Hawk engine cutting off

Ac21 · 08-08-2018, 09:07 PM

The bike has about 600 miles on it, I adjusted the valves maybe 100 miles ago again. The last two days I noticed when it warms up and I pull in the clutch the engine quits and have a hard time restarting. Giving it a little throttle while cranking up again seems to help. Any ideas?

ChrisWNY · 08-08-2018, 10:08 PM

Sounds like it's not getting enough fuel when idling or running at low throttle. Have you tried to adjust the idle or the fuel mixture screw on the carb? I think the issue will boil down to something related to the carb...remove the carb (it may be as simple as adjusting the idle screw). Take it apart, make sure it's free of debris and none of the jets are clogged. Adding an in-line fuel filter will prevent debris from getting into the carb, if that's what turns out to be the issue.

Ac21 · 08-08-2018, 10:32 PM

Yes I tried adjusting the idle screw and I have the air mix screw out about 2 turns its been running fine so far, I also noticed at a quick throttle blip it will bog down also. I Re adjusted valves again tonight, Re adjusted spark gap also. I'm going to pull carb off and check now. Tomarrow a new 110 main jet is coming.

In school we spent one day on carburetors the teacher said you won't need this anyway

ChrisWNY · 08-08-2018, 10:34 PM

The main jet will only affect performance when you're near full throttle or wide open. I know some have had to install larger pilot jets to fix idle issues on the stock China carbs. I haven't personally experienced any idling issues with my Mikuni VM26.

pete · 08-09-2018, 03:59 AM

Quote:

Originally Posted by Ac21

Giving it a little throttle while cranking up again seems to help. Any ideas?

And when it dose fire up how dose it run ?
dose it fire up clean or fart around for a few seconds
before it clears out...

.

ChrisWNY · 08-09-2018, 07:49 AM

Also another obvious thing to consider but sometimes overlooked...are you starting with half or full choke and allowing the engine to warm up before making any adjustments to it? Depending on the temperature in your area, you'll likely need to choke the engine at first and let it warm up a few minutes, then judge performance based on how the engine is running warmed up with the choke off.

Weldangrind · 08-09-2018, 11:17 AM

What did you adjust the valves to? Wouldn't hurt to confirm that they're still in spec.
I had to clean two carbs on the weekend that had goo in the pilot mixture screw passage; they both refused to idle before I did that.

Ac21 · 08-09-2018, 06:50 PM

Valves adjusted to. .003 intake, exhaust a little loser. I normally don't use choke and temps here in TX hasn't changed. Yes I pulled carb yesterday and don't see anything obvious tho I didn't pull pilot out, will do that next.

I don't know if I was clear but the bike when cold or sitting for a while starts no problem the issue is when I ride around for a while and I go to up or down shift, pulling in the clutch kills the engine like I hit the engine kill button. Then when I come to a stop it won't start for a good minute no matter what. After a min or so I can give it a little throttle and it starts and rides fine for another 5 to 7 mins then same thing..

Like I said I pulled carb yesterday left the pea cock up which I thought was closed and today I see its been dripping gas into the garage all day went to wipe it off the bike and the paint came off :(

Gh426 · 08-09-2018, 06:53 PM

vapor lock?? vent on gas tank clear??

Ac21 · 08-09-2018, 09:25 PM

that's possible and the problem sounds like it. where is vent on tank?

just got back from riding with it stalling two times, opened the cap and i can hear the vacuum.

i think this is it. Can i shoot some compressed air into the hole on the bottom on the cap to free what ever is blocking it? or i need a new cap?

**JerryHawk250** · 08-10-2018, 08:19 AM

Do you still have the stock exhaust with the catalytic converter? We have a couple of members on here that had issues with the exhaust getting hot enough to boil the gas in the bowl and cause the same symptoms you are experiencing. Either wrap the exhaust or put some kind of heat shield. Or remove the cat or install the ebay exhaust system everyone else is using.
Personally I would get rid of the cat and rejet the carb for better performance. The exhaust will run much cooler.

