Very loud tapping top overhaul

[crazydj]

Hi guys

 

I went to send my YBR125 for a top overhaul. Replaced the piston, piston rings, valves and the various gaskets. After the overhaul, i went to ride it and there were very loud tapping noises coming from the engine, but it only happens below 60km/h and only when i open the throttle.

 

I went back to the mech for him to adjust the tappets because he said need for the valves to seat first.

 

Now after adjusting the valves, the tapping sound is even louder, horrible pickup, when open throttle, the bike will keep jerking and like the throttle "on-off-on-off" at irregular intervals. Like before, this happens at only below 60km/h. The worst part is that my RPM is like at 6k-7k but i am only travelling at 60km/h at gear 5. It used to be 7k at gear 5 moving at 90++km/h. It feels like its "choked" or "choking".

 

Is this normal? I was just wondering. I am still in the runnig period for the bike, done 200+km already with the new piston, rings, gasket and valves.

[ulysses_sc]

No it's not normal. Did the mech adjust the valve clearances when the engine is hot or cold?

[Terrible One]

I think the valve clearance not done properly-too tight. Ask them to check the specs again

[ulysses_sc]

Too tight clearances will not make any noise. Chances are they are way too loose.

 

Worst case scenario - timing not set correctly, resulting in valves kissing the piston crown.

[crazydj]

Okay. My mech set the valves like many times. In all cases, they set it when it was hot.

 

They even reset the timing chain. I used to have the engine rpm hitting 2k when the engine is hot but 1.3 when the engine is cold. But now, hot or cold, it stays at 1.5k. So this problem solved.

 

The thing is that, now that everything is adjusted, the engine tapping noise gets noisier, with random jerkiness when throttle is opened. Its like i open and close the throttle at random. At gear 5, i will always get throttle lag. Open throttle, then suddenly big acceleration, my body will always jerk backward.

 

My mech say that its most likely to be the cam thing. Any other ideas on what could be the problem? The thing is that its dangerous to the point where i try to escape vehicles on the road but the throttle is so unpredictable at certain speeds and RPM that i could have almost banged into the vehicle in front of me.

[ben1112]

Is he noob? Valve clearance is ALWAYS adjusted cold. No matter Hayabusa or Wave.

[crazydj]

So even though the valves are nice and tight, when its done hot, will still have sound is it?

 

And when its done when its dead cold, nice and tight, will have sound?

[ben1112]

It should never be done hot because it wont be accurate. Say you want to adjust the gap to 0.02mm, if the engine is hot the clearance will vary due to expansion from heat. When cool at room temp, it is more constant. So that's why we always set valve clearance when the engine is totally cool down like left overnight.

 

If too tight, the valve will not be able to fully close and heat will escape continually causing the valve to be burnt. If loose it simply goes ticking away, louder when more loose. Slight ticking will be perfectly ok.

 

Just my layman interpretation.

[Phang]

A tappy valve is a happy valve. If my valves are too quiet, I will start to worry

[ben1112]

So even though the valves are nice and tight, when its done hot, will still have sound is it?

 

And when its done when its dead cold, nice and tight, will have sound?

 

When done properly should hear only very very soft ticking or cant hear due to other engine noises. But soft tick is safe.

 

Ask your mech what valve clearance does he set to in mm. It is written in the workshop manual.

 

And if he doesn't use a feeler gauge and your bike does have a problem, then he sucks. Normally chapalang bike shop dun use feeler gauge but the mech seasoned enough until he can agar until so zhun the range the bike can work properly. But he not season den anyhow agar plus dun use a feeler gauge, comfirm he will not get it in the right range.

 

This kind of thing is like drawing a straight line. Small bike only have one cylinder so it doesnt require so accurate to match other cylinder setting. So its like draw str8 line free hand looks str8 can alr. But if u have a 4cyl bike or one that does require more, the feeler gauge is like a ruler you can draw a very good str8 line.

 

So like how i give the example, if your mech is not gd and does not use the appropriate tool, he screws u up.

[ben1112]

A tappy valve is a happy valve. If my valves are too quiet, I will start to worry

 

That's what was taught from every source i learnt from too. So i always set towards the looser spectrum of what is specified in the service manual.

[Phang]

That's what was taught from every source i learnt from too. So i always set towards the looser spectrum of what is specified in the service manual.

