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poping on decel

B

bbarrows

Bicycle
put this in the wrong place the first time my bike is poping on deceleration, while I kinda like the sound, i have read that this is indicative of having too lean a mixture. if this is true are there other symptons and effects of having the mixture to lean, in particular negative ones, ie heat, milage etc. also i don't seem to recall the bike doing this prior to baffelectomy.
 
Mine was popping...well rather a backfire on decel. It turned out to be a combination of a card boot (the one between the carb and airbox) that wasn't installed correctly and/or a float valve that wasn't seating properly (I'm willing to beat it was mostly the float valve). I bought new boots and new float valve, gave the carbs a good cleaning and problem solved. Dave Muir 1980 LTD1000 - Rocket 1999 Concours - Rocket II 1997 Dyna - wife's CT-COG #3649 Merchandise Czar
 
Mine has done this when I have a dirty float valve. It will "pop" quite a bit on decel and I even get a little gas drip from air box if it sets and idols very long on the side stand. The last time it happened to me, I turned the whole bike upside down and shook it a little. Not recommended, but I've put a couple of thousand miles on it since with no more problems. Try flushing the float valves by draining the float bowls with the bike on center stand, then with the drains open switch the petcock to prime and let the gas flow for a little bit. Use some provision to catch the gas in a clear jar and check for dirt both when draining and flushing. This will usually clean the float valve. Also, how long since last valve adjustment? COG # 8062 AMA # 1084053 ROMA or Scarlet harlot acording to my wife
 
Rob, It's possible that the baffleectomy has opened up the exhaust flow a bit so that it pops on deceleration. Sometimes a lean condition will cause this to happen. Can you be more specific on when it pops - every time you decelerate, or when you wind first gear up to 5k and chop the throttle off, or just rolling off the throttle when preparing to slow down for a traffic light? (I do all things when riding, sometimes higher than 5k rpm.) If it's popping all the time when decelerating, then it may be worth looking at the idle screws. Do you know if your bike has the stock setting for the air screws? These are usually plugged from the factory and it involves taking the carbs off, drilling out the thin aluminum plate that blocks access, the adjusting the screw. We're here to help, and I'm sure others will join in to assist. Cheers, David David in Jax COG# 7898 NE FL AAD & COG Vendor www.dreamjobresumes.com preparing resumes for COG members and friends I ride a KAWASAKI ZZR1200 Euro Review http://www.motorbikestoday.com/reviews/Articles/ZZR1200.htm US Review http://www.motorcyclistonline.com/roadtests/2002_kawasaki_zzr1200/inde
 
seems to do it when I have had the rev up over 5k, then back off quickly approaching a stop or when just chop off throtle in second gear and let engine back pressure slow the bike down. carbs I am pretty sure are still factory sealed. is the access to the seal and pilot screw from the underside of carb?
 
Rob, if your bike was on the lean side already like mine then it might have a slight pop. I do get a slight pop at times when on decel when the throttle is not quite closed.After the bafflectomy I did open the pilot jets some more to cure the 2500 surge that came back. Bike runs GREAT now, just got back from a 250 mile run today, first ride in 2 weeks thanks to Mother Nature. I don't think the bike could be lean enough to do any real damage but it might be a good winter project to pull the carbs and drill the caps off to adjust the pilots. I adjusted mine till the engine pulled its highest vac on the gauge, about 28 in at idle. they ended up about 2 1/2 turns out. No effect on MPG for me, just went 245 till I had to hit reserve, was 235 before.
 
