HELP help please... poppings backfires hesitation

[biofractal]

Hello everybody... lets beat a dead horse...

 

Before I post something I try to read as much as possible to avoid the repetition. However after reading and reading I need some human interaction and ideas. If this is the wrong place to post this please instruct me where is the right place.

 

On a previous thread SARNA66 posted this:

"It seems like when I twist my throttle there is an initial slight stumble..."

 

Well my case is exactly same or worse... when I roll that throttle the bike does not respond properly.. it just don't. After that initial hesitation the bike revs fine.

 

One of the ideas given to SARNA66 was to Sync the carbs. OK... good idea. I decided to purchase the new Motion Pro based on the reviews and good comments. In their instructional video they explain that you must calibrate the gauges before using it and for that you must connect all 4 hoses and I quote to " The Master carburetor". Here is link to the video http://www.motionpro.com/motorcycle/articles/view/2099/how-to_video__08-0411_sync_pro_carb_tuner/ (min 6:14 of the video)

In their video the master carb is #2. Does any one knows which one is our master carburator????? has anyone used the non-mercury version of the Motion Pro?

 

OK... that's one issue.... the other issue is the backfires and poppings...I mean, is waaaaay to much... just from revving the engine. I know the theory behind the backfire thanks to the knowledge gained reading this forum.

I have replaced the original mufflers with HD CVO Screaming Eagles. I remove everything, took out the thick fiber glass sheet wrapped around the baffles and put everything back together less that fiberglass because it provided the best sound posssible (I tried all possible combinations) Here the link to my youtube video if you want to see what I did. I made the video explaining everything so people that want to install them can replicate my mod if they like it. Also you guys can clearly hear the popping from min 10:00

[ame=http://www.youtube.com/watch?v=TqS323IDYp8]Yamaha Royal Star Venture exhaust mod screaming eagle mufflers - YouTube[/ame]

 

Also new spark plugs, new air filter (UNI filters) and I haven't block/plugg the AIS yet.

 

A friend of mine who used to be a motorcycle mechanic when he was a civilian (we are both Navy now) tells me that I must tune the carbs, then sync them. Reading about backfires and running lean etc I decided to give it a try and adjust the Pilot jet screws to make the mix richer. The bike had the copper protective caps, so I assumed that the haven't been touched ever. 12000 is the millage of the bike.

I started with a 1/4 of a turn as recommend in this forum. Nothing.... I gave it another 1/4 turn, no changes. I end up having each screw with a total of 4 full turns,... same result... don't know what to do.

 

In conclusion and summary:

#1) Hesitation when revving the bike from Idle

#2) Screaming eagle mufflers intalled (watch the video so you know who I modified the muffler), UNI Air filters same as K&N but cheaper and new iridium spark plugs.

#3) A lot of popping and back fires...

 

Ok guys... don't let me die here... THANK YOU IN ADVANCE

[Venturous]

With bike running, take a propane grill lighter and run it slowly around all your exhaust system joints. If you see it blowing the flame or sucking it in... you have a leak. This is how I found that my rear exhaust gaskets were shot and why my bike was backfiring. New gaskets and all backfiring stopped. You can also do same to check for vacuum leaks around the carbs, but be careful you don't have any wet gas first. A vacuum leak could also maybe effect throttle response.

 

Another thought beside the carb sync (which is a good idea) is to run some Seafoam though the carbs. Maybe you have something sticking in the carbs from being a little dirty.

[cowpuc]

Definitely do as Gary mentions, exhaust leaks can certainly cause the popping.. Also do your carb sync,, not for sure if #2 carb is master on a 2nd Gen - never did do one - but I bet it is.. Sitting on the bike, front carb on the left is my guess..

