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i have the carb farts

Old 09-30-2011, 04:53 PM
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i have the carb farts

its me again.
i have fixed all my issues with the carbs but one. i now have the farts at idle and between 2-3K and it some times kills the engine at idle. my current setup is two brothers pipes, stock air filter and air box, dyno jet, jet kit. my jetting set up is 175 front 180 rear main 45 pilot jets, needle is set at the 4th notch from the top with one spacer under the clip and one on top of the clip and i have 3 holes on the shuttle.
what i have not been able to find is what causes the farts. is it because it is too lean or because it is too rich?

Last edited by 3amta3; 09-30-2011 at 04:57 PM.
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Old 09-30-2011, 06:28 PM
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Originally Posted by 3amta3 View Post
its me again.
i have fixed all my issues with the carbs but one. i now have the farts at idle and between 2-3K and it some times kills the engine at idle. my current setup is two brothers pipes, stock air filter and air box, dyno jet, jet kit. my jetting set up is 175 front 180 rear main 45 pilot jets, needle is set at the 4th notch from the top with one spacer under the clip and one on top of the clip and i have 3 holes on the shuttle.
what i have not been able to find is what causes the farts. is it because it is too lean or because it is too rich?
Carb farts aren't necessarily due to a rich/lean running condition.

Have you synced them? I had them once in a blue moon because they were a tiny bit out of spec.

And what are the condition of the slides in your carbs? if one of them is sticking, under beginning vacuum it can "falter" and the engine will try running the two cylinders at different speeds and it can "fart" as well through the carbs.
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Old 09-30-2011, 06:50 PM
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the sliders are great.i did however notice the front one sticks a little when you push it open. how can i fix it sticking? the sync on the carbs was ****, i will check them again tomorrow and see if they went out of sync. i herd that you dont need the 3rd hole is the slider, is this true? i would be perfect if i could just get this problem solved.
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Old 09-30-2011, 07:56 PM
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Originally Posted by 3amta3 View Post
the sliders are great.i did however notice the front one sticks a little when you push it open. how can i fix it sticking? the sync on the carbs was ****, i will check them again tomorrow and see if they went out of sync. i herd that you dont need the 3rd hole is the slider, is this true? i would be perfect if i could just get this problem solved.
The third slide hole, when closed, is to prevent the front cylinder from becoming too rich in the mid-range IIRC.

It shouldn't solve the problem, but it can always help

If it's sticking, you can either pull it and use plastic polish and remove any marring and double check in the slide guides (square guide holes on the sides of the bore) and make sure they are clean and unobstructed.

Outside of that, I just dabbed some PB blaster on the slide and the guide when mine started fighting with me after cleaning.

And as another question for you, how does the bike run over the entire rev spectrum? and how is your A/F setting?

Also, double check the o-ring and seal of the air-cut offs because if one is leaking air, it will give you a broad range of problems that are difficult to diagnose.
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Old 09-30-2011, 09:20 PM
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Simple check is to pull your choke cable a little bit while you're riding. If it runs better, then you're lean, if it runs worse, then you're rich. If it doesn't change, you probably have choke cable/ enrichment circuit issues.
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Old 09-30-2011, 10:04 PM
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I have this aswell. Sometimes I think it's going to blow the gas tank right off the bike lol. Mine happens around 2-3 aswell but regularly if the bike is not up to mid temp. It i'ts below then it will reliable do this if trying to cruise within this range, but if accel thru the range it's fine. My bike performs well imo through the whole rpm.

