Fuel Leaking Out Of Float Bowl Overflow!

[marky g]

my 2002 250 rev3 is nearly always leaking fuel out of the carb floatbowl (not the breathers as mentioned before on here)

Checked out the past posts on this subject and found this

Done what the mod says with my float 'tang' but it still leaks.......correct me if Im wrong but I think the drawing in the link is wrong ! if you want to restrict the fuel going into the bowl you want the tang going the other way than what Clark says....whats reckon?

Edited August 14, 2005 by Marky G

[bikespace]

Looks right to me mate, what I see is basically straighten the 90 deg bend in the tang out a bit rather than bending it more.

As the floats drop, the tang can only go so far down and allows less fuel to flow.

Where's yours leaking from now if you've got the breathers connected together?

[lineaway]

Looks right to me mate, what I see is basically straighten the 90 deg bend in the tang out a bit rather than bending it more.

As the floats drop, the tang can only go so far down and allows less fuel to flow.

Where's yours leaking from now if you've got the breathers connected together?

<{POST_SNAPBACK}>

The picture you are looking at is to limit the travel. the tang above the needle is the one to limit the flow/and or level.

[stuessenhigh]

You'll probably think me a t*** for saying the obvious Marky, but is your float bowl screwed down really well?...mine seems to have to be screwed down REALLY well, else it leaks....mind you, I probably need a new gasket on it. ...good luck...

[marky g]

Looks right to me mate, what I see is basically straighten the 90 deg bend in the tang out a bit rather than bending it more.

As the floats drop, the tang can only go so far down and allows less fuel to flow.

Where's yours leaking from now if you've got the breathers connected together?

<{POST_SNAPBACK}>

Fuel is coming out of the float bowl overflow, the breathers on the side of the carb body are sound

Don't forget the carb is upside down in the pic !, just picture the carb bowl filling up with fuel and the floats rising onto the brass fuel supply stops......just does not look right to me !

[bikespace]

Don't forget the carb is upside down in the pic !, just picture the carb bowl filling up with fuel and the floats rising onto the brass fuel supply stops......just does not look right to me !

<{POST_SNAPBACK}>

Still not quite sure what you mean, although I think we've got crossed wires. I can see that bending the tab as shown will make the fuel flow slower, because when the floats drop, the tang will be stopped at a higher level. I don't really see it's an accurate way of stopping the flooding entirely, and I could see it starving the fuel at high revs. Not sure what you mean about when the floats are on their way up - bending it like that would be for when the floats are dropping, to stop the fast fuel flow (wouldn't it?).

As an aside, are your floats floating???

I'll butt out when it comes to setting float heights, my clumsy hands only hold hammers.

Hopefully someone who knows what they're on about will come in and take over soon Mark

[digger]

marky, My 05, 250 rev 3, does exactly the same, fuel almost constantly dribbling out of overflow spigot below float bowl , I couldnt make sense of the pics either thats just limiting travel of tangs, what i tried was i bent the other little brass tab which actually pushes the pointy plunger (fuel valve) up and off ,up a bit towards plunger to shut fuel of sooner ie lowering the level of fuel in bowl, it still dribbled but not so bad , but engine was pinking and knocking when throttle was rolled off, quite bad, and i did not bend tab a lot , so i gave up and bent tab back to original position . Have read all post on this topic and no one seems to have the answer . does my head in having a new bike and having to watch the fuel constantly dribbling out . dont know if this post helps you but couldnt pass up a chance of a good moan.

[bikespace]

I would hate that. I can't understand it. It shouldn't be rocket science. Works just like a toilet cystern I would have thought. Float comes up, and turns the fuel off. Are the floats not "floaty" enough to force the fuel off or summat? How much pressure does it take to push the fuel off when the float bowl is off? Are the floats an awkward or smaller shape compared to other bikes?

Just curious, it would bug me if mine did it.

Edited August 18, 2005 by bikespace

[stuessenhigh]

sorry you're still having problems Marky ...mines allways been OK..but I know where you mean for the leak...and have seen many leaking from there.

BVM do a mod for the Beta carbs which they say cures everything....if its not too pricey, it might be worth posting it to them to get it sorted once and for all??

