New float needles and seats....maybe? Yup!

[Mrjohnahawley]

Hey people! I have disassembled and cleaned and reassembled my carbs only to find the dreaded gas leak I have read sooooo much about in the forums. I have boil tested my brass floats... They passed with no problems. I have set and checked and rechecked the float height at the max of spec range. Still leaked! I found a thread that advised removing the bowls and testing upside down with a fuel source. I tried that today and found that carbs 1 and 3 immediately leaked even when manually pushing on the needles. The fuel was leaking past the needle, not from the fiber washer. So I cleaned up the gas removed floats and pulled the needles and seats. I can't find anything visually wrong with them. The needles are metal tipped and from what I have read here, that is stock for a '79 standard. The seats have no debris in them and appear nice and shiny. So are there any tips for me? I feel like I have followed all of the clues and hints in the forums and have kind of come to the conclusion that I need new seats and needles. Where would be the best/ cheapest source for 4 new seats and needles that are correct for a '79? If the are repairable how or what would I do? Thanks very much and sorry for the long winded post. Just trying to provide enough info.

[bikerphil]

You can polish the seats with a Q-tip and chrome polish and replace just the needles. This is the cheapest method and it works fine for me, I usually change the needles every 40K or so. Here are the needles from Z1....

http://www.z1enterprises.com/ItemDet...item=KL18-8956

[Mrjohnahawley]

You can polish the seats with a Q-tip and chrome polish and replace just the needles. This is the cheapest method and it works fine for me, I usually change the needles every 40K or so. Here are the needles from Z1....

http://www.z1enterprises.com/ItemDet...item=KL18-8956

Cool tip! I'm gonna try that tonight!

[bikerphil]

Yep, if the needles have rings worn into them they should be replaced. If you really want to try to save them, you can put them in a drill chuck and try to polish the ring out. The seats can be reused with some minor polishing. GL

[MarkD]

FWIW--I got carb rebuild kits off ebay and they came with needles/seats. I think I paid $59 for 4 kits. I figured new gaskets, etc. were in order anyway. I then ordered Mikuni jets, because of revving issues, and I was a green carb rebuilder at that point. I think I can remove 4 carbs and tear them apart in about 1/2 hour now.

http://www.ebay.com/itm/330838357949...S:1123&vxp=mtr

[Mrjohnahawley]

Yep, if the needles have rings worn into them they should be replaced. If you really want to try to save them, you can put them in a drill chuck and try to polish the ring out. The seats can be reused with some minor polishing. GL

Well....no luck on that experiment. The seats and needles polished up very nicely but 1 and 3 still leak. I even tried swapping the needles from the non leaking seats and same result. The needles did have rings on them, though they faded some while polishing. Really neat trick though! I will keep that in the memory banks for maintaining my new parts. I had my tank on a five gallon bucket over the carbs and ran them on prime. Is that an issue at all? Should I maybe have run them in the on position? Gonna give that a try in the morning. Thanks again

[Mrjohnahawley]

FWIW--I got carb rebuild kits off ebay and they came with needles/seats. I think I paid $59 for 4 kits. I figured new gaskets, etc. were in order anyway. I then ordered Mikuni jets, because of revving issues, and I was a green carb rebuilder at that point. I think I can remove 4 carbs and tear them apart in about 1/2 hour now.

http://www.ebay.com/itm/330838357949...S:1123&vxp=mtr

Thats a good deal! I will look into that. This is my first bike and definitely my first carb rebuild. I have gotten through this thanks to this great forum! I am getting much faster at float disassembly

[TopCatGr58]

Hey John,

Yes, your leaking is probably what you've found/described as worn needle faces/tips. Another tip is to lightly file/grind/sand the float post PINS down a little bit so that they easily slide in and out and not get stuck/bind when inserting and removing them. This can also help ensure that the floats are not binding against/on the pins which could prevent them from moving as freely as possible so that they can exert the needed pressure to push the valves closed. This also helps you NOT break a float post while R&Ring the pins. They do NOT need to be a snug/interference fit, they can be LOOSE, the sides of the float bowls will keep them in place so that they won't slide out.

