As Per Rick's Carb Rebuilding - Still Popping At No Load RPM

Carbs have been rebuilt and removed from the bike 3 times to reinspect. did the synch and colortuning and bike runs ok. Problem is still with popping noises coming from the right exhaust in "no load" conditions... Like driving down the road with the throttle not applying power nor allowing the engine to lose rpms. The right exhaust also sounds less loud than the left side and then it seems to kick in and then the sounds are equal out of both sides. The jets are the originals, the exhaust is a MAC 4-2, and the airbox is original. Good spark out of the plugs. Gonna try some seafoam today. When accelerating, the engine runs great, no hesitation, no pops. Idles good. Starts right away. Help?

 

popping is can be a sign of a lean condition you have an advantage with the 4 to 2 exhaust that means you know it is one of the two right hand cylinders giving you the problem. Here is my suggestion find a sctretch of road where you can get the bike to act up. Preferably to your drive way or a friends where it is safe to let the bike cool for a few minutes. go 1/4 mile or so with the bike popping hit the kill switch and let of the throttle at the same time and coast to a stop. Pull the right side plugs and inspect the ceramic on them. My guess one of them is going to be light that is the cylinder you will have to richen up a tad. while the colortune is a great tool real world testing and plug chops is the best tool for fine tuning IMO.

 

x2
but I would encourage checking ALL plugs while your at it.
might as well tune ALL cylinders for performance.

 

Ok folks...did the plug chop and the plugs 1,2, and 4 are sooty, while #3 is a tan color. Tried colortuning and the #3 is so dim as to not being able to see the color until you rev the bike to about 3k...then it's blue. What now?

 

you are beyond the colortune at this point it is trial and error by plug chop. Get them all a nice tan color.. It is a time consuming thing plug chops tweak... plug chops tweak you will feel and hear that you are getting closer and closer until it is right.

 

Re: As Per Rick's Carb Rebuilding - Still Popping At No Load

With what he's said, doesn't it sound like #3 is getting weak to no spark at an idle?

Which would indicate a cracked wire or connector, ignition possibly?

 

i'll continue plug chopping but I'll also look at other options like ignition as well. Yesterday I poured some seafoam in and took a highway ride. It popped at that no load point for the first 20 km, but coming back, it hardly popped at all which was a blessing. Will try it again today to see if it's gonna pop again. In the meantime, if the plug chopping shows sooty plugs on some cylinders, I would want to tweak those carbs by turning that screw clockwise (further into the hole) by small degrees...correct? Soot indicates rich burning and going in should lean it out I believe. Correct me if I'm wrong eh?

 

you are correct soot mean rich= a few degrees clockwise. Now you want a nice tan color and not black. On the notion that your #3 is not getting spark when you pulled the plug was it wet or did it smell like fuel at all??

 

Actually, it was the only one that was tan!! Yet it didn't seem to colortune nicely! Will continue plug chopping I guess.

 

john,

like 85max said, is the plug covered in fuel when you pull it? or does it look like a perfectly good plug?

covered in fuel=problem with ignition
not covered in fuel= fuel or compression issue.

are you plug chopping @ ~5k rpms. 15 secs long duration

 

All the plugs were good, no wetness or fuel smell. The 3 sooty ones just wiped clean and the tan one wasn't wet either. As far as plug chopping, i would make sure the bike was under load at between 6k and 7k for about 30 seconds, then kill the engine and coast into my driveway. According to your plug chopping method, can I achieve the same result just reving it to 5k for 15 seconds or am I real dense? My beloved sometimes thinks I am lol. As it's gonna rain tomorrow, not having to ride it before plug chopping would work well for me.

 

some guys do the stationary chops. I personally do not like to rev any motor into that range 5-7krpm without load on the engine. But that is my preference. As long as you are above ohhh 4500-5000k you should be ok to do chops. I know guys who have blown up 2-stroke revving them with no load. Admittedly they did not blow for no reason there were engine problems already present and the motor would have let go down the road anyways. They just sped the process up a bit. Which in that case it is better to break down in your garage then away from home or camp( as these were on snowmobiles).

 

Re: As Per Rick's Carb Rebuilding - Still Popping At No Load

Well, I think we're making some progress here. The popping was gone for one tankful of gas with Seafoam added...now on a refilled tank without seafoam and the popping has started again. I did another plug chop today while it was popping. I decided to do it under load then coast into my driveway with the engine killed. Here are the pics of each plug. they were not wet with fuel. The colour looks good I think...the fine tuning might be working. I'll let the experts tell me how the plugs look as i'm a novice at this. Now about the popping, it's usually at 3k plus rpms when a no load ride condition happens. Suggestions?

