random dying out???

98blaster+4

Member
Oct 12, 2008
2,131
20
74
vermont
it will fire and rev right almost long enough to warm up before take off then half way through first gear it shats out.
it feels like its emptying the bowl very quickly and will sputter spit to a stop. i wait a few moments and it will fire again.
is it possible to be so rich on the pilot that it just stalls out? but only under the load while riding?
im stumped.
 
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changed out the cdi box, same thing.

the float height is at 19mm per specs but its definately emptying the float bowl and dying.

fuel flow is good on both reg and reserve.
squeaky clean carb.
float height set.


the only thing that puzzles me is that on the bowl there is a 17mm plug that threads into the bowl and surrounds the jets area. on the bowl there are two grooves running vertically on either side of the threaded portion. on the plug that threads into the bowl there are two holes in either side that can be lined up with the vertical lines on the bowl. but the holes never get to where they would allow fuel through them. seems like they should be a passage to supply the jets.
 
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this is the plug that threads into the bowl underneath the jets
30k802b.jpg

egz9li.jpg


this is the bottom of carb
29w7thw.jpg

this shows the grooves that the holes in the plug seem like they would line up to allow fuel to flow through to fill the liitle well that is inside the plug
21likc1.jpg

2w4z14l.jpg


this is the underside of carb without bowl on
33escir.jpg


this is the inside of the bowl
2zrgu8y.jpg

29vkvwm.jpg


you can see the grooves again in this one
n6283n.jpg


now the holes in the plug are nelow the threaded area and the bowl only has the grooves on th threaded area. so they never get to meet up.
ay0f15.jpg
 
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this may be kinda jerry riged but put loc tite on it and loosen it up until the holes line up. just a thought
 
the problem with that is if its not tight enough it wont reach the opening anyways. i just went and tightened the piss out of it and it lined up but i dont like having things that tight. either way it didnt help. i dont understand how the bowl can be emotying that fast. it has good flow to the carb and i have hooked the gas up with the bowl off and it pours quickly through the carb.
 
they line up so you can empty the bowl when you partially unscrew the 17mm bolt. maybe your float is holding fluid? try removing the needle valve and blowing or spraying it out. how long are you letting fuel flow out when you test the petcock?
edit: having fuel in the floats would overfill it...
 
pwk 28. dynoport pipe, boyseen superstock reeds. uni clamp on.
had it running great then while out on a ride it started doing this crap.
 
thats a good one bud.. ha i dont really know what else to check specifically but i guess you should start checking over everything. maybe when its heating up the headgasket is leaking? maybe you have an electrical short somewhere? bad ground? it seems like you have been over the carb pretty well so i dont know how your running out of fuel...
 
the reeds are good
compression checks out at what it always has been.
leak test is good.
all electrical connections test the way they are supposed to.
float height is spot on.
jetting is good

just runs out of fuel when the bowl is empty
fuel flows well.
new plug.
no tors system

also i have had the carb with the bowl off and the gas hooked up to it. turned the gas on and it flows freely through where its supposed to. and when i attempt to take the bowl off its full
 
no the bowl fills up and will run....then all the gas in the bowl gets used and doesnt fill back up.

confirm that, start it, when it dies shut off the petcock and while on the bike, remove that bottom nut/drain and see if the bowl is holding fuel ???

it is also possible the floats are hanging up, look where the float tang meets the cast "posts" of the carb body, where the pin goes thru, i had a mikuni do that once, a quick file job of the "wear marks" on them posts fix'd it right up

don't hesitate to check your coil wire and plug cap very very closely, swapping in another coil if possible
i saw a bad plug cap drive 305 and about 6 good blaster techs nuts for 3 days at busco last year