Hi:
Took my '85 for a ride tonight, and this was after doing a bunch of work to it in the last month or so. Front forks flush and freeing up the preload adjusters, new straight-wound springs, completely going through front brakes and anti-dive units, new chain, new tires, AND doing the stiffer spring and new o-ring thing for the petcock. The latter was in response to the (continuing) problem of having the bike leak out a small amount of gas after I ride it. Doesn't show up right after I shut it off, but appears about a half hour later. I don't understand it, because I went through the carbs thoroughly, installing new float needles and seats, and carefully adjusting (what a drawn out process!) the float levels to within spec.
The bike runs great, and I feel good that all of the work (and money) that I put into it has paid off, yet I am plagued by this nagging problem with the gas leak. Any thoughts?
I wouldn't be suprised if the carbs have to come off again, but everyone who's done that, and put them on again, knows that it's a pain.
Thanks in advance.
Marty
Hey Marty,
If it's not the carbs, then there could be only 1 thing left.
DavidR had a hell of a time getting his petcock to stop dribbling. So after reading what he went thru with different O rings, etc... I said, screw it and bought a new petcock assembly. Less than $100 from Power Sports Plus.
See my post here: http://www.fjowners.com/index.php?topic=6469.0 (http://www.fjowners.com/index.php?topic=6469.0)
Quote from: FJ1100mjk on April 24, 2012, 09:24:20 PM
Oh! I thought you had a problem with distances between long ride stops kind of bladder problem. Sorry, as you were.....
Side stand or center stand?
Either or both?
Randy - RPM
I couldn't get the petcock or the carbs to stop leaking. I tried several different (old) petcocks that I had, all kinds of o-ring and spring combinations, nothing would stopo the fuel.
The carbs were just as bad, swapped several needle/seat assemblies, new floats from Randy, float tweaks, etc. If I let them sit for several hours under a tank of fuel, one (or sometimes more) would start seeping. Just a slow drip that would not stop.
I finally had enough and installed a new petcock and a complete new set of late model carbs from Randy. Still running a gravity feed with pump-sized needle seat diameters.
Still haven't had time to further diagnose the original carb set.
DavidR.
I've got an '87 with a later model tank and petcock and had the same issues. I installed a fuel cutoff switch/petcock from Dennis Kirk that pokes out the right side cover and haven't had any problems since.
Kind of cheese-y fix, but it was cheap and quick. I think I spent about $15 - $20 with the new petcock, fuel line and clamps.
Quote from: SlowOldGuy on April 24, 2012, 10:07:15 PM
Still running a gravity feed with pump-sized needle seat diameters.
Yea, I remember what you went thru David, made me think that it was the best $100 I've ever spent.
Hey, I got 27 hot sweltering summers and148k miles out of the oem '84 petcock so the next oem should be good for a few more summers and miles...........
How's those little needle seats working out for you? Any full throttle starvation?
All, thanks for all of the replies and ideas.
Randy, for the most part, I have been parking the bike on its centerstand when I return from my rides. the bike is on pretty much a level surface in my garage too. And, the gas seeping stops after its initial spew. Hope it doesn't come to a new petcock setup, but it's really frustrating dealing with this fuel leaking issue. Especially now that a lot of the hard work is out of the way and the bike is running great.
Marty
Can you determine which hose it is coming from. I suspect it will be coming from one or more of the small hoses that are the choke enrichment circuit.
Do you have the complete rubber back heat shield under the carbs. I suspect the bowl(s) are heating and causing the fuel to purge through the choke circuit.
What float level did you adjust too.
Randy - RPM
Randy:
The heat shield is installed. I'll need to ride and park to update on what hose(s) the fuel may be coming from. Perhaps tonight after work.
I set the fuel level in the bowls at approximately 3mm below the gasket sealing surface on the carbs bodies.
Marty
Quote from: FJ1100mjk on April 25, 2012, 11:24:10 AM
I set the fuel level in the bowls at approximately 3mm below the gasket sealing surface on the carbs bodies.
Marty
Is that via fuel level when mounted on the engine at the angle or off the engine measuring the float to the gasket surface?
