Author Topic: bad gas leak!!!!! (Read 2923 times)

kopptl · « **Reply #25 on:** October 08, 2009, 04:28:57 PM »

you are right on how the fuel is routed!! i will try it in a little bit later tonight!

Spanner 1 · « **Reply #26 on:** October 08, 2009, 04:58:32 PM »

My 2c is that the floats are binding against the bowl seals which are ' bowed' in and not seating properly...very small clearance 'tween seal and side of float....also aftermkt. seals may be a tad wider, not helping either.....

Markcb750 · « **Reply #27 on:** October 08, 2009, 05:05:53 PM »

My 76 did this also. I found it was improperly set floats. Took me three times with the carbs on the bench and tinkering with the floats and passages to get the carbs running well and stop the over flow out of the intake passage/into the air box.

It is possible to install the floats upside down...

kopptl · « **Reply #28 on:** October 08, 2009, 05:10:25 PM »

people keep mentioniung the floats being upside down, now im doubting myself!! how will i know if they are in right??

mystic_1 · « **Reply #29 on:** October 08, 2009, 05:20:41 PM »

Quote from: kopptl on October 08, 2009, 05:10:25 PM

people keep mentioniung the floats being upside down, now im doubting myself!! how will i know if they are in right??

Got a manual?

Get one here

http://forums.sohc4.net/index.php?topic=17788.0

Also get the Honda Carburation Manual
   http://www.sohc4.net/index.php?q=content/fuel-system-carburetion

and the Honda Common Service Manual:
   #1: http://www.mediafire.com/?9o4y2jfv3r9
   #2: http://www.mediafire.com/?6xnfimecei2

both are interesting reads.

mystic_1

PS:

BeSeeingYou · « **Reply #30 on:** October 08, 2009, 05:27:20 PM »

They should look like this. Mine is a 76F but they should be the same.

mystic_1 · « **Reply #31 on:** October 08, 2009, 05:29:47 PM »

BTW, this is when us 750 folk get to lord it over the others with our clip-on float bowls. Makes procedures like this MUCH less painful

mystic_1

BeSeeingYou · « **Reply #32 on:** October 08, 2009, 05:51:39 PM »

Quote from: mystic_1 on October 08, 2009, 05:29:47 PM

BTW, this is when us 750 folk get to lord it over the others with our clip-on float bowls. Makes procedures like this MUCH less painful

mystic_1

Yeah, tell me about it.

My XS650's have four screws per bowl and you need a very short one to get the inside ones out.

kopptl · « **Reply #33 on:** October 08, 2009, 07:52:04 PM »

going off of his pictures, i have my floats installed right!! : ) tommorrow, i will try what mystic_1 has to say. how would you block off the lines??

mystic_1 · « **Reply #34 on:** October 08, 2009, 09:32:35 PM »

A pen cap and a hose clamp works in a pinch

mystic_1

kopptl · « **Reply #35 on:** October 08, 2009, 09:50:17 PM »

ok! i really appreciate all the help thus far!!! just trying to get this old beast to run at all!!!!

kopptl · « **Reply #36 on:** October 09, 2009, 05:10:50 PM »

i tried what you said. no gas leaked at all when i tried 1-2, then 3-4!!! what does that mean?? did i mess something up??

kopptl · « **Reply #37 on:** October 09, 2009, 06:11:36 PM »

when i took the #3 bowl off, the gasket is a little puffy or something as i couldnt get it to go back on properly so i left it off for today.

mystic_1 · « **Reply #38 on:** October 09, 2009, 06:41:06 PM »

Quote from: kopptl on October 09, 2009, 05:10:50 PM

i tried what you said. no gas leaked at all when i tried 1-2, then 3-4!!! what does that mean?? did i mess something up??

OK this means that:

1. the float valves themselves are capable of stopping the flow of fuel. This is good.
2. fuel is not coming in from some other source This is also good.
3. for whatever reason, the floats are not shutting off the flow of fuel when the float bowls are full. You problem lies here.

