TOPIC:

Kawboy wrote: You'll have to humor me here Paul. The only time you can have backfiring through the carbs is when the spark occurs when the intake valves are open so either the intake valves are tight (not likely) or your firing is way off and since you have 4 cylinders related to 2 of the 3 coils not firing properly, I suspect that your wiring is mixed up. Either the wires feeding the coils on the lower coils is backwards or your HT leads are backwards.

So humor me here please and take the coil wires from 2 and 3 and swap them and take the wires from 4 and 5 and swap them. Fire it up and see what happens. I suspect it will run fine. If so then you can figure out whether the primary fees to the coils is wrong or your HT leads are wrong.

Just a simple little test to see if in fact the wiring is off.

Very happy to humor you and if we can get sorted even better! I'm a little confused though with the terminology - When you say coil wires are you referring to the wires that connect to the Primary? (I feel confident that's where I stuffed up)

kawboy point is valid ! My point was that if idles aren't delivering fuel correctly and this is the case if the circuits are dry and haven't been charged it is usually at this time you'll hear some soft "popping" until the idle circuits are full.

I'll go so far as to say both ideas are correct but with out being able to actually hear the severity of the popping/backfiring either or both conditions may be present. Admittedly to suggest that 4 of the six are partially restricted and/or blocked may sound like a real exaggeration, but is is completely possible given the condition of some of the carbs I have rebuilt. My theory behind this is simply too lean a mixture won't "fire" and the raw mixture is then exhausted into the header pipe. When the idle-circuit is occasionally correct the hot exhaust gases will ignite the previous un-burned (lean mixture) creating the popping sounds. A partial blockage especially if a piece of debris is floating around where it shouldn't be will allow the intermittent correct mix. I say this with some experience because what I've cleaned out carbs is nothing short of incredible.

kawboys point, again, is completely valid to a more technical end. If this condition you refer to is something that has just developed or slowly developed recently then I will lean (no pun intended) towards the fuel issue. Valves don't go "outta whack" that quickly and across multiple cyl. that coincidentally, that suddenly. Fuel issues will. If on the other hand you or someone has done recent valve-adjustments or it's the way you received the bike ( sorry - not familiar with the history) - then kawboys theory would be more applicable. Then there's the possibility of a combination of both. This is where a methodical and correctly ordered and systematic assessment will be important. The valve clearance would be my starting point if unknown and not 100% assured they are correct. You don't need the engine running to do this. Carb issues generally require the engine to run to some degree and if the valves haven't been confirmed to be set correctly then you'll be chasing your tail with the unknown.

Yaegunp wrote:

Kawboy wrote: You'll have to humor me here Paul. The only time you can have backfiring through the carbs is when the spark occurs when the intake valves are open so either the intake valves are tight (not likely) or your firing is way off and since you have 4 cylinders related to 2 of the 3 coils not firing properly, I suspect that your wiring is mixed up. Either the wires feeding the coils on the lower coils is backwards or your HT leads are backwards.

So humor me here please and take the coil wires from 2 and 3 and swap them and take the wires from 4 and 5 and swap them. Fire it up and see what happens. I suspect it will run fine. If so then you can figure out whether the primary fees to the coils is wrong or your HT leads are wrong.

Just a simple little test to see if in fact the wiring is off.

Very happy to humor you and if we can get sorted even better! I'm a little confused though with the terminology - When you say coil wires are you referring to the wires that connect to the Primary? (I feel confident that's where I stuffed up)

This little test I'm referring to is to take the plug wires off of 2 and 3 and switch them and also take the plug wires off of 4 and 5 and switch them as well. My suspicion is that the primary wires from the ignitors are backwards on the 2 lower coils and are firing the cylinder out of sequence. By just switching the coil wires to the plugs as I've suggested and firing it up. If it runs like it should, then we'll know that the wiring to the coils from the ignitors is backwards. All you'll have to do then is swap the 2 wires feeding the coils.

Scotch isn't wrong either depending on exactly what you're hearing. This is one of the reasons we struggle on a forum site trying to help each other out. Sometimes it's a language barrier, sometimes it's a knowledge based barrier and sometimes it's just a descriptive barrier. My understanding of the term "backfiring" usually means an explosive discharge coming out of the tail pipe and "firing backwards" from the vehicle. Backfiring out the carb is in essence firing backwards through the whole engine system and thank you for adding the descriptive in your original statement of backfiring out the carbs since it puts a whole different light on the problem.

