| Author | Message | ||
     Sparky |
I still get the sticking tank vent anomaly on the 98 S3, but only when it rains! It doesn't matter how much fuel is in the tank. It happened on the rainy day during the Calif BRAG Ride and on the last day it rained substantially here while I was going to work. The symptoms sound similar to yours -- it starts losing power gradually then quickly dies. If I open the filler cap, letting air in, all is well again and the problem doesn't reoccur for the rest of the day. You might have her try that the next time it happens. Mine could be due to rain condition humidity while yours is temperature dependant. On the float bowl level indicator thing, that'll only tell if there's gas in the bowl. If the tank vent is blocked, a partial vacuum is created in the float bowl & the carb would starve for gas because the bowl needs atmospheric air pressure to operate normally. Sparky | ||
| Sarodude |
Sparky- The 40mm Keihin CV carb vents to the air intake via the breather dealie (10 or 11 o'clock position?) up front. The bowl would indeed empty if the tank vent stuck. In either case, it's good (uh, what?) to know that may be the problem despite the not full tank. -Saro | ||
| Hans |
Carburettor ice ?? Hans | ||
| Sarodude |
Hans- Good thought. I was riding the Dyna (a 1450cc beastie breathing through what is essentially the same carb) at the same time. No problem there. Not exactly apples to apples but you sure got me thinking. I never even considered icing. I'm with Sparky on this so far. It wasn't raining but the dropping temps could have caused some sort of condensation related phenomenon similar to his rain related phenomenon. Keep 'em coming! -Saro | ||
| Kdraw1 |
I recently rejetted my '98m2 with an aftermarket needle and a 45 slow jet. I added a Buell race air filter and a V&H slip-on. Now I've noticed that the carb is pooling gas. If left with the petcock on long enough, gas will drip out onto the floor. I've checked and cleaned everything I can think of, but it still does it. It also stumbles and practically dies whenever I rack the throttle while driving it. It seems fine when sitting in the driveway and idleling. Help, I wanna ride. PS also see my oops on the quickboard under "Can this be fixed." Thanks, Kevin | ||
| Sarodude |
Kevin- First guess would be some kind of debris / damage to the float valve if any of the drillings made it down that way. Even if it's now clean, maybe something got damaged enough to not seal. Just a thought... -Saro | ||
| Sparky |
Saro, You're right, I got it mixed up. Let me paraphrase what I meant to say, "When the tank vent is blocked, the carb doesn't suck so well." Is your tank still vented through the charcoal cannister? I took mine off and am now wondering if this might be contributing to the problem although strangely I don't have this anomaly with the 96 S1 which is also minus the cannister. Wait, I don't ride the S1 in the rain -- moot point. Kdraw1, my S1 had your symptoms exactly but only after being thoroughly warmed up. I checked the float level and it was OK. Looking at the float valve tip however showed a slight wear band in the shiny neoprene surface. I replaced it, rechecked the float level and the problem went away. BTW, I found out I could ride the bike when it tended to overflow the bowl by alternately shutting off the petcock briefly then turning it back on. That always made the ride interesting. So if yours seems to run better by doing this little exercise, that means either the float is too high, leaking or misaligned, or the float valve is worn, or debris is keeping the valve from seating. Sparky | ||
| Sarodude |
Sparky- I do still have the charcoal can on there. How did you wind up yanking yours on the S3? Does the tank vent line just dump into nowhere? Actually, this got me thinking... I remember reading a while back about someone having probems with a clogged charcoal cannister causing fueling headaches. Might have even been a Blast. Interesting. One more thing to keep in mind... -Saro | ||
| Sparky |
Saro, The tank vent exits down by the kickstand, downhill all the way. Pretty hard, I'd think for water to get sucked into the tank vent. Water vapor, on the other hand, could probably get there. My best bet though is to cut off the anti-spill gizmo of the vent valve and have it vent freely. What good is it when the darn thing leaks as I tilt the tank up while R&R'ing the tank? Sparky | ||
| Sarodude |
Sparky- That was my plan. I'm kinda tired of that thing causing headaches. I think I'll keep everything as is except just ditch the check valve... -Saro | ||
| Sarodude |
Blast Fuel System (?) Update Behavior repeated last night. This time I kept Loli in sight and she kept the bike running. Similar conditions - except not a beach / canyon ride beforehand. Tank had about 65 miles on it since fillup. Heading home from Burbank (after visiting Glendale HD / Buell) the bike REPEATEDLY developed what Loli keeps describing as a lean, surgey type of feeling. We wound up exiting the freeway. Once the demands on the fuel system were reduced (by way of tamer running on the street) the bike behaved. I'm gonna rip into the whole fuel system this weekend. The tank vent check valve is gonna come off and be replaced with an unchecked nipple. The charcoal can is gonna be yanked just to eliminate it as a possibility - though I personally don't want to run without it indefinitely. Tank will be drained and cleaned. Petcock / screen inspected / cleaned. All fuel system lines - uh, inspected, maybe replaced. Carb will be disassembled and cleaned. Before I do any of this, though, I'm gonna try something Matty suggested. He remembers some intermittent ignition problems a few years back that were diagnosed with a running bike and a heat gun aimed at the ignition module. I doubt what I'm seeing is an ignition thing - but that's a simple enough check that doesn't require my hands to smell like fuell for a couple of days. Anyone have anything to add? If it is an ignition topic let's redirect it to the ignition section... -Saro | ||