Randy - RPM
Randy,
The carbs were off the bike, mounted on a test stand that kept the carbs level to the horizontal. I used a clear piece of tubing connected to the carb's drain and held that vertical to the carb, then filled the carb up with fluid, waited for things to stabilize and noted the fluid level in the tube relative to the gasket sealing surface. I adjusted the floats ever so carefully (many times) and repeated the process to get the fuel levels at the aforementioned levels.
Marty
Floats are going to be too high. The carbs mount on the engine at a downward angle. When float is high the choke circuit is covered with fuel and drains when the vacuum bleeds off.
I will be back to shop on Friday and will scan the service manual.
Randy - RPM
Randy:
The clear tube was held on the centerline of the carb slide bore. According to a comment made by a fellow forum member (I believe DavidR), if measured in this manner, the carbs' incline effect on the measurement is taken out of the picture. Seemed like a valid statement at the time so I ran with it when I did my float level adjustments.
Like I stated in my initial email, I wouldn't be surprised if the carbs were coming back off again.
Randy is not saying your measuring technique is bad, the level you chose is bad. It should be at least 5mm below the gasket surface.
Allow me to calrify what Randy is saying:
Yes, your measurement is correct and does not depend on the angle of the carbs as long as you referenced the center of the float bowl. However, 3mm is too high. When the carbs are on the bike, they are tilted forward, causing the fuel level at the front of the float bowl (near the choke air intake port) to be way too high and thus causing fuel to seep out of the choke air port.
DavidR.
:dash2:
I don't have my end-all, use with concidence, Clymer manual in fronrt of me right now. However, I thought that I was in the tolerance +/- zone given by that manual for the maximum (high) fuel level in the bowls.
I know Randy had posted pics of the official Yamaha's Service Manual's diagrams for the float and fuel levels. I need to do a search and find those again. BTW, what do you use as a value for the maximum fuel level wjen you do your adjustments? I also read (here we go again) that using too low of a level will cause mid-range performance issues. Possibly.
Thanks.
Marty
5mm maximum fuel height. It's easier to lift/richen up the needles to compensate for a lower fuel height than try to drop them further to correct a too rich fuel height.
Also, I've seen far more midrange acceleration problems from high fuel level than low fuel level.
Plus (minus?) it causes fuel leaks. :-)
DavidR.
David:
Thanks for the info. So if I use your 5mm value and adjust to that using the method that I described above, then I shouldn't have the fuel level set so when the carbs are mounted on the bike and there inclined, the level will not be such that fuel will not overflow and run out of the overflow tubes?
Thanks.
Marty
How many negatives are in that sentence??
I can't really guarantee you won't have a fuel leak since I still can't explain why mine were leaking. But that fuel height adjustment "should" give you the best opportunity to NOT have a leak and get proper tuning of the mixture.
You might want to try a new set of brake shims also. :-)
DavidR.
David:
Which sentence is "that" sentence? Not the one where I'm thanking you, I hope :-)
Seriously, I'm not looking for any guarantees, since as the saying goes, there are none in life. A should is good enough for me. Your Super Hero Member status and you being a carb SME (Subject Matter Expert) carry a lot of weight with me and I appreciate the constructive feedback that you and others who share this forum provide.
Off come my carbs. Again. I don't think I'll use those brake shims for the carbs. I'd hate to add their mass back onto my bike. The old FJ handles so much better with the two grams that I lost from each caliper. You know what they say about the benefits of reducing un-sprung mass :-)
Marty
Quote from: SlowOldGuy on April 25, 2012, 08:28:02 PM
5mm maximum fuel height. It's easier to lift/richen up the needles to compensate for a lower fuel height than try to drop them further to correct a too rich fuel height.
Also, I've seen far more midrange acceleration problems from high fuel level than low fuel level.
Plus (minus?) it causes fuel leaks. :-)
DavidR.
All:
New float settings (5mm) with carbs on the bike worked! No more leaks or smells. Filled the tank up and got it nice and hot, then put it on the center stand, and waited. Nary a drop! Yippee!
Also shimmed the needles while I had it apart. Ran good, and hope to get more time in the saddle after work in the coming days.
Thanks for the help.
Marty
:dash2:
Started to leak again, damn it!
