Carbs and gas smell "not really new topic though"

[Shaun]

So I have been reading Andy's carb rebuild post have searched carb leak and found lots of good pointers and comments. Where I am at is I went for a ride on Sunday afternoon and got it up in the kookaloo zone once or twice, (Buell induced) bike performed fine. When I got home parked the bike all was fine, bike sat all day Monday and Tuesday. Came home from work Tuesday afternoon opened the garage door and was greeted by the strong smell of gas. There were no puddles to be seen, no wet gas spots on the bike that I could find so I left it overnight. This morning yup, gas stench again. So for the day I have rolled the bike out of the garage and left it to vent outside, before I moved it I had another check around and found that the airbox just stinks of gas. This is new and has never smelled like that before, hot after a good ride but never smelled like that more than 24hs after being parked. As a general rule bike runs well, I have noted that the rpm does pick up at idle when properly warmed but otherwise everything appears good. This winters project was to get into, clean out and work through the carbs but we are not in winter teardown weather yet. Any thoughts as to what a guy should look towards or for in particular, haven't tried the one comment of ride it of a curb yet and give things a jolt yet but you never know. I have not been into the carbs yet and it will be a new experience for me, done lots of cars but not bikes. Bike is a 1990 and just coming up on 80,000Km no major motor/carb mods that I'm aware of, Cobra F1 slip on exhaust 5 deg advance plate stock airbox. Any other thoughts and pointers would be appreciated.

Thanks for looking

Shaun

[hein]

 Morning Shaun. The only two ways that I can think of fuel smell getting into your airbox is either from the carbs or your crankase breather. If the fuel level in the carbs was too high the excess fuel should come out of your overflow hose and dribble onto the ground unless its plugged. Now if that was the case then fuel could possibly get past the intake valves, past the piston rings and into the crankcase and then through the crankcase breather and into the air filter box. Do a sniff test on your oil for fuel smell. Since summer has finally arrived on the island a very small amount of fuel leakage would evaporate on the ground pretty fast but the smell would remain. Again, assuming that a high fuel level is a potential problem, or a very slight leak past the needle and seat of a carb, is it possible for the excess fuel to evaporate in the carb body and , providing that the intake valve is closed, for the smell to transfer to the air intake box? How about a fuel tank that's not venting properly causing air pressure forcing fuel past the needle and seat in small amounts? If I can think of anything else I'll pm you.  Good luck. Hein

[Shaun]

Thanks for the input Hein I appreciate that, went to start the bike this morning and it didn't really want to kick over as well as it usually does. It kind of sounded like it was starting on less than all four cylinders, eventually it cleaned up and idled on the choke proper. It hunted up and down in the rpm range, not much mind you but different than the normal hum. Gas tank vent seems to be working fine it "meows" at me like normal after a ride. I will keep an eye or rather nose on the oil smell for gas though. I think the bike is just letting me know I have to get into things a little more this winter.

Shaun

[yarin]

Try draing your float bowls one at atime with a clean hose connected from the drain outlet into a clear glass jar.  turn on the ignition while you do this each time to flush anything that might be inside. is there dirt in the jar?  you might have a sticky float needle seat.  check your air filter to see if it has gas on it.  check to make sure your vent hoses arn,t clooged or kinked.  check your oil level, has the level gone up?  order the rebuild kit from Randy rpmracingca.com 

Tom

[mijohnso]

Don't be too worried about digging into the carbs. This was the first set of carbs I really took apart and cleaned (Andy's post is really helpful), and it was not as bad as I was thinking. That being said, it did take longer than I'd like to admit (it will go much faster next time, I was trying really hard not to screw anything up).

I didn't end up taking the carbs off the body... didn't really see a reason too and I did not want to have to put all those springs and bolts and such back together. My diaphragms were in pretty rough shape, when you take the top cap off, be really careful not to rip or tear those guys. You might want to pick up the rebuild kit from Randy at RPM so you can get a bunch of sweet new allen-head hardware. It takes more tools to take things apart but you don't have to worry about stripping all of the bolts when you take it apart next time.

Also, I waited until the winter to get into them which condemned me to the basement with a bunch of fans. I don't know what your work area looks like, but I would try to get it done on a rainy day off during the summer rather than fumbling them out in the cold and killing half my brain cells trying to clean the stupid things...

Good Luck!

