Cylinder Head Guard Bolts

It looks like what happened is the bike was dropped, hence the scratch marks, and the guards were bent. Getting the bolts to line up is a right b’stard and it’s tempting just to use brute force and strip the threads. I’d helicoil like those then be very careful refitting the guards.
 
Greenman14 said:
It looks like what happened is the bike was dropped, hence the scratch marks, and the guards were bent. Getting the bolts to line up is a right b’stard and it’s tempting just to use brute force and strip the threads. I’d helicoil like those then be very careful refitting the guards.
Click to expand...

Yes, I'd agree that's probably how/why it's happened but my desire to drill in that part of the bike is very low so I'll leave that to our mechanic when he services next month. However, in case he's reluctant too I think there is plenty of thread left if I get slightly longer bolts :beerjug:
 
And get the guards straight, holes lined up before you paint them. I should have thought that through when I did mine :blast
 
Greenman14 said:
And get the guards straight, holes lined up before you paint them. I should have thought that through when I did mine :blast
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My mechanic is going to tackle this and has said he doesn't use helicoil but a 'threaded insert' which in his view is stronger and better. I'll report back when it's done if anyone is interested.
 
it's like 'hoover'. helicoil is a brand. lots of other thread repair products but helicoil is now generic term as well as a single brand

Doing it once and doing it properly is def the best option
 
NicD said:
it's like 'hoover'. helicoil is a brand. lots of other thread repair products but helicoil is now generic term as well as a single brand

Doing it once and doing it properly is def the best option
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Ah, I see re name/brand. I think he's going to use a solid threaded insert as apposed to a coil of wire similar to something called Tappex :thumb2
 
The only downside with using solid steel inserts instead of wire inserts ( helcoils) in aluminium engine casings, is the different rates of expansion and contraction has been known to allow the inserts to come loose.
 
Mistacat said:
The only downside with using solid steel inserts instead of wire inserts ( helcoils) in aluminium engine casings, is the different rates of expansion and contraction has been known to allow the inserts to come loose.
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So, are you saying the helicoils won't do that and are more reliable?
 
Either will do, but given the choice under these conditions I would ere towards Helicoils.
If using Helicoils you can set them a couple of threads down the hole which makes it easier to locate the guard and start the thread.
 
A problem that can arise if you have the standard type metal guards is, IF you do have an off or incident where the guard
gets a real belt and distorts badly it can transfer the loads generated to the mounting bolts either snapping them and
or cause damage to the mounting holes. For that reason, plus they are easier to fit and, look better i have these.

https://machineartmoto.com/products/x-head/x-head-dohc/
 

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Mistacat said:
Either will do, but given the choice under these conditions I would ere towards Helicoils.
If using Helicoils you can set them a couple of threads down the hole which makes it easier to locate the guard and start the thread.
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Thanks for that I'll chat to the mechanic next week. :beerjug:
 
I hate Helicoil never seen a good one

not saying you'd want to do this.... but a 1/4 UNF thread can tap a 6mm metric threaded hole to perfection and make for slightly stronger fix than the original. Without any nasty junk that will just fail anyway.
 
If you have never seen a good Helicoil I doubt that you have spent very long in engineering. I have done hundreds without problems.
Manufacturers sometimes use Helicoils in new aluminium castings.
What I hate is when someone brings me a casing with badly drilled sheared bolts, or with broken extractors stuck in them.
And when the thread has been butchered I.e a 1/4 unf tap into an M6 thread !!!! , I end up either grinding the area back and building it back up with weld before re- machining it.
Or machining an oversized insert to bring it back to the correct size. Easier to Helicoil it in the first place.
In this instance the M6 thread has been pulled leaving a 6mm hole the tapping drill for 1/4 unf is #3 approx 5.5mm . you will end up with 0.175 mm thread depth instead of 0.5 mm thread depth.
how is that going to be stronger ???
 
Mistacat said:
If you have never seen a good Helicoil I doubt that you have spent very long in engineering. I have done hundreds without problems.
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This is the kind of comment that to me is worthwhile. Someone who knows what they are talking about speaking sense
 
Mistacat said:
And when the thread has been butchered I.e a 1/4 unf tap into an M6 thread !!!! , I end up either grinding the area back and building it back up with weld before re- machining it.
Or machining an oversized insert to bring it back to the correct size. Easier to Helicoil it in the first place.
In this instance the M6 thread has been pulled leaving a 6mm hole the tapping drill for 1/4 unf is #3 approx 5.5mm . you will end up with 0.175 mm thread depth instead of 0.5 mm thread depth.
how is that going to be stronger ???
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hole for the original 6mm thread that's now damaged was 4.7mm, wind in the 1/4 UNC tap, jobs a good un, I didn't say drill it out did I
 
botus said:
hole for the original 6mm thread that's now damaged was 4.7mm, wind in the 1/4 UNC tap, jobs a good un, I didn't say drill it out did I
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Look at the photo on #1 and you can see that it has pulled the threads. = 6mm.
The original hole before being tapped would be 5.1mm not 4.7mm. At 4.7mm you would stand every chance of breaking the tap in the hole, another of my pet hates removing broken taps.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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