I'm not going to do any carb work bc I never have and don't have time to learn about carbs, I just set my idle up to ~1400 so that it at least wont stall the bike when it's not full at temp yet and I'm at a stop. it just hicups now and continues to run instead of dying on me.
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Old 10-01-2011, 05:57 AM
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BASS.
my A/F is 2 1/2 turns out, the bike performs well throughout the whole range BUT if i am cruising between 2-3k or if i rev between 2-3k it will fart and if i am at idle after the bike is well warmed up it will fart and sometimes die on me. my idle is set at 1200 and can be sporadic at times. i have a set of two brothers pipes i am going to get rid of and go with something a little milder with more back pressure. yoshes maybe.
i dont think what i have going on is all that bad but it is a real pain in the @$$ when it dies at a traffic light right before you go to take off. i think i am going to bypass my neutral switch so i can start it without having to go to neutral first
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Old 10-01-2011, 07:24 AM
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Originally Posted by 3amta3 View Post
BASS.
my A/F is 2 1/2 turns out, the bike performs well throughout the whole range BUT if i am cruising between 2-3k or if i rev between 2-3k it will fart and if i am at idle after the bike is well warmed up it will fart and sometimes die on me. my idle is set at 1200 and can be sporadic at times. i have a set of two brothers pipes i am going to get rid of and go with something a little milder with more back pressure. yoshes maybe.
i dont think what i have going on is all that bad but it is a real pain in the @$$ when it dies at a traffic light right before you go to take off. i think i am going to bypass my neutral switch so i can start it without having to go to neutral first
if you are at a light and the side stand is up adn in first gear with the clutch in you shouldnt have to put it in neutral to restart.... I can start my bike in first as long as the side stand is in the up position.
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Old 10-01-2011, 07:31 AM
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You should be able to start the bike in gear. If not, your clutch lever is not making good contact with the switch when you pull the clutch. When I had my lever set where I liked it, it did not fully press the switched when pulled to the grip. I used some JB Weld and glued a few small squares of plastic to the contact point on the lever.
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Old 10-01-2011, 07:49 AM
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i will have to look into that, i figured it was supposed to do that. thanks for that bit of info. my farts are a bigger bother for me though.
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Old 10-01-2011, 08:17 AM
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My vote's on the choke cable still.
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Old 10-01-2011, 11:22 AM
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next time i ride it and it starts doing it i will pull it out and see what happens. so if i pull it out and it runs better, then what do i do?
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Old 10-01-2011, 11:25 AM
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you shouldnt be riding at 2-3k rpm
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Old 10-01-2011, 11:37 AM
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Originally Posted by jay956 View Post
you shouldnt be riding at 2-3k rpm
qft. although doesn't rectify the issue, lol
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Old 10-01-2011, 11:45 AM
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I was kinda reading it like the carb farts were just in that range, like he used 2-3k rpm to get to 5k rpm where he wanted to ride?

Either way, if it runs better with the choke out a bit, you're lean in that range, so I'd say go up to 48 pilots, or at least turn your idle screws out a bit. If it runs better with a small amount of choke engaged in the higher rpm's try moving the needle clip one notch downward (so 5th for you).

If it runs worse, do the opposite; turn the idle screws in a bit and go from there. The best way to adjust this is with and idle drop test, but that requires and 80 dollar tool.

I will say that I had similar symptoms and it turned out that my choke cable wasn't working properly. I couldn't pinpoint it until I pulled my choke all the way out and it ran exactly the same

Last edited by 7moore7; 10-01-2011 at 05:18 PM. Reason: Needle position correction
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Old 10-01-2011, 02:52 PM
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Originally Posted by jay956 View Post
you shouldnt be riding at 2-3k rpm
+1
When you drop below 3k rpm, you should downshift.
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Old 10-01-2011, 03:18 PM
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just so you know, i dont race my bike i use it around town and to and from work. so yes i do use it in the 2-3k range.
i am concerned with it cutting out on me at idle, i care about that more than anything.
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Old 10-01-2011, 03:40 PM
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Oh in that case I'm gonna go with these guys then. The only reason my tach touches the 2-3k rpm range is because it's between idle and 4-6k where I cruise at through town.
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Old 10-01-2011, 03:56 PM
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does the pilot jet(the 45 or 48 one) control fuel mixture in the idle range?
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Old 10-01-2011, 04:02 PM
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Short answer: Yes.

