Stripped engine threads repair.

[DT675]

Hello, Short story, was riding the T7 on a trip and one of my main frame-to-engine bolts ripped out taking all the aluminum threads from the engine with it.  As much as I would like to blame Yamaha for this as a defect, I know it's the tech at the dealership who likely over tightened the bolt while mounting the crash bars.  Fortunately, I was able to remove a washer/bushing and get the bolt back in enough to grab just a couple of the threads that were left, and head home. 

 

I think I am likely going to have to tap and heli-coil the engine. But, if I do that I wouldn’t be able to drill the next size larger hole (to tap to make room for the coil) with the frame directly in the way? (Unless I drill the frame hole a little larger too which seems like a bad idea)  I think I may have to drop the engine ? 

This is the offending bolt in question (right side of the engine), after I removed the washer and re-installed  it.

 

Edited October 9, 2022 by DT675

[Buggy Nate]

Yes a heli-coil is a good repair for the engine bolt. If you haven’t used one before get some professional help. There are a few key things to do. You may be able to swing the engine down and repair the thread in place.

 

After the threads are repaired your next point of call is to ensure the engine crash bars bolt is actually long enough for the job. I have seen numerous poorly made Chinese crash bars with sub standard quality bolts to cause similar issues.

 

It could also be a differing length bolt was placed in the wrong holes.

[Robo]

I would be checking with the dealer that done the previous work first. If it’s their stuff up that has caused it they should be repairing it. 

[Fzrcraig]

I agree that drilling the frame mount hole isn't the best idea. As stated, I would try to remove enough engine bolts to allow it to swing down or back enough to clear in order to make the repair. Not a quick and easy job, but it comes with the satisfaction of doing it right, IMO.

[Hollybrook]

I like Time-serts better than helicoils for important bolts.

 

++ TIME-SERT Official Threaded inserts for stripped threads, blown out sparkplugs,

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[Dougie]

2 hours ago, Hollybrook said:

I like Time-serts better than helicoils for important bolts.

 

++ TIME-SERT Official Threaded inserts for stripped threads, blown out sparkplugs,

---

threaded inserts threaded, stripped threads, threaded inserts, blown out sparkplugs, stripped threads, stripped out theads, inserts threaded inserts, ford...

 

100%. Brilliant for ally engines etc. Couldn’t do without them on a classic. 

[Black99S]

Drop the engine and check the other side. 

[DT675]

22 hours ago, Buggy Nate said:

Yes a heli-coil is a good repair for the engine bolt. If you haven’t used one before get some professional help. There are a few key things to do. You may be able to swing the engine down and repair the thread in place.

 

After the threads are repaired your next point of call is to ensure the engine crash bars bolt is actually long enough for the job. I have seen numerous poorly made Chinese crash bars with sub standard quality bolts to cause similar issues.

 

It could also be a differing length bolt was placed in the wrong holes.

I’ve used several heli-coils. I’m hoping I can just “lower” the engine rather than remove it. 
 

These are the OEM Yamaha crash bars. But after a little research tonight I see in the instructions they reuse that bolt. So I’ll see about sourcing a slightly longer one. 

[DT675]

18 hours ago, Robo said:

I would be checking with the dealer that done the previous work first. If it’s their stuff up that has caused it they should be repairing it. 

I agree. But in the US we only have a one year warranty. And I’m over year 2.  That and my purchasing dealer is about 6 hours away. 

[Buggy Nate]

3 minutes ago, DT675 said:

I’ve used several heli-coils. I’m hoping I can just “lower” the engine rather than remove it. 
 

These are the OEM Yamaha crash bars. But after a little research tonight I see in the instructions they reuse that bolt. So I’ll see about sourcing a slightly longer one. 

You should be able to lower the motor enough to do it, still have to disconnect throttle bodies, exhaust, possibly the radiator and cooling system. Most wiring should have enough slack. Been a mechanic for over 20 years, time serts are definitely stronger but not needed in this application. A helicoil is stronger than the original alloy thread. I’m wondering if the tech just jammed in it with a rattle gun sideways or something. Bloody hard to overtorque that.

[DT675]

8 hours ago, Black99S said:

Drop the engine and check the other side. 

Yeah I’ve been thinking about that… If they used an impact on one bolt they did on all of them. 

[Black99S]

12 minutes ago, DT675 said:

Yeah I’ve been thinking about that… If they used an impact on one bolt they did on all of them. 

Short steel bolts into Aluminium. No torque wrench. No feel. No experience. 

Sorry you are having to deal with this.

Friend finally tore the same bolt out after multiple crashes riding up to forest lookout towers I wouldn't even attempt.

He had to drop the motor partially out of the frame to get access. Helicoiled the bad one and did the other side preemptively.

Good luck on the repair.

[DT675]

Tonight I pulled the crash bars off to investigate further. I found quite a few threads left after the length of the bolt. This bolt is too short. In this pic the screw driver and bolt are at a slight angle so you can’t exactly judge distance, but their are just over 1/2” threads left after the end of that bolt, which are more than the amount of threads that stripped out.
 

 

So this will be an easy fix. Given the amount of good threads left, I’ll be chasing the bad threads with a tap and getting longer bolts and some loctite. I’ll be replacing this same bolt on the other side too since it will also be too short, preventatively.

 

This is a pretty good warning to others with the OEM crash bars, in the install manual it shows reusing these 2 frame-to-engine bolts. The rest of the bolts are supplied with the crash bar kit. These 2 bolts are too short.  If mine can pull the threads out without having dropped the bike, I imagine a drop might do worse. 

