[B]New Hawk Engine Noise[/B]

T1jeep · 02-04-2021, 07:59 PM

Newly built Hawk 250. I gapped valves and started. This is recording after it’s been warmed up, I s this noise normal? It sounds same with stock carb as well as Mikuni I just put on with 110 jet.

Please give me feedback if it sounds normal or not. And I haven’t changed oil yet. I know that will help some.

China Rider 27 · 02-04-2021, 10:19 PM

Sounds like you set your valves to loose. Which is better than too tight. They are tough to get right. There is a tool for it helps some. When I broke in my motor I stayed on the loose side some so no issues.

Here is a good thread.

http://www.chinariders.net/showthread.php?t=25660

T1jeep · 02-04-2021, 10:31 PM

Thanks for link. I checked valves twice. Am I missing something with the gap?

Correct me if I’m wrong but for every revolution when I rotate engine to TDC I should get same spacing? I did notice the height of the springs and valves go to different heights on intake and exhaust at TDC. But the pushrods appear same height. Is that normal?

I had read somewhere I might have to rotate around again but I’m not sure why.

XLsior · 02-04-2021, 10:53 PM

valve lash tick is normal when running. Will be more noticeable on a cold engine. as the engine gets to operating temp the tolerances will tighten up as the metal expands and oil becomes less viscous. or is that the other way around, i might be getting confused with diesel fuel injectors...

As for adjusting valve lash as long as the valve is off* cam then its ok to adjust. If you can wiggle the valve adjuster and make it click then its reasonably safe to adjust. The only time of concern is if the lash adjustment is tight throughout the entire crank revolution ergo its over tight so back off adjustment. Ignition timing requires the TDC on the compression stroke...

If you don't have a set of feeler gauges that a standard double side razor blade is about .004 some people use business cards at a pinch but even I have my tolerances for shade tree mechanics.

T1jeep · 02-04-2021, 11:01 PM

I have a set of gauges. I wonder as I would check it. Spin the engine counterclockwise with bolt and recheck. The lash spacing would be tight. I would loosen, reset and spin again and it was too loose. I spun again and it seemed good.

But I got this sound.

I don’t mind riding some and rechecking again. I just want to ensure I’m doing correctly.

XLsior · 02-04-2021, 11:17 PM

ok i just listened to the audio and to me it seems exhaust related...but that's just my inclination.

Something seems loose.

Definitely abnormal.

T1jeep · 02-04-2021, 11:21 PM

Here’s another way to ask this, is there a TDC on compression stroke and exhaust stroke?

Meaning does it take 720 degrees of rotation to go through a full cycle, or is it 360 degrees?

T1jeep · 02-04-2021, 11:22 PM

When you say something seems loose, do you mean valve or something in engine?

XLsior · 02-05-2021, 12:05 AM

In a 4 stroke engine there are 2 ups and 2 downs. compression/exhaust, intake/power. So a full 4 stroke cycle is indeed 720* of revolution. but the spark likely fires every 360 or even 180...but I don't think this relates to the noise. Its hard to diagnose as you sort of have to move around feel out a noise location.

I am not inclined to suggest your engine needs re timing or a tear down.

To me the sound I hear is in tandem with the exhaust pap. So I would start at the muffler tip check and tighten every fixing all the way to the header flange. Something sounds loose and or is making contact with something else but not necessarily from inside the engine.

T1jeep · 02-05-2021, 12:07 AM

Thanks. I will check. How do I know which 360 cycle of me turning crank is the TDC I want to check valves?

XLsior · 02-05-2021, 12:34 AM

Not taking any credit but this is the first search result on YT regarding 'hawk 250 valve adjustment'

other YT videos exist that might be better but this seems to cover all the bases.

T1jeep · 02-05-2021, 10:31 PM

Thanks, my lashings are correct. I had seen this video in past. I guess at the time I overlooked explanation of the which revolution mattered...

I did recheck bolts and the header flange bolt on one side was looser then other and tightened to what I think it should be. I tightened up and sounds much better.

What should torque be on these bolts? I don’t want to crank too much on them. And should I loctite them, or will heat break it down anyways?

XLsior · 02-05-2021, 11:37 PM

Referring to the 2 header flange stud nuts, Some bikes came with acorn/cap nuts, others didn't so torque setting don't really apply.
I think the head bolts are only 25ft pounds so i doubt anything on the rest of the bike is over that and my torque wrench doesn't do less than that.
All you are trying to do is clamp down the header onto an installed copper ring/crush washer. overtime with vibration and heat cycles things can come loose so just nipping them up is enough. say 1 click of the wrist. Anymore and you might bend the flange which is not good.
All part of the general bike inspection and servicing mantra

Add a second nut if there is enough thread showing to lock it, if it concerns you.

