Loud Exhasut popping, Question??

[Lee Harvey Griswold]

Hey fellas, So I just got my bike all wired up and have been taking some short runs around the neighborhood! It seems that when I fire it up its missing pretty good on the left side and popping pretty loud out of the left side pipe! Ive already replaced the plugs, tightened down my pipes, and connected a hose between the two vacuum ports on the carbs which helped a little, but its still doing it! The bike would run solid if it wasnt for that issue! So any suggestions on whats going on, or places to look at would be greatly appreciated! Im running stock jets, pod filters, and g.scott exhaust.

Thanks again guys,

LHG

 

[Inked Monkey]

I'm running the same setup. I had to up the mains and pilots to get a nice tan color on my plugs.

 

[anysnail]

you're running too lean. put more fuel into your motor and you will take care of that pop. i upped my mains and rebuilt the carbs on mine. new gaskets and a thorough clean made a lot of difference and when i put in the bigger main jet it was night and day difference.

 

[Sundie]

bs38's? Recently rebuilt? What are your current plug conditions? When does it pop?

 

[anysnail]

i have the more restrictive 34's. my plugs are a light brownish grey and it used to pop during deceleration and when i'd grab the clutch. especially when i would be slowing down from highway speeds to turn. it would crackle and pop like a demonic bowl of rice crispies.

 

[kent_in_kc]

As you know, an exhaust leak will do that for sure. Did you use brand new gaskets? I like to put a skim of high-temp silicone (the copper stuff) on my gaskets to make sure they don't pop. Also, be sure you tighten the two header bolts evenly to the head. Finally, its a good idea to put some star lock or new split lock washers under the two nuts to be sure it doesn't work loose.

I'd check this before you start into the carbs.

 

[Lee Harvey Griswold]

Thanks for the reply's fellas, I cant tell you all how much I appreciate it!! So I went ahead and replaced both of the plugs just hoping that maybe I had a bad plug and was causing it not to fire on the left side.That didnt help and now Im afraid to ride it if its only hitting on one cylinder and popping loudly out of the left pipe. But when I looked the old plugs that I took out the left was dirty and little oily and the right was a nice tan color! So that would lead me to believe its running lean? Im going to do a compression check tonite just to rule out a bad valve, and then I feel I should re jet the carbs due to pod filters, and great scott pipes. And Kent in KC, thanks for mentioning that, When I installed my pipes I got from Mr Scott I never put my stock gaskets on those pipes so they are currently without them but I know they are both tightened down evenly, but will check again tonite when I run a compression check! I will keep you guys posted on this issue! My bike is so close to Rock N Rollin I just need to get this resolved quick! After all, riding time is fading fast in my neck of the woods!!!

Thanks Again.

 

[Lee Harvey Griswold]

Thanks for the reply's fellas, I cant tell you all how much I appreciate it!! So I went ahead and replaced both of the plugs just hoping that maybe I had a bad plug and was causing it not to fire on the left side.That didnt help and now Im afraid to ride it if its only hitting on one cylinder and popping loudly out of the left pipe. But when I looked the old plugs that I took out the left was dirty and little oily and the right was a nice tan color! So that would lead me to believe its running lean? Im going to do a compression check tonite just to rule out a bad valve, and then I feel I should re jet the carbs due to pod filters, and great scott pipes. And Kent in KC, thanks for mentioning that, When I installed my pipes I got from Mr Scott I never put my stock gaskets on those pipes so they are currently without them but I know they are both tightened down evenly, but will check again tonite when I run a compression check! I will keep you guys posted on this issue! My bike is so close to Rock N Rollin I just need to get this resolved quick! After all, riding time is fading fast in my neck of the woods!!!........Oh ya, also forgot to mention the popping mainly starts up when its idling and you give it gas, and at random while riding, which my buddy thought that since it's missing so bad that's why its popping when its trying to hit on that left side??

P.S. Sorry for the double post, Couldnt figure out to delete one!!

Thanks Again.

 

[5twins]

If the plug in one cylinder is good the other's is dirty and oil covered, that's not usually related to carb jetting. The jetting would effect both cylinders equally. I think you should re-jet eventually but I don't think it is the root cause of the current problem. Something else is wrong with that left cylinder. It could be in the left carb, in the ignition for that cylinder, or related internally (like rings or valves) to that side.

 

[gordonscott]

I agree with 5twins (again) but before we panic I think a good carb cleaning is due. Also you "must" use gaskets even with the tight seal my pipes provide Dissmantle carbs and clean real good and then clean again! Also use a inline fuel filter, can't hurt. Let us know how you make out and you can email me direct if need be, I'll help all I can. Scott

 

[Lee Harvey Griswold]

Thanks 5twins,....and Scott I will be sure and keep you posted on this issue! Im just leaving work now and gonna go home and check compression. If that all checks out Im guessing that it will rule out anything serious going on correct? And I am running an inline filter and will try and locate a couple gaskets for the pipes also!!!

LHG

 

[Inked Monkey]

If you're still having the problem, you can always switch the plug wires side to side and see if the other cylinder starts firing. Make sure you have both wires installed before running though.

 

[gentlemanjim]

Try one range colder plug on the popping cylinder DPRe8. Check for an air/vacuum leak, tight valves.

 

[rockdr]

Ironic. just fired a 77 up just pulled from the bone yard, doin the exact same thing. could be the carb. Just flushed the bowl out. But sure is the left and sure is popping consistantly. right is strong. The timing was off had to set to get running.will try compress check on the valve thing.