[Vishal993]

Hi guys, I recently started to notice tick-tick type noise through engine head. So, decided to check one by one
1. I checked the operation of chain tensioner, working good.

Removed valve cover for further investigation
2. Checked timing chain so check whether it is tight or not. It was tight.

3.So finally I decided to do valve clearance measurements
Inlet
0.16mm & 0.15mm (requires 0.13mm~0.19mm) OK

Exhaust
0.19 mm & 0.20mm (requires 0.24mm ~ 0.30)
Not Ok
So, I do the math and found that I need to choose thinner shims.

So, here I was little confused that how the hell valve clearance became tighter(usually it wear out so, need to loose).
So, I called the friend who was working in Ducati as Service engineer. He told me, Due to exhaust gas heat, the valve gets heated and the heat is transferred to the top part of the valve called steam And Shims are placed in between valve steam and fingers follower. Due to which shim size gets expanded over the period of time. Which makes the valve clearance tight. He also told me that, due to this problem manufacturers given Exhaust valve clearance is more than Inlet valve clearance.

I thought why not share it with others owners too to make some awareness.

Thank you

 

[Tamir]

I recently started to notice tick-tick type noise through engine head.

Hi. YES, It would be right to say that the immediate suspect falls on the tensioner.

1. I checked the operation of chain tensioner, working good.

But if the suspicion falls on the tensioner, the tensioner should be replaced, because in the test it comes out FALSE NORMAL (test by pressing in with the force of the hand). The "test" of the tensioner is performed by counting the kilometers, and it is recommended to replaced it earlier every 20,000 km.

Exhaust
0.19 mm & 0.20mm (requires 0.24mm ~ 0.30)
Not Ok

As a result of abrasion the spacing increases, and then the thickness of the shims has to be increased too. But you ware measuring a smaller space than required, which is weird ???

So, here I was little confused that how the hell valve clearance became tighter(usually it wear out so, need to loose).

YES

And your friend is right, the heat does affect on the Valve Clearance, in the heat the metals are expanding. The Valve Clearance measurements given by the manufacturer are measurable when the engine is cold at room temperature (about 25 degrees Celsius). It is therefore advisable to perform the test after a night's rest, when the engine is cold.


1. How many Km's have been past since the last tensioner replacement ?
2. Was the Valve Clearance test done with a cold engine?

 

[Vishal993]

1. How many Km's have been past since the last tensioner replacement ?
Bike is running 23,000km odo. Not changed the tensioner yet. Checked the operation it thoroughly. And even though it was giving false reading, timing chain should be loose.

2. Was the Valve Clearance test done with a cold engine?
Yes, bike was complete rest since last 10days.

 

[Tamir]

How many Km's have been past since the last tensioner replacement ?
Bike is running 23,000km odo.

Definitely it's time to replace it, and yes, there's a good chance the noises you hear will stop. The component is known to be problematic. Replacement at 23,000Km It's mandatory, it's not an argument👩‍🔧🤷‍♂️

2. Was the Valve Clearance test done with a cold engine?
Yes, bike was complete rest since last 10days.

I have not heard of a case where the Valve Clearance gets smaller, and needs to be replaced with thinner shims. Maybe the measurement did not go well? Something weird here ???

 

[Vishal993]

That's why asked to the Ducati mechanic, and asked the reason. He said what I have written above and shared with you guy's.
To confirm the fact here's some videos from YouTube

and another one from MC Garage

both which have exhaust Valve clearance towards tighter side.

 

[Tamir]

Vishal,
The shims do not wear out so fast, and even in the case of the first vide(LINK), it turns out that it did not wear out, and should not have been touched. If the spec is 0.13 to 0.18 the measures 0.13 is OK, the measurement is in the spec.
And he replaces the shims of the exhaust for no reason or need!
The master in the first video lowers 0.02mm so it leaves him in the right range(0.15), but it was unnecessary at all. And as Ari say(LINK), it's better to be on the loose side, but everything in that range is OK, which means 0.13 is fine and should not have to been touched.
And I know it's the opposite, it's better to be on the tight side, because the shims later on only wear and the gap grows(get more loose).
The GAP is always only increasing and can not decrease.

Also in the case of our friend Ari, as happened to you my dear friend Vishal, Ari measured exhaust-shims that is thicker than necessary, and this time Valve Clearance 0.12 that is out of range(0.13-0.18), and that too is very strange and unusual. Since Ari's measurement went out of the range, the replacement he made was indeed helpful and necessary.

