Norvil iso conversion

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Aug 20, 2005
Has anybody fitted iso conversion to shim type machine? I bought one for the front today & it fits great till you try to put it back on the bike! It seems impossible to fit in assembled form & there is no way to assemble it other than off the bike. Am I thick?
Geoff, it depends what you've bought.

When fitting the original MK3 type vernier isolastics to the earlier shim type mounting tube, the tube needs modification. Look at this link,

but I see that Norvil are apparently (if I understand things correctly)selling a conversion kit 066130 that apparently needs no modification when fitting to the earlier mounting tube. So have you bought the earlier type and haven't modified the mounting?

The only other reason that I can think of is that you haven't screwed the short abutment up fully before tightening the grub screw.

Someone with more knowledge will be along shortly!
I fitted the Norvil kits to my '72 750 when I did the rebuild. I used the front one that does not require machining the mount and had no problems with it.

The rear, when assembled, would not fit into the frame however. It was just a little too wide, even with the powdercoating removed from the frame. We tried another engine cradle, same thing. Then we tried the cradle on another frame and it slipped right in. I measured my frame and the distance between the mounting plates was narrower than it's supposed to be. So I spread the frame rails out with some threaded rod and nuts, and put it together. All seems good now. Maybe there's a similar issue with your front mount? Or perhaps you have the one that requires machining the mount?

I had the same problem and until recently did not find out why.
Because the whole thing is assembled complete before installing, (compared to the old shim type) there is very little clearance between the rails for the mount to be pushed up in place and the short case bolt bosses behind the mount get in the way, pushing the mount towards the front ( I ground/filed some material off mine). You also need to ensure the side plates are not too tight over their bosses on the cases and that the mount is not being pushed over to one side.
What I did was remove top mount and lower the engine, pivotting from rear ISO, tighten down the adjusters as far as possible and slip the mount in place from below so it just sits on it's bosses. You may have to raise or lower the engine and jiggle it into place. If like mine the engine was 'misaligned' in the frame the ISO will be pulled over to one side and will be difficult to slip over the case bosses and inside the frame tabs.
Assuming you have been sold the correct conversion it will go in but it's not always that easy. Good luck.
I have bought kits from both Norvil and RGM, the Norvil kit slips nicely into the front mount and also between the frame mounts, the RGM unit requires machining of the engine mount tube an equal amount on either side. I will check the dimensions when I return home tonight.
On my 850 MkIII I think that I had to spring the frame rails apart slightly with a lever to fit the front Iso.
Thanks chaps

I did phone Norvil & they assured me that the kit should fit no problem, but some crankcases did not have the boss round the short bolt properly finished, leaving too much sticking out. If I attack this with a file they reckon it should go in no trouble. The boss on mine does have a lot of spare metal & this was getting in the way, so this will probably be the solution. Just out of interest, the old outer rubbers were deformed so the tube was nowhere near the centre, this must be due to the weight of the engine on them, so I reckon that with the Mk3 spring device fitted it would stop uneven wear on these rubbers & extend the life. Perhaps I could lash a few bungees under the tank!
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