Let us know how the test works out.
KB

scotch wrote: kawboy point is valid ! My point was that if idles aren't delivering fuel correctly and this is the case if the circuits are dry and haven't been charged it is usually at this time you'll hear some soft "popping" until the idle circuits are full.

I'll go so far as to say both ideas are correct but with out being able to actually hear the severity of the popping/backfiring either or both conditions may be present. Admittedly to suggest that 4 of the six are partially restricted and/or blocked may sound like a real exaggeration, but is is completely possible given the condition of some of the carbs I have rebuilt. My theory behind this is simply too lean a mixture won't "fire" and the raw mixture is then exhausted into the header pipe. When the idle-circuit is occasionally correct the hot exhaust gases will ignite the previous un-burned (lean mixture) creating the popping sounds. A partial blockage especially if a piece of debris is floating around where it shouldn't be will allow the intermittent correct mix. I say this with some experience because what I've cleaned out carbs is nothing short of incredible.

kawboys point, again, is completely valid to a more technical end. If this condition you refer to is something that has just developed or slowly developed recently then I will lean (no pun intended) towards the fuel issue. Valves don't go "outta whack" that quickly and across multiple cyl. that coincidentally, that suddenly. Fuel issues will. If on the other hand you or someone has done recent valve-adjustments or it's the way you received the bike ( sorry - not familiar with the history) - then kawboys theory would be more applicable. Then there's the possibility of a combination of both. This is where a methodical and correctly ordered and systematic assessment will be important. The valve clearance would be my starting point if unknown and not 100% assured they are correct. You don't need the engine running to do this. Carb issues generally require the engine to run to some degree and if the valves haven't been confirmed to be set correctly then you'll be chasing your tail with the unknown.

Hello Scotch, I had recently given myself to the end of the year to get the bike in order (due for rego next month) and I have other projects to get on with, therefore the time frame I have set. I hate quitting on anything (read obsessive) so I am 100% committed to have success. If not successful all I can think about is the knowledge I have acquired from the web regarding the Z1300 (in many cases from the likes of yourself, kawboy, Rick, kza13 etc, too many to mention) would be superfluous and therefore wasted energy. I will be forever grateful for your input and years of experience that's been passed on to me without which I wouldn't of stood a chance of getting this far. There are many blokes out there who would not even consider passing on this knowledge without charging upwards of $70/hour. So I would never take the efforts of anyone willing to try and help for granted - to be sure!!

Anyway stayed up much of the night doing the carbies as you described, I also did other tweaks at the time. So short story is it was well worth while and I learned a few more things about our Mikuni BSW32 carbs. It turned out not to be the problem. Please see my message to Kawboy in this thread to see the outcome of the HT leads.(will type that up next)

Cheers
Paul

Kawboy wrote: So humor me here please and take the coil wires from 2 and 3 and swap them and take the wires from 4 and 5 and swap them. Fire it up and see what happens. I suspect it will run fine. If so then you can figure out whether the primary fees to the coils is wrong or your HT leads are wrong.

Just a simple little test to see if in fact the wiring is off.

It Solved the Problem!!

Not the HT Leads but the wiring at the primary coil connection. I removed the ignition coils a couple of months ago and ordered new ones, then I sent the IC Igniter away for testing, so it's been a while since removal. I took photos and a video before removing them but as you know you won't see anything whilst the coils are installed. My blunder, I should have taken photos with those wires still connected (semi-removed). My novice brain decided that it didn't matter the order of wires to/from the ballast resistor so the order didn't matter to the primary coils on each ignition coil. Of course those wires head back to the IC Igniter and it likes to know these things I guess. John, please see my post to Scotch in this thread passing on my gratitude to one and all.

Thank you

Glad to be able to help out. Hell, I've been stalled out on my own project for weeks now since it's Deer Season up here and my camshaft grinder decided it's more important to go deer hunting than it is to provide a service to his customers. Also, I love the challenge of diagnosing things like this. Keeps my brain in gear. We used to have watch dogs up here in Canada that would go around to different automotive shops and before they showed up would mess around with carb settings and cross ignition wires and then bring in their vehicle with "problems" and then see how much you gouged them for the "repair". Then they would report the bad guys who took them to the cleaners.

Anyway, glad your back on track and kudos to you for doing up the carbs. That's another big item ticked off the list.

Cheers,
KB