I know of only two explanations for this situation:
1. Incorrect measurement (standard caliber does not measure the accuracy of one hundredth of a millimeter), or another measurement error.
2. The motorcycle had previously been serviced by an unskilled mechanic, or some other malfunction, and accidentally put in an unsuitable shims(Too thick).

So, If you are sure you have no measurement error, then yes, you are required to replace with thicker shims.

 

[Vishal993]

OK, I able to source new shims, I will update results. Currently I was facing two issues
1. Exhaust gas smells was different (like mixture is rich). Which makes sense now that due to tight clearance exhaust Valve was opening earlier and closing late (which result some unburn mixture escape out).
2. This tick-tick noise which is confusing here, as noise should only be there when something is loose.
As sourcing such part is task in India. let's see what happens after new shims.

 

[DannoXYZ]

I race in same AFM organization couple years after Ari, he's really cool guy. Thanks for video!!!

As a result of abrasion the spacing increases, and then the thickness of the shims has to be increased too. But you ware measuring a smaller space than required, which is weird ???

I have not heard of a case where the Valve Clearance gets smaller, and needs to be replaced with thinner shims. Maybe the measurement did not go well? Something weird here ???

I've adjusted valves on all my bikes for past 38-years and have found clearances always gets tighter over time with wear (I've owned over 30 bikes, well some of them don't have valves). This is area where people need to get out of their heads working with insufficient background experience and get their hands dirty actually working on bikes to understand why this happens.

1. what parts of valvetrain wears fastest? the parts that are hottest

2. what parts of valvetrain are hottest? exhaust valves and exhaust valve seats

3. what happens when valve faces and seats wear? material is removed

4. what happens when material is removed from valve faces and seats? valve sinks deeper into seats

5. when valves sinks deeper into seats, what happens to other end of valve? As in location of valve stem tip? It moves closer to cam!!! Valve clearances decrease over time with wear!!!


Changing shims is to compensate for wear at opposite end of valve where most wear occurs, not for cam-lobes. This is also why exhaust valves gets tighter faster than intake, they face much higher heat during their open time when exhaust flows out. Don't let exhaust valves get too tight as their contact time and pressure when closed cools them by transferring heat to head. Can get fried exhaust valves if they don't have sufficient cooling time. Best to adjust them to maximum end of range.

I've owned this bike since 1986 and have adjusted valves on it over 10x. Ever single time, I've had same experience as Vishal, valves always gets tighter.

 

[Tamir]

I've adjusted valves on all my bikes for past 38-years and have found clearances always gets tighter over time

You explain excellently, and I'm always happy to learn from you. Right, if the bracket of the valve wears out then the gap becomes smaller, but in the normal state the exhaust gases do not wear the metals LIKE metal on metal as happens in the shims area (even though there is oil between the metals).
I have been adjusting valves for over ten years and have always had to reduce spacing. It did not happen that I had to increase spacing.
I guess the gap between our two explanations may go through the degree of effort.
From what I learned from you in the engine that works all the time close to the red RPM line, there is wear in the valve bracket which is greater than the wear on the shims. Thanks!

 

[DannoXYZ]

It's not exhaust gases that wear out valves, it's the heat. Temperatures on exhaust valves and seats can get over 750C. This softens metal, causes valve to stick to seat. Some material is lost as valve breaks free. Also softer heated seat compresses causing valve-seat recession.

Keeping Engines Cool, Part 1

There’s way more to engine cooling than just fins or radiators. Cycle World’s resident expert, Kevin Cameron, reveals the secrets.

www.cycleworld.com

https://www.ms-motorservice.com/en/technipedia/post/valve-damage-and-causes/
https://www.motorcyclecruiser.com/valve-adjustment-simplified/
https://journals.sagepub.com/doi/abs/10.1177/1350650119872093

If you're getting excessive wear on cam-lobes so clearances increases faster than valve-wear, you've got lubrication problem:

• idle-speed too low... causes
• low oil-pressure at idle
• using low-quality oil, always use MA-rated full-synthetic oil. Auto oils are not good enough for moto lubrication

I've got 92K on my VF and it's as strong as when I first got it 35-yrs ago

 

[Vishal993]

4. what happens when material is removed from valve faces and seats? valve sinks deeper into seats

5. when valves sinks deeper into seats, what happens to other end of valve? As in location of valve stem tip? It moves closer to cam!!! Valve clearances decrease over time with wear!!!

Thank you sharing the valuable information about the tighter valve clearance, as I was thinking that if shims worn out evenly, the clearance has to increase not decrease. Thanks adding the missing points and sharing the experience of doing it, as for first time starter we need confirmation even if is small things.

Thanks @Tamir for lots feedback, as even though we are are from different parts of world, only few people are interested to share their experiences and knowledge.