If all the above doesnt help with throttle response and excessive popping (not really sure that I would call the popping I heard on the Vid excessive,, running open pipes usually makes some poppin and snappin) here are some thoughts.. Most of the Uni's I have used on both dirt and street bikes tend to supply more air than stock.. Couple that with running open pipes and you end up with a scoot that is able to flow alot more air threw the boom chamber.. That results in running lean.. IMHO and experience in toying with this stuff,, this leaned out condition usually shows itself right off idle and up to the mid range by an off idle hesitation and unhealthy throttle response.. Almost like a weak accellerator pump on a carbed car..

The most effective way to fatten em up is by raising the slide needles.. My 83 got so tired that she couldnt handle the fuel she was getting,,, making her fat on the bottom.. I tweeked Tweeks (thats her name - Tweeks:)) by dropping the needles 70 thou and it worked great.. I did her by using nylon washers (the 1st Gens have "non adjustable slide needles,, suppose to anyway:whistling:).. In the process of doing that I had someone - I think it was Skydoc,, mention that he sells the kit for doing this.. Not sure if the 2nd Gen is adjustable or if you have to use the ol nylon washer routine..

I would definitely follow Garys solution first,, might get lucky and find a pipe gasket in rough shape, bolt missing in a pipe or whatever... Also, complete a sync on your bike cause that could cause it too BUT,, again,,, from listening to your bike,, I gotta hunch your main issues are its flowing more air...

On another note,, I personally have not had that good of luck with Iridiums,, may sound nuts but those good ol standard spec NGK plugs always seem to work best for me,,,, course,,, folks in the hood here say I am a little strange and so is Tweeks so take that bit of advice for whats its worth:rotf:

BEST OF LUCK GETTING HER WHERE YA WANT IT BIO!! LOVED YOUR VIDEO - THANKS FOR POSTING IT!!!!!

Puc

Edited October 15, 2014 by cowpuc

[tz89]

Yes do investigate air leaks at the pipes and carbs. Find em and fix em. I had a carb port cap that was cracked and leaking.

 

The idle mix screws adjust the mix of the idle circuit. The bike runs on that at low RPMs and the circuit is part of higher RPMs too. You didn't say which way you turned those screws but I presume you turned them out 2 turns. That made your idle richer. You may notice that you don't need as much or any choke on a cold start. I'm glad you counted your adjustment - put them back. Adjusting these is more art than science imho and so if your adjustment didn't make the difference you wanted put them back for now. I do mine by 'ear'.

 

If increased airflow has leaned out the bike then you will be rejetting or adjusting the slide needle shim height. I don't have a 2nd gen so I don't know exactly what you have to work with. Reducing shim to the needles on the slide leans out the primary circuit, and so increasing may make the circuit richer if it is possible to do this. I think this is true - we have carb experts on here but I'm not one of them. It is typical on other bikes to rejet after putting on new pipes.

 

Popping is from air leaks or from the bike being too lean for some reason.

[syscrusher]

I may be completely wrong but many newer bikes have catalytic converters and an air injection system to help consume unburned fuel in the cat. Since you changed mufflers you wouldn't need these and the extra air in the exhaust steam will certainly cause popping from fuel detonation in the muffler. On fuel injected bikes we add a little more fuel to the map at near closed TPS and higher rpm to stop decel popping. I don't know the 2nd gen that well but I thought I read a thread here where someone had capped the air lines using some socket cap screws. Look into this, and enrich your mixture to keep the fuel/air ratio in the sweet spot. As has been said you're flowing more air and more air needs more fuel for a constant (effective) ratio.

[biofractal]

Hey thanks for your ideas... it was raining today in the afternoon so I couldn't check anything. I will give you some updates soon. I received today my Motion Pro.... can't wait to use it.... but still not sure which one is the master carburetor.

 

I was reading a lot about plugging the AIS... some are Pro plugging some against it. I think i will give it a try.

 

COWPUC said that he doesn't hear that much pooping... the issue is that is a cell phone video. I have a warrior with Vance Hince pipes and it does pop now and then.. but this way to much for just revving the bike... I know something isn't right.

