Check those bolts!

[ReidMcT]

I've learned the lesson more than once: Loctite everything on the 390. I learned it again today when I was truly surprised that the upper rear engine mounting bolt had lost its nut and backed out. It looks like it must have happened quite a while ago, judging by the reshaping done to it by the drive chain.

Fortunately, I had a spare engine bolt that was just a bit longer than I needed, so I cut and re-threaded it... and installed a new nut with blue Loctite.

This bolt is not noticeable unless you have the sprocket cover off, but you can inspect it by looking from an angle.

 

[Botts]

Yikes. I'm going to go pull that sprocket cover and check torque!

Thankfully even though it wasn't acting as a bolt, it still functioned as a pin.

 

[ReidMcT]

Yikes. I'm going to go pull that sprocket cover and check torque!

Thankfully even though it wasn't acting as a bolt, it still functioned as a pin.

Yes, the sprocket cover prevented the bolt from coming completely out. So the bolt did act as a sloppy pin, though it was only pinning one point, and thus putting a twisting stress on the frame, in addition to the extra load transferred to the other bolts.

Having an engine bolt do this is a first for me; and it hadn't been messed with since leaving the factory.

Live and learn....

 

[Andy]

Torque wrench and Loctite are your friends!

 

[1JZSupra]

Pretty much have to with most bolts on this bike, torque alone is not enough as the bolts are made of swiss cheese lmao (Maybe no some of the bigger ones)

 

[KBear]

Yes

Yikes. I'm going to go pull that sprocket cover and check torque!

Yes, guess I'll been heading out in the morning to remove my sprocket cover as well!

Thank you for the heads up ReidMcT.

 

[KBear]

Just wanted to do a follow-up. Yep the same bolt was loose on my bike as well. I did tighten it but didn't put any Loctite on it yet. Once again thank you for bringing this issue to our attention! I wouldn't have thought this bolt would come loose as it did.

 

[KBear]

Just a Heads UP.

An addition to this loose bolt thread. I pulled the lower cowlings to change the oil and the radiator spacer fell out on the floor. The spacer bolt had vibrated out and thankfully left the spacer in the cowling. Item number 15 below. It's not critical but there are mounting points that could potentially break if the bolts are not all there.

 

[Formula390]

Get some Loctite 248! https://www.amazon.com/Loctite-QuickStix-442-37684-Thread-Treatment/dp/B000132VH6 and use it on EVERYTHING!!! If you touch a bolt, Loctite! If you look at a bolt. Loctite! Use it like hotsauce... put it on EVERYTHING!!!

 

[SWdragon]

What's the torque for it? I been checking all the nuts and bolts on the bike and in the owners manual (don't have service manual) I can't find torque no. for it. Additionally, I notice some oil on one of the sprocket cover mounting bolts. Oil was only on the threads, I guess I need to replace the ignition cover gasket as KTM calls it. Anybody had this issue?

 

[Formula390]

The bolts are open to oil on the other side. No gasket required. Torque should be like 8-10 ft lbs

 

[SWdragon]

Thanks Formula 390 for info on cover bolts. I was actually asking for the torque of the upper rear engine mounting bolt that the OP had talked about. Mine was loose and want to torque properly.

 

[ReidMcT]

I was actually asking for the torque of the upper rear engine mounting bolt that the OP had talked about.

45 Nm (33.2 lb ft)