 

Re: As Per Rick's Carb Rebuilding - Still Popping At No Load

Your Plugs are looking pretty good.
Add 1 degree of Richness to Number-4.
Lean 3 ... 1 degree. Get them all a deep tan.
A "HAIR"

The popping might not be related to Mixtures.
There are other factors to consider.

Tight Valve
Exhaust Leak
Intermittent Air Leak -- (Manifold)

You are where you need to be.
Any further adjustments you make should be just a hair.
Almost just a nudge over from where you are right now.

Nice work!
Hows the Idle?
Hows the Throttle Response?
What happens when you are Cruising and close the Throttles?

 

Thanks Rick...patience is a virtue and I must have bought the last jar of it today because I sure needed it!! I'll follow your "hair tweaks' and let you know how I make out. The bike is working so well now, it's a shame to disturb the settings. The idle was a little high but I brought it down tonight, and the throttle response is instant. Never had a bike with that kind of response to it...kinda scary till you get used to it. Turning at an intersection while shifting gives a whole new meaning to the word "gentle"! Hit a bump while doing it, your arm moves, and so does the throttle...really cool. Now when I'm cruising (no load, above 3k), the right pipes pop...when I close the throttle, the popping stops. It's just while cruising that the annoying pop occurs. I'll be trying it again tomorrow and if it pops, I'll add some seafoam to see if that works. I'm also using regular gas, not hi test. Regular gas is $1.30/liter here. Hmmm...you mentioned exhaust leak...there appears to be a bit of leakage on the right side where the pipes connect to the muffler as I'll see some dripping water from the clamp area occasionally...could this be it?

 

Forget the Seafoam.
Run some Mid-Grade gas in it for a tank.

Check for an Exhaust Leak at the Head Pipes.
If you have a small leak it will introduce enough air to cause exhaust gases to reburn.

That could be your popping.
I doubt the popping has anything to do with the Mixture you have dialed-in!
How well are the Carbs synced-up ... Vacuum wise?

 

well even if we didn't get your popping solved yet at least we got you to dial in your bike and get it running great LOL!! These X's run very nice when tuned up right.

 

Definitely!
There's no greater reward for getting the Tuning right on-the-money than you get when your on-the-road and surprise some other bikers with some dialed-in speed.

Get a bunch of Harley Boys riding together with some of them on older carbed bikes and they all need to thunder past you like they own the road.
So you watch them as they near their Red Lines passing you just to be King of the Road.

They are wound-up tight and you were Cruising at 48-Hundred rev's with another 4,000 before you need another gear.
Down shift.
Throttles.
Tach that mother up, Jack ... and tell Scottie to give you all she's got!
Push 3rd to the limit. 6, 65, 7, 75, 8, 8,500 and change. Shift!
Hit 4th and sprain your wrist! Watch the Tach because the reactor will be OK right up into the Red a bit.

You catch-up with the Milwaukee Brewers and show them how well you got the bike you found, and cost you less than one of their payments, all tuned-up and running good!

That's when you know you're havin' some fun!

 

Re: As Per Rick's Carb Rebuilding - Still Popping At No Load

Rick you have a mean streak that I admire greatly I'm waiting for my chance to wipe the smile off their faces....

 

Rick:

I love your descriptive sense of humour!! As I've never owned such a fiery beast, letting the revs go above 4500 is really hard for me (Venture days). I'll start experimenting until my courage leaves me comfortable at higher revs...can't wait. I'll definately try higher grade gas plus check for a leak at the headers. What kind of torque setting would you use? Those studs are pretty wimpy! I've synched the carbs really well as I do it on a regular basis. You guys are awesome and Rick, keep up the sage advise to everyone on this excellent bike and site! Time to go for a ride.

 

I know you should torque them; but I really don't.
I just lay a wrench on them to check that they aren't and ready to fall off.

If you have run with a lean condition for a good while; it is not uncommon to find SMALL leaks at the Exhaust Header Collars.
The Flange Donuts get cooked if the Mixture is too Lean and burn through the center to the edge.

Having a Flange Donut get burned through can be a very frightening situation!
The Exhaust Leak that happens when there is a leak at the Header Collar can sound more like a really serious Engine Knock making you think you missed that shift ans Spun-a-BigEnd or caused a Connecting Rod to knock.