 

A question for VENTUREOUS: what gaskets are you talking about? the ones that are between the exhaust and the engine? I kinda rock back and forth (to the sides) the pipes when installing the mufflers, because my left hand is not fully functional right now, so I had to wiggle the old mufflers out and the new ones IN.... maybe that caused the pipes to get loose in the front... would check using the grill lighter as suggested.

 

I forgot mention that when I bought the bike 3 month ago i was not running. I pulled the carbs they were super dirty... with green sludge and stuff....and clean them following all the instructional videos and manuals I could find. I did not touched the floats calibration. I clean them and put everything back. The bike runs perfect with no hesitations at any speed ... I did run two tanks with sea foam. The bike was popping a little but not like now.

 

ok.. got to go for now... will caught up with you guys later... keep and eye on my coming posts.

[videoarizona]

Bio,

 

Yep..you are running lean. Not much actually...just enough to cause the popping. An air leak can cause same as well as an exhaust leak. But I'm betting lean due to less restriction in the pipes.

 

I had the same problem with my last carb bike. Changed exhaust and made it more free flow caused an overly lean mixture...corrected by re-jetting in my case.

 

One thing to think about...running slightly lean is good for gas mileage!

You might consider taking bike to a dyno shop and have them run a test. Just to see how lean you are running...might be OK...(unless the popping really bothers you)

 

To richen the carbs, either re-jet or shim the slider... I personally don't know what would be best for your bike...

 

Sounds great though!! Thanks for the video...

david

[midnightrider1300]

my 2010 was POPPING badly and I didn't know what to do...turns out I adjusted the IDLE UP, and no more popping.... Some may scoff at this, it has NOT popped 1 time since I upped the idle...

[biofractal]

here is some updates... hopefully somebody will read them...

 

I got the motion pro to sync the carbs. Based on the description and the instructions the master carburetor is Carb #2, since all the cables (throttle) are connected here. I followed the instructions carefully reading twice. When was time to calibrate the tool (this is why you need to know which one is the master carburetor) I started the bike and all the liquids columns started to rise......... almost all the way up... I knew instantly that something was not right. After a lot of thinking and guessing; two things kept coming to my head:

#1: I didn't know how many rpms my idle was because I don't have a tach..

#2: The bike must be tuned before sync the carbs.

 

I turned the idle screw up and the columns started to go down to a more normal level. However the bike keep increasing and lowering the rpms by itself.... up and down... in a low pace... don't know why.

I also returned the pilot jet screws back to zero, then give them 1 full turn out. Before they were like 3.5 turns out to try to enrich the mixture and get rid of the poppings.

 

After this was done I managed to "Sync" the carbs... the hesitation when rolling the throttle from idle improved a lot. The Popping was also improved.... not for too long... Today I started the bike and even when she was ready up to working temp.. the hesitation and the popping came back. I was pissed.

 

To make a brief pause here.... When I got this bike it was not running... the carbs were an absolute mess. I pull them and clean them to the best of my abilities given that I have never done this before. I put all together and the bike has been running without problems, and I still feel proud about it. However I knew I need it to tune and sync them... but I don't have $500 plus to pay for that. This is why I have tried to do it myself.

The fact that I changed the mufflers for the HD CVO made things a bit worse.

 

I wonder... what the heck am I doing wrong... something must be. The bike idles Ok... revs with a lot of popping ... and I can' t test drive it at the moment due to my hand injurie...

 

For now I am done... I decided to purchase a book about fuel systems to learn more... and stop guessing. It shouldn't be this hard... but for some reason it is.

 

Thanks for all your advice and time... if you want to keep throwing ideas please do so.... its refreshing ....

[midnightrider1300]

try turning the idle up.... and then back it down....When I got my bike I have now it backed fired awful...I adjusted the idle upward and back fire stopped.... I don't have a tach, but I know the idle is noticeably higher....sounds like a HD idle...

[biofractal]

I tried that... but is not helping..

