Rocker arm tappets not sitting flat on valves

pablordf · 05-18-2021, 01:38 PM

I was adjusting the valve clearence on my bike because they seemed to be too tight when I noticed that the rocker arm tappets didn't sit flat against the tip of the valves, Is this normal? The bike has only 10k miles.

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Piglife · 05-18-2021, 03:24 PM

It's exactly the same on both of my Hawks and Magician. I haven't had any problems caused by it though and since all 3 were that way I haven't worried about it to much.

Not sure if this is helpful but I hope so.

Skyd · 05-18-2021, 03:42 PM

Yes, that's normal and if you imagine the rocker arm pushing the valve down the point where they meet will become more flat, if that makes sense. Because of the arc of travel.

Oh, and my hawk looks exactly like that too :-)

idle_purr · 05-18-2021, 11:59 PM

My Brozz and Fathers Hawk look exactly the same.

Does anyone by any chance know the size of the locknut and the square of the adjustment screw? I believe the locknut was 10mm but have no idea the size of the square.

I am trying to order a valve adjustment tool but I am not sure what size I need and I am trying to avoid removing the cover again until the next adjustment, but I would like to have the tool by then.

I have adjusted my valves twice and each time it was a major PITA... I felt like for the life of me I could not get it to lock down at the right gap. I would get it perfect then tighten it down and it would be too tight. Finally I went up a size to .08mm and when I tightened it, the gap was correct at .07mm on the gauge. After the engine break in I will readjust them to .05mm

ChillRider · 05-19-2021, 03:11 AM

The size of that adjustment square on my ZongShen Sierra would fit in a size #2 square drive screw, and in fact using one of those was one way to build such an adjustment tool.

TBQH I didn't have any such screws laying around when I did the adjustment, nor the specialized Yamaha tool, I simply used some pliers to turn the square and tried to tighten the nut without moving stuff too much.

It worked, but the downside was that I had to re-check the tolerances several times, as tightening the nut would somehow throw them off (looser) after another couple cranckshaft revolutions.

Megadan · 05-19-2021, 04:24 AM

Quote:

Originally Posted by pablordf

I noticed that the rocker arm tappets didn't sit flat against the tip of the valves, Is this normal?

Yep, normal. Two flat surfaces, one travels in an arc, the other in a linear fashion at an angle to the arc. The adjuster sweeps down and in, so at a certain point the two faces will be in full contact, and as it keeps sweeping the other edge will then be the only contact point.

herbie · 05-19-2021, 05:11 AM

[QUOTE=ChillRider;360407]The size of that adjustment square on my ZongShen Sierra would fit in a size #2 square drive screw, and in fact using one of those was one way to build such an adjustment tool.

Great idea!

mtiberio · 05-19-2021, 05:46 AM

take a picture with the valve fully open, same but reversed.

idle_purr · 05-19-2021, 01:24 PM

Quote:

Originally Posted by ChillRider

The size of that adjustment square on my ZongShen Sierra would fit in a size #2 square drive screw, and in fact using one of those was one way to build such an adjustment tool.

Brilliant! I will give it a try in about 75 more miles

Skyd · 05-19-2021, 01:33 PM

ya I might have to give that a go myself...handy and I might already have the parts laying around.

pablordf · 05-20-2021, 12:27 PM

Thanks for your advice, I adjusted the clearence with 0.05mm intake and 0.08mm exhaust and now it seems to run fine

Hunnicutt · 05-21-2021, 08:37 AM

ChillRider - that is an absolutely awesome idea!!!

Does the screw in the wire nut loosen up when you twist it? If it does, I think adding some gorilla glue to the wire nut would hold the screw in place.

DSM · 05-21-2021, 05:12 PM

Quote:

Originally Posted by pablordf

I was adjusting the valve clearence on my bike because they seemed to be too tight when I noticed that the rocker arm tappets didn't sit flat against the tip of the valves, Is this normal? The bike has only 10k miles.

Attachment 24652
Attachment 24653

10k miles!