| Aaron |
Easy way to diagnose a tank vent issue: while the bike is acting up, reach down and pop the gas cap loose. | ||
| Court |
Saro: If you need a fuel vent and your dealer doesn't have one, let me know and I'll get one on the way to you today. Court | ||
| Sarodude |
Aaron- That would be cool if I was on the bike. It's kinda hard from a staggered riding position, though...  I'll try to get Loli to be conscious of the fuel cap - but on a crowded LA freeway just getting the living crap outta the way is sort of a priority... Court- Thanks for the offer. I'll let ya know - but Glendale (my preferred dealer) does tend to be pretty good on stuff like that. Here's my thing... I'd like to find out exactly what is causing it. Loli would like a bike that runs properly ASAP. These 2 things are at least slightly conflicting - so I just wanna eliminate all possibilities. -Saro | ||
| Sarodude |
Forgot to mention something... Last night after I parked the bikes in the garage I smelled fuel. This is unusual. I looked for obvious leaks but found none. My nose became very quickly used to the smell, anyway. I wasn't able to track it down. -Saro | ||
| Sparky |
Fuel smell & no leaks could be the insidious stuck float anomaly although, in my case, it'll dribble out the aircleaner. Is the petcock off when parked? Be careful if you suspect a stuck float because this can fill a cylinder with enough gas to cause hydraulic lock & engine damage upon startup. One thing to look for if you can take the float bowl off without spilling too much is significant water in the gas. Nowadays Calif gas has alcohol added which will attract slight moisture from the air. I noticed this as what looked like little bubbles mixed with the gas film on the bowl's mounting surface when I worked on the S1's float valve a couple weeks ago. This alone shouldn't cause problems, but if there are water blobs at the bottom of the bowl, this could contribute to your problem. Sparky | ||
| Kdraw1 |
OK, I've totally cleaned the carb (see above post)with carb cleaner, blew out all of the passages with compressed air and placed it back on the bike. It started fine, ran a little rough at first, but then smoothed out, I revved it a few times, shut it off and checked on it a few times and there was no leaking out of the carb. THEN... I took the bike for a ride down the road. Ran it up to about 75 and it ran fine---until I slowed down, then it just hogged up. I rode it back home, parked it, and once again, gas is just flowing into the carb. It looks like it is coming up through the main jet. Would a sticking fuel inlet valve cause this, or maybe the float needs to be adjusted? Or could some of that JB Weld I used to plug up that hole cause these kind of problems? I'm out of ideas here. My next step is to buy a new carb, but I'd rather just fix this one. Also, would the wrong jet needle cause this kind of problem? I'm asking this because I changed from the stock needle to a 1988XL 1200 needle as recommended on American Thunderbike.com. Thanks, Kevin | ||
| Sparky |
Kevin, Hang in there. Sticking fuel inlet valve, inlet valve worn, float too high, dirt in inlet valve seat, float leaking (not floating), float hanging up on something inside carb -- these are all suspect especially if someone's been in the carb before. Inspect the inlet valve carefully. If the neoprene seating surface is not uniformly shiny, replace it then adjust the float level according to the service manual. If you don't have the procedure, get back here and I'll post the specifics. Jet needle should not cause this problem. What's up with the JB Weld? Sparky | ||
| Lgpch |
Can anyone help? Im running a mikuni 42 with a #25 pilot jet, force winder air cleaner and vance and hines exhaust, on 2000 M2. Is the pilot jet the optimum size? The tuning manual states that when setting the idle mixture screw on the carb,if you continue to turn the screw out (counter clockwise) and there is no change in RPM's (this after counting how many turns you screwed it in before RPM change)then your pilot jet is too large. Does anyone know the optimal jet size for that set-up? Help would be much appreciated. | ||
| Sarodude |
Blast Update I was just starting some basic recon on the bike's fuel system. I started with the float valve. I think I may have ended there too... The thing would BARELY flow any air. Tapped it and it let go and started to flow for a bit. I think it was actually closing without tipping it. Either way, whether tipped or just spontaneously closing, it needed to be tapped to open up. I opened the think up so there's no ball / valve anymore. We'll see how things run. I'll also call Glendale and see if they have the part or if I need to wait some days - which is no problem in this event. Keping my fingers crossed... -Saro | ||
