Author Topic: Looses power  (Read 1296 times)

Clausen10

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Looses power
« on: August 16, 2016, 05:11:52 PM »
While riding my key west 49cc...it was running great, hit a bump and now it looses power and acts like it's not getting gas. Shut off and restarted again then works for about two blocks then fails again. 2006 with 1850 miles. Added sea foam, changed plug, fuel filter and new battery, air filter is clean.....any ideas?

Miker the Biker

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Re: Looses power
« Reply #1 on: August 24, 2016, 06:27:12 PM »
What a coincidence.

I just got a used Key West, cleaned the carb, had it up to about 35MPH.

A bit later, going slower, hit a bump.
Now it will do 10 to 15 MPH, and then, if I try get going any faster, it dies.


Miker the Biker

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Re: Looses power
« Reply #2 on: August 24, 2016, 06:34:49 PM »
Wonder if the BUMP jerked the bowl float.

There's this knurled brass knob on the side of the carb.
Might THAT be the float adjuster?
And if so, which way should I turn it??

harry

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Re: Looses power
« Reply #3 on: August 24, 2016, 08:41:10 PM »
there are bumps everywhere and most carbs don't need the floats
re-adjusted that i have herd of but i guess it could happen.  :o
well there are 2 adjustment screws...
one you see first is the big one about in the middle
of the carb  that is the idle adjustment, in makes the
barrel slide go up opening up  the carbs intake causing fast idle.
 the tiny one that is recessed is the air/fuel mix  screw.

check the plug wire and replace the plug if you haven't already.
i've had a bad plug act like a fuel issue.
check you have full travel of the throttle cable
and while your at it replace the fuel filter.
otherwise you might check for water/crud/rust in the tank
 and that happens when you buy ethanol fuel and let the scooter sit
for a while.

hitting a bump would/could stir up any crud in the fuel bowl.
if you were at wot or close to it  the main jet  is running fuel
and would possibly clog up.
the mid range throttle is opening the needle jet but they don't
clog  but some passages in the carb body can

 oilyhans

i own a scooter shop  with rentals ,sales& racing parts.
i also appraise scooters for KBB.

2003 Vino classic stage 0.75
de-reged stock variator w/8g sliding weights.
1.5k rpm  springs
42mph
2005 veniceLX ~70cc~upjet~1.5k rpm springs & 7gr sliders
46mph
KeyWest de restricted~8gr slide

Miker the Biker

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Re: Looses power
« Reply #4 on: August 25, 2016, 04:44:00 AM »
Thanks for the advice.

I drained the tank, even pushed a clean old sock in there and drew it out dry, and cleaned the carb.
New filter.
Problem persists.
Will replace plug once the auto parts store opens today.

What's the big knurled knob on the carb for?
Does not seem to appear on the photos of the carb as posted on this site.


Miker the Biker

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Re: Looses power
« Reply #5 on: August 25, 2016, 09:25:55 AM »
New plug, fresh gas, seems to have NO effect.

Hate to haul it 30 miles to the nearest place that works on TGB scooters.

Miker the Biker

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Re: Looses power
« Reply #6 on: August 25, 2016, 03:31:47 PM »
Not only did I make sure the gas cap wasn't causing a vacuum....

I clamped off the line FROM the gas tank, PULLED the fuel line off just above the filter, put a couple of feet of CLEAR fuel line onto the top of the filter, stuck the other end into a pint of gas, and started it up. Figured IF it was a tank-to-line problem,  it would make a HUGE difference not to have THAT line feeding the carb.

It didn't make a difference.

So I took the hose out of the pint, ran the engine until the line and filter were EMPTY, and the engine KEPT RUNNING!

Where the 4nick8 is the gas COMING from?

Then I took the spray tube and sprayed straight carb cleaner down, to fill the clear line.
Started the engine again, revved it up, watched as the carb cleaner got sucked down the tube, through the filter, and into the engine.

Ran EXACTLY the same as GAS.

I am amazed and dazed.

harry

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Re: Looses power
« Reply #7 on: August 25, 2016, 07:33:17 PM »
that's why scooters get 80-100mpg they sip the fuel
 one drop at a time . surprising how much the fuel bowl holds...
a clogged fuel vent  acts different , the scooter will run for a bit and
the stop due to vac in tank and that doesn't work well with
gravity feed fuel systems.

 as said :
the idle jet is low speed  0-10+ mph
the needle jet &needle mid range 10-20+mph
main jet is 15 -30+ mph
but really its in relation to the throttle @1/4+ , 1/2+ ,3/4+
 so if you are not getting full throttle i'd be looking at the main jet
and related passages. you can use a wire from a wire brush to make
sure the jet is open. try not to scratch the inside of the jet
hitting a bump would most likely shake up loose crud in the fuel bowl.....

oilyhans
« Last Edit: August 25, 2016, 07:39:01 PM by harry »
i own a scooter shop  with rentals ,sales& racing parts.
i also appraise scooters for KBB.

2003 Vino classic stage 0.75
de-reged stock variator w/8g sliding weights.
1.5k rpm  springs
42mph
2005 veniceLX ~70cc~upjet~1.5k rpm springs & 7gr sliders
46mph
KeyWest de restricted~8gr slide

Miker the Biker

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Re: Looses power
« Reply #8 on: August 26, 2016, 05:51:24 AM »
I make banjos.
So, rather than risk scratching the jet innards with a wire, I use a nylon banjo string, or a piece of heavy nylon fishing line, to poke through the various holes.

The main jet SEEMS clean.

I'll do it all again, see what happens.
Thanks again for your patience with a near-clueless newbie.

Miker the Biker

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Re: Loses power
« Reply #9 on: August 26, 2016, 07:12:11 AM »
Cleaned everything again.

There is a very THIN hose coming into a brass fitting on the front of the carb.

I can blow AIR through there, but I cannot push the nylon line through.
Is that some kind of one-way valve that's SUPPOSED to have an obstruction in the middle?

Put it all back together, same symptoms.

Am draining the tank, will see if I can get a look at the tank outlet, any crud blocking it.
Gas flows down the clear fuel line apparently well enough.

What are the chances that hitting a bump caused something to obstruct the MUFFLER port, making back pressure at higher speeds?


Miker the Biker

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Re: Looses power
« Reply #10 on: August 26, 2016, 08:30:40 AM »
Took the muffler loose, makes no difference.

Bike will slowly (and I mean SLOWWWWWLY) accelerate to about 15-20 MPH, but any more, and it starts to stall.

jwhood

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Re: Looses power
« Reply #11 on: August 26, 2016, 09:08:56 PM »
Air leak or to lean on gas mixture,I'm leaning towards an airleak

Miker the Biker

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Re: Looses power
« Reply #12 on: August 27, 2016, 09:55:51 AM »
Air leak WHERE, though?

I notice bubbles in the clear tubing between the gas tank and the filter, but do they STAY as gaps in the flow, once they're past the filter and down into the bowl??

Meanwhile, "back at the wrench"......

Dumped in more than the recommended dose of BERRYMAN'S B-12 gasoline additive, and put the scooter up on the kickstand.

Revved it up way to hell, and watched a LOT of smoke come out the back.

Then took it out on the street, got it up to 40 for half a mile.
 Seems to be cured!

That crap must be MAGICAL!

Saved ME $85 and  120 miles of round trips to drop off the carb, have a pro service it, and go get it when it was done..