[tz89]

If your idle speed is wandering by itself that suggests you have an air leak. Since you pulled your carbs that may be where the leak is.

 

You probably are still lean. Setting up the idle speed means you are drawing from the primary circuit a bit and thus covering the lean condition in the idle circuit on one or more carbs. This suggests the idle screws need adjusting. But the popping could be from the new pipes, or an air leak from where they attach, or it could be something else. It is hard to isolate. In any case the air/fuel ratio is off.

[biofractal]

If your idle speed is wandering by itself that suggests you have an air leak. Since you pulled your carbs that may be where the leak is.

 

You probably are still lean. Setting up the idle speed means you are drawing from the primary circuit a bit and thus covering the lean condition in the idle circuit on one or more carbs. This suggests the idle screws need adjusting. But the popping could be from the new pipes, or an air leak from where they attach, or it could be something else. It is hard to isolate. In any case the air/fuel ratio is off.

 

I pulled the carbs like 3 month ago... and the idle never wander like that before. Lean... Yes.. almost sure of that.

There is an air leak.... the funny part is that I cant freaking know where is coming from. Is NOT from the union with the new pipes... I could say I am 95% sure. I put my hand around the union and I can't feel any air.... however I do feel air where the arrow that points "here". See the other pic with the blue arrows representing the air. ... I don't know what I can do in that regard... when I slide on the pipes the fit was really tight... the clamp is tighten to its max... and gain I don't feel air comming out of the muffller union. See the picture and imagine you are on the left side (picture is taking from the right side) you will put your finger in between the chrome heat shield and the main pipe.... obviously I did this when the pipes temp is not hot to the touch. The air that I feel is comming down... not from the side of the muffler.

[ATTACH]87604[/ATTACH]

 

[ATTACH]87605[/ATTACH]

[BlueSky]

Did it start popping right after you changed the air filters to the UNI design?

 

When someone posts on the Kawasaki forum they changed to the uni air filters, the advice is always to put the stock filter back on.

[tz89]

A wandering idle air leak is ahead of the cylinder, not on the exhaust side. Some use starter spray to determine. I've used a rubber hose like a doctor's stethoscope to listen in close. I don't know anything about the Uni filter but it is worth a try to install a stock filter. The leaking spot you point to on your pipes is close enough to the rear cylinder to be igniting - not sure if it is close enough to the front.

[biofractal]

The day I cleaned the carbs was the same day I put new oil, new spark plugs and the filters...I have no reference in regard to the stock filter.... agrrr I really wont like to just throw this ones away.... uhmmmm but I guess that will be worth trying. It will be cheaper than re-jetting the carbs.

 

How do you use the stater spray to find leaks?

[tz89]

There are posts. Basically, the idea is that if you spray near where an air leak is drawing in air toward combustion, the starter spray will be drawn in and you will notice the engine respond by speeding up a bit. This would be a good way to test whether your removal and installation of the carb set left a leak on either side of the carbs (airbox or intake).

 

If you eliminate the air filter as the problem, and everything easy like vacuum hose and port caps, then it is time to try the starter spray test.

 

My recent air leak turned out to be a port cap. I found that just by close inspection.

[Venturous]

Yes, I was referring to the gaskets between the engine and the exhaust. And I tried the starter fluid method first and that did not indicate any leaks. But once I put that lit grill lighter around the exhaust... it did not take long to visually see where the leaks were.

[Neil86]

The UNI filters...made of foam I guess?

 

They were oiled before installation, correct?

[V7Goose]

I do not know how much I can help you, since you have modified the exhaust and the intake - either of those acts can screw things up bad.

 

First, make sure you have your idle set to 1,000 RPM - if you are not very familiar with this bike, you cannot do that by ear - 1,000 RPM sounds higher than most of us would guess is right, especially if you are coming from any twin cylinder engine.

