To all Mechanics Back fireing

[PRNTTEK]

I have a 2006 RSTD all I have changed on it is the air filters to (K&N) and I put a set of road king exhaust on it I like the way it sounds now.

But when I throttle down to change gears I get a loud Pop most of the time but not always. Now I have read that with these changes I do not need to modify the carbs but why am I getting the backfire?

Thanks for the help.

PRNTTEK

[gibvel]

Carb sync or plug the AIS or both may be required. Had the same problem and I just plugged my AIS. Very easy here's the link to how to do it.

 

http://www.venturerider.org/forum/showthread.php?t=485

 

You'll need 2- 7/8" rubber stoppers. I had to us 15/16" stoppers from the hardware section of Home Depot in the metal drawers with all the nuts and bolts and things. I had to cut about a 1/4" off of the top of them to allow the hose to fit back on.

[gibvel]

The Venture is setup to run a pinch lean from the factory but what you've done in making those changes is to make the engine run leaner than it was intended to run. This means there is always a possibility of burning the valves in time. While everyone plugs the AIS as a quick fix the correct action is to richen the carb settings back to the 15:1 ratio where the bike is intended to run.

 

To do this you pop out the plugs over the carb mixture jets and readjust them but you need a tool to read the combustion changes while doing this. (Colortune & Carbtune)

 

This is the correct way but no one does it, only a few of us who have never had to plug our AIS because we actually know how to setup an engine.You could learn however.

 

 

Spud,

Are you coming to Fort Collins? I'd love to learn.

 

Either that, or could you do a tutorial for the Tech section?

[PRNTTEK]

Thanks to all for the replys I guess that I can take it to a good shop And have the carbs adjusted, Any one know a good place in Tampa Florida or near by. I sure don't want burnt valves and yes my bike is still under warranty and I dont want to plug any hoses if there is a correct way to do this.

[Denden]

Most dealers won't actually make the adjustments that Spud mentioned, because it would change the emissions...an EPA no-no. They will probably sync the carbs and tell you they did the adjustment you asked for. But if you follow Gibvel's suggestions, you will probably get rid of the popping, and not have any problems. Many, many Ventureriders have done this (the way Gibvel suggests) and I haven't heard of anyone having a problem with the valves. Spud is right that the engine is lean to start with, and the changes you made make it slightly leaner, but it doesn't seem to be a problem. He is right that the carbs SHOULD be re-adjusted, but most of the guys here don't do that.

[gibvel]

Denden,

 

I'd love to get the carbs adjusted correctly. Is this the adjustment you're talking about?

 

http://www.venturers.org/Tech_Library/

 

(Okay, it wouldn't let me link directly but if you go the the venturers tech section under 2nd gen then to fuel system and then to "adjusting the pilot circuit")

 

I've got a unique situation though. When I got my 99 I got it from a guy in Texas. I brought it up to 5000' so I figure it was running rich at that point. It had the BUBs on it already and regular air filters. I put K&Ns on it so I figure that's going to lean it out some but don't know if that would be a 1 to 1 trade off for the altitude. I was thinking that I could just take it to the dealer and have them do an adjustment on the EGA. Well, the guy at the dealer said it was more than just a simple adjustment and I'd have to have it re-jetted......of course that would cost $400.

 

I did plug the AIS and a good sync. and that lessened the popping. I don't know if I had it that bad to begin with though, no back firing, just annoying popping.

 

Anyway, it's getting less than stellar gas mileage as well....34.... so I don't know if it would be worth it to have the thing re-jetted or not or if a simple adjustment could make it all better.

 

[foundryratjim]

I also have a 2006 rstd. I do not believe that it has the adjustments you spesk of. They may only be on the older style engines.

 

 

 

The Venture is setup to run a pinch lean from the factory but what you've done in making those changes is to make the engine run leaner than it was intended to run. This means there is always a possibility of burning the valves in time. While everyone plugs the AIS as a quick fix the correct action is to richen the carb settings back to the 15:1 ratio where the bike is intended to run.

 

To do this you pop out the plugs over the carb mixture jets and readjust them but you need a tool to read the combustion changes while doing this. (Colortune & Carbtune)

 

This is the correct way but no one does it, only a few of us who have never had to plug our AIS because we actually know how to setup an engine.You could learn however.

[Denden]

Denden,

 

I'd love to get the carbs adjusted correctly. Is this the adjustment you're talking about?

