will the wrong fuel valve effect starting

mgibsonaz · 10-18-2015, 02:31 PM

I had to replace a leaky fuel valve on my KPXZ200 and now it will only start with a shot of starting fluid, and doesn't want to idle. It also stays revved up for a moment before coming back down after giving it throttle. The new valve I installed does not have the small reservoir under the valve like the old one did.

Weldangrind · 10-19-2015, 12:22 AM

The symptom of the engine staying revved up after releasing the throttle is usually a vacuum leak. If you start the engine and then point an unlit propane torch at the carb intake tube, you should hear the revs increase when the propane finds the leak. It'll suck the propane right in.

I'd need to see the two fuel valves in order to understand. Did you dismantle anything else when you replaced the valve?

mgibsonaz · 10-19-2015, 10:11 AM

ok thx, I will look into a leak.
This is what the valve I took off looked like http://www.ebay.com/itm/ATV-Go-Cart-...-/161040330517
And this is what the one I put on looks like ebay.com/itm/NEW-1984-Honda-TRX-200-Fourtrax-Fuel-Petcock-TRX200-ATV-Gas-Tank-Cock-Tap/221443704844?_It doesn't have the small bowl on the bottom.
Nothing else was involved other than replacing the valve.

Mudflap · 10-19-2015, 10:34 AM

First thing I would suspect is a piece of debris becoming dislodged when you changed the petcock, ending up in the float bowl, getting sucked into the jets.

Weldangrind · 10-19-2015, 03:18 PM

I agree. Have you removed the bottom cap of the valve for inspection? Perhaps there is junk in there. Are you using an inline filter? I always do. Remember that your specific application might be better suited to a 90 degree filter, so bear that in mind while you're shopping.

Have you changed the fuel line? I use clear or blue snowmobile line, as it is still flexible in cold temps, and I can see that fuel is flowing. I don't trust the black fuel line that is often shipped with China bikes, as it can break down and clog the jets.

mgibsonaz · 10-19-2015, 09:10 PM

Thanks for the tips. I will be taking off the carb to check and probably put on the 30 mm Mikuni while I'm at it. I ordered what I hope is the correct vale as well. I will replace the old black fuel line and put on a new inline filter and let you know what the results are.

mgibsonaz · 10-22-2015, 04:40 PM

well, threw on the 30 mikuni clone with 110 main and 27.5 pilot and she started first kick. I had to adjust the idle up about an 1/8 but so far so good. Might have a slight bog going from low to mid, but I have to go and and test further. I was in flip flops and just crusing around the block. Thx again for the advice

mgibsonaz · 10-22-2015, 05:47 PM

Took it to get gas, wot after 10 secs cuts out and then after letting off throttle and re-applying it bogs a few times before coming back to normal. According to the mikuni site top end is determined by the main? So maybe try the next step up from a 110? I have a k&n and stock exhaust with the guts ripped out. I'm Phoenix AZ so pretty much sea level.

Weldangrind · 10-23-2015, 01:17 AM

Top end is determined by the main. The bog from idle to mid should be correctable with the pilot mixture screw.

Maybe a 112.5 main is a good step. If it helps a little, but not enough, try a 115.

10-18-2015, 02:31 PM	#1
mgibsonaz Join Date: Apr 2012 Posts: 36	will the wrong fuel valve effect starting I had to replace a leaky fuel valve on my KPXZ200 and now it will only start with a shot of starting fluid, and doesn't want to idle. It also stays revved up for a moment before coming back down after giving it throttle. The new valve I installed does not have the small reservoir under the valve like the old one did.
	0

10-19-2015, 12:22 AM	#2
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	The symptom of the engine staying revved up after releasing the throttle is usually a vacuum leak. If you start the engine and then point an unlit propane torch at the carb intake tube, you should hear the revs increase when the propane finds the leak. It'll suck the propane right in. I'd need to see the two fuel valves in order to understand. Did you dismantle anything else when you replaced the valve? __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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10-19-2015, 03:18 PM	#5
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I agree. Have you removed the bottom cap of the valve for inspection? Perhaps there is junk in there. Are you using an inline filter? I always do. Remember that your specific application might be better suited to a 90 degree filter, so bear that in mind while you're shopping. Have you changed the fuel line? I use clear or blue snowmobile line, as it is still flexible in cold temps, and I can see that fuel is flowing. I don't trust the black fuel line that is often shipped with China bikes, as it can break down and clog the jets. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

10-23-2015, 01:17 AM	#9
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Top end is determined by the main. The bog from idle to mid should be correctable with the pilot mixture screw. Maybe a 112.5 main is a good step. If it helps a little, but not enough, try a 115. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

10-19-2015, 10:11 AM	#3
mgibsonaz Join Date: Apr 2012 Posts: 36	ok thx, I will look into a leak. This is what the valve I took off looked like http://www.ebay.com/itm/ATV-Go-Cart-...-/161040330517 And this is what the one I put on looks like ebay.com/itm/NEW-1984-Honda-TRX-200-Fourtrax-Fuel-Petcock-TRX200-ATV-Gas-Tank-Cock-Tap/221443704844?_It doesn't have the small bowl on the bottom. Nothing else was involved other than replacing the valve.
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10-19-2015, 10:34 AM	#4
Mudflap Join Date: Sep 2014 Posts: 1,891	First thing I would suspect is a piece of debris becoming dislodged when you changed the petcock, ending up in the float bowl, getting sucked into the jets.
	0

10-19-2015, 09:10 PM	#6
mgibsonaz Join Date: Apr 2012 Posts: 36	Thanks for the tips. I will be taking off the carb to check and probably put on the 30 mm Mikuni while I'm at it. I ordered what I hope is the correct vale as well. I will replace the old black fuel line and put on a new inline filter and let you know what the results are.
	0

10-22-2015, 04:40 PM	#7
mgibsonaz Join Date: Apr 2012 Posts: 36	well, threw on the 30 mikuni clone with 110 main and 27.5 pilot and she started first kick. I had to adjust the idle up about an 1/8 but so far so good. Might have a slight bog going from low to mid, but I have to go and and test further. I was in flip flops and just crusing around the block. Thx again for the advice
	0

10-22-2015, 05:47 PM	#8
mgibsonaz Join Date: Apr 2012 Posts: 36	Took it to get gas, wot after 10 secs cuts out and then after letting off throttle and re-applying it bogs a few times before coming back to normal. According to the mikuni site top end is determined by the main? So maybe try the next step up from a 110? I have a k&n and stock exhaust with the guts ripped out. I'm Phoenix AZ so pretty much sea level.
	0