| Kdraw1 |
Sparky, The JB Weld is for an "accidental" (read stupid) drilling out of a plug that I thought hid the idle mixture screw. I've inspected the neoprene and it looks fine. I can hold the float in place and stop the fuel flow, but when I put the float bowl on, fuel will just flow up through the needle seat and through the air holes in the front (not sure what they are called). I have adjusted the float to extremes in both directions and it didn't stop the flow up into the carb body. I have the shop manual in order to adjust the float level, I'm just not exactly sure how to get the carb tilted between 15 and 20 degrees to adjust the float. I also need to buy some calipers to measure the distance from the body to the perimeter of the float. I bent the float tab to the extremes to see if I could at least stop the flow of fuel when the float bowl is on. I'm doubtful that it is the fuel inlet valve because I can stop the flow by holding the float. I just seems to go against physics. Why is fuel being pulled into the carb? I thought liquid always leveled out- unless under pressure/vacuum etc. I'm about to just take it to someone, but at $45/hr. I'm holding out. I may just keep checking ebay or look in junk yards. Thanks Kevin | ||
| Aaron |
Have you verified that the tank is not pressurized when this spillage is occurring? | ||
| Kdraw1 |
Yes, that was one of the first things I checked. Thanks, Kevin | ||
| Sparky |
Kevin, I use a small protractor & a 6" scale rule left over from my school supplies to eyeball the 0.413 - 0.453" measurement to the nearest 0.010". You could try a hardware, stationery or school supply store. It's good to know the inlet valve works by hand. The float itself could be bad. It could have a tiny pinhole causing it appear OK at first then slowly fill & fail to stop the gas flow. This happened with my Quicksilver carb which had a clear plastic float. I could see the gas inside. To check the Keihin's float, you'd have to remove it and listen for gas sloshing around. Or possibly there's some stiction in the float inlet valve. I reread your "Is this fixable?" post. Just wondering if the accidental drilling could be related to the overflow problem. How far did the drill go? Thanks, Sparky | ||
| Kdraw1 |
Sparky, The drill did not go that far-- I was worried about hitting the screw head. I thought maybe a piece of metal may have slipped in, or maybe some of the JB Weld dripped in. "It could have a tiny pinhole causing it appear OK at first then slowly fill & fail to stop the gas flow." The problem is having too much of a gas flow, not not enough. I'm thinking about redrilling out the JB Weld area and attempting run a wire through all the areas I can get to. Although I'd be doing this in vain because I really don't think that is the problem. I'm at my wits end with this. I just can't figure how it can keep spewing gas into an area that is higher than level without the engine running. I've looked at it about 10 times and studied the manual of how the fuel flows, and the fuel inlet valve seems to be the only "logical" answer. Thanks again for the help, Kevin | ||
| Sarodude |
Kevin- A hole in your float WOULD cause too much fuel. The float would float less. Check for those pinholes! -Saro | ||
| Sparky |
What Saro said. If the float fills with gas, it will sink and NOT close the inlet valve, causing the carb to overflow. "I just can't figure how it can keep spewing gas into an area that is higher than level without the engine running." As Court might say, "Stand back and get the big picture." Look at the entire fuel system. The fuel is seeking its level in the fuel tank which is higher than the carb. Sparky | ||
| Kdraw1 |
Sparky and Saro, Yeah, you're right, I didn't think about the fuel tank being higher than the carb--duh! Well, after meditating and going with my theory of pressure forcing the fuel upward, I thought about what creates pressure. In the float bowl with the fuel entering an inclosed space it creates pressure if there is not some place for it to vent. Well, low and behold, I looked at what I continually mistake for a bolt hole, but is actually an airhole on the intake side of the carb right above one of the bolt holes and found that my JB Weld job had sealed that little hole up. So, out came the drill, I drilled out the JB Weld plug, stuck a small screwdriver into the vent hole and unplugged the vent hole. I then tested it by meticulously cleaning everything again and attaching the fuel line to the carb and turning on the fuel. Guess what? No leak! Now, I have to figure out some way to plug that hole without plugging up the vent hole. I'm going to look tomorrow for a rubber cover that will fit tightly over it. I'm not 100% sure as this is the culprit, but I'd almost bet the old breadbox aircleaner that I've got it nailed now. If anyone has any doubts or comments about my revelation, please let me know. Thanks for the input. Kevin | ||
| Kdraw1 |
I SMELL VICTORY!!!! (and like gas)-- Well, looks like my theory panned out. The vent hole was the culprit. I re-set the float level, adjusted the idle and the bike runs like a charm. Thanks for the help- Once again, the BadWeb saves my ass and a lot of money. Until my next crisis- over and out. Kevin | ||
| Forevernow |
kevin,how is it running with the pipe and race filter now that you have the jetting worked out,did that adapter work out all right? |