 

http://www.venturers.org/Tech_Library/

 

(Okay, it wouldn't let me link directly but if you go the the venturers tech section under 2nd gen then to fuel system and then to "adjusting the pilot circuit")

 

I've got a unique situation though. When I got my 99 I got it from a guy in Texas. I brought it up to 5000' so I figure it was running rich at that point. It had the BUBs on it already and regular air filters. I put K&Ns on it so I figure that's going to lean it out some but don't know if that would be a 1 to 1 trade off for the altitude. I was thinking that I could just take it to the dealer and have them do an adjustment on the EGA. Well, the guy at the dealer said it was more than just a simple adjustment and I'd have to have it re-jetted......of course that would cost $400.

 

I did plug the AIS and a good sync. and that lessened the popping. I don't know if I had it that bad to begin with though, no back firing, just annoying popping.

 

Anyway, it's getting less than stellar gas mileage as well....34.... so I don't know if it would be worth it to have the thing re-jetted or not or if a simple adjustment could make it all better.

 

Yeah, that's a good article. It's what Spud was talking about. But the article is just a "ballpark" adjustment that will work in most cases. I think Spud meant going into it a little more. But this article will work in most cases.

BUT, not in your case. Changing alltitudes like you did usualy means re-jetting, and re-adjusting the pilot screws more exactly. The pilot screw just adjust mixture at idle, and at very small throttle opening. Re-jetting adjusts the mixture for the entire throttle range. Your gas mileage will end up better, and probably slightly more power and all around better running. I'm sure you noticed the soot build-up on the outlet of your mufflers. There is an article in the Ventureriders Tech library on how to re-jet with pictures.:

http://venturerider.org/forum/showthread.php?t=502

But an altitude change re-jet will reqire different jets than are in the article. If you are mechanically inclined, re-jetting isn't really all that hard (if you have the article and pictures to help). Ask on the forum if there are others in your area, what size jets they are using. Your dealers $400 is only a little high but in the ballpark for the time it would take. You could do it yourself in a day, or at least in a weekend. but the question would be what size jets to use.

-------------------

(from the Venturers.org tech library)

(For second gen Ventures and 2005 and up RSTD)

Adjusting the Pilot Circuit

 

Contributed by Dan Abbott The backfire is caused by too lean a setting of the pilot circuit. This causes hotter exhaust gas temps. which ignite any unburned mixture in the exhaust pipe. On a cold day, these temps would be lowered by the ambient temp enough to prevent backfiring. This is no mystery, it just confirms the too lean pilot circuit.

So, how to fix your backfire problems in the 99 venture?

1 - Why

 

The Backfire is caused when coming off or going on the pilot circuit of the Mikuni 32bds carbs. In other words, coming of idle or decelerating with the throttle closed. The pilot circuit mixture is preset to a too lean position at the factory. Too lean means that the fuel air ratio is more air than fuel, resulting in high combustion and exhaust gas temperatures. When the super heated exhaust hits any unburned fuel mixture which is in the exhaust pipe/muffler, it ignites it and your bike says Pop POW Bang etc. 2 - How to fix it

 

a. Fire your mechanic and learn to fix it yourself.

b. Get a service manual and 4 tube mercury manometer for syncing carbs available in any city or by mail order from any one who sells motorcycle tools (try Vance and Hines or motorcycle accessory warehouse.)

c. Read and understand the simple procedure for synchronizing the carbs. This can be done without removing the tank seat or anything except the two rubber caps covering the intake manifold vacuum access tubes on cylinders 2 and four and the two vacuum hoses on cylinders 1 and three.

d. Synchronize the carbs. You should do this annually. Note: YOU CAN FIX THE BACKFIRE WITHOUT SYNCHRONIZING THE CARBS WHILE WAITING FOR YOUR SERVICE MANUAL BY DOING THE FOLLOWING PROCEDURE FIRST. BUT DO THE SYNCHONIZATION AT THE FIRST CONVIENIENT TIME.

Now for the good stuff, which is not in the service manual, but which every mechanic who is worth a rat's behind should know.

e. Here is how you change the mixture in the pilot circuit quick and dirty.

The pilot mixture screws are hidden behind removable brass caps which look like an upside down paper cup with a 0.1mm hole in the bottom of the cup. These are about the size of a pencil eraser. These are located on the insides of each carb (toward the center of the bike). You can see and access the ones on the right side carburetors #3 and #4 by looking through from the left side of the bike, and access the left carbs #1 and #2 by looking through from the right side of the bike.

