99 Carenata - Engine Mounts

thinkingfeller

thinkingfeller

New member
Location
Seattle, WA
Hey all!  I recently acquired a 1999 750s Carenata and was hearing an awful racket at rpms below 4k.  Turns out the right rear engine mount bolt was loose.  Any ideas what size that nut is, its torque spec, and the best way to reach it?  (see image, the nut is behind the engine where the right red circle is).  I'm assuming I have to remove the rear wheel and/or front sprocket cover?  Any wisdom to share would be appreciated!
 

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Hi and Welcome to the Forum

Much of the info you're seeking can be found in parts books and/or workshop manual, freely available on Tinternet.  Like this for example:

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And the torque value for the bolts is 44NM.

HTH

Craig

 
4 bolts that hang the mufflers, 4 springs, 1 bolt centre of exhaust crossover, 2 bolts to remove the exhaust crossover bracket. Then you can get a spanner on the nut...
 
As an after thought I would check the tension on all 6 engine mount bolts to be about the 45Nm. Before doing that, check that the adjuster (part # 35) is in contact with the engine on both top and bottom. The top one is a bitch to get to, but loosen the bolts, and drop a set spanner in from the top between the wiring harness and the fuel tank to adjust.
This adjustment is about setting the frame to the engine, so set it up to hold the engine with the bolts tightened. Not to push the frame apart. If you take the nut and washer off the top bolt, good luck! It took me an hour + to get them back on..blue tack and magnets, or someone with very very small hands.

Regards
 
All Zane owners should check these bolts regularly!!

Some years back I acquired the remains of a crashed 668 Formula.  The frame was broken right through the swingarm pivot, which I first assumed to be due to crash damage.  The police apparently wrote the crash off as 'speeding'.  A cursory look showed that the lower engine mounts were intact and the bolts were totally missing.  My conclusion was that the bolts were either omitted or vibrated out, which took away support to the frame.  Due to the high load from the suspension linkage, the frame was overloaded and cracked through the pivot, causing the rear end to collapse and the rider to lose control.  This is consistent with the accident info I saw.  Tragically the rider was killed in this accident, so please folks - check these regularly!
 
That?s a really sad story about the 650 Formula  :(
These bolts used to break regularly, and fall out losing the spacers. Piet may remember making me a spacer in 1997 (thanks again!).
After initially blaming under torquing, it became clear to the factory that the bolts needed to be tougher.  They upped the spec from 8.8 to 12.9 in the last year of manufacture, but never did a recall.  Perhaps this was a tragic error in hindsight.

My 668 has a full set of 12.9 bolts.  They cost very little.  I suggest you should change them if you still have shiny 8.8 bolts.
 
Yes, very sad story.  I was able to contact the guy's sister and advise her of what I thought caused the crash, that it was likely a mechanical failure rather than irresponsible riding.  Same outcome unfortunately.

That's also great info about them being 12.9 bolts on the later bikes, I would strongly advise everyone to upgrade them and also still check them regularly.  With a monoshock bike the linkage brackets on the crossover tube under the pivot is a quite highly loaded part of the frame, and it appears the crankcases contribute to the strength of the frame in this case.  The 668 in question cracked right through the pivot casting on one side, and through the same casting somewhat lower down on the other side.  I imagine it was running with the bolts missing for quite some time to develop the first crack.
 
Not the most exciting picture, but here is what the replacement bolt looks like (left) compared to the original (right).  Quite a lot of wear visible on the original bolt.
The bolts (socket head cap screws) are easy to get, but iirc you need three different lengths to do the lot...
 

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