[marky g]

marky, My 05, 250 rev 3, does exactly the same, fuel almost constantly dribbling out of overflow spigot below float bowl , I couldnt make sense of the pics either thats just limiting travel of tangs, what i tried was i bent the other little brass tab which actually pushes the pointy plunger (fuel valve) up and off ,up a bit towards plunger to shut fuel of sooner ie lowering the level of fuel in bowl,

Nice to see someone else thinks the pics were not quite right, as you say bending the tag in the pic only limits the travel of the float arm, and as you mentioned I would have thought that you need to bend the actual tab that push's the float needle valve down..that was my next move but....after reading what happened to you with the knocking etc I'm at a loss now!

I would hate that. I can't understand it. It shouldn't be rocket science. Works just like a toilet cystern I would have thought. Float comes up, and turns the fuel off. Are the floats not "floaty" enough to force the fuel off or summat? How much pressure does it take to push the fuel off when the float bowl is off? Are the floats an awkward or smaller shape compared to other bikes?

Just curious, it would bug me if mine did it.

As you say BS it ain't rocket science, the float seem to be in good order, they don't seem to have split or anything, I will check out the float needle valve and it's seat next.

I'm spending all day on it this Sunday to sort it...the last thing I want is to run it lean on your Novagar round

sorry you're still having problems Marky ...mines allways been OK..but I know where you mean for the leak...and have seen many leaking from there.

BVM do a mod for the Beta carbs which they say cures everything....if its not too pricey, it might be worth posting it to them to get it sorted once and for all??

Will ring BVM in the AM Stu, will post pics of my findings / new bits etc

[stuessenhigh]

Yeah...please post pics of the findings etc....theres several guys here would be interested since sending a carb over to UK for a fix from here, means being bikeless for FAR too long

I'm very interested to know what mod. BVM do, IF you do go down that route.

Damnnnn....wish I was back in time for that novogar round....NEXT year..definate!!!!!!!!!

[marky g]

Spoke to BVM today, said 'they all do it mate' !

He did say the float needle valve and it's seat can wear so there sending some new ones....he did mention something about drilling the carb ?? whats that all about then? and can the budding home mechanic do it ?

[digger]

Marky , go to www.kdmototrials.com, scrole down , on right hand side click on mikuni carby fix in tech tips. I emailed the author of this mod to ask why he says to only drill down existing hole at C 28mm, and if i could drill all the way through to come out at point B in so doing raising the level of the outlet (overflow)ie. instead of the outlet of the overlow being on underside of moulding (dont forget pics of carb are upside down) the outlet would be on end of moulding raising the outlet a smidgeing and hopefully cureing the dribbling mikuni. But he replied the fix was to just move outlet of overflow over 28mm ! cant for the life of me understand how that would make any difference at all.Anyway, he then said to go to trialscentral and set float height as stated in articles on beta forum and that would cure it! So that puts us back where we started from.I have bought 2mm long series drill bit to drill out carb all the way through but havent plucked up enough courage to do it yet! Might do it in foreseable future, who knows, if this bloody carb doesnt stop leaking soon I will be reaching for the drill

[stuessenhigh]

ages ago BVM also told me that they can do a mod involving drilling the carb

It would be good to see some pics of one done....I guess its similar to the kdmoto thinb, so I'll have a look at their website too.

[ronm]

I did the kd moto mod to my 2004 Rev3 270. The instructions in the article were not exactly accurate for my carb. The drilling from the outside that was described was not necessary as my carb already had the passage open from the manufacturing process. Basically if you look at the overflow hole in the carb body, you will notice an undrilled boss about 10 mm away - toward the center of the carb. All you have to do is drill a hole in the unused boss. You will only have to drill a mm or two deep and the hole will meet the same passage that the overflow hole connects to. Then you plug the original hole. The article says to use epoxy. That may be ok, but I drilled and tapped the original hole and fitted a small socket head screw to plug it. The result simply serves to move the overflow hole uphill (since the carb is tilted down) a few mm. Is this needed? I can't say for sure. What I do know is that I modified the float level as previously described. I am still using the stock vent tubes, but I cut the ends at an angle and pricked small holes on the inside of the bend. This prevents siphoning which is the main cause of the problems. I can park my bike with the front facing down hill without any leaking and start it with one kick.

I could just be lucky, but I suspect that if done properly, these simple mods will solve the problem on any Beta. (assuming your needle and seat are ok).