Using a long slotted screw driver, pry off the brass covers (they come off very easily). Throw the covers away, you won't be replacing them. You now will be able to see the pilot screws with a cross pattern on each head.

Turn each pilot screw counter clockwise exactly 1/4 turn out (90 degrees) Note the original position of the screw and be sure you turn it only 1/4 turn.

This will fix your problem.

The complex way to adjust the pilot screw is to use an exhaust analyzer probe on each cylinder and adjust for 2 to 2.5 % CO and 600 to 800 PPM hydrocarbons. But since the factory gets it close, but too lean, the 1/4 turn method will work fine for you.

[Denden]

I also have a 2006 rstd. I do not believe that it has the adjustments you spesk of. They may only be on the older style engines.

Hey Jim, all the Royal Star Ventures and Royal Star Tour Deluxe 2005 and up use the same carbs. The idle mixture adjustment screws are hidden under a brass cap, about the size of an empty .22 shell. Described in the article I copied from the Venturers (above).

[gibvel]

Yes, I do notice the soot build-up but they were that way when I got them. So, does that mean the guy before me was running too rich?

 

The guys at Fort Collins Motorsports have been pretty good to me when it comes to work, that's for sure. I AM mechanically inclined but I'm really not wanting to get into all that it takes to do the carbs.

[Denden]

Gibvel...there is another article on the Venturers.org tech library under "performance". It's about how to open up the hole in the airbox so the engine breathes better. it will allow more air in, and might work to lean out your engine a little. It might be worth a try if you don't want to get it re-jetted for $400.

Copied from Venturers.org tech library:

-------------------------

Air Inlet Hole

 

At the front of the air filter housing, where the air enters, is a 1-1/2" hole behind the D shaped cover. The engine needs air, so I got a Dremmel tool and cut out the opening to match the D shaped cover leaving a small lip for support. It makes a big difference. The small hole from the factory is there to keep the noise level down. I heard no increase in noise, just more power. I did not rejet the carbs or install different mufflers. Yamaha spent millions of dollars in time and R&D to make it run the way it is. This just makes it a little better.

-----------------------------

[gibvel]

Thanks Denden, but I think I'm just going to suck it up and pay the cash and have it done right. Would it hurt the engine any to drive it like it is for awhile?

[Denden]

Thanks Denden, but I think I'm just going to suck it up and pay the cash and have it done right. Would it hurt the engine any to drive it like it is for awhile?

No, it won't hurt at all. A mixture on the rich side won't do any damage. Well, except use up more gas, and stink up the air. If you're getting 34 mpg, it's not extreme. As a matter of fact, you could probably skip the re-jetting and go on as you are, if you don't mind the gas mileage and slightly poor performance.

I was wondering...how much time do you spend at 5000ft, and how often do you ride at lower altitudes? For instance, my bike is tuned for near sea level. But a coule times of year I head for the mountains. I don't get as good mileage up there, and I feel the power drop. How does it go in your position. If you get your bike tuned for 5000 ft, and go on a trip to the plains, your bike will run slightly lean. Would an extended trip at sea level be lean enough to cause engine problems? I don't know, I'm not experienced with how much of a jetting change is involved.

Anyone have any input on this?

I'm just curious.

[gibvel]

Well, I live at 5000' so I'd say the majority of my riding is done at 5000 and above. I've not really taken that many trips but it would be nice to go all over. If I did go down would a change to regular filters help richen the mix enough to get some make a difference. I also have the old pipes and I could change all of the above out if that would help.

 

Don't know if that answers your questions or not.

 

I had a question about the "soot" in the outlet of the mufflers. Since it was already there when I got the bike, and the guy had it in Texas, does that mean that he was running it rich down there as well? He had the carbs overhauled in July of 05.

[BuddyRich]

Mine is pretty much stock and I get soot on the mufflers. But she still sounds like she's runnin lean when its hot out. I would say just ride it. That way your good at lower elevations also. Check your plugs. if they are the right color don't mess with it

[Leland]

Well, I live at 5000' so I'd say the majority of my riding is done at 5000 and above. I've not really taken that many trips but it would be nice to go all over. If I did go down would a change to regular filters help richen the mix enough to get some make a difference. I also have the old pipes and I could change all of the above out if that would help.

