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Going to fix the carb leak issue when the gas is on and engine is off. I'm guessing the only reason it doesn't leak when running is that it is using gas fast enough to not let it leak. I do get a whiff of gas now and then when running it.

What is the most likely cause? Stuck float shutoff?

Can I get to what I need to by removing the float bowl on the bike or do i have to remove the entire carb?
 

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Going to fix the carb leak issue when the gas is on and engine is off. I'm guessing the only reason it doesn't leak when running is that it is using gas fast enough to not let it leak. I do get a whiff of gas now and then when running it.

What is the most likely cause? Stuck float shutoff?

Can I get to what I need to by removing the float bowl on the bike or do i have to remove the entire carb?
While it can be a stuck float, in my case it was a bad/old/cracked valve seat o-ring. There are lots of threads about it, but here is mine from this past spring. Hope it helps.
http://tw200forum.com/forum/technical-help/14440-admirals-mayflower.html
 

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Most likely, it's what Admiral said... ^^^^^^^^^^above.
 

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"Going to fix the carb leak issue when the gas is on and engine is off" - yes, best to fix all gas leaks while the engine is off, less fire hazard.:p
Sorry to be such a terrible tease Little Brute, couldn't help myself.
Say, where do you think the gas leak is showing up? Leaking from petcock, fuel line, carb body, float bowl cover gasket? Knowing this will help us help you.
 

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Discussion Starter #5
"Going to fix the carb leak issue when the gas is on and engine is off" - yes, best to fix all gas leaks while the engine is off, less fire hazard.:p
Sorry to be such a terrible tease Little Brute, couldn't help myself.
Say, where do you think the gas leak is showing up? Leaking from petcock, fuel line, carb body, float bowl cover gasket? Knowing this will help us help you.
I'll be sure to shut everything off before sitting down with my cigar to get started...

Leaking out of one of the hoses that run below the frame. My guess is a carb float bowl overflow, but not sure. Going out to look at it soon.
 

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...Leaking out of one of the hoses that run below the frame. My guess is a carb float bowl overflow,....
Good guess. What Admiral said....bad o-ring on the float valve seat if it is a sloooow drip from overflow tube.

If it is a fast drip, drip, drip....then the float valve may not be fully closing.

Here's the result of an o-ring leak:




jb
 

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Another thought.....on occasion I have had to nearly destroy the float valve seat when trying to remove it.

It is made of brass and is easily marred.

The last time I coated the o-ring with a thin layer of petroleum jelly (Vaseline). When I had to remove it again, the float valve seat easily slid out.

jb
 

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I did that too. Hopefully the next time will be a long time from now!:p
 

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Discussion Starter #10
Good guess. What Admiral said....bad o-ring on the float valve seat if it is a sloooow drip from overflow tube.

If it is a fast drip, drip, drip....then the float valve may not be fully closing.

Here's the result of an o-ring leak:

jb
Yeap, that's what it does. Slow dip. I thought it would be an easy fix. Doesn't do it when running either. Thanks.
 

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Discussion Starter #11
Another thought.....on occasion I have had to nearly destroy the float valve seat when trying to remove it.

It is made of brass and is easily marred.

The last time I coated the o-ring with a thin layer of petroleum jelly (Vaseline). When I had to remove it again, the float valve seat easily slid out.

jb
Oil looks good. No change in the inspection window.
 

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Discussion Starter #12
Well, I went out in the garage to fix it, but it doesn't do it anymore. It happened when I bought it, so I've just been turning the fuel off each time I turn the engine off. Now after riding it for some time it doesn't leak anymore...

Probably was just due to something from sitting in the PO's Palm Springs garage without being used much. Woo-hoo, she's good to go!
 

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Sometime my float get stuck after the fuel valve is off for a few month, (winter time ) when I turn it on it will drip out the overflow, I smack the float assemble with the screw driver handle and it will be good ! This has only happened a few times.
 

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Brute.

Leave it tonight on. You will find stain tomorrow.

Pro Cycle your friend. Not your wallet's.

Not only the oring nasty, but the screen is too.

Please read the float removal thread.

:eek:ccasion14:
 

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Discussion Starter #15
Brute.

Leave it tonight on. You will find stain tomorrow.

Pro Cycle your friend. Not your wallet's.

Not only the oring nasty, but the screen is too.

Please read the float removal thread.

:eek:ccasion14:
Well you're right, I spoke too soon. Left it on just to be sure and when I went back to check the pie tin had a little gas in it. It's leaking from the hose coming out of the bottom of the float bowl (bottom arrow),



so it must be going into the brass tube (top arrow). I'll go read the float bowl thread to see if it ID's the part I need. Everything I can see is clean as a whistle.
 

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Brute.

The oring you need. UNDER the needle's seat. Has a screen hat on.

But you need to understand how the float pin comes out. It's tight.

See pics in Admirals post (oring)
 

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Discussion Starter #17
Brute.

The oring you need. UNDER the needle's seat. Has a screen hat on.

But you need to understand how the float pin comes out. It's tight.

See pics in Admirals post (oring)
Thanks. I just read the float pin thread. Looks easy, but not sure I want to do this with the carb on the bike. Have others done the O-ring repair with carb on the bike?

Oppinions welcomed on this one. Won't be getting to it until tomorrow, it's going on 8pm and this old man needs his beauty sleep...
 

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Discussion Starter #18
Everything went well in removing the float pin and valve seat. You can see the degraded o-ring on the seat.



When I removed it with an ice pick it just crmbled and broke.



Clearly that is the problem. Everything looks really clean. I know the PO said he would turn off the fuel while the bike was idling and run the bowl empty each time he parked it for any length of time, plus it's probably the original 12 year old O-ring.

So what is the size and part number for just the O-ring? I have tons of them, but understand that it needs to be the exact right size and fuel tolerant material. Can just the O-ring be bought at the Yamaha dealer? Seat and shut-off valve look and were working fine.

It might be nice to add the size and part number to the Technical write mentioned above for easy referrence.
 

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:icon_thumright:Exactly what my o-ring looked like when I removed it!
 

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Discussion Starter #20 (Edited)
:icon_thumright:Exactly what my o-ring looked like when I removed it!
Burnt toast! Oh, and sorry to here about the Mayflower. I know that feeling to well. Mine usually goes POP-BANG and locks up the rear wheel; typically do to over reving and valves hitting pistions. Same general fix. My condolances...

Went to my local lawn mower and small engine repair shop. He didn't have any O-rings the right size, but turned me on to a Honda/Yamaha dealer that I didn't know was fairly close by. Stopped in there on my way home. The counter jockey pulled up the micro film of the carb showing the float shut-off needle, seat, screen and O-ring only sold as a kit. I didn't even ask the price. Then he said let me see your seat, so I handed it to him. After a few minutes he emerged with an O-ring on my seat and asked if that looked about right. I said it looks good to me, all mine at home where just a bit to thick. Asked him what I owed him and he said nothing. Wow! They've got a new customer for life.

I also asked him if he knew what size it was. He went back and looked at the label where he got it and said either 1.25mm or 1.05mm X 0.75mm, unfortunately I can't remember for sure and didn't have a pin at the time to write it down. I know the 0.75mm was one of the numbers.

Going to go put it all back together and will report back.
 
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