Thu Aug 04, 2022 7:56 am

Ossessionato
Joined: 24 Jan 2008
Posts: 2087
Location: Santa Margarita,Ca.
 
Ossessionato
Joined: 24 Jan 2008
Posts: 2087
Location: Santa Margarita,Ca.
Thu Aug 04, 2022 7:56 am linkquote
It'll start right up but as I open the throttle the engine will stall repeatedly when cold or when started after a while sitting. Holding the rear brake as I open the throttle quickly seems to help it not stall until it warms up.

Any guesses?

I'm thinking valve adjustment as the previous 250 had similar problems prior to selling it and it ended up being tight valves at around 20,000 miles, and that about where the 300 is now. This is a stock bike, over due for belts and rollers, Valves were spot on when checked at 10,000 miles.

I have no clue with fuel injection so talk down to me if trying to explain that. TIA
Thu Aug 04, 2022 8:47 am

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 41203
Location: Pleasant Hill, CA
 
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 41203
Location: Pleasant Hill, CA
Thu Aug 04, 2022 8:47 am linkquote
Before doing a valve adjustment, check and clean the throttle body idle bypass passage:
https://cheekythoma3.wixsite.com/itsme/idle
Fri Aug 05, 2022 9:30 am

Ossessionato
Joined: 24 Jan 2008
Posts: 2087
Location: Santa Margarita,Ca.
 
Ossessionato
Joined: 24 Jan 2008
Posts: 2087
Location: Santa Margarita,Ca.
Fri Aug 05, 2022 9:30 am linkquote
THANKS! I'll do that first and check the results!
Fri Aug 05, 2022 3:16 pm

Ossessionato
Joined: 24 Jan 2008
Posts: 2087
Location: Santa Margarita,Ca.
 
Ossessionato
Joined: 24 Jan 2008
Posts: 2087
Location: Santa Margarita,Ca.
Fri Aug 05, 2022 3:16 pm linkquote
Did the throttle body cleaning. Not it. It will rev right up on the stand, but with the wheel on the ground it stalls as I begin to open the throttle.
Fri Aug 05, 2022 3:37 pm

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 41203
Location: Pleasant Hill, CA
 
Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: 26 Aug 2007
Posts: 41203
Location: Pleasant Hill, CA
Fri Aug 05, 2022 3:37 pm linkquote
If the air filter is clean(ish) then I guess checking the valve clearances would be prudent as the next step.
Fri Aug 05, 2022 4:20 pm

Molto Verboso
Dongfang 170cc, CF Moto Fashion 250
Joined: 07 Dec 2008
Posts: 1598
Location: Hyde Park, New York
 
Molto Verboso
Dongfang 170cc, CF Moto Fashion 250
Joined: 07 Dec 2008
Posts: 1598
Location: Hyde Park, New York
Fri Aug 05, 2022 4:20 pm linkquote
That almost sounds like a vacuum leak. Are all the hoses intact?
Fri Aug 05, 2022 5:05 pm

Ossessionato
Joined: 24 Jan 2008
Posts: 2087
Location: Santa Margarita,Ca.
 
Ossessionato
Joined: 24 Jan 2008
Posts: 2087
Location: Santa Margarita,Ca.
Fri Aug 05, 2022 5:05 pm linkquote
kz1000ST wrote:
That almost sounds like a vacuum leak. Are all the hoses intact?
I'll order up an intake manifold gasket for good measure. Not much else on the suction side of the GTS. Runs good once warmed up.
Fri Aug 05, 2022 5:14 pm

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11456
Location: The state of insanity, SoCal
 
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11456
Location: The state of insanity, SoCal
Fri Aug 05, 2022 5:14 pm linkquote
check your manifold for cracks and the evap line that plugs into the barb on the manifold, sometimes those crack out too.

good luck my dude!
Fri Aug 05, 2022 9:12 pm

Ossessionato
Joined: 24 Jan 2008
Posts: 2087
Location: Santa Margarita,Ca.
 
Ossessionato
Joined: 24 Jan 2008
Posts: 2087
Location: Santa Margarita,Ca.
Fri Aug 05, 2022 9:12 pm linkquote
I don't know if this is means anything but on the center stand the engine revs right up. Put the wheel on the ground and it dies as the throttle is opened.
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