 

Don't know if that answers your questions or not.

 

I had a question about the "soot" in the outlet of the mufflers. Since it was already there when I got the bike, and the guy had it in Texas, does that mean that he was running it rich down there as well? He had the carbs overhauled in July of 05.

Mark,

 

I've got a combustion analyzer that I use on boilers. But I don't know where these engines should run, plus If we stick the probe in either exhaust, we'll be reading two cylinders.

 

Does anyone know what "% O2" (oxygen) readings are typical? (20.9% O2 in air). Also typical CO (carbon monoxide) in parts per million?

 

Leland

[PRNTTEK]

Well I took the easy way and pluged the AIS ports front and rear and it did the trick no more popping or backfires , I reconnected the hoses still looks factory so I guess when I go in for my maintenance they won't be able to tell. Thanks for so many replies.

 

Do I need to have the carbs sinked up as it seems to run just fine?

[Stoutman]

Go ahead and sync the carbs. A good carb sync makes this bike and entirely different animal.

[Guest GUZZI]

My 06 RSTD had the usual EPA lean pop back on decelleration. Looked over the emissions reroute like others had done, but decided it was to much hassle. Simply purchased the Dyna 3000 ignition module; set the dip switch to #3 position, and installed. Now my stock pipes not only sound good, but the annoying pop is so little, it actually sounds correct, and does not annoy! Set the rev limiter to 7000, and picked up performance, and also fuel mileage. Easy install and cure for the lean condition, if you want to spend the money for the module.

GUZZI:sun:

[Al Bates]

Popping or Backfiring. AIS (Air Induction System)

 

This may not be the solution for some folks. There are many ways to do this. This is how I correct the popping or backfiring on my 2002 RSV. I purchase the RSV used with 6000 miles from a dealer. On the way home I heard this popping or backfiring noise. I return to the dealer and explain the problem to him. He kept the bike for 4 days. When I got it back it started popping again. Then I decided to look into this myself. After looking over there work I have to say I was surprise of the poor work men ship. They half way plugged the AIS system and said it was fixed. I then research and figured out how the AIS works. To make a long story short I found that fuel was leaking from the carburetor and running down the carburetor manifold into the vacuum port then down the vacuum hose to the back AIS air cutoff valve. This 1/4 inch vacuum hose controls the AIS air cutoff valve. What I found was that fuel (maybe from seating) run down to the AIS air cutoff valve and prevented it from working properly. My solution was to plug the four AIS cylinder ports. That's were it all starts. (See picture) By plugging the AIS tubes that would eliminate the AIS from that point on. Now all the AIS can be removed. (see other post on how to permanently plug and remove the AIS) I decided not to go this route because of the warranty. This is my fix. Follow the rear steel cylinder AIS tubes down (see picture) there will be a short 1/2 rubber hose at the end of each pipe. Remove the short rubber hose and place a marble or still ball bearing into the 1/2 rubber hose (lubricate if you wish). After installing the ball bearing or marble move it up until it touches the steel cylinder pipe were the rubber hose slips back onto the steel pipe. Replace clamps. Do this to both rear cylinder pipes. Next I placed a small steel ball bearing into the 1/4 inches vacuum hose from the carburetor manifold. (this is on the opposed side) (left side setting on seat) next to carburetor. Slide the 1/4 inch ball bearing next to the manifold port. Install the clamp (see picture) I did the something to the front AIS tubes. The fronts are arrange a little different. I did not fine any fuel in the front AIS air cutoff valve. The front requires pulling the bottom of the radiator away so I could get to the short 1/2 inch rubber hoses. I had to drain the radiator first. It seems to be only the rear causing the problem. A friend did only the rear. We spent about 15 minuets and it corrected the problem. (stop the popping) I sense help a few others this way. I hope this helps.

 

AL Bates

[gibvel]

Well, just got the bike back from being "re-jetted". Cost far less than I was told because they didn't re-jet the thing. They just did a CO adjustment. Okay, that's what I wanted you to do in the first place why did you tell me I needed to re-jet......DUH!

 

They said that they like to keep the percentage at about 4% and mine was running @ 1.8% or so. Popping is gone, even with the AIS returned to normal. Is it my imagination or is the exhaust quieter as well. It didn't seem to be nearly as loud as it was before but I can't think of an explaination as to why that would be so, I figure, I'll just chalk it up to not rememebering as well as I should.