02-04-2021, 10:53 PM	#4
XLsior Join Date: Aug 2020 Location: Australia Posts: 1,281	valve lash tick is normal when running. Will be more noticeable on a cold engine. as the engine gets to operating temp the tolerances will tighten up as the metal expands and oil becomes less viscous. or is that the other way around, i might be getting confused with diesel fuel injectors... As for adjusting valve lash as long as the valve is off* cam then its ok to adjust. If you can wiggle the valve adjuster and make it click then its reasonably safe to adjust. The only time of concern is if the lash adjustment is tight throughout the entire crank revolution ergo its over tight so back off adjustment. Ignition timing requires the TDC on the compression stroke... If you don't have a set of feeler gauges that a standard double side razor blade is about .004 some people use business cards at a pinch but even I have my tolerances for shade tree mechanics. Last edited by XLsior; 02-05-2021 at 06:59 PM.
	0

02-04-2021, 10:19 PM	#2
China Rider 27 Join Date: Dec 2018 Location: PNW Posts: 982	Sounds like you set your valves to loose. Which is better than too tight. They are tough to get right. There is a tool for it helps some. When I broke in my motor I stayed on the loose side some so no issues. Here is a good thread. http://www.chinariders.net/showthread.php?t=25660
	0

02-04-2021, 10:31 PM	#3
T1jeep Join Date: Jan 2021 Posts: 29	Thanks for link. I checked valves twice. Am I missing something with the gap? Correct me if I’m wrong but for every revolution when I rotate engine to TDC I should get same spacing? I did notice the height of the springs and valves go to different heights on intake and exhaust at TDC. But the pushrods appear same height. Is that normal? I had read somewhere I might have to rotate around again but I’m not sure why.
	0

02-04-2021, 11:01 PM	#5
T1jeep Join Date: Jan 2021 Posts: 29	I have a set of gauges. I wonder as I would check it. Spin the engine counterclockwise with bolt and recheck. The lash spacing would be tight. I would loosen, reset and spin again and it was too loose. I spun again and it seemed good. But I got this sound. I don’t mind riding some and rechecking again. I just want to ensure I’m doing correctly.
	0

02-04-2021, 11:17 PM	#6
XLsior Join Date: Aug 2020 Location: Australia Posts: 1,281	ok i just listened to the audio and to me it seems exhaust related...but that's just my inclination. Something seems loose. Definitely abnormal.
	0

02-04-2021, 11:21 PM	#7
T1jeep Join Date: Jan 2021 Posts: 29	Here’s another way to ask this, is there a TDC on compression stroke and exhaust stroke? Meaning does it take 720 degrees of rotation to go through a full cycle, or is it 360 degrees?
	0

02-04-2021, 11:22 PM	#8
T1jeep Join Date: Jan 2021 Posts: 29	When you say something seems loose, do you mean valve or something in engine?
	0

02-05-2021, 12:05 AM	#9
XLsior Join Date: Aug 2020 Location: Australia Posts: 1,281	In a 4 stroke engine there are 2 ups and 2 downs. compression/exhaust, intake/power. So a full 4 stroke cycle is indeed 720* of revolution. but the spark likely fires every 360 or even 180...but I don't think this relates to the noise. Its hard to diagnose as you sort of have to move around feel out a noise location. I am not inclined to suggest your engine needs re timing or a tear down. To me the sound I hear is in tandem with the exhaust pap. So I would start at the muffler tip check and tighten every fixing all the way to the header flange. Something sounds loose and or is making contact with something else but not necessarily from inside the engine.
	0

02-05-2021, 12:07 AM	#10
T1jeep Join Date: Jan 2021 Posts: 29	Thanks. I will check. How do I know which 360 cycle of me turning crank is the TDC I want to check valves?
	0

02-05-2021, 12:34 AM	#11
XLsior Join Date: Aug 2020 Location: Australia Posts: 1,281	Not taking any credit but this is the first search result on YT regarding 'hawk 250 valve adjustment' other YT videos exist that might be better but this seems to cover all the bases.
	0

02-05-2021, 10:31 PM	#12
T1jeep Join Date: Jan 2021 Posts: 29	Thanks, my lashings are correct. I had seen this video in past. I guess at the time I overlooked explanation of the which revolution mattered... I did recheck bolts and the header flange bolt on one side was looser then other and tightened to what I think it should be. I tightened up and sounds much better. What should torque be on these bolts? I don’t want to crank too much on them. And should I loctite them, or will heat break it down anyways?
	0

02-05-2021, 11:37 PM	#13
XLsior Join Date: Aug 2020 Location: Australia Posts: 1,281	Referring to the 2 header flange stud nuts, Some bikes came with acorn/cap nuts, others didn't so torque setting don't really apply. I think the head bolts are only 25ft pounds so i doubt anything on the rest of the bike is over that and my torque wrench doesn't do less than that. All you are trying to do is clamp down the header onto an installed copper ring/crush washer. overtime with vibration and heat cycles things can come loose so just nipping them up is enough. say 1 click of the wrist. Anymore and you might bend the flange which is not good. All part of the general bike inspection and servicing mantra Add a second nut if there is enough thread showing to lock it, if it concerns you.
	0