You can't even find the leak, sometimes.
That's the frustrating part about having the Header Donuts burn-up.
But, you do hear them making their scary noises on you.

 

The flange nuts were loose on both right side headers and I tightened them up. Will try the bike out tomorrow and see what happens. i must say that the throttle response is awesome and the power is there in spades. The donuts appear to be in good shape, they were new about 3 weeks ago before I got her on the road, so if it were lean, it's only been that way for 3 weeks...about 800km in total.

 

Exhaust leaks will give the same type of pop one might hear from carbs....especeally when off the throttle say when going downhill.

 

Looks to me like we are going to be adding you to the list of those who are:
"Dialed-IN"

Now, don't go for too long without looking at your Plugs to make sure you're not too close to Critically Lean.
Critically Lean will cripple you.

I think you are in good shape, though.
You'll know by looking at the Odometer.
Having a Bike that's on the Hairy-Edge is tough to leave parked when it's nice out.

I suspect you'll be watching the miles add-up and grinning at yourself for bringing that Bike to where the Fun Factor is out of sight!

Nice work.
Stop by the Office and pick-up your "Tweakers License"
You earned it!

 

Gee Rick..Nova Scotia to Mass is around 12 hours drive time...would even have time for a coffee before heading back up eh??

 

Re: As Per Rick's Carb Rebuilding - Still Popping At No Load

Ok guys...tried higher grade of gas, still popping and backfiring at high revs. I've also noticed that when I start the bike hot or cold, the right side muffler doesn't make the same level of noise as the left side, but after about 10 seconds or so of playing with the throttle, it comes to life and the sound is even on both side. Could this be a plug wire or coil or efi? Although plug chopping shows things are good tuning wise, could a misfiring cylinder cause this popping sound while cruising and the decreased sound on the right side? Clutching at straws here but it's driving me nuts! Could an intermittent fuel line narrowing cause the popping noise? My line has a couple of sharp bends in it but the in-line fuel filter shows gas in it about 1/2 way up. Thanks again folks.

:?

 

If you have a miss ... for some unknown reason ... the unburned fuel gets its chance to burn (and pop or backfire) within the next time the cylinder fires and the hot exhaust gases ignite the rich exhaust mixture not yet out the tailpipe.

Depending on the Mixture and the amount of unburned gases in the Exhaust System ... the resulting ignition of those unburned gases can be powerful enough to split a seam or burst a weaked spot in the Collector of one of the Silencers.

Fortunately, the amount of unburned gases isn't very much when the Engine is running and the miss is intermittent.

But, if you were cruising along and inadvertently hit the Kill Switch and shut-off the Ignition for a short period ... then, returned Power to the Ignition after a few moments ... the resulting ignition to the unburned Mixture that had accumulated in the collector and/or the Mufflers would be enough to cause them to explode open.

A miss can occur for a great number of reasons.
Some of the most common reasons are Improperly Gapped Plugs, Spark Plug Wires breaking-down and discharging to Ground, Weak Supply of Electrical Current to the Primary Connections and Moisture making a path to Ground lessening the Output of the Coils to the Plugs.

If you have been over your whole Ignition System and have not found a fault that can be blamed for causing a misfire ... another factor to consider is "Age."
The Coils and Wires could be simply be "Getting Old" and becoming unreliable; needing to be replaced or upgraded to a more reliable set of Ignition components.

It would be impossible to detect using just a Multi-Meter and checking known values for within Specs.
The Bike would have to be hooked-up to one or two pieces of diagnostic machines and run; while watching scopes to determine what is is and under what conditions the misfire occurs.

The charges for the testing equipment time and technicians labor would cost more than it would for you to buy new coils, wires and plug caps and have a new and improved ignition system placed on the bike.

 

Rick:

That's my suspicion as well. As I stripped the bike down for rebuilding, I measured the coils and wires and once in a while, the resistance would jump but come back to within specs. This could be replicated by moving the wires or tapping the coils. But even that stopped before I put the bike back together. The plugs and caps are new, but I'll try reversing the coils to see if the popping switches sides...can this be done? I suppose reversing the coil inputs and outputs will do it right?

 

Yes.
All you need to do is SWAP the two Plug-ins from the Coils to the Plug-in Connections on the Wiring Harness.

That will effectively cause the Coils to fire the opposing Holes.
If the problem shifts to one of the other Cylinders ... the Coil's bad.