extreme popping and back firing - help

[cntnvision]

Ok. I bought a 1999 Venture a few weeks ago. I know the last guy that had it let it sit for about 3 years. He also apparently tried to do some exhaust mods to the stock exhaust and totally butchered it. The bike runs pretty good so I thought I would take it into the local shop and have the carbs cleaned and synced. They did but it still backfired a lot. They said it was the bastardized exhaust causing the issue. So I bought some LA Custom slip-ons. I just put them on and it did not fix anything. Sounds louder and good but still backfiring. This all happens with little to no load on the engine. I also note that if I am in 3rd or 4th gear and cruising along and decide to speed up a little, it tends to bog. I told the local shop this and they said I need to rejet. I'm very new to Yamaha and know very little about their engine setup. It is just plain embarrassing to ride like this. I've hear different things about some circuit that is supposed to open something up during decel, low load, etc. to let more air in or something. What do you guys think? I know somebody has the answer and I'm not quite sure that the garage has the answer. I already spent money on a new exhaust that they said would fix it. I'm running out of money. Any help would be greatly appreciated. I have not replaced the plugs yet.

 

Thank you.

[eusa1]

Tom,

give me a call this evening if you have time to be near the bike, and I will help you fix it.

call me after 6pm and we will get it taken care of. 8154400287. call or text

[cntnvision]

You are the man. Not a single pop or backfire now and all fixed through text messaging. Incredible.

[Bert2006]

So what was the issue

[cntnvision]

So simple. But it took someone with know how to tell me how to fix it. So the backfiring and popping was coming from the AIS circuit. From what I have learned and been told is that puts more air into the exhaust to help burn anything fuel that is left over after combustion. So, we disconnected the front and rear AIS connection and put a cork in each of them and put the tubing back in place. I didn't have any corks so I went across the street to a local Italian Restaurant figuring they would HAVE to have corks. They did and gave me a few. One cord is awfully long so I cut one in half. Put one half in the front circuit and other half in the rear circuit. put the tubes back on and started it up. I just couldn't believe my ears. No popping or backfiring. So I took it for a test ride. Perfect. Just incredible.

[eusa1]

just leave a quarter near the keyboard, I'm working up to the cost of a quality root beer!

[videoarizona]

just leave a quarter near the keyboard, I'm working up to the cost of a quality root beer!

 

 

That's going to be hard, Mike. The last soda fountain in Phoenix no longer serves the old style root bear and I haven't seen an A&W stand in a while.

Dad's isn't on to many shelves either. There was a old time name that sold the best root beer in bottles, haven't seen that in so long I no longer remember the name. Maybe it's still back East...

 

I love good old fashioned root beer!

[eusa1]

The best is located rite here in Oglesby Illinois and I'm a regular customer there and often.

they still make it 300 gallons at a time. I host a root beer run there every year on the last Saturday in June.

 

That's going to be hard, Mike. The last soda fountain in Phoenix no longer serves the old style root bear and I haven't seen an A&W stand in a while.

Dad's isn't on to many shelves either. There was a old time name that sold the best root beer in bottles, haven't seen that in so long I no longer remember the name. Maybe it's still back East...

 

I love good old fashioned root beer!

[videoarizona]

(I host a root beer run there every year on the last Saturday in June.)

 

Illinois. Sigh. Why cant all the good things be located closer to me! If I rode up to your part of town, I could visit Venture riders for 2 months and stay within 500 miles of you all. Guess I should start thinking of a road trip back East!

 

[eusa1]

I know most of them, pick a route!

[djh3]

Last A&W I remeber going to was in Plymouth Wis. Still was a mom n pop private job, had good grub too. IBC makes a good old style root beer.

[RSTDdog]

While you cured the symptoms you technically didn't fix the problem. The problem is not the AIS. If carbs are tuned correctly and floats are set properly these bikes will not back fire or pop with the AIS fully functioning. While you removed the air supply to the exhaust to stop the ignition of un-burnt fuel, the un-burnt fuel entering the exhaust remains. Subtle point but Carbs are running richer than they need to. Plugging the AIS is easier than working on the carbs and most shops don't take the time and care to clean and examine carefully. My guess is your floats are set incorrectly, the needle valves are worn, the orings on the seats for the needles are leaking fuel by or some combination of these three.