 

Based on some of the earlier posts, I suspect ongoing problems inside your carbs. A stuck choke plunger can cause surging idle - make sure they are all pushed totally in. You should not have been able to make all the changes you did to the idle mixture screws without noting some significant changes in idle speed - that suggests you have problems with the idle jets. Start by setting all of them out 3 full turns. Then with engine warmed up, turn one in slowly until the idle speed starts to drop - this will prove that the idle jet is providing fuel (maybe not totally clean, but at least working at a basic level). When the idle speed begins to drop, start slowly opening the screw until the speed stops increasing - that is about where you want to leave it. Repeat this process for the remaining three carbs. If done right, it will give you settings close to what you will get with an gas analyzer, and certainly better than the factory settings.

 

When you had the carbs out, did you set the floats? If not, they are way too low and can easily contribute to your hesitation problem. Other general thoughts on the hesitiation - this is a common problem with constant velocity carbs whenever the air flow is not correct. Since you have messed with both intake and exhaust, I'd bet a lot your air flow is not correct. A hesitation generally says that you are getting more air than the carbs can properly supply fuel to match. CV carbs have a designed-in hesitation to the vacuum circuit that slows the initial jump of the slides just to avoid this type of problem, but if your idle circuits are not able to provide enough fuel to match the sudden opening of the butterflies, then you will have it anyway.

 

If your carbs are properly cleaned and the floats set right, then you may simply need larger idle jets - this is NEVER needed on this bike unless someone has already screwed up the system by making unwise changes to the intake and exhaust without the proper knowledge and testing tools to do it correctly.

 

As for your exhaust leak at the "Y" connection - that is very common on these bikes - poor manufacturing. The joint is not welded, just crimped, and that crimp can often leave two large holes that cause the leak. In bad cases, those leaks can let enough fresh air get sucked in to cause the after-fire popping. People who are insistent that they have the right to annoy everyone else by running excessively loud pipes can often cause the same problem by removing all the insides of the mufflers. But the closer the air leak is to the exhaust port, the worse the problem will be. That is why you have been told to check the header gaskets and make sure the bolts are tight.

 

If there is not a significant exhaust leak, the after-fire problem is most often caused by screwed up carbs or vacuum leaks on the intake tract.

 

Lastly, your Motion-pro tool is total junk - I'm sorry you were mislead into buying that tool. It is better than nothing, but not by much. As for the calibration - any single vacuum source will work - this bike has no 'master' carb, so just forget about that. When you sync them, you match the left two together, then you match the right two together, then as the third step, you match the left pair to the right pair.

 

When you try to calibrate that POS, you should have a vacuum source somewhere around 10" Hg - of course, you will have no way of knowing that unless you have a proper vacuum gauge, but that is about what you should see on each cylinder at idle on this engine. One of the problems you will have using a single cylinder as your calibration source is the significant vacuum pulses you will see at 1,000 RPM. But do not be tempted to rev the engine to smooth out those pulses - that junk tool you bought wildly changes calibration at higher RPMs.

 

The spec for carb sync is to be done at idle speed. Some of us like to compare the sync at idle to the sync at 3,000 RPM or higher, just to verify that the slides seem to be operating properly and all else remains good - but you CANNOT do this with that tool, at least not the ones I tested. I wish you the best of luck getting that all sorted out.

Goose

[biofractal]

The first time I had the idea to buy a Yamaha Vmax 1st gen I backed out because I didn't want to deal with the carbs .... and here I am..... I was right some how....

 

Venturous: believe it or not I can't perfom properly the grill lighter test because I dont a garage... and is always windy... I tried but was not conclusive.

 

TZ89: I am to test everything you mentioned... plus the starter spray test. Can you perform this test with the tank on?

 

Neil86: UNI filters are foam indeed. Oiled as directed.

 

V7GOOSE: First THANKS for your time and dedication... I will try do touch all the subjects that you mentioned.

