running but popping

[Guest]

good morning well put the bike back together after cleaning fuel system tank, petcocks,new lines, filters, cleaned carbs main nozzles were pluged solid. cleaned gas cap vent i pre syn carbs the bike fired right up at 4000rpm adjusted to 1000 idles nice but when i throttle up 2000 or more i get slite popping on left side, runs down the road smooth let off the gas and it starts popping, checked for vacum leaks none, now when i got the bike 1,3 &4 plugs were solid carbon 2 was wet, now 1, 3 &4 are great 2 is alittle wet puled plug caps 1 at atime when running 1-3-4- would drop idle and 2 no change but i can hear arking when putting the cap back on? is this the start of a weak coil??or something else could use some ideas thanks guys
dick
78e

[tinman905]

Had the same problem with mine I had a exhaust leak just tightened the band and it went away. It might also be your carbs are set too rich .

[Guest]

popping

Originally posted by tinman905
exhaust tite haven't final syn carbs yet thank you tinman
Had the same problem with mine I had a exhaust leak just tightened the band and it went away. It might also be your carbs are set too rich .

[81xsproject]

If you had 4-1, I would tell you that is normal. However with 4-2, you may need to richen up the idle mixture a little.

[mro]

Did you put new plugs in it?
Try switching plug wires, #2 and #4.
If #2 starts to fire and #4 stops...problem with cap or wire.
If it still does not fire try switching plugs to be sure.

How far out are the pilot screws?
How many miles on your bike?


mro

[mro]

BTW

Did you check for a vac leek where the intake boots meet the head?


mro

[fredintoon]

pulling plug caps

" pulled plug caps 1 at a time when running 1-3-4- would drop idle and 2 no change - - - "
>
Hi Dick,
as I understand it, each coil needs 2 plugs connected in order to work.
That is, pull #1 plug cap off and just leave it hanging and in addition to #1 not sparking, neither will #4. Same with #2 & #3.
Try repeating the test but ground out the pulled cap onto the head (perhaps use a spare plug snapped into the cap and laid onto the head) and see what happens then.
It's been my experience that the most likely cause of exhaust popping is a leak somewhere in the exhaust system.

[Guest]

Originally posted by 81xsproject
thank you 81

If you had 4-1, I would tell you that is normal. However with 4-2
, you may need to richen up the idle mixture a little.

[Guest]

Originally posted by mro
Did you put new plugs in it?
Try switching plug wires, #2 and #4.
If #2 starts to fire and #4 stops...problem with cap or wire.
If it still does not fire try switching plugs to be sure.

How far out are the pilot screws?
How many miles on your bike?
mro yes new plugs @ 40 k
thank you for the help

mro

[Guest]

Re: pulling plug caps

Originally posted by fredintoon
" pulled plug caps 1 at a time when running 1-3-4- would drop idle and 2 no change - - - "
>
Hi Dick,
as I understand it, each coil needs 2 plugs connected in order to work.
That is, pull #1 plug cap off and just leave it hanging and in addition to #1 not sparking, neither will #4. Same with #2 & #3.
Try repeating the test but ground out the pulled cap onto the head (perhaps use a spare plug snapped into the cap and laid onto the head) and see what happens then.
It's been my experience that the most likely cause of exhaust popping is a leak somewhere in the exhaust system.

hi fred i checked exhaust at head it ,was tight might exhaust gasket and i'll try the plugs useing your method
thank you for the help
dick

[mro]

At 40K...
when were the valve clearences last checked and hows the compression?


mro
BTW, XS has a "waste spark system"
one and three on one coil, two and four on the other.
Each coil fires both plugs attached to it at the same time.
If one works and the other does not (on same coil) switching wire is just a quick check to see if problem is with cap/wire or plug.

[79XS11F]

Popping in the exhaust pipes is a fuel jetting or air leak issue. the most common place for leaks to happen are at the exhaust ports or where headers meet muffler. If you confirm that there are no leaks then you need to look at jetting or intake system leaks which affect jetting. If both the intake and exhaust connections are not leaking its carb jetting. Leaks in the intake system can be "seat of your pants" checked by spraying a little quick start around the connection while listening for increased idle. A better way is to try to sync the carbs. Leakage at the boots will make sync of the carbs difficult as in bouncing needles or fluid level in carb sticks.

check your plug wires with the plugs attached but laying on the head. turn over the engine in low light and observe spark consistence and strength.

Rob

[81xsproject]

MRO, don't you mean 1&4 on one coil and 2&3 on the other?

[mro]

MRO, don't you mean 1&4 on one coil and 2&3 on the other?

Yup, your right 81xsproject....
brain fart, getting old sucks!


mro

[Guest]

Originally posted by 79XS11F
Popping in the exhaust pipes is a fuel jetting or air leak issue. the most common place for leaks to happen are at the exhaust ports or where headers meet muffler. If you confirm that there are no leaks then you need to look at jetting or intake system leaks which affect jetting. If both the intake and exhaust connections are not leaking its carb jetting. Leaks in the intake system can be "seat of your pants" checked by spraying a little quick start around the connection while listening for increased idle. A better way is to try to sync the carbs. Leakage at the boots will make sync of the carbs difficult as in bouncing needles or fluid level in carb sticks.

check your plug wires with the plugs attached but laying on the head. turn over the engine in low light and observe spark consistence and strength.
hey rob ihave no vac leaks the spark is even on all4 but have exhaust leak on both sides at muffler conn. waiting to borrow syn guages do you think it could the exhaust,and final syn.?
thanks again dick

Rob