No 3 & No 6 cylinder not working

[cbx6ss]

Carb insulator tight. Carb sync
Brad

[Littleeagle28]

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

Have cleaned out no 6 carb 3 times now, still no bangs emitting from it, although bike did seem to want to idle a little this time. But would really love to know why six is refusing to bang.

Have swapped carb tops from No 1, and also tried swapping HT line ( I have a good spark, but just trying everything I can think of).

If any one knows of a Brit near North lincolnshire who can help, please let me know?
Arnie

[Goss]

Hello Arnie,

Number six will at least warm the header pipe if revved up to 4,000 rpm as the carb will supply the cylinder fuel from one of many circuits...idle, primary and main, they can't all be blocked. The idle circuits are the main problem with regard to how clean these carbs are which generally means in the higher rev range they will at least fire.

Whilst your carbs may not be completely clean it sounds to me as though compression and/or spark may be the issue. To eliminate the spark you could feed number 6 with the other other lead from the coil supplying it just to eliminate that there is no internal problem with the coil to number 6 supply terminal. Check your compression again even at 70psi you would expect an intermittent bang.

No luck call me on 07971 169980.

Regards

Goss

[Littleeagle28]

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

Have cleaned carb now 3 times still no bang from No 6. Even tried swapping carb tops and needles from good cylinder, No 1.

So unless some one has any other ideas, I'm stuck.
Arnie

[daves79x]

May have been mentioned, but how are your valve clearances? I'd take a quick check on that.

Dave

[Goss]

Arnie,

If you are certain you have a good spark then you need fuel and compression, as long as you have these that cylinder will pop and bang. Check the plug, if it is wet then you either have no spark or no compression. If it is dry then there is not enough compression to suck fuel into the cylinder or some serious carb issues (unlikely).

Regards

Goss

[Littleeagle28]

Arnie,

If you are certain you have a good spark then you need fuel and compression, as long as you have these that cylinder will pop and bang. Check the plug, if it is wet then you either have no spark or no compression. If it is dry then there is not enough compression to suck fuel into the cylinder or some serious carb issues (unlikely).

Regards

Goss

Did another comp test, and also added oil for second test and comp reading increas from around 60psi to around80psi, so suspect worn rings.

Any suggestions to how best to do this and what else should I do when messing about in there?

[cbx6ss]

back to Dave's suggestion; valve clearances. I will share what shims I have when you get to the numbers.

/r
Brad

[cbx6ss]

i re-read the thread; did not see the mileage of your engine. What is the mileage on the clock?
/r
Brad

[Littleeagle28]

i re-read the thread; did not see the mileage of your engine. What is the mileage on the clock?
/r
Brad

36000km around 22000miles, but who knows if this is accurate though.

[Littleeagle28]

back to Dave's suggestion; valve clearances. I will share what shims I have when you get to the numbers.

/r
Brad

Not done this, so reading the manual to understand how, I hope.

[EMS]

Not done this, so reading the manual to understand how, I hope.

It's not rocket science, once you understand the clearance compensation and follow the instructions. Make sure you have a chart to take notes. I am not sure if the manual states this explicitly, but DO NOT, NEVER, turn the engine without ALL shims in place.

[Littleeagle28]

Not done this, so reading the manual to understand how, I hope.

It's not rocket science, once you understand the clearance compensation and follow the instructions. Make sure you have a chart to take notes. I am not sure if the manual states this explicitly, but DO NOT, NEVER, turn the engine without ALL shims in place.

Gotcha boss.

[Littleeagle28]

Re-checked all cylinders for compression, with throttle and chokes open, (figures in PSI)1=85,2=90, 3=90,4=85,5=90,6=85.

No. 6 still not going bang! Either at idle or above 4000 rpm

Spark is very good, plug is wet though and carb cleaned several times.

Stuck for ideas.

[daves79x]

Again, check your valve clearances. You need to know what they are anyway. Then try all new plugs again. Wet - fouled plugs don't work in CBXs.

Dave