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Primary chain: tight control

Discussion in 'Norton P11 Motorcycles' started by pierodn, Jun 6, 2018.

  1. jerrykap

    jerrykap VIP MEMBER

    Joined:
    Jul 23, 2014
    I agree that an O-ring chain is made for unprotected applications. In the past I've only used these on pre-Commando models (Atlas' & ES2) where the tin primary covers always did a poor job of keeping the chaincase oil in. BUT, I see no harm in using an 0-ring chain in the fairly well sealed P11 primary? Better is better right?
     
  2. p400

    p400 VIP MEMBER

    Joined:
    Jul 14, 2014
    There is not enough side clearance in my P11 primary chain case to allow the extra width of an o-ring chain.
    The stock plain primary chain rubs the inner primary chain case.
     
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  3. jerrykap

    jerrykap VIP MEMBER

    Joined:
    Jul 23, 2014
    You're probably right? I'm setting mine up now and will check for adequate clearance. Also converting to Pazon and freshning up the top end as well. Found Commando pistons already installed and it has been running for a long time with a missing center 3/8" head bolt.

    C-ya, Jer
     
  4. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    No harm if the O-ring chain fits, except that the lubricating oil is restricted from entering the inner parts of the chain for continuous lubrication. The result _may_ be that the chain suffers a shorter life than the standard 428 type chain (1/2"x5/16")! Apart from this comment, the single row chain used in Atlas-engined bikes really takes some pounding and requires frequent replacements.

    -Knut
     
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  5. p400

    p400 VIP MEMBER

    Joined:
    Jul 14, 2014
    tried to find a photo that shows my P11 concerns. I wanted to up grade the single row primary chain as well, but backed off when I did measurements.

    This photo does not really show my inner case rub areas of concern very well, but it shows a couple.


    20150115_PrimaryChainRub.jpg
     
    Last edited: Jun 13, 2018
    jerrykap likes this.
  6. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    428 chains are not symmetrical. One side is 9.7mm, the other 8.55 mm measured from the C/L. Maybe this explains the rubbing?

    https://www.yaban.com/upload/en/85/14_file_1.pdf

    https://asiakas.kotisivukone.com/fi...otisivukone.com/Renold_Transmission_Chain.pdf

    In fact, Renold chains are slimmer. The simplex chain, Renold #110046, for which the transmission was designed, has a width of 17 mm only, while width of the japanese chain is 18.25mm.
    I suggest you fit a Renold chain and your problem should be history. When fitted to the P11, Renold chains are long lasting according to Anthony Curzon.

    Should you want more clearance, there is the option of surface grinding spacers by 1 mm.

    Please check that your clutch wheel is free of wobble effects!

    -Knut
     
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  7. p400

    p400 VIP MEMBER

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    Jul 14, 2014
    I think it is the master link dimension that is not symmetrical. F&G

    So maybe a continuous o-ring might be fine?

    My particular P11, I took off a Renolds primary chain and put back a new Renolds primary.

    ChainDimensions428MasterLink.jpg
     
    Last edited: Jun 13, 2018
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  8. jerrykap

    jerrykap VIP MEMBER

    Joined:
    Jul 23, 2014
    Whatever chain I put on I'm not likely to wear it out. But, I do know that my original Renold chain did break rather dramatically on the Golden Gate bridge long ago in 1971. Caused a lurid rear wheel slide, fortunately I was able to stop safely and get out of the way without getting hit from behind by an automobile. To the chains credit though it already had high mileage with lots of abuse drag racing, road racing and touring 2 up in Europe & North Africa.

    On another note, anyone know the purpose of the empty hole in the inner primary? The one just above the foot peg stud. Is it merely a vent? It never seems to leak oil. Whereas the alternator wires have a rubber grommet that protects the wire from chaffing and prevents oil leakage.
     
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  9. p400

    p400 VIP MEMBER

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    Jul 14, 2014
    I would guess this extended hole on the rear primary case is strictly a primary case vent.
     
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  10. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    A bit off-topic. There is no empty hole in the inner primary cover for the P11. One bore is to accomodate the foot peg stud, one bore (in the boss above) is for the power cables and the associated grommet, and the third bore next to it is for the primary cover fixing.