ChrisWNY · 08-10-2018, 11:13 AM

If the flow of fuel is being obstructed from lack of proper venting, you can try riding for a while with the cap a little loose to rule that in or out. I've never looked to see how the gas tank is vented, whether through the cap or somewhere else. If venting was an issue I'd probably just drill a small hole through the cap.

Ac21 · 08-12-2018, 02:32 PM

drilled A hole n the cap...seems to be working

OneLeggedRider · 12-02-2018, 05:52 AM

A couple of years ago I got a nice Honda ATC 250SX that was doing the same thing. The owner was so fed up with it he sold it to me for $50. I drilled a tiny hole in the cap and it ran perfectly after that. 🙂

Ac21 · 12-02-2018, 10:31 PM

update ...still working fine

08-08-2018, 09:07 PM	#1
Ac21 Join Date: Jun 2018 Posts: 54	Hawk engine cutting off The bike has about 600 miles on it, I adjusted the valves maybe 100 miles ago again. The last two days I noticed when it warms up and I pull in the clutch the engine quits and have a hard time restarting. Giving it a little throttle while cranking up again seems to help. Any ideas?
	0

08-08-2018, 10:08 PM	#2
ChrisWNY Join Date: Jul 2018 Posts: 212	Sounds like it's not getting enough fuel when idling or running at low throttle. Have you tried to adjust the idle or the fuel mixture screw on the carb? I think the issue will boil down to something related to the carb...remove the carb (it may be as simple as adjusting the idle screw). Take it apart, make sure it's free of debris and none of the jets are clogged. Adding an in-line fuel filter will prevent debris from getting into the carb, if that's what turns out to be the issue. __________________ 2018 RPS Hawk 250cc Mods so far: 1. Mikuni VM26 Carburetor w/#115 main jet 2. 17T/45T JT sprockets 3. JT 428 X-ring chain 4. Air box mod 5. Hawk Digital Cluster 6. Aftermarket IMS shift lever 7. Performance Aftermarket Exhaust 8. 295mm Nitrogen Gas Monoshock, 20W oil front forks
	1

08-08-2018, 10:34 PM	#4
ChrisWNY Join Date: Jul 2018 Posts: 212	The main jet will only affect performance when you're near full throttle or wide open. I know some have had to install larger pilot jets to fix idle issues on the stock China carbs. I haven't personally experienced any idling issues with my Mikuni VM26. __________________ 2018 RPS Hawk 250cc Mods so far: 1. Mikuni VM26 Carburetor w/#115 main jet 2. 17T/45T JT sprockets 3. JT 428 X-ring chain 4. Air box mod 5. Hawk Digital Cluster 6. Aftermarket IMS shift lever 7. Performance Aftermarket Exhaust 8. 295mm Nitrogen Gas Monoshock, 20W oil front forks
	0

08-09-2018, 07:49 AM	#6
ChrisWNY Join Date: Jul 2018 Posts: 212	Also another obvious thing to consider but sometimes overlooked...are you starting with half or full choke and allowing the engine to warm up before making any adjustments to it? Depending on the temperature in your area, you'll likely need to choke the engine at first and let it warm up a few minutes, then judge performance based on how the engine is running warmed up with the choke off. __________________ 2018 RPS Hawk 250cc Mods so far: 1. Mikuni VM26 Carburetor w/#115 main jet 2. 17T/45T JT sprockets 3. JT 428 X-ring chain 4. Air box mod 5. Hawk Digital Cluster 6. Aftermarket IMS shift lever 7. Performance Aftermarket Exhaust 8. 295mm Nitrogen Gas Monoshock, 20W oil front forks
	0

08-09-2018, 11:17 AM	#7
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	What did you adjust the valves to? Wouldn't hurt to confirm that they're still in spec. I had to clean two carbs on the weekend that had goo in the pilot mixture screw passage; they both refused to idle before I did that. __________________ 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