i don't seem to recall the bike doing this prior to baffelectomy. >grumble grumble grumble< Bingo, Rob. This is likely the cause. Now what to do about it? Two things happen when someone commits a baffelectomy. One, the exhaust breaths freer, so yes, the engine now is getting a leaner mixture. This has to be compensated for at the other end. Kawasaki engineers carefully balanced the carb velocity to the exhaust velocity, and vice versa, to optimize gas flow. Remember, an internal combustion engine is really nothing more than an air pump with the side benefit of being able to move a crank shaft. The second thing that happens is the exhaust pipe's normal back pressure is disrupted. This is really a misnomer, as it is really a standing shock wave caused by the rush of exhaust meeting the restrictions of the system. Once again, the engineers take extreme measure to design the exhaust so the shock wave is at a specific point in the system so that it allows the gasses to escape the cylnder via the valve, but with enough restriction to contain the flame. Obviously, now that this shock wave is either gone or farther down stream, the flame (pop) is getting father aft into the audible range. If this same mod was done to a bike with exposed chrome pipes, the pipes would now be showing a darkening blue, even possible rust, from the heat travelling down the pipe. Another side effect of disturbing the back pressure is that the interior pressure on the intake stroke is changed, resulting in more oil getting by the rings or valve seals. Ever wonder why you see a big brown stain all over the rear bumper of "sport compact" cars that have an aftermarket boomer or stinger exhaust? It ain't because the car goes so fast it craps itself. Can't do anything about the big brown stain except recommend liberal and frequent application of Simple Green, an old spnge and a water hose. As far as the popping, you can go to the carbs and try a large jet. Or live with it. And Ron, let me apoplogize in advance if I sound like I am pontificating, because personally I hate that. I'm not grousing at you, but rather the practice of "bafflectomies," which I consider butchery. At the same time, I realize that the mere fact we all ride motorcycles indicates we all do damn well whatever we please and I understand the rider's desire for a little more sound coming from the engine room. I really do understand that: my daily driver is a Corvette. But I am also of the opinion that not all the consequences of the procedure are being thought out. I would have wished you purchase a pair of after-market slip-ons, and put the original 10-ton cans on the shelf. Then, with the weight reduction and a carb re-tune, you really would have noticed a real gain in performance (albeit most of which is from the weight loss). Anyway, good luck with whatever you decide.
 
WOW Rich, I see you and I are at opposite ends of the modification spectrum. I won't take it personal that you consider these things to be "butchery", nor will I be insulted that you consider these things not well thought out. I wonder if, as time goes on and you see more of the things I do, (and share with others) that you may find a place for them in your heart of "all things connie". steve
 
I bought a used 1997 Concours (the particularly beautiful dark metallic green color) and soon found out the gas mileage was awful. I was getting maybe 32mpg around town though the bike ran good. I applied the baffleectomy and went immediately to 38mpg around town. I did some research, and found the previous owner had the carbs rebuilt and a "Stage 3" jet kit put in. He sold the bike due to bad mileage and I bought it from the dealer he traded it in at. I've baffelectomized my ZZR1200 and made some minor carb changes as well. The bike needed some carb work because it was really lean and surged and was not fun to ride in town. With all that power, you have to be smooth and if not, it really shows. Like my Connie, now long gone, some minor carb work can make a lot of difference. Winter will come to New Hampshire and it would make a good winter project, though it's not so hard that you couldn't do it now. Riding it the way it is now should not cause any damage to the bike, and it will be more fun to ride once you adjust the air screws. David in Jax COG# 7898 NE FL AAD & COG Vendor www.dreamjobresumes.com preparing resumes for COG members and friends I ride a KAWASAKI ZZR1200 Euro Review http://www.motorbikestoday.com/reviews/Articles/ZZR1200.htm US Review http://www.motorcyclistonline.com/roadtests/2002_kawasaki_zzr1200/inde
 
+1 what Steve said. I'm kind of new to all of this but I thought, I have seen right here in these forum's, dino testing results that showed that the "butcherizing" of our exhaust systems actually showed an increase in HP, with what I know first hand
 
for what it's worth, i do feel, post baffelectomy, that my bike accelerates stronger and has a smother broader power band. i haven't experianced any negative effects save the poping, which really doesn't bother me
 
Sorry, Steve, didn't mean to come across as anti-mod. For the record, I am not against modifications. Anyone who has ever seen any of the Concours I rode would attest to that. Also a review of the pictures in my camera after Fontana showed I had an eye for al the neat mods, with no pictures of stock bikes. The "butchery" comment was not directed at modifications per se, but to irreversable modifications that will, in the end, detract from the overall value and originality of the bike, regardless of the horsepower/mpg/rumble gained. The main point of the whole posting is that mods done to the outgo have to be matched by a mod of some kind to the ingo and vice versa. Ripping out the airbox and replacing with K&N single-unit filters requires an exhaust mod. If the stock exhaust is in place, things won't go well. A secondary point I was try to make is that once the bafflectomy is done, it's done. But removing the airbox, installing slip-ons (gee, are they still even available?) and other mods such as that can at least be eventually returned to stock, if the owner so desires. For example, did you ever respond to an ad for a neat car or truck you wanted only to find when you got to the sellers house it has an aftermarket sunroof (a.k.a. rain hole)? That was the message I was trying to get across. You guys keep on modding the bike. It gives guys like me something to write articles about.
 
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