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MkHonda

Aww snap... gas is running out vent tube of float chamber

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Rebuilt the carb on my 91 TRX300FW but now there is gas running out of the float chamber vent tube. Item 20 in the parts diagram. After consulting a friend the first thought was that the float valve wasn't properly seated or something mis aligned on the float when assembling things. Pullled it apart to make sure the top of the float valve was positioned correctly with the float.  After the first assembly gas was running literally running out of the tube. Second time it was a drip every couple of seconds for the first 10 minutes then was a couple of drops per second.

 

Any one else experience this or have a potential remedy?  Much thanks in advance.

 

 

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I would guess more than likely , your tank and or petcock has trash in it , like grit , rust , granulated ethanal and it keeps getting reintroduced into the carb , cause the float valve to stay cracked open , cleaning the tank out may solve that ---- also could be the float valve sticking , tooth paste and a q-tip can polish that up ---also could be #18 in the pic , not indexed right and jamming the float 

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agreed^^^^ i was thinking float valve .... also take the petcock screen off, and check /clean it, and does this bike have a aftermarket inline fuel filter ? if it does ? change that to. 

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Had the same problem on my 450 a couple years ago, installed an inline fuel filter like I have on my mowers, golf cart.  Never had an issue since, I do shut my fuel petcock off when shutting down tho just in case.  Nothing like going out next day and seeing a large fuel puddle on the cement.  Just keep an eye on your filter and change when needed, I do mine every 6 months just because its easy and cheap....

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I did have my tank off and thought I had cleaned it thoroughly but as fish stated in the post above, it only takes a small particle to keep that float valve open...

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A new K & N in line filter was installed after reading some  posts here and seeing it suggested in videos. It was a bit bigger than expected but made it fit.  Hard to believe that Honda thought the little screen below the peacock would be enough to keep junk out. 

 

Toothpaste and a q tip will be something to try. 

 

Item 18 gave me some concern also. On assembly made sure it was seated properly.

 

Would trying the original float valve be worthwhile?

 

It might be the weekend before i get time to try these suggestions. But who knows.

 

Thanks for for all your thoughts.

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1 hour ago, MkHonda said:

Would trying the original float valve be worthwhile? 

 

could be if the tank trash was the issue to start with, but I'd keep it as a backup, and just use the new one, just depends on what shape the tip is in. 

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trash on float needle or float seat ?, does not take much to keep the float needle from sticking open.

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Posted (edited)

that brass float seat can build up a thin layer of oxidation. Be very gentle with the float seat—I only use carb cleaner and a cotton swab. Scratches in the seat could ruin the carb. Toothpaste is the mildest abrasive that I’ve heard you can use.

 

perhaps the only way the seat can be replaced is by special kits and tools. Ive seen the kits on fleabay but don’t know of anyone who’s used one. 

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Edited by Goober
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15 minutes ago, Goober said:

that brass float seat can build up a thin layer of oxidation. Be very gentle with the float seat—I only use carb cleaner and a cotton swab. Scratches in the seat could ruin the carb. Toothpaste is the mildest abrasive that I’ve heard you can use.

 

perhaps the only way the seat can be replaced is by special kits and tools. Ive seen the kits on fleabay but don’t know of anyone who’s used one. 

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the seats are pressed in the carb body. i have never seen a new seat anywhere online to replace them with ?. even if i did ?, i'd be weary of trying to get the old seat out ?!..lol.

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5 hours ago, shadetree said:

the seats are pressed in the carb body. i have never seen a new seat anywhere online to replace them with ?. even if i did ?, i'd be weary of trying to get the old seat out ?!..lol.

 

The last float I put in came with a new seat.  I didn't use it 😕 because I wondered how you could get it out without doing some damage.

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44 minutes ago, superrman77 said:

 

The last float I put in came with a new seat.  I didn't use it 😕 because I wondered how you could get it out without doing some damage.

that is a first, i've bought many shindy kits, not one ever came with a float seat..yer's musta be a china knock off ?..lol. you are correct..chances of getting it out without some damage ?..slim to none..lol.

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1 hour ago, shadetree said:

that is a first, i've bought many shindy kits, not one ever came with a float seat..yer's musta be a china knock off ?..lol. you are correct..chances of getting it out without some damage ?..slim to none..lol.

 

It was in a float kit.  It came with it.

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Posted (edited)

i found this video very interesting .... and i have seen older carb kits for certain (carburetor powered) equipment with steel balls included. never tried this myself, (on a carb float seat valve, but it does work on other applications) and most likely would be a last choice. (pinging the brass seat) this of corse would be after a new kit and a good cleaning and slight polishing didnt work, and the seat can't be replaced. 

 

 

Edited by _Wilson_™
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Peening the valve seat would be a last step. The interesting thing for me from this vid is how he did a test to see if the valve was seating properly.

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Has any one used the float measurement tool shown in the manual?  It looks like some kind of flimsy caliper.  Is it possible to use a regular caliper? 

 

Thanks again for for all the thoughts and suggestions.

 

Hoping tomorrow evening I'll be able to get beyond theorizing and pull the carb to try out some of these ideas.

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I don't figure why they didnt make them where the seat could be replaceable being the 300 fourtrax was one of the most popular utilty honda atv's they ever made, for the seat, my thinking would be they would have to be carefully drilled out, then a new oem seat pressed in ? I've done small engine carbs like that, but I'm not chancing those honda carbs, being there getting hard to find, and most likely no chance of finding a oem seat. 

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20 hours ago, Goober said:

that brass float seat can build up a thin layer of oxidation. Be very gentle with the float seat—I only use carb cleaner and a cotton swab. Scratches in the seat could ruin the carb. Toothpaste is the mildest abrasive that I’ve heard you can use.

 

perhaps the only way the seat can be replaced is by special kits and tools. Ive seen the kits on fleabay but don’t know of anyone who’s used one. 

3150FD13-6276-43B3-8B35-420AD1E16763.jpeg

The carb on my 02 rancher was prone to leaking. I took 2 cotton swabs and wrapped the ends with a thin layer of 0000 steel wool and gently spun them between my index finger and thumb against the seat. My carb no longer leaked after I did this. I didn’t know any better. Maybe I just got lucky but it worked. 

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Well this weekend had a chance to dig into this. Long story short... polished with toothpaste and cleaned with a q tip.  The new float needle would seal if there wasn't much movement to simulate riding.  However a little jiggle like you would get riding a washboard road and lots of fuel coming out. 

 

In the end it worked best by using the needle it had. 

 

For what it's worth I did rig up a way to measure the float. 20210807_114601.jpgThe manual says it should be .730" with no tolerance range. My original jet measured .710 and the new one was at .735.

 

Thanks everyone for the suggestions.

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11 hours ago, slowindown said:

Does it have the rubber tipped float needle or just metal?

 

Yes it did. The silver looking one is what was supplied with the kit. The tarnished one at the bottom of the image is the original.

 

The other interesting thing about this float needle is that it has a spring inside it that pushes on the tiny pin at the top of the needle. 

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I looked back and never did see if you purchased a Shindy carb kit or some other brand ???  the two float valves in the pic are different , might replace one and other on paper , but they are different if you look at the tip area  , no sure if that will solve anything for you , but I would start there 

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