 

Idle: Indeed, I am coming from a V twin... the RS warrior... so you advice comes very handy because I am pretty sure my idle is slower than it should... 1000 rpm probably sounds a bit high to me... will try to find a tach

 

CARBS: I can't assure that I did everything right... more likely I did screw somewhere. When I put them together I tried very hard to make sure a free motion of the choke components... including the plungers.

 

IDLE mixture screws: Yes... I can see a change in the idle speed when I move them. I will try adjust as you are recommending here... set 3 turns out and go from there.

 

Floats: NO... I did not set them... didn't know how to do that.

 

Carbs cleaned: I did all that was in my power to get them as clean as possible. even used a guitar string (the firt metal one ) to clean the jets wholes that were clogged, and another part that looked like a small flute with very tiny wholes on each side of the brass.

Floats NoT SET ... tried to not even move them much. And I know... I am probably one of those making uninformed changes and messing thing up:confused24:

 

"Y" Connection: Good to know that is a common problem on this bikes.

Loud pipes: I do not believe in having the right to annoy people with loud pipes and I agree 110% with you on that. I believe in a deep throaty roar... that has a low tone which will alert distracted drives.... It has worked for me in the past saving me from getting run over.

 

Motion pro: Man... dont tell me that.. Oh wow... I am glad I bought this through amazon because I am going to return it. I did help a bit though... but I know it is not even close to a quality tool.

 

I going to do this. I am going to place stock air filters, move the idle screws as you recommend and perform leak test and see what happens.

 

 

 

Don't get me wrong... the bike is not running like a POS... is not that bad.... right know has a little bit of uneven (rough) idle... like a HD sort off idle... But after that little hesitation on the very first twist then she revs fine... even a very high rpms... but I am OCD.... I want my machine to work as she is supposed too.

 

that's why I am going like this... my weather clock is running close to zero... because the colder it gets here in Norfolk VA, the less I can work on the bike.

[bkuhr]

I also tried to clean my jets with a very small wire, but in "forcing(turning)" the wire thru the jets, I actually, unintentionally, enlarged the jets and caused issues with running performance. Ended up buying new jets to get every thing right. Just saying

[biofractal]

I see.... Sounds very reasonable... I did not force the guitar string through the hole... but hey anything is possible... specially talking about such a small hole..

 

[V7Goose]

Jets are made from soft brass - never never use anything metal to clean them. Some people say a copper wire is OK (technically softer than brass), but I won't even agree with that. The only thing I use to clean jets is spray cab cleaner in a small bowl or cup, then compressed air. If you have stuck something in your jets, you may already need to buy new ones.

 

The tech section of this site has a very detailed article on setting floats. You can also find many old threads where I have discussed this - bottom line is that not a single RSV carb is set even close to correctly from the factory. That may sound doubtful and even stupid, but in my experience with these bikes (considerable), it is a fact.

 

As for carb sync tools - the only one I personally find acceptable is the four gauge set, generally available for between $50 and $100. I have discussed this in many older threads, including very detailed reasons on what I find good and bad about the other tools. I do not suggest you blindly agree with my opinions - many people do not! Just read the information - look for facts to analyze instead of just unsupported opinions, and then make up your own mind.

Goose

[Freebird]

Biofractal, since you are relatively new here, I'm going to offer a bit of input. V7Goose is a stubborn and opinionated person. He does not just talk to be talking, what he says comes from years of his own personal and extensive experience from working on these bikes and many others. He is brash and straight to the point and some folks get put off by that.

 

I just want to day though. When he writes something, people should listen. It is generally not just speculation or an unsubstantiated opinion but facts based on his personal experience. You don't have to agree with everything that he says, that is up to each of us. I can only say that I've learned an awful lot from him and listen when he talks.

 

If he is unsure about something and only offering a suggestion of what may be possibly causing an issue, he will say that when he posts. If he has addressed the problem though and offers his advice on the do's and don'ts of what to do, always pay attention.

 

Now back to your regularly scheduled program.