huile sur pneu arrière MATCHLESS G12 CSR de 1964

Information relating to the Matchless G12 or AJS Model 31 650cc twin
didier43
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huile sur pneu arrière MATCHLESS G12 CSR de 1964

Post by didier43 »

Bonjour à tous, je suis un nouveau membre et je relance un sujet récurent à savoir beaucoup d'huile sur la chaine secondaire qui asperge le pneu au bout de 4 ou 5 kms. Pas trop d'huile dans le carter primaire mais 1/2 litre d'huile dans carter moteur. Je précise que j'ai un robinet sous le réservoir d'huile. Je suis en train de reconditionner mes pompes à huile car on m'a dit que ça venait de là même si elles paraissent en très bon état. La moto marche très bien mais je n'arrive pas à résoudre ce gros problème. Autre petit souci, embrayage très dur ! Si certains ont des solutions, je suis preneur et vous en remercie d'avance.
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cbranni
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Re: huile sur pneu arrière MATCHLESS G12 CSR de 1964

Post by cbranni »

juste pour aider

Just to help out.


Hello everyone, I am a new member and I am relaunching a recurring subject, namely a lot of oil on the secondary chain which sprinkles the tire after 4 or 5 kms. Not too much oil in the primary crankcase but 1/2 liter of oil in the engine crankcase. I specify that I have a tap under the oil tank. I am in the process of reconditioning my oil pumps as I was told it came from there even though they appear to be in great condition. The bike is running very well but I cannot solve this big problem. Another small problem, very hard clutch! If some have solutions, I am interested and thank you in advance.
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dave16mct
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Re: huile sur pneu arrière MATCHLESS G12 CSR de 1964

Post by dave16mct »

Hi Didier,
when you say 'not too much oil in the primary chaincase' try reducing the amount of oil until it only just touches the bottom of the primary chain. Also check it isn't leaking from the gearbox seal behind the sprocket. The clutch cable should be routed very smoothly, no sharp bends. On the handlebar lever the distance from the centre of the pivot to the centre of the nipple should be 22mm. Oil the cable. Also check the lever inside the gearbox is in line with the cable entry. The clutch springs may have been changed for heavy duty Norton springs.
Dave.
mdt-son
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Re: huile sur pneu arrière MATCHLESS G12 CSR de 1964

Post by mdt-son »

Consider fitting a Venhill featherlight Teflon lined cable. The handlebar lever has to have a 7/8" pivot (fulcrum bolt) to cable radius. Check your clutch springs. They may have been turned too far in to compensate for clutch plate wear. Adjust as per service manual.
You may need a new clutch stack. Also check your clutch center and clutch chainwheel basket. These parts wear and guides for splines may have become jagged. New parts are available.

-Knut
Reynard24
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Re: huile sur pneu arrière MATCHLESS G12 CSR de 1964

Post by Reynard24 »

+1 for the Venhill Featherlight clutch cable - I have these on all my AMC clutches and they give a much lighter clutch operation when combined with the 7/8" fulcrum lever. They will also improve a heavy clutch action with levers that have a greater fulcrum distance. These also do not require lubrication and indeed will bind if oiled.
didier43
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Re: huile sur pneu arrière MATCHLESS G12 CSR de 1964

Post by didier43 »

Merci pour vos réponses. Le dernier essai que j'ai effectué, huile dans carter primaire juste sous la chaine, réservoir d'huile bas niveau, boite de vitesse avec niveau normal, carter moteur vidangé. J'ai roulé à peu près 10 kms et quand je suis rentré le pneu arrière commençait à avoir de l'huile. J'ai vidangé le carter moteur et il y avait un 1/2 litre d'huile ! Merci à tous !
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SPRIDDLER
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Re: huile sur pneu arrière MATCHLESS G12 CSR de 1964

Post by SPRIDDLER »

didier43 wrote:Merci pour vos réponses. Le dernier essai que j'ai effectué, huile dans carter primaire juste sous la chaine, réservoir d'huile bas niveau, boite de vitesse avec niveau normal, carter moteur vidangé. J'ai roulé à peu près 10 kms et quand je suis rentré le pneu arrière commençait à avoir de l'huile. J'ai vidangé le carter moteur et il y avait un 1/2 litre d'huile ! Merci à tous !
(My approx translation, but no advice as I'm twin-ignorant)....................


Thanks for the replies. Last time I tried I had the oil just under the primary chain, oil tank level at minimum, gearbox oil level normal, crankcase emptied. When I returned after 10km the rear tyre had begun to get oily. I emptied 1/2 litre of oil from the crankcase.. Thanks everyone
Last edited by SPRIDDLER on Mon Nov 09, 2020 5:49 pm, edited 1 time in total.
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clive
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Re: huile sur pneu arrière MATCHLESS G12 CSR de 1964

Post by clive »

I have no idea if 1/2 litre of oil in the crankcase is correct but it sounds a lot. I wonder if the supply and return pump bodies have been reversed? The return pump should be bigger and I think on the left someone will confirm. If the crankcase is too full it will breath into the primary and out around the gearbox and onto the chain etc. However there is another possibilty. I get exactly this problem when i overfill the oil tank on my G11CS. The oil comes out of the breather pipe which is set to vent above the chain. The oil then gets to the rear chain and from there to the tyre. Stops once the oil level is correct which took about 50 miles last time i did it! The tank should ony be about 2/3 full. I imagine it would happen on a G12 too.
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mdt-son
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Re: huile sur pneu arrière MATCHLESS G12 CSR de 1964

Post by mdt-son »

Clive, the possibility of overfilling can be ruled out here. OP states he kept the oil level in the oil tank at a minimum. OP should try to vent the oil tank into a catch bottle, at least until his problem has been resolved.

I think it's pretty obvious the engine pushes excess oil from the crankcase into the primary chaincase. Question is, how? Has OP ensured the scrolled spacer / seal 023163 is in place? If the oil reaches the crankase vent (through the crankshaft drive side), I am assuming a hydraulic lock would occur.
Even if crankcase pressure should build up, I think very little oil would escape via the flapper valve, so maybe the scrolled spacer / seal is failing due to pressure build-up?

OK, these are secondary effects to the high oil level in the crankcase. It seems OPs scavenge doesn't work well. Has he checked the return output in the tank while the engine is running?
If the engine was rebuilt, has OP cleaned out all oil channels by means of a piano wire and subsequent compressed air? Maybe a piece of metal is blocking the scavenge line. He should poke the wire backwards, from the pump down to the sump.

The scavenge pump is the rear one.

Next step would be to dismantle the oil pumps, especially the scavenge pump. Maybe the gears are damaged?

Finally, both oil lines to the oil tank need to be checked for free passage. OP should also check the pipes inside the oil tank, to rule out any blockage, especially in the return pipe.

OP needs to read the chapter OILING FAULTS in the workshop manual (p. 13). The manual can be downloaded from the archive.

Good luck with your detective work!

-Knut

PS. Maybe "cbranni" would be so kind as to translate into French? ;-)
MikeM.
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Re: huile sur pneu arrière MATCHLESS G12 CSR de 1964

Post by MikeM. »

If the oil tank is over filled then the surplus oil will be blown out of the oil tank breather and distribute on to the secondary chain thence onto the rear tyre. MikeM.
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