No start/pet valve issue?

Nkf · September 13th, 2023, 06:10 PM

So I bought the bike a few years ago not running and I ended up now putting it back together recently and it will not run. It cranks and tries to start but to no avail doesn’t run. I sent the carb off to get ultrasonic cleaned and I believe tuned to run by ducatiman as many people spoke up for his work. I am familiar with working on efi motors but not familiar with carburetors. I think I’m at a vacuum issue so I’m not sure if the vacuum side of the petcock has gone bad and should buy a rebuild kit for the pet valve/a new one, or if the problem is the vacuum valve for the entire system. I have tested the petcock and tried to apply vacuum to the valve but I don’t think valve is working as there is no air flow coming through the valve or does that mean the valve is good? I have spark, the bike doesn’t not slow crank(new battery), the air filter is not clogged, I can see some smoke coming out of the tailpipe and it does puff like there is compression so I believe it’s down to the fuel system. I currently only have about a half gallon of gas in the tank in case I need to pull the tank off. Any suggestions? The bike has only 1400 miles and I don’t think there is anything mechanically wrong with it. The title says it’s a 2007 250 but I believe it maybe a newer generation of the 2008. Any help is appreciated

ducatiman · September 13th, 2023, 06:27 PM

petcock flow test....pull both the fuel line and the vacuum line at the carb...apply vacuum to the vac line and fuel should flow. Rather than sucking on the vac line, I prefer to use a medical syringe.

If no flow...remove it, send it to me, i stock all rebuild parts needed. Cost will be about 1/2 of what a new one would.

DannoXYZ · September 13th, 2023, 08:19 PM

Petcock diaphragm is dead-end passage, so there should be zero flow. That's how vacuum is generated and difference in pressure between vacuum and atmospheric is how it moves plunger to unblock flow. Yes, sucking on vacuum hose can be dangerous if there's crack in diaphragm.

Do petcock flow test. This is from Honda manual. Kawi in RES still needs vacuum to flow. How much petrol do you collect in 10-sec?

Can also bypass petcock completely to rule out or pinpoint it as problem. Use squirt bottle to spray 2-3cc petrol into airbox. Wait 15s for it to vapourise, then start engine. Does it run?

September 13th, 2023, 06:10 PM	#1
Nkf ninjette.org newbie Name: Noah Location: Pittsburgh Join Date: Oct 2021 Motorcycle(s): 2008 ninja 250 Posts: 4	No start/pet valve issue? So I bought the bike a few years ago not running and I ended up now putting it back together recently and it will not run. It cranks and tries to start but to no avail doesn’t run. I sent the carb off to get ultrasonic cleaned and I believe tuned to run by ducatiman as many people spoke up for his work. I am familiar with working on efi motors but not familiar with carburetors. I think I’m at a vacuum issue so I’m not sure if the vacuum side of the petcock has gone bad and should buy a rebuild kit for the pet valve/a new one, or if the problem is the vacuum valve for the entire system. I have tested the petcock and tried to apply vacuum to the valve but I don’t think valve is working as there is no air flow coming through the valve or does that mean the valve is good? I have spark, the bike doesn’t not slow crank(new battery), the air filter is not clogged, I can see some smoke coming out of the tailpipe and it does puff like there is compression so I believe it’s down to the fuel system. I currently only have about a half gallon of gas in the tank in case I need to pull the tank off. Any suggestions? The bike has only 1400 miles and I don’t think there is anything mechanically wrong with it. The title says it’s a 2007 250 but I believe it maybe a newer generation of the 2008. Any help is appreciated

September 13th, 2023, 06:27 PM	#2
ducatiman ninjette.org certified postwhore Name: Gordon Location: new york Join Date: Sep 2009 Motorcycle(s): '95 DUCATI 900SS/SP '07 DUCATI SS800 '19 HONDA CBR650R Posts: A lot. MOTM - Nov '18, Mar '17	petcock flow test....pull both the fuel line and the vacuum line at the carb...apply vacuum to the vac line and fuel should flow. Rather than sucking on the vac line, I prefer to use a medical syringe. If no flow...remove it, send it to me, i stock all rebuild parts needed. Cost will be about 1/2 of what a new one would. __________________________________________________ gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com

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September 13th, 2023, 08:19 PM	#3
DannoXYZ ninjette.org certified postwhore Name: AKA JacRyann Location: Mesa, AZ Join Date: Dec 2011 Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C Posts: A lot. MOTY - 2018, MOTM - Nov '17	Petcock diaphragm is dead-end passage, so there should be zero flow. That's how vacuum is generated and difference in pressure between vacuum and atmospheric is how it moves plunger to unblock flow. Yes, sucking on vacuum hose can be dangerous if there's crack in diaphragm. Do petcock flow test. This is from Honda manual. Kawi in RES still needs vacuum to flow. How much petrol do you collect in 10-sec? Can also bypass petcock completely to rule out or pinpoint it as problem. Use squirt bottle to spray 2-3cc petrol into airbox. Wait 15s for it to vapourise, then start engine. Does it run?