popping sound

[garyrc]

I have a question. when i sit at idle i seem to have a little bit of a pop out of my pipes, not from the carbs but the pipes. any ideas?
oh yes did i mention i have 4into one pipes.
thanks gary

[garyrc]

popping sound

I have a popping sound coming from my pipes at idle. some have said it could be clogged jet or to lean. plugs look fine and screws are out 1 1/2 turns. any ideas?

[randy]

Could be leaky exhaust, check for leaks. that can cause lean condition as easily as out of adjustment carbs.

[garyrc]

what is the worst that can happen by running lean other than some loss of power?

[randy]

Some not so nice things that can be caused by lean condition:

1. Overheating.

2. Blueing of exhaust pipes.

3. If it gets really hot, spark plug damage.

[John]

Don't forget damaging the pistons. They may burn through if the mixture is too lean/hot. The mixture also performs a cooling function.

[garyrc]

so bring my screw out about another 1/4 turn?

[John]

What are your mods? You may need to go a little fatter on the main jets. Is the problem just during idle or is it at a higher rpm? Thepilot screws just affect idle and partial throttle. As far as I'm concerned, too rich is better than too lean.

[garyrc]

just checked the plugs and no joke they look new i mean no color on tips or the electrod. around the screws of the plug aliitle very little black. and the popping is just at idle or very extreme down shifting. and it is not all the time

[John]

It has been said here that popping is a sign of exhaust leaks, so check your exhaust system really well, especially at the head. You may need new gaskets. The torque on the header nuts is 14-15 ft. lbs. or the good old German torque...goodntite!

[TopCatGr58]

Hey Gary,

IF your plugs are bleach white, then you are definitely running too lean, and probably need to fatten up your MAIN JETS a few sizes at least! For now, try turning your pilot screws out another FULL TURN! But this is just a stop gap approach. You need to find out what your mains are, and compare to stock values, and if you're running aftermarket pipes, Indy filters, then at least 3 sizes up from stock is in order!

Of course burning holes in your pistons could give you a good excuse to put the big bore kit in, but kinda expensive!
T.C.

[garyrc]

just checked the plugs and no joke they look new i mean no color on tips or the electrod. around the screws of the plug aliitle very little black. and the popping is just at idle or very extreme down shifting. and it is not all the time

also just took it for a ride and opened it up pulled 8 grand on the tack in first and hit about 64mph. so i think it ok on power?

[TopCatGr58]

Gary,

Mine came with stock 110's across all four carbs, and I first had put a 4-1 set of pipes on it. It pulled hard to 8.5K, then after I did my topend rebuild with Indy Filters, it still seemed to pull very well to 8.5K, but as mentioned before, my plugs were bleach white...no tan or gray color on the white electrode!! THIS IS TOO LEAN, and you are asking for trouble running this way!! I know pulling the carbs is a PITA, but after doing all of this work resurrecting your machine, you don't want to go burning holes in your pistons! But, hey it's your machine, just don't want to be saying "told you so" when you post back in a month or so that you burned up your engine in the SUMMER HEAT!!
T.C.

[garyrc]

does no colar mean bleach white? what i mean is that the electrode looks like it did new maybe a little brown but not much. the plug tips are mare metal. and if too lean bring screws out another half turn?

[TopCatGr58]

Check out this tech tip:
Plug Diagnostics

Look at #1, 6, 10, and read description for each.

Turning back/out Pilot screw will mostly affect IDLE circuit and low rpm range only. Pulling your plugs WITHOUT doing the Throttle chop isn't showing you the true burning conditions OFF IDLE that the engine is being run in most of the time!