Topic: Carb 1 Intake Boot Gas Leak (with picture)

[gregripko]

Looks like the leak is coming from boot... Any ideas/suggestions? Looks like the boot is cracked and leaking gas... Guessing it's time to replace but is it possible, because it's carb 1, to maneuver carbs and replace without ripping whole carbs out?

[martin99]

Don't see a way of changing the boot without removing your carbs. You're likely to fack up your new boot if you start using levers in there.

[Vinhead1957]

Are you sure the source of the leak is from the intake? I would look above the intake to be sure.  Leaks on intakes are usually vacuum and fuel should be vaporized by the time it gets there!

[taggat]

overflow?

[martin99]

It looks like the level in your float bowl is too high. Suspect leaking petcock, sticking needle valve, float set too high, or maybe a combination.

Likely to show on #1 if the bike is left on the prop stand. If you have one, use the main stand when you park up and turn the fuel off.

Personally, I would need to rectify the problem before worrying about the boot before the fuel contaminates the oil.

[gregripko]

Thank you for all the good responses... I checked oil and could not smell gas... Maybe float level is somehow off :/ but I would suspect it to drain out of the bowl overflow not the boot... Can you explain a sticking needle valve and what would occur?

[martin99]

It's the action of the rising float that closes the needle valve, stopping the flow of fuel into the bowl. It only takes a tiny piece of crud to prevent the valve seating properly, in which case fuel will continue to enter the bowl above the level it's supposed to be.

I would expect it to drain from the overflow too - it's uncommon, but not unknown for these to get blocked as well. Easy enough to check without removing the carbs. As said before, parking up at an angle might have something to do with it.

[gregripko]

Hmm..... I'm eliminating possibilities today to narrow it down... Cleared the overflow with air so that there no chance of crud coming out so if it overflows from inside the bowl it should now come out of the overflow tube rather than the intake boots...

[gregripko]

I was using aftermarket float valve and switched back to old stock float valve.... So far so good but I haven't really ridden it too hard yet to feel comfortable that I solved the issue

[gregripko]

Ugh still leaking... I don't get it... The worst part is that I don't know where it's coming from... Just appears to be the intake boot... Got a random question... When the bike is on side stand and you're looking down into engine from the valve adjustment hole... Should I be able to see fluid below the valve adjustment point? It looks like oil but it's really high up in the engine

[vames]

Don't complicate things by looking under the valve adjustment covers or anywhere else. You've got gas coming out of a crack in an intake boot. That means:

1) You have to change the cracked intake boot. And why not change them all while you're at it? Try these guys: http://www.claussstudios.com/id45.html or davidsilverspares.com. If your airbox rubbers are crusty, why not change those at the same time?

2) You have to figure out and fix a) why your carb is overflowing, b) why it's not coming out via the overflow tube. While you have the carbs off, clean all of them. You recently cleaned them? Clean 'em again. You can use a little metal polish on a q-tip to polish up the both sides of the float valve -- that may help it seal.

3) Even if you don't have a strong smell of gas in your oil, if it's making it to the crack in the carb boot it's probably making it into the chamber and past your rings and into the oil. Change your oil once you fix the problem. 

4) Make it a point to turn off your petcock every time you park the bike. Even float valves that are working great get stuck or get dirt in them every once in a while. Turn off the petcock and you won't fill the floor or the case with gasoline.

[mono]

Don't complicate things by looking under the valve adjustment covers or anywhere else. You've got gas coming out of a crack in an intake boot. That means:

1) You have to change the cracked intake boot. And why not change them all while you're at it? Try these guys: http://www.claussstudios.com/id45.html or davidsilverspares.com. If your airbox rubbers are crusty, why not change those at the same time?

2) You have to figure out and fix a) why your carb is overflowing, b) why it's not coming out via the overflow tube. While you have the carbs off, clean all of them. You recently cleaned them? Clean 'em again. You can use a little metal polish on a q-tip to polish up the both sides of the float valve -- that may help it seal.

3) Even if you don't have a strong smell of gas in your oil, if it's making it to the crack in the carb boot it's probably making it into the chamber and past your rings and into the oil. Change your oil once you fix the problem. 

4) Make it a point to turn off your petcock every time you park the bike. Even float valves that are working great get stuck or get dirt in them every once in a while. Turn off the petcock and you won't fill the floor or the case with gasoline.

+1 million to all of that.  just needs to be done.  you really need to check what the float bowl heights are, and the only way to do that is to pull them and drain them.  since you have to do that.... might as well clean them.

[martin99]

It's normal to see oil in there. The valve train needs lubrication.

Here's what I suggest regarding your fuel leak.

1. Run your hand along the tank seam. Satisfy yourself it is not leaking, dripping down and giving the impression it is leaking at the inlet rubber.
2. Same with the petcock. Make sure that externally it is fuel tight.
3. With the petcock turned off, remove the fuel supply line from the petcock to carbs, Place a rag/some paper under the petcock and go and have a beer. When you come back, check the rag. If it is wet/smells of fuel then your petcock is not working properly and will need to be refurbished/replaced.

Remember if you have a weeping petcock and your bike is on the side stand, fuel will continue to flow. This was mentioned to you in your earlier post, and whilst you verified that the float valve wasn't letting fuel by you did not clarify whether you had investigated the petcock. Also, I assume you removed the float bowl to clear the overflow tube rather than blow air up it from below - if you did this you could well have dislodged some crud only for it to manage to block something else.

If you are happy your petcock is not leaking, then the problem must lie with the fuel supply line or the carbs themselves. On the subject of float valves, I noticed when I replaced all four of mine, with good quality aftermarket replacements, the new ones were slightly longer than the old. If you have substituted your new valve with the original, you may well have replicated a problem as your float may now be set too high. Have you checked your float heights?

All of the above is just general advice and may not be specific to your carbs, but to me are the first things to eliminate. From your question regarding boot removal without removing the carbs, I suspect you may be a little reluctant to pull them but I think you may well have to bite the bullet. Not as scary as you may imagine once you get into them, and if you follow the advice on here.

[gregripko]

Thank you guys for all your input.... Extremely helpful... I'll try to dig into the carbs when I have free time next but I feel like I'm getting closer to the answer by eliminating the possibilities. My petcock isn't leaking... When I remove the tank and set it aside there's no drips forming or drops below...