Valve Clearance Kept Changing

ralphbalena · 10-24-2022, 09:45 AM

I don't know why the valve clearance of my bike kept on going bad almost every single month.

my last valve clearance adjustment was last October 8. and then today October 24 it started to act like it needs an adjustment, AGAIN!

How did I know? its hard starting in the morning. There are times that its very hard to start that I have to use a hair dryer pointed at the valves just to warm them up. Also the rpm sometimes drop when I'm riding and about to do a full stop. (you can feel that the bike will stall so I just rev it slightly)

Its been like this for several months already. so annoying that I have to kept on going back to my mechanic for adjustment.

This is my daily ride to work which is just about 30km per day (18miles). I don't ride hard since here in Manila, traffic is terrible.

**JerryHawk250** · 10-24-2022, 10:13 AM

I know some of the older engines there was an issue with the valve seats recessing into the head.

ralphbalena · 10-24-2022, 10:21 AM

my bike is 2015 rx3. What is the solution to that recessing problem? change head?

**JerryHawk250** · 10-24-2022, 10:24 AM

I think SpudRider had a write up in one of the stickies at he top of this section. I think a new head was the solution.

Wild Dog · 10-24-2022, 06:02 PM

Quote:

Originally Posted by ralphbalena

Its been like this for several months already. so annoying that I have to kept on going back to my mechanic for adjustment.

Uhmm i think here is your problem.

In just 16 days, your valve are once again out of spec.
If you do 30 km per day, that's just 480 km, way too little for valves get out of spec.

Since you didn't do the valve adjustment it's pretty much impossible to know what kind of spec he is using to set the lash.

You should talk to him and ask him why you have to keep coming back for a valve adjustment. Either he is doing a poor job or there could be something wrong with the valves.

Give my own experience with "mechanics" i would guess he is doing it wrong.

Nonetheless go and talk to him, because it's quite clear that your motorcycle is not running like it should and i don't he is working on your motorcycle for free.

clash 168cc · 10-24-2022, 10:16 PM

Check the compression first then if the compression is good do the adjustment yourself. You can lose power if your rings are worn out or your valves are not seating. New head.

Working_ZS · 10-25-2022, 12:14 AM

Given your probable mileage from your stated usage, 54,600 kms or 33,900 miles, your valves and, or your valve seats in the cylinder head may be worn out. It could also be a problem with the lock nuts on the valve lash adjusters being unable to hold their torque due to worn threads.

If it were my bike, I would do an adjustment myself. Use a torque marker on the nuts to see if they move. If it doesn't hold and the nuts have moved, I would readjust and install new lock nuts. If it still doesn't hold and the lock nuts are staying tight, then I would look into replacing the cylinder head. Last time I looked they were going for US $150 shipped on AliExpress, probably cheaper to your location.

ralphbalena · 10-25-2022, 03:29 AM

Quote:

Originally Posted by Working_ZS

Given your probable mileage from your stated usage, 54,600 kms or 33,900 miles, your valves and, or your valve seats in the cylinder head may be worn out. It could also be a problem with the lock nuts on the valve lash adjusters being unable to hold their torque due to worn threads.

If it were my bike, I would do an adjustment myself. Use a torque marker on the nuts to see if they move. If it doesn't hold and the nuts have moved, I would readjust and install new lock nuts. If it still doesn't hold and the lock nuts are staying tight, then I would look into replacing the cylinder head. Last time I looked they were going for US $150 shipped on AliExpress, probably cheaper to your location.

Well my total mileage for this bike is around 35,000kms.

I'll have to check with the mechanic on how he made the adjustment last time. and ask him why it kept on changing for only a show period of time.

might as well source a new head for this hehe

Wild Dog · 10-25-2022, 10:43 AM

Quote:

Originally Posted by ralphbalena

Well my total mileage for this bike is around 35,000kms.

I'll have to check with the mechanic on how he made the adjustment last time. and ask him why it kept on changing for only a show period of time.

might as well source a new head for this hehe

You can get a new head, but at that mileage you should not need a new head.
Plus if the head came bad from the factory it would have had valve issues since day one or at least before the 10.000 km.
I know few Rx3 with over 50.000 km, that still have their original head.
The NC250 is reliable engine.

ralphbalena · 11-05-2022, 07:08 AM

just had my valve clearance adjusted today. as suspected 1 intake valve is already out of specs. its below .05mm which is causing the hard starting and rpm drop.

they did the correct procedure in adjusting the valves. saw it my self hehe

mechanic suspects that the valves are worn.

10-24-2022, 09:45 AM	#1
ralphbalena Join Date: Sep 2021 Posts: 12	Valve Clearance Kept Changing I don't know why the valve clearance of my bike kept on going bad almost every single month. my last valve clearance adjustment was last October 8. and then today October 24 it started to act like it needs an adjustment, AGAIN! How did I know? its hard starting in the morning. There are times that its very hard to start that I have to use a hair dryer pointed at the valves just to warm them up. Also the rpm sometimes drop when I'm riding and about to do a full stop. (you can feel that the bike will stall so I just rev it slightly) Its been like this for several months already. so annoying that I have to kept on going back to my mechanic for adjustment. This is my daily ride to work which is just about 30km per day (18miles). I don't ride hard since here in Manila, traffic is terrible. Last edited by ralphbalena; 10-24-2022 at 10:21 AM.
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10-24-2022, 10:13 AM	#2
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,725	I know some of the older engines there was an issue with the valve seats recessing into the head. __________________ 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
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10-24-2022, 10:24 AM	#4
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,725	I think SpudRider had a write up in one of the stickies at he top of this section. I think a new head was the solution. __________________ 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
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10-24-2022, 10:21 AM	#3
ralphbalena Join Date: Sep 2021 Posts: 12	my bike is 2015 rx3. What is the solution to that recessing problem? change head?
	0

10-24-2022, 10:16 PM	#6
clash 168cc Join Date: Jul 2022 Posts: 94	Check the compression first then if the compression is good do the adjustment yourself. You can lose power if your rings are worn out or your valves are not seating. New head.
	0

10-25-2022, 12:14 AM	#7
Working_ZS Join Date: Aug 2016 Posts: 365	Given your probable mileage from your stated usage, 54,600 kms or 33,900 miles, your valves and, or your valve seats in the cylinder head may be worn out. It could also be a problem with the lock nuts on the valve lash adjusters being unable to hold their torque due to worn threads. If it were my bike, I would do an adjustment myself. Use a torque marker on the nuts to see if they move. If it doesn't hold and the nuts have moved, I would readjust and install new lock nuts. If it still doesn't hold and the lock nuts are staying tight, then I would look into replacing the cylinder head. Last time I looked they were going for US $150 shipped on AliExpress, probably cheaper to your location.
	0

11-05-2022, 07:08 AM	#10
ralphbalena Join Date: Sep 2021 Posts: 12	just had my valve clearance adjusted today. as suspected 1 intake valve is already out of specs. its below .05mm which is causing the hard starting and rpm drop. they did the correct procedure in adjusting the valves. saw it my self hehe mechanic suspects that the valves are worn.
	0