Crossover Pipe Leaks?

Getting a fair bit of popping when coming off throttle and still in gear at speed, esp when coming down a hill, but even around town and I lift. Off throttle without clutching.

Could my crossover pipe between headers be leaking air causing ignition of residual fuel in exhaust stream? Does anyone use a sealant on the crossover joints? What about the header sealing rings/washers, are these a potential leak point? Have not checked/replaced mine.

Cheers.

...Certainly could be. Could also be an obstructed or misadjusted idle (pilot) circuit, tight exhaust valve(s). I'm sure that I'm overlooking thousands of other maladies, that members will chime in with shortly. It would be helpful if you shared the history of the motorcycle in greater detail, especially the engine/exhaust

You can test for an exhaust leak rather easily when you start up from cold (ambient). You'll have about 20 seconds to run your hands all around the exhaust system after start-up before you run the risk of being burned. Check the exhaust nuts first, then the cross-over pipe and lastly the header/muffler joint.

Before you take the risks involved with the tactile test above look for visual clues, notably soot from around the joints and intersections.

Unless you removed the exhaust the most common place for leaks are cracks in the welds between the cross-over abutments and the headers.

Tune your pilot jet for best idle first when the engine is fully warmed, retest and if it's still popping then check for air leaks.

I had the same problem once. turned out it was a broken flare on one end of the header pipe which goes into the head. I'd check that too.

All good suggestions.
Re. Bike story....'74 850 had it 6 months bringing it to read worthy state. Had 8300 miles on clock which though hard to believe, seems correct for state of components etc.
Single 932 carb at the moment. I put in Vape Wassell EI, fresh plugs/wires.
During all the messing around getting the bike to run consistent over several weeks, headers blues quite a bit. Have removed bluing last week with BlueJob and Autosol. Since running about 200 miles now, getting a few patches of bluing returning, even on crossover pipe.
Will give pilot a poke through with #78 drill;check/clean/gap plugs and try to look for pipe joint leaks.

Pretty sure I mentioned blue pipes several posts ago (months) one of your first videos and suggested you prolly running too hot .... not sure cleaning the pipes is the fix .....

Agreed...but I needed to know if bluing issue had been solved by more recent changes (EI, new needle and jet etc). So cleaned headers last week to see if bluing returns...showing some blotches after some distance runs.

Blue-away is chrome away too. Don't go overboard with it.

Sorry , Have been out of your post loop for sometime .... didn’t realize you had to attempted several remedial measures .... best to go one step at a time at this point , going to have several suggestions no doubt .... good luck with it ,lots of possible causes , you will sort it out

Checking plugs...light grey at tips, light black on ceramic and body...not soot loaded. Cleaned up and confirmed gaps at. 023".
Ran #78 bit into idle jet (screw was at 1 1/4 turns out). Will fire her later today for a test run.

I'm not a serious rider, but I know many, and not one has ever commented about the blued pipes on my bike. I bought the headers brand new, the bike was running well, and I coated the inside of the each header with almost a half can of HT paint. One eventually turned blue , the other not so much. No discernible difference side-to-side between pipe temperature or the plugs.
I've concluded that when/if they turn blue is a finely-tuned variable concerning the material composition and/or plating thickness and I'm not gonna worry about it.
Batrider is correct: the more blue you pull off, the thinner the chrome will become.
Your plugs sound good, if maybe a little hot. You might wanna try retarding the timing a couple of degrees?

Retarded timing can cause the engine to run hotter and will turn pipes blue in a heart beat. I suggest that before you muck around with ignition timing that you check to see where it is set at. Something about measuring twice and cutting once.

Fill up with 97 Octane (was running 87 beforehand) to see if any effect. Does not seem so...still popping on decel. Messed with idle mix screw a bit...may have knocked the pops down a wee bit. Once I had it back home, still hot, checked the exhaust collars and they took a moderate amount more torque...so maybe some leaking there. Will ride again tomorrow to see.

not sure what octane the book say for your bike .... mine calls for 100 , this year got some race gas 114 with lead , been mixing it half and half with our pump high test (91) , I think that puts it right around 100 .... engine seems very happy , better performance , plugs clean and tan , even top end might/could be a bit quieter ..... you got a lot of things to consider ..... one change/adjustment at a time ....
Craig

Tornado said:

Fill up with 97 Octane (was running 87 beforehand) to see if any effect.

Click to expand...

Craig said:

not sure what octane the book say for your bike .... mine calls for 100

Click to expand...

The "books" refer to RON octane which is approximately 4-6 numbers higher than the equivalent US/Canadian AKI (R+M)/2 octane so 100 RON is 94-96 AKI.

https://en.wikipedia.org/wiki/Octane_rating