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Hitachi carbs leaking gas- hydrolocking (SOLVED)

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Hitachi carbs leaking gas- hydrolocking (SOLVED)

PostAuthor: Markjaws » Thu May 21, 2020 11:49 am

Continuing my work on a garage find 1985 XV1000. Rebuilt Hitachi carbs last fall and after a lot of other fixes and maintenance I got it running pretty well. I am building my version of a street tracker. I have raised the tank in back, removed the fuel pump and went gravity feed with a new “on-off-reserve” petcock (no vacuum). Removed AIS and plugged holes as recommended in posts here. Here’s my problem- when I attempted to start it for the first time this year I put gas in it, opened petcock, pulled choke lever and got distracted for 5 minutes. When I got back I found gas leaking profusely from both carbs. I attempted to turn it over but got nothing- hydolocked. I drained everything- removed the carbs and cleaned them and inspected. The float needle and seats are new and appear to function. I set the carbs in approximate position under tank- hooked up fuel lines and tested float bowl level with clear tube and levels appeared to be close to recommended levels. But- fuel is still finding a way to squirt through and dribbling out the intake ports. I’m not much of a mechanic and I am much appreciating the posts and recommendations I get here. How might gas leak through if the float needles and seats appear to be doing there jobs?
Thanks in advance.

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Re: Hitachi carbs leaking gas- hydrolocking

PostAuthor: mark75 » Thu May 21, 2020 3:55 pm

"appear(s) to be doing their job" is the key phrase here.
BTW good choice to change your oil. the contaminated stuff can kill your engine. :skull:

>>> https://www.mrcycles.com/oemparts/a/yam ... -xv1000l-n

float valves --- #16 in the above diagram --- they can be tricksters. they can appear to work perfectly while "dry", then when carb is filling hang-up in the open position, and allow flooding.

two ways to "prevent" that; [well help anyway]

1] while you have the carbs off, pre-fill the float chambers with fuel (admittedly difficult to keep fluid in there while re-installing carbs).

2] after carbs are installed yet before they are filled --- as they fill with fuel rap on the float bowls to 'jar' the floats enough to prevent them getting hung-up.
{a screwdriver handle is the tool I usually use --- adequate size and mass to deliver sufficient vibrations, but not enough to really damage carb}

don't forget to turn petcock off when parking (and then on when you take-off) --- seems like it could be a PITA, but it quickly becomes 'habit' in your usual riding routine. [like checking side-stand is up]
"Over the Mountains of the Moon,
Down the Valley of the Shadow,
Ride, boldly ride" ... E.A. Poe


Time flies >>> whether you're having fun __ :bike: or not :fan: ---

Any day above ground is a good day.
so Laissez les bon temps roulez. just roll safely --- Semper Vigilans...always watchful

"I hear and I forget, I see and I remember, I do and I understand." ... Confucius*

If you don't read the news you are not informed.
If you read the news you are misinformed.
... Mark Twain


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Re: Hitachi carbs leaking gas- hydrolocking

PostAuthor: Markjaws » Thu May 21, 2020 7:24 pm

Thanks for the quick reply. I will follow your suggestions tomorrow morning and hopefully get better results.
1 final question: From your response I can assume there is no other way for fuel to get into the carbs except through the float valves? Dumb question then- why did the clear tube test show top fuel level in bowl just below bowl gasket?
Thanks again.

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Re: Hitachi carbs leaking gas- hydrolocking

PostAuthor: Flyingdog » Fri May 22, 2020 4:01 am

As Mark pointed out, the word "appears"..is very subjective and quite often leads to very creative/descriptive vocabulary. Kinda like saying: Well, that car "looks good", till you open the door and it falls off. Among "all" working parts in a carb..float pins are probly the most critical. Outside of obvious plugged ports, cracks etc etc etc. Few areas worth noting: The float valve "tips" are rubber and should be flexible. Float seats absolutely smooth, shiny and clean. Q-tip in a drill w/polishing compound can restore (usually) rough surfaces. Float seat gasket in perfect shape. Otherwise float valve can seat, but fuel will leak pass this into carb. Float tang shape critical...as fuel in bowl drops, float valve and the little wire hanger can tilt, off-center, just enough to allow the valve to rub/get hung up on seat. Float valve shock pin should still move. Floats' pontoons have to be parallel to each other and not touch float bowl sides. Hence, the rapping on the float bowls to dislodge any hang-ups. But, if they hang up "once", they will hang-up again...and usually at an inconvenient moment. Also worth noting, fuel level might appear to be correct in a static or bench setting, but level can be different when bike is running. Not always, but can happen, good idea to always check level with bike running. Fuel can also leak pass the needle/needle jet.
Ever have a leaky ceiling? The source will always be at the opposite end of the house. :bg:
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Re: Hitachi carbs leaking gas- hydrolocking

PostAuthor: Markjaws » Fri May 22, 2020 7:29 pm

IT’S ALIVE! Followed your suggestions and with a bit of tapping and persistence she started first crank. Obviously the float valves had been hanging up. Assembling with full bowls was the ticket. While fiddling with reinstalling the carbs I had to remind myself a dozen times or so how much fun I was having. After almost a year of putzing I finally got to ride around the block. Final assembly and details tomorrow and phase 1 of the extreme budget XV1000 street tracker is complete. I probably would have put her on the shelf if it hadn’t been for all of the tips and support I got through this Forum. I’ll send pics and a description of my mods in a few days.
Thanks again my friends.

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Re: Hitachi carbs leaking gas- hydrolocking (SOLVED)

PostAuthor: rchawaii » Sun May 24, 2020 8:25 pm

:GJ: :urock: :wav:
My Ride is a 1983 XV 500 :usa:
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Re: Hitachi carbs leaking gas- hydrolocking

PostAuthor: Flyingdog » Sun May 24, 2020 11:38 pm

Markjaws wrote: I had to remind myself a dozen times or so how much fun I was having.


:GJ: Yep...that's the key!
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