Check for obstructions and smooth action at the pivot points. Make sure there's no crud floating around anywhere in there. Was there any debris in the float bowls when you pulled them off?

When you adjusted the floats, where did you measure from on the carb body? You should be measuring from the edge of the flange, not at the gasket surface.

Dirty or maladjusted float valves is my guess at this point.

mystic_1

kopptl · « **Reply #39 on:** October 09, 2009, 06:48:25 PM »

the floats operated freely and smoothly!! the float bowls are clean, i used B-12 chem tools, great stuff!! i did measure from the edge of the carb body!!! this kinda makes me wonder what i did wrong.

kopptl · « **Reply #40 on:** October 12, 2009, 12:45:07 PM »

still needin help if anybody has ideas.......

Markcb750 · « **Reply #41 on:** October 12, 2009, 01:15:10 PM »

The carbs can leak because the bowl seat gasket is not working, the overflows are plugged, or the needle valves are not seated, caused by contamination of the needle seat(s), wear of the needle seat(s), wear of the needles,

...or something like the floats installed incorrectly.

kopptl · « **Reply #42 on:** October 12, 2009, 09:16:54 PM »

i know i put the floats in correctly and measured them correctly!

BeSeeingYou · « **Reply #43 on:** October 12, 2009, 09:49:48 PM »

Is it possible that the kits you got were maybe a cheaper knock off and not OEM. There has been some discussion about these cheaper kits having sloppy tolerances. When you did the test that mystic suggested how much pressure did you put on the needle valve for the fuel to shut off? Now I am guessing that the float would not exert too much and maybe this lighter pressure is not enough to make a good seal on a less than perfect needle valve.

Have you checked for a leaking float? Hold it up to your ear and shake it.

mrbreeze · « **Reply #44 on:** October 12, 2009, 10:17:24 PM »

I'll chime in. When I rebuilt my carbs and ignition ,exhaust,airbox to pods,etc. + moving from 5K elevation to sea level......not very many people here jumped in to help me out so I had to conduct my own experiments. I found that even though you set your float heights "Dead Nuts"........they can be off. I drained my bowls into a baby-food jar and while #1,2, & 4 were dead on........#3 was low. I adjusted the tang on the float till it matched the other carbs and it fixed my problem. What I am saying is don't just assume your float bowls are even because you set your float heights.

kopptl · « **Reply #45 on:** October 12, 2009, 10:53:11 PM »

thanks!

Terry in Australia · « **Reply #46 on:** October 13, 2009, 03:19:01 PM »

I was sure I was right with my "blocked drain" post, but if you're saying that the both the drain hoses and the tubes in the float bowls are clear, (not the drain screws, that's an entirely different function)then is it possible that you've installed your float valves upside down? Presuming, of course, that there are float valves in the seats?

Float height being out a tad can certainly affect your engine's performance at highway speeds, but should not have any affect on the fuel leaks that you describe. Cheers, Terry.

kopptl · « **Reply #47 on:** October 13, 2009, 04:57:42 PM »

yep all the passage ways are clear, i cleaned all of them b-12 good!! the floats are correct and i made sure they were all at 26mm. i dont know what i did wrong........ cuz ive never heard of them leaking like that!!

mystic_1 · « **Reply #48 on:** October 14, 2009, 01:28:03 PM »

Leaking like that is actually very common, in bikes that have sat a long time or for whatever other reason have malfunctioning floats. It's a classic sort of symptom actually.

You problem is almost 100% certain to be with the floats somehow. Try increasing the float height (thereby lowering the amount of fuel in the bowls) in increments until it stops flooding. Then measure the float height and let us know.

Finally, since you don't have a center stand, find a way to block up the bike so that it's level. All this work goes much easier that way.

mystic_1

JBMorse · « **Reply #49 on:** October 15, 2009, 05:31:32 AM »

Have you checked your needle valve orientation? My carbs were draining gas after a rebuild and after repeatedly trying to figure out what happened, I discovered by accident that I had put the needle valves (or float valves) upside down. Double check that.

News:

Author Topic: bad gas leak!!!!! (Read 2923 times)

Markcb750

Markcb750