[cntnvision]

While you cured the symptoms you technically didn't fix the problem. The problem is not the AIS. If carbs are tuned correctly and floats are set properly these bikes will not back fire or pop with the AIS fully functioning. While you removed the air supply to the exhaust to stop the ignition of un-burnt fuel, the un-burnt fuel entering the exhaust remains. Subtle point but Carbs are running richer than they need to. Plugging the AIS is easier than working on the carbs and most shops don't take the time and care to clean and examine carefully. My guess is your floats are set incorrectly, the needle valves are worn, the orings on the seats for the needles are leaking fuel by or some combination of these three.

 

I get that. I have been told that the AIS circuit is there to burn extra fuel in the exhaust. Someday I will have to have them looked at again. I've put a bit of money into this bike to get it running and I just can't stand the thought of paying the local dealer another $350 bucks to do it again. Although I think he should do it again for free since it wasn't right the first time.

 

At least I can ride it. It runs good and sounds good. But I do agree with you. Just happy to be able to ride again.

[eusa1]

well, as long as we are not fixing the problem and only making the requested noise to go away, lets dive into the problem a little further:

 

The dealer may very well have set the carbs to all the proper settings to try and compensate for the butchered exhaust that was on the machine at the time... do we know? guess not. and now we have an aftermarket set of slip on mufflers that may or may not have exhaust leaks at the poorly designed clamping system that comes with most all aftermarket slip on mufflers.. do we know? guess not? .. then there is the remote chance that this bike has a y pipe/ header pipe leak at a weld on the right bank, as I have found on several occasions while trying to help a fellow member fix, or in other members words cure the concern.

I asked all the questions about the owners concerns about disabling the Ais before making my suggestions before calling him and walking him through the "not fix" procedure .getting shot in the foot for helping a fellow club member is better received if they know all the information involved in the request for help, and they have a better answer than to suggest a dart board of possible repairs that could cost the owner hundreds of dollars to repair a concern that he just wants a quick cure and maybe not a fix for.

my idea did come with a full money back guarantee also.

[VerntureVet]

Nice fix (or band aid) however you look @ it. AIS does nothing for the bike it is purely an emissions thing. What @eusa1 suggested sounds like a a good fix for the complaint. Now what is probably happening is the butchered gutted pipe is causing the A/F mixture to be out of tune. Typically gutting the exhaust will cause a more lean running engine in the lower throttle positions. The popping is cause by extra fuel igniting in the exhaust when the carbs lean out and the exhaust gas become hotter. Not knowing the condition of the carbs or what the shops idea of cleaning was can complicate things. The AIS was probably contributing to the popping when adding more air to an already slightly lean run. If disabling the AIS fixed the popping I would guess that it was just slightly lean on the pilot and or needle. The bogging you mentioned is a sign of lean running also.

 

Get you a wide band Air Fuel meter you can pick them up for ~$100-$150 or find someone who can loan you one. Check your A/F ratio @ idle, 1/4, 1/2, and WOT. That will tell you if you need a rejet. Running a little lean is not so bad you get better mileage but loose some power. Too lean and you can burn valves.

If you go this route and find your in the 13-15.5 range your OKish. The theoretically perfect ratio is 14.7. at 13-14.7 your slightly rich and @ 14 your optimal for power. Anything over 15.5 is running too lean and could damage your engine from too much heat.

 

I also want to add that the AIS was designed for the stock tuned exhaust. Changing the mufflers changes the effectiveness of the AIS as it injects air to a spot that is best suited in temp and many other factors to not cause the popping in the 1st place. Just like a leaking collector or clamp seam can cause the same issues because air is being introduced someplace it was not intended to be. The whole issue just may be the AIS dumping air into the exhaust where it is now too hot still due to more flow in the 1st place.