They also have a slight effect in the higher range but the way it works is the pilot jet controls your fuel in the low rpm's. This mixture is fine tuned by the pilot screws that are located on the outside of the carbs. Once you get into the higher rpm's, there is enough vacuum to open the slides, which in turn control the fuel coming out of the main jets.

The pilot jets are active all of the time, although the volume of fuel that they add to the mix once the mains are active is at that point much less significant. But they are the only ones active in the low rpm's.
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Old 10-01-2011, 04:45 PM
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ok now that makes sense, i have a buddy that has some 48's i might try and put in to see if it fixes the problem. for the main jet needle, i am on the 4th notch if i need to richen up the top end i would go to the 5th notch or the 3rd notch? one other thing is there a way to get rid of that annoying main jet slider noise?
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Old 10-01-2011, 05:11 PM
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Making the needle shorter richens the mixture- so 5th clip from the top if you're on the 4th

Have you tested anything or been able to make sure the carbs are sync'd yet? Changing pilots takes a bit of time to do before you rule out the other things...

Last edited by 7moore7; 10-01-2011 at 05:17 PM.
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Old 10-01-2011, 05:42 PM
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i have done many different combinations of things. i have adjusted my A/F screw, moved the main need in and out, shims and no shims. my carbs are synced at 7psi on both cylinders. nothing seams to help besides adjusting the A/F screw it was out about 3- 3 1/2 turns out. that helped the most and made things alot better. and yes pulling the carbs are a pain in the @$$ i have removed them more time than i care to have, the plus is i am getting good at it out and in is about 30min now...lol
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Old 10-05-2011, 03:44 PM
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I have the infamous backfire too, for 12 years now. I brought my bike back to Rich Oliver a few months back at Cycle imports in Santa Cruz as he Jetted my carbs. I was simply getting to many carb backfires lately so I wanted him to check it out. Did most everything you guys are talking about, threw it on the dyno: Played with the jets, screws, idle speed, choke, synced the carbs...he thinks it's the carb boots expanding excessively. He wants to replace those, other than that option, he's kinda baffled, but this is an inherent problem with this bike, so I take that with a grain of salt. I want to say that my VTR hiccuped on my way home from the dealer, I was pretty quick to notice.
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Old 10-05-2011, 03:49 PM
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Did he check the air cutoff valve?
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Old 10-05-2011, 04:09 PM
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All I can say is mine never does anything like what you guys are talking about..... so IMHO you are dealing with a set up issue not an inherent problem with this bike.....
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Old 10-19-2011, 06:04 PM
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ok i still have the farts. it gets worse when the bike heats up and steady low rpms. it has even done it at the 3-4k range but not very often. could it be the fuel petcock clogged up? it is gradually getting worse the more i ride it. i am going nuts trying to figure this out. i just want to push this thing into the river.
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Old 10-19-2011, 06:11 PM
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My vote is still on the choke acting up. Follow the whole cable assembly and make sure it's working properly.

Getting worse as the bike heats up is a pretty good indication that you're running rich
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Old 10-19-2011, 06:35 PM
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Originally Posted by 3amta3 View Post
ok i still have the farts. it gets worse when the bike heats up and steady low rpms. it has even done it at the 3-4k range but not very often. could it be the fuel petcock clogged up? it is gradually getting worse the more i ride it. i am going nuts trying to figure this out. i just want to push this thing into the river.
Mine seems to be getting better the more I ride it . It might just be my imagination but I think it used to do it in the 2500 range and now it seems to have creeped up to the 3100 sometimes. Once everything is hot though it does it a lot less unless it's hot and I'm riding in cool ambient temps
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Old 10-20-2011, 12:59 AM
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Originally Posted by 8541Hawk View Post
All I can say is mine never does anything like what you guys are talking about..... so IMHO you are dealing with a set up issue not an inherent problem with this bike.....

I would say more like an inherent setup issue with the superhawk. It seems to be a very common problem with the bike. Mine had it bad when I first got it. After some fiddiling, all is well. It seems like the carb synch was what helped out the most.
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