Exhaust Valve clearance tight

2782 Views 18 Replies 3 Participants Last post by Tamir, 6 mo ago

Vishal993

Discussion Starter · Nov 20, 2021

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

Save

Reactions: 1

1 - 8 of 19 Posts

Tamir

· #2 · Nov 20, 2021

Vishal993 said:
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.

Vishal993 said:
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.

Vishal993 said:
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 ???

Vishal993 said:
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?

See less See more

Save

Tamir

· #4 · Nov 20, 2021

Vishal993 said:
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

👩‍🔧🤷‍♂️

Vishal993 said:
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 ???

Save

Tamir

· #6 · Nov 20, 2021 (Edited)

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.

See less See more

Save

Tamir

· #9 · Nov 22, 2021

DannoXYZ said:
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!

Save

Tamir

· #13 · Nov 23, 2021

Tamir said:
...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?

Save

Tamir

· #15 · Nov 23, 2021

Vishal993 said:
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.

Save

Tamir

· #17 · Nov 23, 2021

Vishal993 said:
@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.

Font Material property Food Gas Ingredient

See less See more

Save

Reactions: 1

Tamir

· #19 · 6 mo ago

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).

See less See more

Save

Reactions: 2

1 - 8 of 19 Posts

Top Contributors this Month