08-08-2018, 10:32 PM	#3
Ac21 Join Date: Jun 2018 Posts: 54	Yes I tried adjusting the idle screw and I have the air mix screw out about 2 turns its been running fine so far, I also noticed at a quick throttle blip it will bog down also. I Re adjusted valves again tonight, Re adjusted spark gap also. I'm going to pull carb off and check now. Tomarrow a new 110 main jet is coming. In school we spent one day on carburetors the teacher said you won't need this anyway
	0

08-09-2018, 06:50 PM	#8
Ac21 Join Date: Jun 2018 Posts: 54	Valves adjusted to. .003 intake, exhaust a little loser. I normally don't use choke and temps here in TX hasn't changed. Yes I pulled carb yesterday and don't see anything obvious tho I didn't pull pilot out, will do that next. I don't know if I was clear but the bike when cold or sitting for a while starts no problem the issue is when I ride around for a while and I go to up or down shift, pulling in the clutch kills the engine like I hit the engine kill button. Then when I come to a stop it won't start for a good minute no matter what. After a min or so I can give it a little throttle and it starts and rides fine for another 5 to 7 mins then same thing.. Like I said I pulled carb yesterday left the pea cock up which I thought was closed and today I see its been dripping gas into the garage all day went to wipe it off the bike and the paint came off :(
	0

08-09-2018, 06:53 PM	#9
Gh426 Join Date: Feb 2018 Location: LA Posts: 74	vapor lock?? vent on gas tank clear??
	2

08-09-2018, 09:25 PM	#10
Ac21 Join Date: Jun 2018 Posts: 54	that's possible and the problem sounds like it. where is vent on tank? just got back from riding with it stalling two times, opened the cap and i can hear the vacuum. i think this is it. Can i shoot some compressed air into the hole on the bottom on the cap to free what ever is blocking it? or i need a new cap? Last edited by Ac21; 08-09-2018 at 09:57 PM.
	1

08-10-2018, 08:19 AM	#11
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,707	Do you still have the stock exhaust with the catalytic converter? We have a couple of members on here that had issues with the exhaust getting hot enough to boil the gas in the bowl and cause the same symptoms you are experiencing. Either wrap the exhaust or put some kind of heat shield. Or remove the cat or install the ebay exhaust system everyone else is using. Personally I would get rid of the cat and rejet the carb for better performance. The exhaust will run much cooler. __________________ 2024 Linhai 300 ATV 4x4 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel
	1

08-10-2018, 11:13 AM	#12
ChrisWNY Join Date: Jul 2018 Posts: 212	If the flow of fuel is being obstructed from lack of proper venting, you can try riding for a while with the cap a little loose to rule that in or out. I've never looked to see how the gas tank is vented, whether through the cap or somewhere else. If venting was an issue I'd probably just drill a small hole through the cap. __________________ 2018 RPS Hawk 250cc Mods so far: 1. Mikuni VM26 Carburetor w/#115 main jet 2. 17T/45T JT sprockets 3. JT 428 X-ring chain 4. Air box mod 5. Hawk Digital Cluster 6. Aftermarket IMS shift lever 7. Performance Aftermarket Exhaust 8. 295mm Nitrogen Gas Monoshock, 20W oil front forks
	1

08-12-2018, 02:32 PM	#13
Ac21 Join Date: Jun 2018 Posts: 54	drilled A hole n the cap...seems to be working
	4

12-02-2018, 05:52 AM	#14
OneLeggedRider Join Date: Nov 2018 Location: Stockport, Oh. Posts: 1,442	A couple of years ago I got a nice Honda ATC 250SX that was doing the same thing. The owner was so fed up with it he sold it to me for $50. I drilled a tiny hole in the cap and it ran perfectly after that. 🙂
	4

12-02-2018, 10:31 PM	#15
Ac21 Join Date: Jun 2018 Posts: 54	update ...still working fine
	1