Carb flooding new member help

[Bonz]

Ok, I am sitting back to watch the show...

Something in the carbs is hanging up or leaking like a needle seat o-ring or all the other things brought up by all the guys that have a been down this road. There is no other way or reason for fuel to go out the airbox. Once that has been come to grips with, let me know. It is frustrating, but it is predictable as to the eventual discovery of some issue of what is being shared.

Popcorn anyone?

[motoman]

LOL Motoman. I have a number of sets here ready to go, so if I'm doing testing I can have a set off and a new set installed in under 10 minutes. There is a reason the K&Ls are cheap to buy.
cdavidscee: 3 phase was refering to the vent T's. These have been known to cause leaks, particularly if a mistake is made plumbing the carbs and the fuel is hooked up to them not the lower t's. However, if you have 1980 carbs, you will not have vent t's on yours. They are vented through those upper little holes in your bells. Little critters like to build nests in them so if you haven't blown your clear, you should. The bowls need to be vented or the bike will not run properly and can cause a slow seep.

Good advice for those reading Mack. Since I've ridden it on and off(more off than on)......and critters (like some areas have) pretty much don't exist here, nor with my 'fussing' with them would ever have the oppertunity to migrate there, they are clear. Just that I gotta' chase those RUNNING fuel levels(as IS supposed to be done on the 81's and XJ's), file 13 the K&L needles, all's good. I say that cause now it's really close to being perfect(would be for the majority here), but I'm anal bout things operating perfect, and the fact that I know exactly the tone of that exhaust when it is precisely as it was 30+yrs, ago when new. Smoothness especially, and all around performance is unmatched with any other air-cooled inline four when those cyls. are being feed identically. Mixture settings CANNOT compensate for non IDENTICAL fuel levels, and this was 'hashed' out 10+ yrs. ago here by Ken Talbot and PROVEN to be true.

[cdavidscee]

Frustrated

Well I didn't mean to get you guys all riled up. But like I said I have worked on carbs since I was a kid (now 56) so this an't my first rodeo. Although it is with these carbs. Not sure what the brand the needle valves are, I bought them off E-Bay so who knows guess I'll find out.
But just thinking of this logically: If the bike ran fine before I got in there (no flooding one could conclude that:
1. The two fuel line T connectors didn't startling poring fuel on the ground, I can see the fuel running out to the back of the carb through the vent holes.
2. The vent holes are not plugged ie fuel running out of em, not to mention I ran a pipe cleaner through a long time ago.
3. I think now I have mentioned several times that yes I have tested them with fuel flowing from the tank mounted above the carbs.
Sometimes they flood and I take them apart (again) see nothing wrong, put back together, now not flooding. Put them back on the bike and soon after they start flooding again.
4. No I don't stand in a puddle of gas, in the garage with cigarette in my mouth scratching my ass, saying gee Festus I can't see notin ruug here.
5. I think I've said I already replaced the o-rings on the needle seats, but even that would not cause the gross flooding I'm talking about.
It has to be the float assembly and it must be something I've done. maybe just touching it has transferred bad JU JU.
6. I have had the air box off and watched fuel running out of the carb, so there is no doubt where the fuel is coming from.
7. I throw the Octo away and run right to the carb T via the new filters.
Intake (or exhaust) valves clearance have nothing to do with carb flooding.
The metal needle valves are sounding good at this point.
PS I bought a XS850 before this one and it had flooding carbs also. The previous owner had given up and parked the bike for 10 years. I opened em up cleaned em reset the float levels correctly and Walla no more leaks. But they were the Hitachi carbs but looked the same. I used to race a mini sprint, Honda CRX highly modified dyno'd at 85hp (stock 35) with a Mikuni on it. We raced in the dirt with Alcohol as fuel so I had em apart weekly - never had this problem.

[3Phase]

David, no one is riled up.

Do you think I was joking about the fire extinguisher? One guy burned down his house working on his bike on the front porch. I have no idea where or how you work on your bike but since you're trying to find a fuel leak I suggest you do it outdoors with a fire extinguisher handy:-

Click Me

Read the top link. It's called, "Silly way to deal with a bike on fire."

.

