(SG) popping issue moved from the left to the right exhaust?!?!

[ERM83]

ok...I know i've talked/posted about this plenty of times before, but this is strange and driving me nuts. I've had a slight pop out of the left exhaust...I've rebuilt/synched/tuned the carbs...still popped.

It was running like garbage recently (on 2 cylinders), so I changed the coils (despite the coil for 1-4 NOT checking out on the multimeter, the problem was actually the pickup coil wires ), and now the popping is on the RIGHT side. It has a slight low end stumble, between around 2000RPM VERY specifically...when I go above that, zero problems.

Getting backfire/gas out of carb #4. When I changed the coils, I yanked the carbs, cleaned them, etc. I didn't mess with any of the settings at ALL.

I'm going to yank them again (about to get a BUNCH of small stuff for the bike at our local shop), and check everything again. I'm just confused as to why the popping moved to the right?! Anyone ever have this happen??I definitely hooked everything up correctly...

[motoman]

ok...I know i've talked/posted about this plenty of times before, but this is strange and driving me nuts. I've had a slight pop out of the left exhaust...I've rebuilt/synched/tuned the carbs...still popped.

It was running like garbage recently (on 2 cylinders), so I changed the coils (despite the coil for 1-4 NOT checking out on the multimeter, the problem was actually the pickup coil wires ), and now the popping is on the RIGHT side. It has a slight low end stumble, between around 2000RPM VERY specifically...when I go above that, zero problems.

Getting backfire/gas out of carb #4. When I changed the coils, I yanked the carbs, cleaned them, etc. I didn't mess with any of the settings at ALL.

I'm going to yank them again (about to get a BUNCH of small stuff for the bike at our local shop), and check everything again. I'm just confused as to why the popping moved to the right?! Anyone ever have this happen??I definitely hooked everything up correctly...

Should of checked the SETTINGS.......saved yourself a lot of trouble. Float levels NEED to be checked(23mm), and make sure they are ALL the same! Foats need to be visually checked that they all hang straight when inserted back in bowls. Having one cocked the least little bit will have that float hanging up on side of float bowl when back together. With the issue your having, I suspect idle mixtures were not really set correctly. Correct method used is 'lean drop method'. Pick one and back it out quite aways. At an idle, start back in....SLOWLY....when sound slightly changes, stop and back it out 1/8 of turn and no more than 1/4 turn! Do other three same way......NOW you can sync the carbs, preferably with a mercury manometer, or 4 vacuum gauges hooked to vacuum ports at same time. Now, when motor is cooled off a bit, re-start and go back through idle mixture settings again, and THEN do a final sync again. Again, likely the poppin' issue your havin' is from incorrect idle mixture settings along with incorrect carb sync. No offense, just sayin'. BTW, be sure and have a box fan in front of motor doing this process, as it takes a bit to CORRECTLY go through this process, and you don't want motor overheating!

[ERM83]

gotcha...

Should of checked the SETTINGS.......saved yourself a lot of trouble. Float levels NEED to be checked(23mm), and make sure they are ALL the same! Foats need to be visually checked that they all hang straight when inserted back in bowls. Having one cocked the least little bit will have that float hanging up on side of float bowl when back together. With the issue your having, I suspect idle mixtures were not really set correctly. Correct method used is 'lean drop method'. Pick one and back it out quite aways. At an idle, start back in....SLOWLY....when sound slightly changes, stop and back it out 1/8 of turn and no more than 1/4 turn! Do other three same way......NOW you can sync the carbs, preferably with a mercury manometer, or 4 vacuum gauges hooked to vacuum ports at same time. Now, when motor is cooled off a bit, re-start and go back through idle mixture settings again, and THEN do a final sync again. Again, likely the poppin' issue your havin' is from incorrect idle mixture settings along with incorrect carb sync. No offense, just sayin'. BTW, be sure and have a box fan in front of motor doing this process, as it takes a bit to CORRECTLY go through this process, and you don't want motor overheating!

I forgot to mention that I didn't have calipers, so I tried to eye it up as well as I could using measuring tape, just to get an idea. I JUST bought some fancy calipers, so i'm going to dial that in probably in a minute or so here. I really don't mind yanking the carbs off again...I LOVE working on this thing, and I'm trying to learn as much as possible. I THOUGHT I was getting knowledgeable on these things, but....NOPE. Still got plenty to go, obviously. One of my friends who runs a shop in town is CONVINCED that the 79' carbs just don't work with the SG, then I had him look stuff up on here...changed his mind quickly. The idle screws still have the plastic on them, so I guess I gotta take that off?? This has been a really eye-opening/fun experience so far...I want to know these things IN AND OUT, and maybe can finally CONTRIBUTE on here, rather than just asking a million questions.

....something I just thought of...the float for carb #1 was WAY off, and I got that "in the ballpark" of the others, just to see where i'm at. I haven't been riding it, because of a spout of crappy weather....just working on it. Gonna get on this now...thanks for the sage advice, man!! I'll report back later!

[motoman]

Keep those plastic stops!.....as they almost impossible to come by these days!

Using a slide-rule anolog caliper IS your best bet to get those floats all the SAME. Tape measure just doesn't cut it. Even a half a millimeter throws correct volume of fuel drawn off. With that, next thing that happens is no two cyls. are drawing same amount of fuel..........and it just goes downhill from there. I use an anolog slide caliper from my reloading arsenal.

[ERM83]

Keep those plastic stops!.....as they almost impossible to come by these days!

Using a slide-rule anolog caliper IS your best bet to get those floats all the SAME. Tape measure just doesn't cut it. Even a half a millimeter throws correct volume of fuel drawn off. With that, next thing that happens is no two cyls. are drawing same amount of fuel..........and it just goes downhill from there. I use an anolog slide caliper from my reloading arsenal.

I just went all-out, and bought some REALLY NICE husky calipers. When it comes to the bike, I DO NOT MIND spending the extra bucks on tools! When adjusting the float, I fully knew I was going to have to take them out again...I just wanted to get them close, and see how it ran with the new coils. I didn't touch ANYTHING other than the first float. At that setup, it was running "okay", so I just wanted to see what that adjustment would do. I'm trying my hardest to not be COMPLETELY stupid about it, haha. I'm going to replace a turn signal stem quick (old one was dented all to hell from PO, and driving me nuts), then pull the carbs and measure. Again, THANK YOU for your help...Infinitely appreciated!!

Eric

[motoman]

I just went all-out, and bought some REALLY NICE husky calipers. When it comes to the bike, I DO NOT MIND spending the extra bucks on tools! When adjusting the float, I fully knew I was going to have to take them out again...I just wanted to get them close, and see how it ran with the new coils. I didn't touch ANYTHING other than the first float. At that setup, it was running "okay", so I just wanted to see what that adjustment would do. I'm trying my hardest to not be COMPLETELY stupid about it, haha. I'm going to replace a turn signal stem quick (old one was dented all to hell from PO, and driving me nuts), then pull the carbs and measure. Again, THANK YOU for your help...Infinitely appreciated!!

Eric

No problem Eric.....that's what we're here for........and many more here way sharper than I.

[BA80]

When it comes to the carbs you can't halfass anything or you'll be screwing with them forever.

[motoman]

When it comes to the carbs you can't halfass anything or you'll be screwing with them forever.

A huge +1 on that!