 

Edited October 7, 2022 by DT675

[DT675]

On a similar but different note, any idea why the frame hole here is threaded? The threads are much bigger than the bolt that goes through here. 
 

[Buggy Nate]

20 hours ago, DT675 said:

On a similar but different note, any idea why the frame hole here is threaded? The threads are much bigger than the bolt that goes through here. 
 

It is probably just a generic frame mount Yamaha used to make frames where they install a threaded adjuster to take up small gaps. Similar the swingarm one on our bikes.

[DT675]

Yeah that piece is a welded on “tip”  to the rest of the frame. 

[williestreet]

On 10/7/2022 at 12:11 AM, DT675 said:

On a similar but different note, any idea why the frame hole here is threaded? The threads are much bigger than the bolt that goes through here. 
 

As buggy mentioned above the frame has an engine adjusting bolt on the inside of the frame.

 

Similar to a swingarm the frame must be made larger than the width of the engine so it can be installed.

Then the adjusting bolt is turned to push the engine to the left side and take up the slack and line everything up.

 

So if you are dropping or rotating the engine these will need to be backed off to give some room to drop the engine.  Then during install they must be tightened unto remove the clearance and align everything back up.

 

Some frames may have these at all large mounting points.  I think my old SV650 had 3 engine adjusting bolts that had to be reset for engine removal.

 

Look inside and you may see the notches on the inside of the adjusting bolt.  Not sure how Yamaha does it but for Suzuki you needed a special tool to loosen the adjuster.  My guess it will be a similar to the swingarm tool for that adjuster.

 

#9 on this parts fiche is the adjuster bolt in question.

2021 Yamaha TENERE 700 (XTZ7MB) Frame | Babbitts Yamaha Parts House

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Shop online for OEM Frame parts that fit your 2021 Yamaha TENERE 700 (XTZ7MB), search all our OEM Parts or call at (231)737-4542

 

 

[DT675]

Ah this makes sense, thanks! This also explains why each side mount is different.  The left is stationary then and the right side is the adjustable side.  Since my bolt on the right side basically fell out, i'd better make sure the adjusting frame bolt is still tight (if its the non-notched type)

[Lewie]

I’ve some cheap crash bars that I wanted to fit but they attach to this top engine mount - this has kind of put me of fitting them

[DT675]

@Lewie if you do just make sure to replace the bolts with the correct length bolts.  Both bolts in each side is much shorter than there perspective threaded holes "without" crash bars installed.

 

I admit though, while ive just replaced the bolts on both sides last night, for the 1st time i've started to question having the crash bars all-together.  I could care less about protecting the side pannels.  But I think they might prevent the fuel tank from damage when dropped.  This is my one and only concern.

Edited October 9, 2022 by DT675

[DT675]

On 10/8/2022 at 5:00 AM, williestreet said:

As buggy mentioned above the frame has an engine adjusting bolt on the inside of the frame.

 

Similar to a swingarm the frame must be made larger than the width of the engine so it can be installed.

Then the adjusting bolt is turned to push the engine to the left side and take up the slack and line everything up.

 

So if you are dropping or rotating the engine these will need to be backed off to give some room to drop the engine.  Then during install they must be tightened unto remove the clearance and align everything back up.

 

Some frames may have these at all large mounting points.  I think my old SV650 had 3 engine adjusting bolts that had to be reset for engine removal.

 

Look inside and you may see the notches on the inside of the adjusting bolt.  Not sure how Yamaha does it but for Suzuki you needed a special tool to loosen the adjuster.  My guess it will be a similar to the swingarm tool for that adjuster.

 

#9 on this parts fiche is the adjuster bolt in question.

2021 Yamaha TENERE 700 (XTZ7MB) Frame | Babbitts Yamaha Parts House

---

Shop online for OEM Frame parts that fit your 2021 Yamaha TENERE 700 (XTZ7MB), search all our OEM Parts or call at (231)737-4542

 

 

You are exactly right, this side has the "notched" adjustable frame bolt, the other side is stationary.  If this is also in our swingarm, i'll probably be ordering this tool.  

 

Last night I finished this up.  I found a metric bolt (not the same cap head style so i used a washer) that is about 14mm longer, cleaned everything up, Loctite and done.  I decided to pull the otherside too and it happens to be a much more shallow hole with a shorter bolt.  I was hoping to just use the bolt from the right side on the left but it is just a mm or 2 too long.  Given that this bolt is also a cap head style bolt, i removed the washer on the outside of the crash bar to get an additional mm or so insertion into the threads, cleaned it all up, Loctite and done.  This will easily carry me over to the next major service anyway, or maybe forever.

 

Edited October 9, 2022 by DT675

[Lewie]

Heres the 2 I got they’re Allan bolts - 100 and 80mm

[RiderEh]

From what I'm seeing, you can use a M12 x 60mm x 1.25 on the right side. There is currently a 50mm there. You can then use the 50mm on the other side, though may be a bit long, 45mm would be better. The existing was 35mm I think. So you'd gain 10mm on each side.

 

Now to source that bolt, which is kind of hard in Canada unless I want to spend $25 on Amazon!

[Hollybrook]

It is a lot easier to shorten a bolt than lengthen one!  

[concours]

On 10/4/2022 at 5:17 AM, Robo said:

I would be checking with the dealer that done the previous work first. If it’s their stuff up that has caused it they should be repairing it. 

Clearly, that dealer has mechanics not capable of correctly fitting bolt-on accessories. It would be a sure bet they'd fugg up a Helicoil operation.

Sadly, the world we live in.