[mack]

Fire

way too funny Scott. I couldn't believe how long it took them to move the van! Not the sharpest tools in the shed were they.
Dave, you are correct, the valves will not cause leaks. But since these motors are just big air pumps with a controlled leak (carbs). having the cylinders breathing right is important to the performance of the carbs and the bike in general. Always a good idea to check the shims on an unknown (to you)bike. These motors are very well engineered and will seem to be running fine. It's a testiment to design, but there is nothing finer than a fully adjusted, well tuned XS11 motor for smooth performance and reliability. In general, if the valve train is quiet, it needs adjustment! Nice to see your keeping your sense of humour throughout this ordeal.

[Schming]

After reading the whole thread I'll bet the leakage comes from the needle valves but you state you replaced the float pins with looser ones, float travel might be okay, but are you sure they aren't cocking sideways and brushing up against the bowls ?

[mack]

Pouring

So which carb is leaking and describe, pouring. Seep, drip or free flow. I had a plastic float once that looked like it was brand new. Pick of the litter when I was work on some LH carbs. Installed fine and allowed me to set the levels. Then when I turned the carbs over itwould freeze in place. When I looked closer I noticed that the brass sleeve the pins slide through was crimped slightly(not round) the pin went through fine but after numerous articulations I found that every once in awhile the crimp would bind on the pin freezing the float in either the up or down position. I promptly removed the float, threw it on the floor and jumped on it a couple times so that I would never be picking it out of the pile in future carb rebuilds.

[MPittma100]

Great Idea

This is my set up for working on carbs. They are mounted on a 2x4 I cut on a band saw and use old carb boots. The carbs just push on and pull off and I can rotate the whole thing so the carbs are upside down.
I sort of do a lot of work on carbs so this is the most efficient set up for me.If they are going to leak, I like to know it before I mount them on a bike and find a nice flamable puddle on the floor the next morning.
Sounds like you have the same type of luck I do, so when you pull the bottom of the air box off, invariably the leaking carbs will be 2 and/or 3 so that tapping the bowl with a screw driver handle is impossible. Been there. Thats why I built the carb station to do the static testing and set the levels properly. I've worked on carb banks for all four years of the XS's, and they will all leak until they are set up properly.

The set off carbs in this picture were off an SF and all four leaked. I played with the fuel levels for days. They'd hold for an hour or two, I'd leave them over night and find they'd leaked when I came back in the next morning. I changed out needles, floats and trimmed back the bowl gaskets, checked the drop tangs and shook and rotated the carbs by hand to check the action of the floats. Nothing worked. I finally just got rid of the K&L seats and needles and put in an old set of mikuni's I had with metal needles. They have never leaked since. Infact I think they might be the set on my SF right now, or they might be the ones I gave to Rob.
If your carbs are 1980, they have the pressed in fuel seats with little o rings. These are held in with a screw and bracket. If you do take the carbs off again thats a good place to check for leaks. The needles may indeed be sealing but your getting blow by the seat itself.
As stated, they will all leak until you find the cause, but they will all stop leaking once you correct it. We've all been there.
Good luck

Hi Mack,

I like your setup. I share your thoughts on using this method. It works and saves so much time and frustration. It should have been part of the written procedure in the Yamaha Service Manual. I do the same prior to any carb installation. I left the fuel turned on to some carbs for 3 days to insure no leaks on a particular problem set I was dealing with.

[MPittma100]

Fire Extinguisher

David, no one is riled up.

Do you think I was joking about the fire extinguisher? One guy burned down his house working on his bike on the front porch. I have no idea where or how you work on your bike but since you're trying to find a fuel leak I suggest you do it outdoors with a fire extinguisher handy:-

Click Me

Read the top link. It's called, "Silly way to deal with a bike on fire."

.

Scott,

I agree with you. A fire extinguisher in hand is much better than a bike or shop in ashes. I keep several around in strategic locations. There is one in my saddle bag.

[3Phase]

Scott,

I agree with you. A fire extinguisher in hand is much better than a bike or shop in ashes. I keep several around in strategic locations. There is one in my saddle bag.

I have them stashed everywhere and I have a small one in the saddlebag too. I got my Google Fu working this morning and Varnae lost the house. The carburetors were just rebuilt and it caught fire when he started it up on the front porch.

