MK111 isolastic

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Apr 26, 2007
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Hi, I have the new type MK111 isolastic's with the holes in the adjustment ring if someone is familiar with this type where if you were to check the clearance do you place the feeler gauge. I know to adjust manual says tighten up then back off 1.5 holes or 1/5 of a turn. This is to obtain around 006 for a clearance. I have also read to back off 1 complete turn. Also 010 is to say normal clearance and varys 006-010 on the ride you want for handling. So besides the tighten up back off method where would a feeler gauge go to determine the actual clearance. Is it at the adjustment ring or the locking nut or at the other end just where if someone could help thanks. DOXFORD
 

L.A.B.

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None of the info relating to the MkIII type kits seems to specify setting the clearance with a feeler gauge, but if you wish to do so then I suppose using a version of the earlier adjustment procedure will do.

I would try this:
First, the weight of the bike should be supported by the lower frame rails using a jack, blocks of wood or similar, so that the main stand is not touching the floor if it is a later model that has the main stand fitted to the cradle.

Checking front Iso. unit:

Slacken the central Isolastic bolt locking nut, pull the inner part if the L/H Iso. gaiter away from the Iso unit, lever the engine towards the right side and hold it there.
Then insert the feelers to measure between parts [23] and [24] on the left hand side (as shown on the parts book drawing link below)

http://www.bsa-regal.co.uk/norton/parts ... &Plate=015

The front Iso adjuster should be on the right hand side of the front Isolastic unit.

Check/adjust Iso. clearance then re-tighten the Isolastic bolt/nut.

Check rear Iso.

Slacken either Iso. stud nut. Push the rear wheel to the left and hold it there whilst checking, use the same procedure as for the front Iso. but this time check clearance on the right-hand side, the adjuster being on the left side of the rear Iso.

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Update

Backing off the *original* MkIII Iso. unit adjusters by a fifth of a turn sets the correct clearance, however the *conversion kit* adjuster setting could be different?
The Norvil recommendation for their own kit is back off the adjuster by half a turn. http://www.norvilmotorcycle.co.uk/techtalk04.htm
 
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re MK111 iso

Thank you for the info I thought maybe there was a direct location at the adjustment ring to slip in a feeler gauge. Glad I asked I have little to no experience with adjusting procedure other then what I have read. Is the clearance the same for front and back. Does it vary from bike to bike or is tighten up and back off 1/2 turn the normal operating setting. Is there a relationship between either iso for low and high rpm vibes. Like if you have excessive low rpm vibes adjust front iso or vice versa for high rpm vibration is that possible. Or do you just kinda trial an error either iso adjustment and go for a road trip until you get the best feel. Regards DOXFORD
 

L.A.B.

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I posted the wrong parts page info link in my previous message which I have now corrected-sorry.

And to answer your questions, set both Isolastics to the same clearance.

Tighter settings give more vibes but better handling and looser settings vice versa.

It does seem to be a little to do with personal preferences but do not close the clearances up completely 0.005" is really about the minimum setting.

The vibes at any given RPM setting can be more to do with the Iso rubber formulation as it can vary, some rubbers being harder or softer than others. The MkIII version also has an extra suspensory spring device fitted between the frame and the head steady which can be adjusted to change the vibration characteristics.
 
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I would like to add, always check the gap again after tightening the ISO bolt as any play in the adjuster threads will be taken up and can significantly reduce the gap.
 
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