    I note from the picture above that usage of the last two has switched. I find that strange - the G15 is as described. The boss is (was) machined for the grommet!?!

    -Knut
     
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  11. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    I don't know the purpose of the extended hole, but the primary covers don't require a dedicated vent. The sliding plate of the inner cover leaves a gap at the mainshaft providing all the vent you could wish for!

    -Knut
     
  12. vercu

    vercu

    Joined:
    Dec 21, 2010
    My understanding of the extended hole is a vent intended for Matchless engines. They vent through the primary. On P11s the hole is not needed and should be plugged with p/n 03-5072 RUBBER BUTTON Primary Chaincase $0.99 from Walridge. The G15 inner cover is different to the P11 ones in this area.
    Please correct me if I am wrong.

    Peter
     
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  13. jerrykap

    jerrykap VIP MEMBER

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    Jul 23, 2014
    There is no other central fixing bolt on the P11 outer cover other than the one that holds the top of the footpeg assembly. I see 3 holes in the inner primary and can only account for 2. Am I missing something?
     
  14. p400

    p400 VIP MEMBER

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    Jul 14, 2014
    I have never heard or read of a primary case rubber plug, yes there is plenty of vent thru the clutch hole.

    does this 03-5072 show up in any P11 parts lists?

    [​IMG]
     
  15. p400

    p400 VIP MEMBER

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    Jul 14, 2014
  16. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    We are diverting from the thread - there is another thread covering the primary chancases and its fixings.

    I am confused. I guess chaincase center stud 033120 is the bolt through bore 3 in the pic above, also in the picture further up, where a spacer is shown as well (presumably p/n 033140) ? If so, maybe there won't be a need for a separate chaincase stud at bore no. 1, although the arrangement isn't ideal ( the clamping force will be diminished due to bending, and it will not be possible to apply much pretension to the bolt due to the aluminum cover in between nut and spacer. If a separate stud was intended (e.g., 032241 as used on the G15) I would fit it. The picture above (showing the arrows) indicates that a washer and nut has been used previously. So maybe AMC did intend a separate stud for holding the inner cover?

    As for the footrest support, another bolt is listed, p/n 031913? Mayby this is one of many errors in the parts list: It shows two (2) different stud bolts for the R/H footrest support. Surely one of them must be wrong?

    -Knut
     
    Last edited: Jun 15, 2018 at 6:15 AM
  17. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012

    You are right about Matchless G9/G11/G12 venting through a diaphragm at the end of the crankshaft. They were lightyears ahead of Norton with this design .... and there is a vent hole at the rear end of the G15 chaincase, although that shoudn't be necessary as there is ample venting through the hole in the sliding plate where the mainshaft passes through.

    The G15 cover has 2 bores only, one for the power cable + grommet, and one for the central fixing.

    -Knut
     
  18. vercu

    vercu

    Joined:
    Dec 21, 2010
    I also cannot find it in the parts list for the P11 and P11A. Maybe because it was introduced with the Ranger.

    Now I remember where I got my wisdom from: Anthony Curzon wrote the following in "The Norton P11 Ranger - Part 3"

    "Another problem that was designed out was #035072; a rubber plug that filled the inner chaincase breather hole. This being the inner chaincase that was left over from the G12 as that crank shaft had a flapper valve that breathed into the chaincase and the chaincase being modified to fit the Atlas Twin engine."
     
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  19. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Do you have a picture of this rubber button, #035072?

    Are we talking about bore no. 1 (pic above) or the went hole at the rear of the chaincase?
    There was no inner chaincase "left over from the G12" in the literal sense. The first version of the inner chaincase for the P11 used a modified version of the cover used on the G/N15 which itself is a taylored casting. Later on (probably after termination of the G/N15 series) the P11 received a custom version of this cover. If N-V had wanted to delete hole/bore no. 1 they could have done so easily. Thus, I believe bore no. 1 serves a different purpose, namely to provide a dedicated inner chaincase support, maybe for racing.

    -Knut
     
    Last edited: Jun 16, 2018 at 12:43 AM

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