David: get a fire extinguisher. After that, if it's not too much trouble, would you please take off the lower half of airbox and try to figure out which carburetors are leaking? Pretty please? Pretty please with sugar on top?

Oh yeah, if it's too dark to see up inside the airbox, use a flashlight and not a lighter!

.

[cdavidscee]

A morsal appears

Revewing what has been said here, looking for a SPECIFIC cause of carb flooding, I am thinking the K&L needle valves might be the suspect. Motoman you mention having lots of issues with them. It was mentioned the the original Mikuni needles have a solid wire loop rather than the overlapping type. Mine are the over lapping type and I suspect the previous owner must have put them in. As I said he had reported having flooding problems in the past. And on Jeff's link no one has yet identified a specific cause to the identical systems I'm having. I'm wondering if Jeffs carbs also have the non Mikuni needles? I am going to send the one's I ordered back and order some original Mikuni needles and seats. As for the looser float pin causing misalignment of the floats, the reason I put the smaller (by a couple .001's) one in was that I was having to tap the originals out each time (as one end is a compression fit). One of them had a slight bend so that's why I changed (thinking I had some binding going on). This did not change anything they still flooded. And yes Motoman I do intend to trim the gaskets next time in. Thanks for help guys I really do appreciate it. Dave

[motoman]

Revewing what has been said here, looking for a SPECIFIC cause of carb flooding, I am thinking the K&L needle valves might be the suspect. Motoman you mention having lots of issues with them. It was mentioned the the original Mikuni needles have a solid wire loop rather than the overlapping type. Mine are the over lapping type and I suspect the previous owner must have put them in. As I said he had reported having flooding problems in the past. And on Jeff's link no one has yet identified a specific cause to the identical systems I'm having. I'm wondering if Jeffs carbs also have the non Mikuni needles? I am going to send the one's I ordered back and order some original Mikuni needles and seats. As for the looser float pin causing misalignment of the floats, the reason I put the smaller (by a couple .001's) one in was that I was having to tap the originals out each time (as one end is a compression fit). One of them had a slight bend so that's why I changed (thinking I had some binding going on). This did not change anything they still flooded. And yes Motoman I do intend to trim the gaskets next time in. Thanks for help guys I really do appreciate it. Dave

Take those original float pins, chuck them up in a drill, using a fine file endways(thickness is just right for the height of the raised shoulder) and LIGTHLY remove that shoulder of the float pin till it will JUST slide in with a bit of a drag. This is an issue MANY here have resolved this way to keep from breaking a float post, me included.
Doing this and using original pins at least eliminate THAT as causing the overfilling of the bowl(s). BTW, didn't see where you stated which carb(s) was running fuel out. By any chance is it the 'evil' #3 carb?.

[motoman]

BTW cdavidscee, EXPLAINING your reason for the float pin change made alot of difference as to the response resolution.

[clarkcortez]

On a carb rebuild I mistakenly installed the vent T's and the fuel T's in the wrong positions. The longer fuel T in the vent position touched the carb body and would not allow the carb to vent causing a flooding condition. This flooding happened intermittently because sometimes I would get lucky and center the vent T well enough that it didn't touch the carb body. A remote possibility but easy enough to check.

[TopCatGr58]

Hey Dave,

It sounds like you're on the right track to figuring out why they are leaking.

A while back MACK sent me some 78 and 80+ carb bodies that I ran thru my metal cutting band saw and got some interesting insights into the anatomy of our carbs. See this link for the whole thread and photos.

http://www.xs11.com/forum/showthread...t=carb+anatomy

But your earlier statement about the fuel flowing out of the carb "vents" caught my attention, because the 80+ carbs have the bowl vent ports way up HIGH on the inlet bell of the carb. See this photo.



The lower ports are the Pilot air jet holes which is where I really think your carbs were/are leaking from....but NOT from the bowl vent ports which are at the TOP of the carb. And so again we also will reiterate that these upper ports need to be open/clear for the air pressures to equalize properly for the floats to work, if they are clogged, then the floats will not float properly, and the carbs will FLOOD.....same as with the 78-79 series carbs with the side body vent T's being clogged. Just an FYI!

Hope you find that the K&L needles and seats are the true culprit, but didn't want to leave another possibility on the table.

T.C.