NT400 top end noise

[ggdav]

Are these motors just generally a noisy top end? I've only had a few old nut and bolt valve adjustment bikes before, most my bikes have been fairly new. But none of them were as loud as this.
I just got around to doing the valve adjustment on Monday because the tapping has been doing my head in. Found a few well outside spec, but after reassembly the noise was still just as loud. I thought I'd done something wrong so stripped it down and checked them all again, all within spec. 0.14mm on the intake and 0.18mm on the exhaust. Started it up and still loud as hell. I thought maybe I was not getting an accurate read or something was slipping as I tightened it, because I was trying to awkwardly hold a spanner and screwdriver and get around the frame while holding the clearance gauge. So I went and bought a proper motorcycle valve adjustment toolkit and did them all again yesterday for the 3rd time now this week. Still sounds like there's a little guy with a hammer inside my engine hitting things. I'm willing to pull the heads and rebuild them with all new valve gear of that's going to shut it up, but don't want to spend all that money to put it back together and have no difference

[6]

Are these motors just generally a noisy top end? I've only had a few old nut and bolt valve adjustment bikes before, most my bikes have been fairly new. But none of them were as loud as this.
I just got around to doing the valve adjustment on Monday because the tapping has been doing my head in. Found a few well outside spec, but after reassembly the noise was still just as loud. I thought I'd done something wrong so stripped it down and checked them all again, all within spec. 0.14mm on the intake and 0.18mm on the exhaust. Started it up and still loud as hell. I thought maybe I was not getting an accurate read or something was slipping as I tightened it, because I was trying to awkwardly hold a spanner and screwdriver and get around the frame while holding the clearance gauge. So I went and bought a proper motorcycle valve adjustment toolkit and did them all again yesterday for the 3rd time now this week. Still sounds like there's a little guy with a hammer inside my engine hitting things. I'm willing to pull the heads and rebuild them with all new valve gear of that's going to shut it up, but don't want to spend all that money to put it back together and have no difference

No. They are not overly loud or ticky by nature, but i guess that really depends what your level for comparison is. Compared to a Testla they are very noisy.

[ParcNHawk]

That's a lot of valve adjustments in a short period of time. The motor should be stone cold when you adjust them. I usually park it then do it the next day.

[bk94si]

I've had noise from a loose spark plug before. Also, are you sure it is at the top end? If it is while in gear, the chain can make a lot of noise if the slider is worn.

[ggdav]

No. They are not overly loud or ticky by nature, but i guess that really depends what your level for comparison is. Compared to a Testla they are very noisy.

Hmnm ok. I'm guessing I have a problem then. I'll record some audio of it tonight and put it on YouTube so I can link it here. It's clearly audible with my helmet on in traffic

[ggdav]

That's a lot of valve adjustments in a short period of time. The motor should be stone cold when you adjust them. I usually park it then do it the next day.

That's what I did the first and 3rd times haha The second time I was impatient so kept checking the engine with a laser thermometer till it was below 20 degrees and did them 0.02mm tighter

[ggdav]

I've had noise from a loose spark plug before. Also, are you sure it is at the top end? If it is while in gear, the chain can make a lot of noise if the slider is worn.

I don't think it could be a spark plug because I've changed them between the first valve adjustment and now. But I do know the noise you're talking about, I've been tricked by that before.

Id say it's unlikely it's not top end, the old screw driver to the ear is significantly louder on the head and head cover than cylinder or crank case.


noise is consistent with revs, in or out of gear, loaded or unloaded, makes no difference

[squirrelman]

the valve adjusting screws usually develop flat spots on the normally round bottoms, and that makes getting accurate settings difficult, so consider replacing them if the bottoms look mashed.

[ggdav]

the valve adjusting screws usually develop flat spots on the normally round bottoms, and that makes getting accurate settings difficult, so consider replacing them if the bottoms look mashed.

ahhhhhh that makes sense. I did think the angle between the screws and the top of the valve stem looked a little aggressive. Like only the outer edges of the screw were making contact with the valve stem
I've got a packet of new screws sitting right here conveniently, and it's a long weekend

[squirrelman]

ahhhhhh that makes sense. I did think the angle between the screws and the top of the valve stem looked a little aggressive. Like only the outer edges of the screw were making contact with the valve stem
I've got a packet of new screws sitting right here conveniently, and it's a long weekend

please post some photos of the damaged screws.

[6]

Hmnm ok. I'm guessing I have a problem then. I'll record some audio of it tonight and put it on YouTube so I can link it here. It's clearly audible with my helmet on in traffic

Post it up. Can't hurt.

[ggdav]

Hard to get a decent picture with my phone but they're fairly heavily pitted. I'll swap em all out and see how it goes

[ggdav]

Old vs new
Can't get phone to focus properly but those pits are fairly deep

[squirrelman]

once they're pitted they won't hold an adjustment long.

[ggdav]

https://youtu.be/uIv3SaoPG7s

I'm pretty sure this is where all the noise is coming from. This is new screw/nut fitted and the gap is 0.02mm tighter than it should be. But still makes a tonne of noise. No other lifter makes this noise. I pulled it back out again and checked for damage to the valve stem but it looks perfect.