. Get some bulk wiring, or such, to do a temporary wire to see what happens. Even though it appears to be sparking when you test the plugs, the wires might be doing some 'other' things when they are in there installed position. Sparktricity has some strange ways sometimes. Be certain the caps are tight on the wires.

Good luck with this one.

[EMS]

Sparktricity has some strange ways sometimes.

[cross]

I have not been on this site in a week or so either as I was finishing my bike. Finally got it finished and rode it to the DMV for verification and registration yesterday.
This are the same issues I was going through and it ended up being carbs.
Even though there maybe a spark, it may not be strong enough.
Definitely check the cables, trim the ends and reconnect them (providing that they are still long enough). This is part of regular maintenance.
You can also try swapping coils and see if anything changes.

But then again, since you cleaned carbs yourself, it could be that they are not clean enough.
My bike has been sitting for well over 5 years and once i took carbs apart I used the whole can of carb spray just to make sure all passages are clear. I also plucked one strand of wire from my wire brush and went into all passages until it came out on the other end.
After about a week after when i received all parts, i re-did all above and I'm glad i did as one of the accelerator jets was not working at all when it did after first pass of cleaning.
This time i also blew all passages with air compressor with rubber tipped nozzle.
I put everything back together, checked float levels, left pilot screws out 1.25 turns, cleaned and gapped plugs and bike started right up and purred like a kitten so I guess that I was lucky.
When cleaning the plugs, make sure that you blow and completely dry them inside with air compressor.
Another thing that i did is flush out the gas tank and made sure that the filter/strainer in the tank is not ripped and also added another inline filter.
This is very important step, especially for bikes that have been sitting for a long time.
If you cleaned the carbs bit not flushed the tank and lines and added fuel filters, there is a good chance that carbs got clogged again.
All of the tips above were given to me by members from this club so don't hesitate to ask as many question as you may have.
Carb cleaning is tedious job as all passages are so tiny and you need to know where they are. Every passage has another end so carb cleaner needs to come out somewhere otherwise, its not clear.
And as few members have said to me, take your time to make sure all is clear.
Sasha

[cbx6ss]

Sasha; great info! Its all coming back to me... Float levels; and cooil swap (though if bad the mate cylinder should be troubled too). Thats an important one too. Im not sure that CBX carbs can ever be clean enough (except when Dave cleans them). I noticed an amazing difference when following Mikes book completely. Your bike will feel new to you! What a pleasure to ride when COMPLETELY dialed in.
/r
Brad

[Goss]

Wow, 90 psi seems very low to me, is that the same as all of the cylinders or just 1 and 6?

Regards

Goss

[cross]

His compression is very low and that's why I originally suggested leak down test to see where it maybe losing the compression.
But now, one of this cylinders is working so I'm not sure if he had used bad compression gauge or ?
I rented one from local store and my reading was around 110 on all which concerned me but than my neighbor brought his professional snap on gauge and I got reading 135-145.
I still think that carbs need to be looked at again.
I've had the same issue with my bike. I checked everything but when I noticed that one day once cylinder is not working and next day the other, I knew it was the carbs and Dave had suggested the same.
Another thing to inspect are the air box boots. Mine had 4 rips on few and there probably was vacuum leak.
Make sure air box seals properly around the carbs and the air filter box.

Considering that I never could clean carbs properly (my alfa carbs) i'm very happy that these turned out good and that my bike runs so well with carbs just of the bench although they still needs a bit of fine tuning like fuel mixture and carb sync.
I did one mistake by adjusting the fast idle in the wrong place and now I don't have fast idle at all but i'll correct that when I do the valve adjustment.
I'm hoping for good weather this weekend so I can take it for a longer ride,
I'll post some pics if I do!

[Littleeagle28]

Thanks for all info.

Looks like another tilt engine job and re-clean carbs awaits me!

Also, how do I set the idle level on the bike?

Is there an adjustment screw or such like?

[cross]

I think so. Take your time to make sure that when you spray Carb spray that it comes out on the other end and also if you have air compressor and rubber tipped nozzle would help.
Not sure which year your bike is but on my '82, idle adjusting is at the right side of the carbs, between carbs and airbox. If you look there you will see round thumb screw and you can use flat head screw driver to adjust.
Here is the picture, i circled it out

[Littleeagle28]

I think so. Take your time to make sure that when you spray Carb spray that it comes out on the other end and also if you have air compressor and rubber tipped nozzle would help.
Not sure which year your bike is but on my '82, idle adjusting is at the right side of the carbs, between carbs and airbox. If you look there you will see round thumb screw and you can use flat head screw driver to adjust.
Here is the picture, i circled it out

Many thanks.

I did notice the thumbscrew and have turned to both extremes without any difference to the idle settings....so off with the carbs again I think.

Originally when I sprayed with the carb cleaner it did appear to come out of said orifices, however without any other options, this will have to be.

Ta

[cross]

I'm not sure what to say. I'm not an expert but there could be mechanical issue there as well. Once you take them off, take a look at the mechanism and see if everything works correctly when tumb screw is turned. There is info on it in the manual and i maybe some in the Nixons book.
Just see what makes sense