After reporting that all was well, and dry after doing some local rides of 20 miles or so, I figured that I had the leaks fixed for good. I took the FJ out for a 300 mile ride this past Saturday that included all kinds of riding, and the beast didn't miss a beat. On the way back to the stateline, I got caught in a rainstorm with the hardest rain I ever rode in. The FFJ never even hiccuped. After that, I figured that I was golden. Came home with soggy gloves and water-filled boots, but feeling pretty good, all things considered. Parked the bike on its centerstand, went and got cleaned up, and went out for some overnight fun.
When I got home the next morning, and opened the garage door, I was greeted with the all-tooo familiar strong smell of gasoline. To my dismay and utter disbelief, the FJ had once again pissed itself. Suprised my place didn't blow up with the fumes and all.
I'm at a loss to come up with what is the problem.
After, a near week of watching and smelling gas drip, I took the tank off to stop the flow. I expected to see gas flow out of the petcock's outlet after I removed the tank, but none does! I'm stumped and throw myself at the feet of the carb gurus. HELP!
I feel (sometimes) like taking a friggin hammer to the FJ, but love it too much.
Thanks in advance for your assistance.
Marty
Couple of thoughts here.
You could put a solenoid valve inline with the fuel hose. When you turn off the ignition, the valve shuts.
http://www.clippard.com (http://www.clippard.com) should have a unit properly sized for this. Check that it is safe for fuel use. You'd probably have to have port size of .250 inch or greater since your's is a gravity feed bike.
Also, David Godfrey, in WA sent me a couple of pics which showed the socket that the float needle seats fit into, had been machined poorly. This actually cut the new O-rings he'd just installed and let his bike leak, overflow, and run very rich. He cured the problem by touching up the edge of the chamfer with a jeweler's riffle file. Would be worth checking anyhow.
Cheers,
Arnie
This couldn't be a fuel tank venting issue could it? Pressure built up in the tank and pushes fuel past the petcock and carbs. After your next long ride open the fuel tank to 'vent' it when you're done riding.
Guys:
Thanks for the replies.
Arnie:
I looked at Clippard's offerings and some of the spec drawings for their valves. It looks like they may not fit in the space between the tops of the carbs and the bottom of the tank. And when you take into consideration the valve's associated fittings and short runs of hoses for installation, I think that they'd probably add to the space claim problem. I know that there is another valve out there that I could entertain (http://www.dan-marcrvparts.com/12vomufushof.html (http://www.dan-marcrvparts.com/12vomufushof.html)), but I think that it and its associated fittings and short hose runs would cause the same space claim issues. Perhaps others here have some comments related to these valves. I appreciate your feedback though.
Dads_FJ:
Yes, I had considered that there may be pressure build-up in the tank in after the long ride. I'd even thought that when I rode back in all of that hard rain, that perhaps the venting system in the cap became filled with some water, and didn't allow it to vent. I haven't gotten to the point of doing the flapectomy on the vent system in the cap. It's on my list of to-do items, but the tank seems to be venting. I know that after the bike pissed itself in the garage, that there was so much on the floor, that I opened the filler cap to look into the cap to try and determine just how much had leaked onto the floor. A lot after 18 hours of sitting! So, I vented the tank at that point, and the bike continued to leak the rest of the week, until I pulled the tank completely from the bike.
I'm kind of wondering if grit in the tank is migrating through the fuel system and keeping things from sealing. When I last took the carbs off and removed their bowls, I found some particles that had made it by the petcock's and needle seat's screens. Too bad one can't put a better fillter in-line, but because of space problems and concerns of fuel starvation with the gravity-fed system, I guess that 's a no-go too.
I've been in direct consultation with Randy@RPM and he's offered some advice, and some tests to do. I'll get to them and report my findings.
Dads_FJ, this weekend in our neck of the woods, is supposed to be rain-free (and I had my share of rain last weekend) for the first weekend in the last five. I think I'll be riding (non-FJ iron) instead of wrenching on this one!
Thanks again for your help and comments.
Marty
My '84 used to leave a puddle now and then. I took the petcock apart and stretched the spring to give it a little more holding power, which worked for a short while. In the long run I ended up replacing the petcock (new OEM) and all the carb needle/seats. It was spendy, but with the cost of gas, and piece of mind it was worth it.