Also, check the distance the float and needle are travelling when the float is all the way down(right side up). There is a little tang on the side of the flange that hits the float post to prevent it from dropping down too far, which can cause the needle to get cocked at an angle binding and not seal. This happens often when the carb bowls are empty, and then trying to fill with the petcocks on, folks will use a deadblow or HANDLE of a hammer/large screwdriver to tap the carb bowls to try to dislodge the cocked needle and allow it to slide UP into the seat like it should and can then seal. YMMV!

Another option that is noted on the site is a MOD to install Viton/rubber tipped needles, but they require a different seat.....the ones from the XV920 carbs have been found to fit/screw in vs. the XS11 type that are just pushed into place with an O-ring and securing U clamp on the later model carbs.

T.C.

[MarkD]

MrJ.---Here's a helper for you.

https://www.youtube.com/watch?v=95nlrP-yn2I

[Mrjohnahawley]

Hey John,

Yes, your leaking is probably what you've found/described as worn needle faces/tips. Another tip is to lightly file/grind/sand the float post PINS down a little bit so that they easily slide in and out and not get stuck/bind when inserting and removing them. This can also help ensure that the floats are not binding against/on the pins which could prevent them from moving as freely as possible so that they can exert the needed pressure to push the valves closed. This also helps you NOT break a float post while R&Ring the pins. They do NOT need to be a snug/interference fit, they can be LOOSE, the sides of the float bowls will keep them in place so that they won't slide out.

Also, check the distance the float and needle are travelling when the float is all the way down(right side up). There is a little tang on the side of the flange that hits the float post to prevent it from dropping down too far, which can cause the needle to get cocked at an angle binding and not seal. This happens often when the carb bowls are empty, and then trying to fill with the petcocks on, folks will use a deadblow or HANDLE of a hammer/large screwdriver to tap the carb bowls to try to dislodge the cocked needle and allow it to slide UP into the seat like it should and can then seal. YMMV!

Another option that is noted on the site is a MOD to install Viton/rubber tipped needles, but they require a different seat.....the ones from the XV920 carbs have been found to fit/screw in vs. the XS11 type that are just pushed into place with an O-ring and securing U clamp on the later model carbs.

T.C.

Love the tip on the float post pins! Ever since I read that they break easily I have cringed and held my breath when removing the floats. This will really help, thanks! How far is too far down for the floats? I am familiar with the tang you are talking about. I left it alone as I wasn't sure what the setting should be.

[Mrjohnahawley]

MrJ.---Here's a helper for you.

https://www.youtube.com/watch?v=95nlrP-yn2I

Thanks for the link! I had already watched the video a couple of times. It is very helpful and added some confidence for tackling the rebuild.

[TopCatGr58]

Love the tip on the float post pins! Ever since I read that they break easily I have cringed and held my breath when removing the floats. This will really help, thanks! How far is too far down for the floats? I am familiar with the tang you are talking about. I left it alone as I wasn't sure what the setting should be.

The floats only need to move a few mms', just enough to allow the float needle to drop down a mm or 2 away from the seat to let the fuel flow. IF the needle drops more than half it's length then it can get slanted in the seat channel and bind.

T.C.

A couple of photos borrowed from the UK site!

[motoman]

Well....no luck on that experiment. The seats and needles polished up very nicely but 1 and 3 still leak. I even tried swapping the needles from the non leaking seats and same result. The needles did have rings on them, though they faded some while polishing. Really neat trick though! I will keep that in the memory banks for maintaining my new parts. I had my tank on a five gallon bucket over the carbs and ran them on prime. Is that an issue at all? Should I maybe have run them in the on position? Gonna give that a try in the morning. Thanks again

On position opens with vacuum(hose from #2&#3 carb boot). The PRIME position least found the leaking float seats. ON position, with enough fuel in tank should not leak when fuel lines are dis-conected or tank is off the bike.

[Mrjohnahawley]

The floats only need to move a few mms', just enough to allow the float needle to drop down a mm or 2 away from the seat to let the fuel flow. IF the needle drops more than half it's length then it can get slanted in the seat channel and bind.

T.C.

A couple of photos borrowed from the UK site!

Very useful, thanks!

[Mrjohnahawley]

On position opens with vacuum(hose from #2 carb boot). The PRIME position least found the leaking float seats. ON position, with enough fuel in tank should not leak when fuel lines are dis-conected or tank is off the bike.

That's what I was thinking. Thanks for confirming