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In a non fortuitous turn of events I bought back my old '05 Bird (55k) (which I sold when emigrating for a couple fo years) only to find when servicing it the right hand upper engine mounting bolt wouldnt go tight. I had previously installed r&g crash bungs set to the correct torque with no issues, the reason for it not now tightening up: the mount on the engine has snapped in half so instead of being a hole with a thread it is half a hole with half a thread. The bolt engages still with whats left of the thread but does not sit firm.

Has this happened to anyone else?
Remedies?

The bird has no odd vibration, handles normal, and apart from the right crash bung working loose no symptoms.

Can it be welded? Is the bike worth keeping?
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  • Suggestions please would be most welcome
 

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It could be welded It's not going to be cheap and your going to have to pull bodywork and make sure the ECU is unplugged. Also get anything away from that ares that can't handle heat. Heliarc generates a lot of it. I have heard of instances when welding current feeds back through system grounds and kills it.
 

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I had exactly the same thing caused by a set of R&G shrooms too.

As per Bee's advice I was told by my garage that yes it can be welded (engine dropped out, sent to specialist alu welder, old bit cut out, new piece of metal welded in then drilled and tapped for the new thread, then painted up with engine block paint). Likewise I was told it would not be cheap.

I didn't go as far as a quote. I did a temp fix while I saved up. However it's held up to date (even during another recent shroom accident).

I used JB Weld liquid cold weld. It's an expoxy which is rated at 5020 PSI strength and withstands 550°F of heat. https://www.amazon.co.uk/dp/B0006O1ICE/ref=cm_sw_r_apa_i_IcIYEb3BD0XFZ

I glued the piece back in place, purchased a longer engine bolt (extra +10mm length… remember the engine bolts are fine pitched on the thread at 1.25 mm not the standard 1.50 mm) and once the epoxy was fully cured I added a nut to the length now protruding out of the back of the mount. It's fiddly to get a spanner in to hold the nut still but you can still torque up to the correct setting externally. FYI I used JB Weld to hold the nut in place but still applied a spanner as a sensible back up when fitting the bolt. I trialled all this in a dry run before applying JB Weld and found the nut and bolt set up now sandwiched the broken piece held tightly in place by the compressive force now present due to the nut.

Don't forget there's a spacer between the engine and the frame (well there is on my '97… the original was lost prob when the R&Gs were first fitted as it's difficult to see it's even there. So I replaced it with a 6.3mm M10 generic spacer).

Painted the repair up and it "looks" good as new. I say "looks" as it's beyond my expertise to say it's functionally as good as new but it's certainly better than nothing and has held so far. Like your fracture the piece is less than 180° of the bolt circumference so the remaining metal is still contributing to holding the engine re shearing forces else I certainly wouldn't have bothered with this temp fix. Also, the bit that came off may not be the only bit that's fractured just the but that's cone away so far. The remainder surround may be weakened too.

If you follow in my footsteps you do so wholly at your own risk. I'm no qualified mechanic nor engine block specialist so make no representatiin re functional suitability nir safert matters. My patch has just proved better than nothing.

When I'm flush one day I'll get a quote and have it welded fir tge avoidance if doubt.

To limit it happening again I have ditched the R&G shrooms and gone for a Renner set of crash bungs. They employ a dog leg two-stage set up so the engine mounting bolt is less prone to shear or transfer damaging forces. The bung bolt is a softer grade of steel so ought to shear first (if either is to shear).


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The downside of swapping from R&G to Renner (other than extra cost) is the hole through the fairing will be in a slightly different place by about 1-2 cm. So if using the same panels as with your R&G set the hole will end up more of an oval slot.

There's a hidden upside to that though in that the engine bolt can be accessed too if the brigding mount for the bung needs rotating slightly.

I've just installed new panels so cut new holes precisely where the new set needed them.
 

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i had a piece of road debris take out my right slider on a previous blackbird. fortunately, it only broke the bolt which i had a shop remove. for this reason, i'm no longer a fan of them. guess i should be glad it was the slider, and not my knee...
 

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I know what you mean PT, hence me liking the idea of a two-bolt dog-leg set up so the engune bolt and mount hopefully keep out of the damage list. I guess only another crash test will tell and I'm not exactly in a hurry to move to that phase again!

If a debris strike was forceful enought to shear a bolt I'd hate to think what it would have done to your knee or shin! I suppose I'd not factored protection against debris into the benefit side of my calcs. Lucky escape for you!
 
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