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Model 99 timing cover

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Hi, I am having difficulty refitting the timing cover to the crankcase on my 57 mod 99.

When the chains are tensioned it is impossible to get the cover back onto the crankcase without using force. If the half time pinion is removed the cover will go on. Similarly if the cam chain is slackened off the cover will go on.

Am i overtensioning the cam chain? Are the chains worn?

This begs another question - is the half time pinion meant to come out of the crankcase without a struggle. If not what can i do about it?

The bike was running fine before i had to have the mag renovated with no rattles or strange noises.

Any suggestions will be gratefully received.

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I had trouble with a new cam chain being bar tight. So I put the old one back and it was OK. Are you adjusting it with a spare cutaway cover? If not then it might tighten up too much when the cover goes on.
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Previously tim_richards wrote:

Hi, I am having difficulty refitting the timing cover to the crankcase on my 57 mod 99.

When the chains are tensioned it is impossible to get the cover back onto the crankcase without using force. If the half time pinion is removed the cover will go on. Similarly if the cam chain is slackened off the cover will go on.

Am i overtensioning the cam chain? Are the chains worn?

This begs another question - is the half time pinion meant to come out of the crankcase without a struggle. If not what can i do about it?

The bike was running fine before i had to have the mag renovated with no rattles or strange noises.

Any suggestions will be gratefully received.

well you should have 3/8ths slack on the timing chain and you do this with a old cut way outer cover

or see RGM Motor Norton timing tools

Yours Anna J

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You really need an old cutaway cover,especialy on an older motor which has a loose spindle fit.It may help to turn the motor a little to reduce the chain pull by the cam.

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Previously David Cooper wrote:

I had trouble with a new cam chain being bar tight. So I put the old one back and it was OK. Are you adjusting it with a spare cutaway cover? If not then it might tighten up too much when the cover goes on.
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Thanks, i will have to get an old timing cover from somewhere, or as Anna suggested a special tool from RGM or Norvil

Regards Tim

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Previously anna jeannette Dixon wrote:

Previously tim_richards wrote:

Hi, I am having difficulty refitting the timing cover to the crankcase on my 57 mod 99.

When the chains are tensioned it is impossible to get the cover back onto the crankcase without using force. If the half time pinion is removed the cover will go on. Similarly if the cam chain is slackened off the cover will go on.

Am i overtensioning the cam chain? Are the chains worn?

This begs another question - is the half time pinion meant to come out of the crankcase without a struggle. If not what can i do about it?

The bike was running fine before i had to have the mag renovated with no rattles or strange noises.

Any suggestions will be gratefully received.

well you should have 3/8ths slack on the timing chain and you do this with a old cut way outer cover

or see RGM Motor Norton timing tools

Yours Anna J

Dear Anna

Thanks for your help. I shall do as you & others suggest & look for an old timing cover or borrow / buy the tool from a supplier.

How critical is the tension on the chains? The cover has gone back on since i slackened off the cam chain. It is not too slack that it can whip & come into contact with anything else in the timing chest.

Regards Tim

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Just to add to the above. A more recent addition to Andover Norton (Got mine via RGM) is a rubber backed cam chain adjuster now on my 1960 99 restoration) Not sure it helps with the above but it is supposed to quieten things down a bit, just like the Commando.

Permalink

Previously tim_richards wrote:

Hi, I am having difficulty refitting the timing cover to the crankcase on my 57 mod 99.

When the chains are tensioned it is impossible to get the cover back onto the crankcase without using force. If the half time pinion is removed the cover will go on. Similarly if the cam chain is slackened off the cover will go on.

Am i overtensioning the cam chain? Are the chains worn?

This begs another question - is the half time pinion meant to come out of the crankcase without a struggle. If not what can i do about it?

The bike was running fine before i had to have the mag renovated with no rattles or strange noises.

Any suggestions will be gratefully received.

Permalink

Thanks for the reply.

Any advice is gratefully received. My previous experience with Brit bikes is all Triumph Twins. Whats wrong with gear driven timing?!

All of these were rebuilt totally 7 i knew what was going on inside the engine.

My latest aquisition is a departure from the norm & as such is an unknown quantity.

Thanks again for the advice.

Regards Tim

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The designer alleged he used chains because they were quieter...Because the Norton twin had only one camshaft with four lobes it is alleged not to have as much backlash when spinning. So cam chain loads do not reverse (much) so can accept some slack. And the alloy cases expand more than steel chain so they must not be too tight when cold or else they'll do some damage when hottet and tighter.
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Previously anna jeannette Dixon wrote:

Previously tim_richards wrote:

Hi, I am having difficulty refitting the timing cover to the crankcase on my 57 mod 99.

When the chains are tensioned it is impossible to get the cover back onto the crankcase without using force. If the half time pinion is removed the cover will go on. Similarly if the cam chain is slackened off the cover will go on.

Am i overtensioning the cam chain? Are the chains worn?

This begs another question - is the half time pinion meant to come out of the crankcase without a struggle. If not what can i do about it?

The bike was running fine before i had to have the mag renovated with no rattles or strange noises.

Any suggestions will be gratefully received.

well you should have 3/8ths slack on the timing chain and you do this with a old cut way outer cover

or see RGM Motor Norton timing tools

Yours Anna J

Dear Anna & others

I obtained a special tools as suggested & i can now see why i could not get the cover on. The camchain was fer too tight.The jig aligns everything perfectly & hopefully all will now go back together without fuss.

Thanks to everyone for their advice.

Regards Tim

 


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