Carbie Leaking?

MonsterMadMarty · January 18, 2015, 07:49:49 PM

Carbie leaks when ever the motor is running. Any idea why, what causes it and how do I fix it? You can see in the photo the wet nipple where the fuel is leaking!

Cheers in advance

koko64 · January 18, 2015, 10:02:19 PM

On my phone so I cant see the pic. Is that the nipple for the overflow hose that should be there? If so it could be flooding rather than leaking.

MonsterMadMarty · January 18, 2015, 11:56:19 PM

Quote from: koko64 on January 18, 2015, 10:02:19 PM
On my phone so I cant see the pic. Is that the nipple for the overflow hose that should be there? If so it could be flooding rather than leaking.

Cheers Koko, I think it could be the overflow but it's a lot of fuel coming out! (Sorry, I'm still learning!)

koko64 · January 19, 2015, 01:03:17 AM

Ill check on the laptop when I get home.

koko64 · January 19, 2015, 02:01:35 AM

Looks like the overflow nipple for flooding. If the fuel is originating higher than that area then the float bowl gasket could be leaking. If the leak is with the motor running and therefore fuel pump running then it is possibly flooding. Test it while the motor is running, turn off the fuel tap (if it has a manual tap) and the flooding should subside. Maybe a couple of times a year I have to reach down and turn off the tap, let the bowl run down and open the tap to reseat the float needles with the pump pressure. Sometimes a tap on the bowl with a screwdriver seats the floats. Think dunny cistern technology.
Those drain screws can be undone to let fuel out and flush the face of the float needles and hopefully clear the float valve. Put some little hoses on 'em to drain into a bucket.
If you have a vacuum tap get a manual tap you can turn off at night. A manual tap in reach lets you clear the carbs on the run. Drain hoses (you need four on your model) let fuel be safely drained away from the hot motor. Two hoses are for overflow/flooding and two are for those useful little drain screws.

Goop builds up around the float needles in bikes that have been sitting around unridden. Additives that clean injectors at 45psi clag carbs at 3 psi (or gravity).

You may have to pull the carbs and give them a clean if all else fails.

MonsterMadMarty · January 19, 2015, 04:09:35 AM

Absolute gold Koko, I've just brought the bike and the previous owner had it sat four years without starting. Although it didn't take long for me to get it running the only problem has been this fuel leak. Just as a matter of course I shall pull the carbie off and give it a good clean and replace the seals

koko64 · January 19, 2015, 01:54:41 PM

Cheers.

Be interesting to see how the float bowls look inside after four years. It's amazing how badly squashed the float bowl gaskets look and still seal. Don't disturb or chuck any seals until you're sure you can get replacements. Awhile back Brad put us onto Powerbarn in the US for stuff like that. I get my kits from them. Also Jets R Us in the US. Locals will have suppliers.

The Needle jets/emulsion tubes can wear oval pretty quickly. There's a stack of threads on these carbs here.

MonsterMadMarty · January 19, 2015, 02:04:20 PM

I'll update with photos once I've pulled them apart. I already have a couple of the Powerbarn kits so all good on that front

MotoPsycho · January 20, 2015, 05:15:30 PM

I dunno if the diaphragms are the same on 900 vs 750 carbs but FYI Suzuki DR650 carb diaphragms cross reference. Should anybody need to rebuild them that hasn't switched to FCR's yet

MonsterMadMarty · January 21, 2015, 01:45:51 AM

I pulled the carbie apart and all looked fine! Put it back together with hoses attached now only one side leak and fuel is now also coming from the outlet that leads to the plastic breather thing on the left side of the frame that sits behind the fuel inlet to the carbie!

I a spare NOS carbie I might try that next! Although that doesn't have the overflow nipple!

Howie · January 21, 2015, 04:28:45 AM

Take that leaky carb apart again. Check float height and make sure the needle and seat operate properly, or, better yet, replace the needle and seat.

koko64 · January 21, 2015, 04:47:51 AM

Some carbs shared the same nipple for overflow and draining. Means only two instead of four hoses.

MonsterMadMarty · January 21, 2015, 04:53:34 AM

Quote from: koko64 on January 21, 2015, 04:47:51 AM
Some carbs shared the same nipple for overflow and draining. Means only two instead of four hoses.

Cheers again Koko,

I might just replace the whole bloody thing (I have three NOS carbies sat in the garage). If you're ever in Perth, West Australia I think you have earnt the right to borrow a bike

koko64 · January 21, 2015, 05:04:51 AM

Cheers.

koko64 · January 21, 2015, 04:03:41 PM

Yeah, might as well throw on the new carbs (with the correct jetting for the mods) and clean up the old carbs at your leisure.

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Carbie Leaking?