Engine mount loosened

[Ninja Rob]

As the title says,
That is what happened. The engine mount bolt is loose and the nut is lost. Is this nut something I can buy at any tool store or does it have to be specifically OEM? Would anyone know the size of the nut to get?

http://forums.ninja250.org/posting.p...&t=84686&tro=1

[cuong-nutz]

You can actually by that nut at the hardware store. I would suggest you get Grade 8 but grade 5? is ok just so long as your don't super torque it or else you'll strip the threads.

[Ninja Rob]

Originally Posted by cuong-nutz

You can actually by that nut at the hardware store. I would suggest you get Grade 8 but grade 5? is ok just so long as your don't super torque it or else you'll strip the threads.

What do you mean by grade? And what size?

[jkv45]

That's pretty common with the Ninja.

Not positive of the size (there are other threads here with the size, I'm pretty sure), but it's going to be a M10, M12, or something like that. There may be a common and an uncommon thread pitch for the size - so you need to know the correct one.

If there's room, I would use a flat washer and a locking ("nyloc") nut on it. That type of nut has a nylon insert that is not threaded until you tighten it down and cut threads into it. That keeps it from coming loose. It's taller than a regular nut, so the bolt needs to be long enough.

If the bolt isn't long enough, you can use a regular split lock washer and a standard nut.

The "Grade" refers to it's strength. In this situation, I don't think the grade of the nut is critical.

[Motofool]

Originally Posted by Ninja Rob

As the title says,
That is what happened. The engine mount bolt is loose and the nut is lost. Is this nut something I can buy at any tool store or does it have to be specifically OEM? Would anyone know the size of the nut to get?

Please, take a look at this thread:
https://www.ninjette.org/forums/showthread.php?t=221489

The nut you need is M10 x 1.25, which means that it fits a metric bolt with 10 mm of exterior diameter and a thread which pitch is 1.25 mm (measured between two consecutive crests).
Pep Boys has a section of drawers that contain many nuts.
If asked, you can tell that you are looking for a M10 fine thread (M10 coarse is M10 x 1.5, which will not fit).

The threads of the bolt may be damaged by the frame, because there is important shear load over those once the nut is loose.
The reason is that the engine works as a frame's member and that bolt "feels" all the deformations of the frame due to the irregularities of the road, braking and acceleration.
When the nut is torqued and pressing against frame and engine, no movement can happen.

If the threads of the bolt are damaged by the frame, the new nut cannot work properly over the damaged section of the bolt's thread.
Sometimes a thick washer can relocate the nut to torque over a healthy section of the bolt (farther out).
If not, you will need a new bolt.

For general information about bolts, metric threads and grades of material:
https://www.boltdepot.com/fastener-information/

[Ninja Rob]

Here are the pics, just want to confirm that it is the engine mount bolt.

[Motofool]

Originally Posted by Ninja Rob

Here are the pics, just want to confirm that it is the engine mount bolt.

Yes, it is one of them: parts 92002 and 92015A in this schematic:

[agentbad]

Originally Posted by Motofool

Please, take a look at this thread:
https://www.ninjette.org/forums/showthread.php?t=221489

The nut you need is M10 x 1.25, which means that it fits a metric bolt with 10 mm of exterior diameter and a thread which pitch is 1.25 mm (measured between two consecutive crests).
Pep Boys has a section of drawers that contain many nuts.
If asked, you can tell that you are looking for a M10 fine thread (M10 coarse is M10 x 1.5, which will not fit).

The threads of the bolt may be damaged by the frame, because there is important shear load over those once the nut is loose.
The reason is that the engine works as a frame's member and that bolt "feels" all the deformations of the frame due to the irregularities of the road, braking and acceleration.
When the nut is torqued and pressing against frame and engine, no movement can happen.

If the threads of the bolt are damaged by the frame, the new nut cannot work properly over the damaged section of the bolt's thread.
Sometimes a thick washer can relocate the nut to torque over a healthy section of the bolt (farther out).
If not, you will need a new bolt.

For general information about bolts, metric threads and grades of material:
https://www.boltdepot.com/fastener-information/

Hey my sketchy bike is helping people. I found the M10 x 1.25 nut at Lowes in the metric speciality drawer of the hardware section. I got another oem nut off eBay but it's still in my toolbox. A dab of blue locktite might be in order as well. If you want I can send you the Lowes one but you probably don't want to wait.