[Shaun]

So I finally found where the gas is leaking from, I just don't know what it is. I have read through Andy's post again and I don't see any mention of it. Gas leaks out heavily when the bike is running and then slows after you shut it down. No matter what the carbs are coming off and need to be fixed right. The post I'm talking about is in the center of the picture with a red arrow pointing to it, just above the gasket line where the bowl meets the body. Any thought as to why it is leaking there and not out the usual over flow tubes? Sorry the arrow is kinda small and hard to see, no real photo editing software.

Thanks for the help folks
Shaun

[SlowOldGuy]

That port is a choke circuit bleed air intake.  It used to have a nipple for a hose, looks like it's been cut off.  A fuel leak from this port typically indicates the fuel/float level is too high (too much fuel in bowls), the o-ring that seals the needle seat is seeping, or the needles are not fully shutting off the flow of fuel and allowing the fuel level to creep up to the point where the fuel finds its way out of this choke air port.

If you're taking the carbs off, get a rebuild kit from Randy so you can replace the needle seat o rings and be sure to check the needles and fuel level before you re-install the carbs.

DavidR.

[Shaun]

Thanks David, I have been talking with Randy and yup carb rebuild kits are on the list of items to order.

Shaun

[Shaun]

Well started to get into the carbs last night and see what is there, didn't get very far but did discover there are two different types of needles in there. On the left pair of carbs there are the typical ones that I'm used to seeing with a little wire over thefloat tang, on the right side pair there are different ones that are a kind of spring loaded needle that is operated by the tang on the float. Somebody has been creative in these carbs. Is it best to completely remove the carb bodies from the rack that holds them together or to leave them as one bank attached to the rack.

Shaun

[mijohnso]

Sounds like the PO had some fun with your bike... That kind of sucks...

Like I said, I found no reason to remove the carbs from the rack. I couldn't really see that this would help me clean/lube anything, and I didn't find it difficult at all to work with the carbs while still attached to eachother, and that meant I didn't have to struggle to get the bike running after I was done (I did sync the carbs after I was finished). That being said, I am no carb expert, so perhaps I overlooked something...

Sounds like a lot of carb cleaner and a the rebuild kit will do you a lot of good. Have fun!

[racerrad8]

The needles are supposd to be spring loaded.

If you want to replace all of the o-rings that could be a source of a leak, then you will need to seperate the bodies.

Randy - RPM

[Shaun]

So I got right into tearing my carbs pretty much completely apart. These are the things I found and how they were set up
Pilots 42.5
Mains 110
Air bleed 155
After market needles with clips in third slot from the top.
Spring lengths vary from 4 3/8 to 4 ½ inches
Three mix screws turned out 3 full turns, one mix screw ½ turn out.
As mentioned before the two different types of main needles Spring loaded and non spring loaded.
What I noticed about the setup with the bike running is that it was pretty rich at idle or slow speed but did pull pretty well throughout the rev range. I didn't notice any big flat spots, maybe a little sluggish in the low end off idle. What I also noticed is That my fuel mileage sucked, I would use 3/4 of a tank to go from Comox to Nanaimo (70 miles at 70-75Mph average)  I have also fixed the broken overflow nipple on my carb. Well I didn't do it personally I have a friend in the machine shop that is very good at what he does. Next up will be a thorough clean, rebuild kits and Uni filters from randy.

[RichBaker]

The pilots, and mixture screw settings sound fairly rich......  I run 40 pilots and the mixture screws are all around 1 turn out, +/- a smidge. DYNOJet needles, clip in 2nd groove ( from the top), DJ 114 mains.
UNI dual pods, D&D exhaust, DYNA 2k ign.

[andyb]

Look closely at the float needles. I've seen them that were spring loaded until some gorilla got in there with a screwdriver and bent the center pin, so it stuck in a retracted position.  You can adjust around it, but it's more frustrating than getting one that works properly.

I have read through Andy's post again and I don't see any mention of it.

Fooey on you.  It's marked as D.  


What's the rest of the bike's mods?  A 42 is a pretty big pilot for that small of a main, I'm guessing it's either filthy rich at the bottom or a bit lean at the top.  By what you're describing, I'd say a 37 or 40 is likely a better pilot, and should improve your mileage sommat.

[Shaun]

Well done Andy I take it back, the overflow is well marked with "D", I didn't pay enough attention to the details. And yes it was rich down the bottom end, my wife always commented that after I left the house, the garage always stunk of gas. As for getting proper parts they are up next, I'm looking at 40 for the pilots and I think 117.5 for mains and some new needles as well as Uni filters from Randy. Bike is pretty stock just some F1 slip on exhausts on stock header and collector, 5 deg advance.

Thanks for looking and the input to pointing out my oversight.

Andy good write up.

Shaun