 

[Vishal993]

I've got 92K on my VF and it's as strong as when I first got it 35-yrs ago
View attachment 44978

It's really great to see that some one is keeping the bike running for such a long. I wish I could keep min Lil bird too.

 

[Tamir]

...from what I know(LINK) the valve clearance usually increases and does not gets any smaller, and now, if it gets smaller it's for several reasons:
1. Improper adjustment by the previous mechanic.
2. Incorrect measurement of the current mechanic.
3. Riding on GP track at RPM in the red area (wear of the valve bracket)? At least that's what I learned from Danno.

Vishal, do you ride on GP tracks, and are usually on the red RPM's?

 

[Vishal993]

Vishal, do you ride on GP tracks, and are usually on the red RPM's?

No, I even not crossed the 110kmph mark on bike. Using the bike only for touring purposes.

 

[Tamir]

No, I even not crossed the 110kmph mark on bike. Using the bike only for touring purposes.

Me too.
So in my opinion, and I'm sorry, what Danno wisely explained is irrelevant for you.

 

[Vishal993]

@Tamir whatever results i will find out, I will update it. Please don't make diagnosis thing as personal agenda to share he is wrong and I'm right. We are here to share help, feedback and experience.
Even for your pressure drop test we have shared knowledge(as thing was new), and followed process to get results.I have a FAST Pressure Drop in the Fuel Hose 2 sec...
I personally learned few new things too. So please calm down and relax @DannoXYZ and @Tamir, we most probably newer meet to each other so please at least maintain a friendly discussion.

Thanks again for valuable information

 

[Tamir]

@Tamir whatever results i will find out, I will update it. Please don't make diagnosis thing as personal agenda to share he is wrong and I'm right. We are here to share help, feedback and experience.
Even for your pressure drop test we have shared knowledge(as thing was new), and followed process to get results.I have a FAST Pressure Drop in the Fuel Hose 2 sec...
I personally learned few new things too. So please calm down and relax @DannoXYZ and @Tamir, we most probably newer meet to each other so please at least maintain a friendly discussion.

Thanks again for valuable information

Vishal you're really cute. To me there's no argument, there's an exchange of knowledge. The forum is full of useful information, lovely people like you & Danno that sharing, I learn new things from almost every post here. And hope I manage to contribute to the forum little knowledge in return
We can disagree, all is well.

Back to your mechanical problem. As long as your measurements are correct, you need to replace shims, and I understand that there is no debate about that either.

And by the way, my fuel pressure drop problem, in the end you were right too, my fault was multiple heads, and I'm on my way to replacing the IACV Although on its terminals I measured standard values, and I suspect that this is a state of TRUE FALSE. After that replacement I will report an update that thread.

 

[Vishal993]

Hi guys, after long time. Following are the conclusion of my observation after long time.

1. After shim replacement, the noise was not completely gone. But i was in town where I don't have option. But noise was very less, so i continue to ride.
2. After talking with few local Honda mechanic I found that Cbr250r don't have this shims issue, and only by replacing the chain tensioner will short out this issue. I know they are not completely right, still I have checked the tensioner thoroughly and found no issue with tensioner.
3. After riding the bike city traffic found loss of power and engine sound is Lil louder, even engine rpm climbing to 1800-1900rpm from 1600rpm every time I start it (even engine is hot).
4. So figured out to replace the chain tensioner and see, after replacement all the above niggles gone and engine sound become smooth and rpm was settle at 1400rpm instantly. Rode it few kms and found bike performing really good.


So, to conclude please change the chain tensioner as a preventive maintenance. As it is the weakest member from engine assembly (herd from most of local Honda mechanics) to avoid this kind of issues.

 

[Tamir]

Hi Vishal. And thanks for the update!
The tensioner is replaced around 25,000 km, it can be done earlier, it is really not recommended to do it later. The work is really easy, the part is not really expensive, and its effect on the engine's health is great. I have tried more than once to understand what causes the failure of its mechanism, because the mechanism is very simple and reliable, And I wasn't able to prove anything. Apparently, a radical change in the surface of the screw, a "surface crushing", causes it to get stuck. Maybe, or maybe not, that's an academic discussion. The tensioner is replaced and that's it.

Regarding the adjustment of the valves. I adjusted my valves according to the minimum gap.
Advantages:

• An engine that heats up less (Related to the more open passage in the exhaust manifold),
• a quieter engine,
• and the fuel consumption has increased to 39 kpl.

Disadvantages:

• Causes a certain decrease in compression (because the valves are open for a longer time),
• causes a certain increase in the wear of the camshaft mechanism (because it is in a stressed state for longer time).