 

I checked and adjusted the valve clearance of my bike 2 weeks ago, I kept them on a slightly loose side

 

http://img.photobucket.com/albums/v198/Phang/valveclerance.jpg

[MiddleAgedBiker]

Hi guys

 

I went to send my YBR125 for a top overhaul. Replaced the piston, piston rings, valves and the various gaskets. After the overhaul, i went to ride it and there were very loud tapping noises coming from the engine, but it only happens below 60km/h and only when i open the throttle.

 

I went back to the mech for him to adjust the tappets because he said need for the valves to seat first.

 

Now after adjusting the valves, the tapping sound is even louder, horrible pickup, when open throttle, the bike will keep jerking and like the throttle "on-off-on-off" at irregular intervals. Like before, this happens at only below 60km/h. The worst part is that my RPM is like at 6k-7k but i am only travelling at 60km/h at gear 5. It used to be 7k at gear 5 moving at 90++km/h. It feels like its "choked" or "choking".

 

Is this normal? I was just wondering. I am still in the runnig period for the bike, done 200+km already with the new piston, rings, gasket and valves.

 

The first question I want to ask is, does your mechanic even have the right specifications for piston ring end gap and valve clearance for your bike? Ask him to show you the numbers he's supposed to set to.

 

If he doesn't know what the proper clearance is, he's just shooting in the dark, and you risk damaging the engine if you keep running it.

 

Secondly, without hearing the sound, it's impossible to know where the sound is coming from. Do this, take a long screwdriver, put the handle part touching your ear, then touch the tip on the top of the engine where the valves are, then touch the piston area. Try to identify where the sound is coming from.

 

Thirdly it doesn't sound like the problem is a minor valve adjustment issue. If your valve clearance is just slightly loose (i.e. too big) it will create a ticking sound as the cam lobes "slap" into buckets at the top of the valve stem every time it pushes the valve down. It will still open up the valves and engine performance will not be affected much. You won't be able to feel it anyway.

 

But your bike's performance is seriously affected. So it's either so seriously loose that the valves are hardly opening at all, and allowing the intake charge (air + fuel) to come in, or it's preventing the exhaust from fully exiting the combustion chamber. It sounds like it's waaaaaay out of adjustment.

 

Another thing I'd check with him is if he used the correct piston size. I did an overhaul on a 2B bike once, and the guy used a wrong size, and when the engine was started it was slapping around inside the cylinder.

 

And make sure he rejets your carburettors for the larger piston (I'm assuming you went one size larger). Otherwise the mixture will be too lean and it'll cause the engine to overheat.

[failsafe]

My advice is that u leave the bike with ur mechanic until u feel it's comfortable for u.

U never know wats gg on inside with this abnormal noise.

After all, u had paid a premium for the repair...

...some mech will turn over n blame tt u misused ur bike!

[crazydj]

1) He never waited for the engine to cool down all the way.

2) He didn't use a thickness gauge to measure the clearance. Just adjust and adjust, ride, adjust sommore.

3) When he went to adjust the valves, the bike's tapping noise louder. Performance is like when open throttle, very jerky at cartain speeds and RPM.

4) Open throttle at gear 5, got 2 second lag.

5) Timing chain has been adjusted.

 

When riding and get the jerky feeling, it feels as if the valves are not opening and closing at the right time. The feeling is like a chocked airbox, but its like someone got and choke and unchoke it very fast. Got power, no power. Got power, no power.

[ulysses_sc]

1) He never waited for the engine to cool down all the way.

2) He didn't use a thickness gauge to measure the clearance. Just adjust and adjust, ride, adjust sommore.

3) When he went to adjust the valves, the bike's tapping noise louder. Performance is like when open throttle, very jerky at cartain speeds and RPM.

4) Open throttle at gear 5, got 2 second lag.

5) Timing chain has been adjusted.

 

When riding and get the jerky feeling, it feels as if the valves are not opening and closing at the right time. The feeling is like a chocked airbox, but its like someone got and choke and unchoke it very fast. Got power, no power. Got power, no power.

 

How to adjust valves without feeler gauge? And to also do it with hot engine? Sounds like time to change mech.

 

And what do you mean by adjust timing chain? This is something you CANNOT adjust, unless you are using Manual Cam Chain Tensioner (which is unlikely the case), or the mech initially set the timing wrong (cam lobe position when piston is at TDC - Top Dead Center).