Edited October 14, 2015 by VerntureVet

[V7Goose]

You've been duped. You have a serious problem with your engine (ignition or intake), and you chose to simply hide the indications that the problem is there instead of actually fixing it. Besides NOT fixing your bike, you chose to make the air foul for all of us for no reason at all. Very very poor choice in my book.

Goose

[eusa1]

and yet they swoop in a month later to toss yet another stone into the

" I can't or wont help you over the phone, but whatever you did bothers me and could have been done better process"

this group is designed to help each other out, not shoot each other in the foot, so if your not part of the solution.. then your part of the problem...

it's due to the better idea guys, that I talked off board and shared my solution to the concern and at no time did I hear anyone else in the conversation chime in when I told him what he was creating by performing my suggestion, and that the 5 minute plug was easy to remove in 5 minutes to put things back as they were. However the fact remains that nobody else was involved in that conversation and can only ASSume what was said.

It's this type of behavior that will keep folks from helping each other on the site and break it down.

[cntnvision]

So I'm gong to add a little more here. I changed the plugs yesterday. They were all very dark on the end. They are supposed to be somewhat tan aren't they? If that is the case, does that mean I am running to rich? Oh, And I put the stock butchered exhaust back on for now. Now, syncing the carbs just makes sure they are doing the same thing right? It does not do anything for lean or richness. I'm sure there is a procedure for that. Thank you VentureVet for the info. I think that is what you were giving me but I just am not sure how to go about doing what you said. It's always a good feeling when people are willing to help. I know I'll get this bike into shape and running great again. I guess it just takes time and some hints.

[bongobobny]

You are correct, sync'ing the carbs does nothing for the richness/leanness of the mixture. To properly adjust that you need either an exhaust gas analyzer or a color tune plug...

[Bones158]

This is how I resolved my exhaust popping; I'm not saying this is your problem. I reached in under each carb and removed the brass caps covering the PMS screws. Then I turned each screw on every carb, 1 turn counter clock wise, opening the pms to a little rich as the carbs come from the factory in a lean state to meet emission standards. In your case they might of been touched before and you are running rich so you might have to turn them in (clockwise) some. Just lessen to each as you adjust them. My bike runs fantastic with the AIS still operating. No jet change out. Just adjust. lol

I do this on my lawn mower also in the spring. You adjust the carbs.

[MikeWa]

The AIS system adds air to the exhaust to burn excess fuel. The AIS system is supposed to shut down during deceleration. That is what the vacuum controlled valves are for. If an AIS valve is faulty or not getting the proper vacuum you will get popping during deceleration. If you are getting popping during normal idle or during normal cruise you are running to rich.

 

Bypassing or plugging the AIS system is a common repair often performed on the Venture / RSTD. I see nothing wrong with it. It is often an easier procedure than spending the time and energy to isolate the actual problem. That said I prefer to keep my AIS system functioning. It uses no power and does help clean the air. My personal feeling is, if I am getting popping in the exhaust something is wrong and I want to find it.

 

If I were helping someone over the telephone or via text messaging I would go as eusa1 did and just have them plug the AIS. There are just to many variables on a used bike and seen through somebody else's eyes to boot. The OP now has an operational bike and he can track down the issue at his leisure.

 

Mike

[WildBill1]

Eusa1 "you the man", good fix for all the current circumstances.

[ACE50]

I've had 2 RS. (V and TD) Played with carbs a fair bit. Always took off carb heaters (not needed) and AIS sys (also not needed). Both bikes got good mileage (over 40 MPG), spark plugs always looked good and both ran like a bat out of hell. If you worry about pollution on a over 40 MPG vehicle, I hope you're driving a Volt or Prius.

[Du-Rron]

40MPG and driving like a BOH??? The only way I can get 40MPG is to turn off the engine, with a tailwind, going downhill.

[ACE50]

40MPG and driving like a BOH??? The only way I can get 40MPG is to turn off the engine, with a tailwind, going downhill.

They ran like a BOH, didn't say I always drove like that.

Sounds like you need to play with your carb's some.