carb overflowing

[roger]

ive got a 1979 xs1100 thats been setting for a year or so, i pulled the carbs and cleaned. i couldn't get the pilot out of # 2 carb so i got one on ebay. i put them together and ran gas to them. all was good except # 2 was overflowing. ive changed everything but didn't help. with out gas the carb seals off, you can blow in the gas line with the carbs up side down and no air will go through. ive trimed the gaskets, float works good. the carb has the black plastic floats, i set them on 25.7mm i read that they should be set on 23.0mm ive got the early carbs is that wright. could that cause them to overflow? thanks

[bikerphil]

Plastic floats in early carbs should be 23mm with gasket removed. I don't think the 25.7 mm setting would cause the flooding, something else going on there. Make sure to check both sides of each float.



When you're filling the carbs, tap on the #2 carb bowl and see if the problem persists. Is the ring gasket on the float valve in good condition?

[cajun31]

ive got a 1979 xs1100 thats been setting for a year or so, i pulled the carbs and cleaned. i couldn't get the pilot out of # 2 carb so i got one on ebay. i put them together and ran gas to them. all was good except # 2 was overflowing. ive changed everything but didn't help. with out gas the carb seals off, you can blow in the gas line with the carbs up side down and no air will go through. ive trimed the gaskets, float works good. the carb has the black plastic floats, i set them on 25.7mm i read that they should be set on 23.0mm ive got the early carbs is that wright. could that cause them to overflow? thanks

If possible take a couple pictures of the carbs and post. Best if you can take the bowl off #2. Black floats generally don't say early carbs. Most of the early carbs had brass floats in them. Phil's picture shows how the float heights should be measured and set.

[roger]

Plastic floats in early carbs should be 23mm with gasket removed. I don't think the 25.7 mm setting would cause the flooding, something else going on there. Make sure to check both sides of each float.



When you're filling the carbs, tap on the #2 carb bowl and see if the problem persists. Is the ring gasket on the float valve in good condition?

thanks ill try that tomorrow. i wish they made a clear bowl.

[roger]

If possible take a couple pictures of the carbs and post. Best if you can take the bowl off #2. Black floats generally don't say early carbs. Most of the early carbs had brass floats in them. Phil's picture shows how the float heights should be measured and set.

my dad in law bought the bike new, i guess he must have changed then because thats what was in it when i got it.

[oldyam80sg]

How about the float needles? the tips if they are worn can cause issues.

[DEEBS11]

" i couldn't get the pilot out of # 2 carb so i got one on ebay. i put them together and ran gas to them" I am not clear on this. Pilot jet or pilot adjustment screw? What exactly was purchased? A jet or an entire carb rack? If only a part was purchased, how did you make the repair of carb #2? I only ask this because of your original statement that says the part in question is stuck and cannot be extracted. How was this resolved. Did you use genuine Mikuni parts or Chinese parts which are (too) plentiful on eBay.

[roger]

" i couldn't get the pilot out of # 2 carb so i got one on ebay. i put them together and ran gas to them" I am not clear on this. Pilot jet or pilot adjustment screw? What exactly was purchased? A jet or an entire carb rack? If only a part was purchased, how did you make the repair of carb #2? I only ask this because of your original statement that says the part in question is stuck and cannot be extracted. How was this resolved. Did you use genuine Mikuni parts or Chinese parts which are (too) plentiful on eBay.

im sorry it was the pilot jet and i messed the carb up trying to get it out so i bought a # 2 carb on ebay

[DEEBS11]

Ah yes, the eBay carb parts. Beware. My #3 carb had a stuck pilot screw that could not be extracted. I picked up a #3 body on eBay but found out from Crazy Steve's carb comparisons that it had an extra hole in it for passage to the pilot jet that must be plugged with a rubber plug which I did. Thankfully the carbs tuned perfectly and I was lucky to get such good info. Now I have # 1,2 & 4 carbs unplugged and #3 plugged because carbs can look the same but be different. Won't that be fun for the poor guy who gets my bike someday? Bottom line - you may have introduced a problem with the carb body. Check Crazy Steve's writings on the subject. I know this might not effect fuel level but you should take a closer look at what you picked up on eBay. That's when the trouble started.

https://xs11.club/forum/repairs/interchange-guide/36909-carb-identifier-guide

[roger]

Ah yes, the eBay carb parts. Beware. My #3 carb had a stuck pilot screw that could not be extracted. I picked up a #3 body on eBay but found out from Crazy Steve's carb comparisons that it had an extra hole in it for passage to the pilot jet that must be plugged with a rubber plug which I did. Thankfully the carbs tuned perfectly and I was lucky to get such good info. Now I have # 1,2 & 4 carbs unplugged and #3 plugged because carbs can look the same but be different. Won't that be fun for the poor guy who gets my bike someday? Bottom line - you may have introduced a problem with the carb body. Check Crazy Steve's writings on the subject. I know this might not effect fuel level but you should take a closer look at what you picked up on eBay. That's when the trouble started.

https://xs11.club/forum/repairs/inte...entifier-guide

yes you have to be careful, this carb is the wright one and it is clean and everything removed from it.i don't understand why you turn carbs upside down and the needle seals off but when you put gas to it it pours out the carb like the floats not working at all.

[DEEBS11]

I'm sorry Roger, I did not totally understand what you wrote. If you turn carbs upside down fuel will pour out of the vents. Float chambers have vents so the fuel can flow. All flow testing must be done with the carbs upright.

[roger]

I'm sorry Roger, I did not totally understand what you wrote. If you turn carbs upside down fuel will pour out of the vents. Float chambers have vents so the fuel can flow. All flow testing must be done with the carbs upright.

i don't use gas to check up side down i blow in gas line,turn carbs up side down you can't blow in them then turn right side up you can.

[red bandit]

You can check to see if your float needles are working by turning the carbs upside down and apply gas to the carbs. Float bowls off.

[roger]

You can check to see if your float needles are working by turning the carbs upside down and apply gas to the carbs. Float bowls off.

i did that and they don't leak at all. i also put rubber bands around the floats to hold them closed and they didn't leak. thanks

[Ranger_xs1100]

Roger,

Having recently had the same dilemma that you are describing, here’s my assessment of your situation and what I found.

One would think that if there is gas leaking, the bowls are overfilling because the float valves are not shutting off.
But you have proven that the float valves are closing. So that’s not your problem. Time to move on from there.

You had the carbs separated to replace #2.

As it was in my case, You may have scratched or nicked or maybe even cracked the fuel inlet Tee. It is hard to see where the leaking gas is coming from with the carbs on the bike, because the Tees are kind of buried.

It wasn’t until I filled them while off of the bike that I could see gas leaking round the Tees. And a lot of it too, even though I couldn’t see anything wrong with the TEE.

The floats were shutting off the valves as they are supposed to, but that won’t stop the fuel flow if it is leaking at the inlet tees. Only shutting off the petcocks will stop that.

Good luck, I hope this helps you. I’ll be curious to know what you find.