 

As what MiddleAgedBiker said, was the correct size piston and ring set used? Did the mech bore the cylinder?

 

A single cylinder engine is not rocket science. If the mech cannot even get this right, good luck...

[Fried Rice]

what shop is that?

[xXxRatedxXx]

I love armchair mechanics.

[shunoski]

Sounds like I can approach many bros here to repair my bike. All very knowledgeable.

[xXxRatedxXx]

I also very knowledgeable... i copy and paste from wiki... BEHOLD MY MIGHTY HAND....HA HA HA!!!

 

http://mugen.codejin.com/img/database/mugen/characters/onslaught.gif

 

================= Credit: http://en.wikipedia.org/wiki/Tappet ==========================

 

A tappet is the noise made by a worn cam follower, however the term is widely used to represent the cam follower itself. In mechanical engineering it is a projection which imparts a linear motion to some other component within an assembly. Properly speaking, a tappet is the only part of a rocker arm that makes contact with an intake or exhaust valve stem above the cylinder head of an internal combustion engine.

 

As the cam rotates, it creates both a sideways and a downward force on the tappet. Without a tappet (and with the cam acting directly on the valve), the sideways force would cause the valve stem to bend. With a tappet, the sideways force is transferred to the cylinder head so only the downward force acts on the valve stem.

 

Tappets/lifters are engineered to last the lifetime of the engine when the engine is properly maintained, including proper oil and filter changes. Though they are reliable, they have their drawbacks; valve clearances periodically require adjustment as the contact surfaces of both tappet and valve stem wear.

 

On most modern overhead cam engines, the camshaft is directly over the valves, as pictured. In some other overhead cam engines, a rocker arm pivots on a fixed shaft while one projection of the rocker-arm rides on a cam of the rotating camshaft. In both cases, this creates an oscillating linear motion, opening the valve. The closing of the valve is typically accomplished by a compression spring placed between the valve collet (or retainer) and the cylinder head above the combustion chamber. In overhead valve engines, the camshaft is located near the crankshaft and motion of the cam lobes is followed by cam followers (similar to tappets) and transferred up to the cylinder head and the rocker arm assembly by means of long pushrods.

 

Traditionally, the nominal distance (clearance) between the tappet surface and the valve's contact surface was maintained by means of an adjustment screw on the rocker arm. Today, this is typically accomplished by introducing shims into the space between the cam follower (tappet) and cam to create the necessary clearance, or by hydraulic adjusters.

In the future, the use of tappets may stop entirely as engines move to variable valve timing systems.

 

http://upload.wikimedia.org/wikipedia/commons/thumb/e/e3/Ford-I4DOHC-camdrive.jpeg/350px-Ford-I4DOHC-camdrive.jpeg

 

http://www.carbibles.com/images/tappet_valve.jpg

 

http://www.cam-shield.com/acatalog/flat-tappet-engines.jpg

 

http://www.rtsauto.com/wp-content/uploads/2010/11/ValveLifter_Diagram.jpg

Edited July 30, 2011 by xXxRatedxXx

[crazydj]

Okay guys. I just changed the cam to the camshaft and the bearings that hit the valve rocker arm.

 

The loud tapping noises now is reduced to softer and lower pitched tapping noises at certain speeds and rpm. The jerking throttle now is no more. Its much better than before after changing the camshaft and bearings. I'm left with 200km more of riding below 70km/h. After than 500km, i'll see how it goes from here. One thing i know about my bike it somehow "repairs" itself. Haha.

 

Anyway, thanks guys, especially you armchair mechanics! Will update you guys on how the bike performs!

[fleas]

One thing i know about my bike it somehow "repairs" itself. Haha.

 

quote of the year

[xXxRatedxXx]

quote of the year

 

http://www.beastwithin.org/users/wwwwolf/cutethoughts/wolfheadofselfrepair.jpg

[crazydj]

Lousy wolf head...

 

Too many trolls in SBF nowadays.

Edited July 31, 2011 by crazydj

[xXxRatedxXx]

Lousy wolf head...

 

To many trolls in SBF nowadays.

 

They can regenerate

 

http://shufflingdead.com/wp-content/uploads/2011/02/Thrun-the-Last-Troll.jpg