05-18-2021, 01:38 PM	#1
pablordf Join Date: May 2021 Posts: 5	Rocker arm tappets not sitting flat on valves I was adjusting the valve clearence on my bike because they seemed to be too tight when I noticed that the rocker arm tappets didn't sit flat against the tip of the valves, Is this normal? The bike has only 10k miles. Last edited by pablordf; 05-18-2021 at 02:21 PM.
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05-18-2021, 03:42 PM	#3
Skyd Join Date: Mar 2021 Location: New Hampshire Posts: 242	Yes, that's normal and if you imagine the rocker arm pushing the valve down the point where they meet will become more flat, if that makes sense. Because of the arc of travel. Oh, and my hawk looks exactly like that too :-) __________________ 2020 RPS Hawk 250 - Build thread can be found here: http://www.chinariders.net/showthread.php?t=28374 "Do Wheelies and Forget your Feelies" "If vegetarians eat vegetables, what do humanitarians eat?" -unknown
	1

05-18-2021, 11:59 PM	#4
idle_purr Join Date: Feb 2021 Location: NY Posts: 218	My Brozz and Fathers Hawk look exactly the same. Does anyone by any chance know the size of the locknut and the square of the adjustment screw? I believe the locknut was 10mm but have no idea the size of the square. I am trying to order a valve adjustment tool but I am not sure what size I need and I am trying to avoid removing the cover again until the next adjustment, but I would like to have the tool by then. I have adjusted my valves twice and each time it was a major PITA... I felt like for the life of me I could not get it to lock down at the right gap. I would get it perfect then tighten it down and it would be too tight. Finally I went up a size to .08mm and when I tightened it, the gap was correct at .07mm on the gauge. After the engine break in I will readjust them to .05mm __________________ NO HILL TOO STEEP NO MUD TOO DEEP The Brozz \| The Hawk Upgrades, Accessories, Etc... Assembly Checklist: Brozz 250 \| Hawk 250 ~idle_purr Last edited by idle_purr; 05-19-2021 at 02:16 AM.
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05-19-2021, 05:11 AM	#7
herbie Join Date: May 2019 Location: Illinois Posts: 864	[QUOTE=ChillRider;360407]The size of that adjustment square on my ZongShen Sierra would fit in a size #2 square drive screw, and in fact using one of those was one way to build such an adjustment tool. Great idea! __________________ 2022 Venom KPR 200 Red- the fastest color 16t and 46t sprockets, NGK Iridium CPR8EAIX-9, aftermarket full exhaust system. Top speed 81GPS 2023 Venom SS3 KP mini 150– Nibbi carb, Nibbi air filter, aftermarket muffler, decat 2022 Venom Ghost chopper 250 1997 Honda GL1500 Goldwing 1978 Kawasaki KL250 https://youtube.com/@herbiesgarage681
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05-19-2021, 05:46 AM	#8
mtiberio Join Date: Jun 2016 Location: Arlington, VA Posts: 258	take a picture with the valve fully open, same but reversed. __________________ 4 time WERA SuperVintage Roadracing National Champion, SCTA Land Speed Record Holder, 3rd AMA Motorcycle GP of Miami
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05-18-2021, 03:24 PM	#2
Piglife Join Date: Apr 2021 Location: New Mexico Posts: 24	It's exactly the same on both of my Hawks and Magician. I haven't had any problems caused by it though and since all 3 were that way I haven't worried about it to much. Not sure if this is helpful but I hope so.
	1

05-19-2021, 03:11 AM	#5
ChillRider Join Date: Jun 2020 Location: A small country with a funny name Posts: 164	The size of that adjustment square on my ZongShen Sierra would fit in a size #2 square drive screw, and in fact using one of those was one way to build such an adjustment tool. TBQH I didn't have any such screws laying around when I did the adjustment, nor the specialized Yamaha tool, I simply used some pliers to turn the square and tried to tighten the nut without moving stuff too much. It worked, but the downside was that I had to re-check the tolerances several times, as tightening the nut would somehow throw them off (looser) after another couple cranckshaft revolutions.
	3

05-19-2021, 01:33 PM	#10
Skyd Join Date: Mar 2021 Location: New Hampshire Posts: 242	ya I might have to give that a go myself...handy and I might already have the parts laying around. __________________ 2020 RPS Hawk 250 - Build thread can be found here: http://www.chinariders.net/showthread.php?t=28374 "Do Wheelies and Forget your Feelies" "If vegetarians eat vegetables, what do humanitarians eat?" -unknown
	0

05-20-2021, 12:27 PM	#11
pablordf Join Date: May 2021 Posts: 5	Thanks for your advice, I adjusted the clearence with 0.05mm intake and 0.08mm exhaust and now it seems to run fine
	0

05-21-2021, 08:37 AM	#12
Hunnicutt Join Date: Apr 2021 Location: Central Florida Posts: 103	ChillRider - that is an absolutely awesome idea!!! Does the screw in the wire nut loosen up when you twist it? If it does, I think adding some gorilla glue to the wire nut would hold the screw in place. __________________ ___________________________________ 2021 CSC TT250 - Silver (Mine) "Buzz" 2021 CSC TT250 - White (Wife's) "Seymour" 2021 CSC TT250 - White (Daughter's) "Gemini"
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