no oil returning to the tank

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Re: no oil returning to the tank

Postby Pharisee » Mon Dec 10, 2018 7:42 pm

willowbedone wrote:Do I time the inlet cam using the g3 marks or not Anyone who has done this ? Is it an improvement or will it cause any troubles


I've timed up my '55 AJS M18S using the 350cc marks and I've also fitted the inlet pushrod rocker arm from a lightweight engine to give a little move valve lift. If you're tempted to do that, check that the pushrod clears the top of the pushrod tube. Mine didn't... they were aftermarket stainless tubes and the top was 'swaged' in a lot so I had to remove some of the material with a Dremel. There is a difference in performance but it's not huge. It seems to breath a little easier and pull better from around 3000 rpm but it's a bit subjective and my goggles may just have a rose coloured tint. The exhaust note is a bit 'sharper' and possibly a little louder, too. So far, it hasn't caused any problems so I won't be swapping back anytime soon.

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Re: no oil returning to the tank

Postby willowbedone » Tue Dec 11, 2018 8:47 pm

Sorted collected the engine bottom half today not a bad journey there and back Engine looks pucker Ken has done a very good job He explained camshaft timing and what it does it do if I use g3 or g80 valve timing It's a busy day tomorrow

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Re: no oil returning to the tank

Postby willowbedone » Wed Dec 12, 2018 4:32 pm

Thanks Neville they both make good reading I've assembled the engine on the bench That's the cams in, outer cover and oil pump end covers fitted.The bottom end us back in the frame Another busy day tomorrow

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Re: no oil returning to the tank

Postby SPRIDDLER » Wed Dec 12, 2018 4:51 pm

Excellent!
Tip: Before you put the top pushrod washers and rubber (flat washer, rubber sleeve, dished washer) into the head make absolutely sure that you have removed the old flat washer (the one that was put into the pushrod hole first). It's easy to think it isn't there. Best way to check is to probe the hole in the head from the top (rocker box side) with a small screwdriver and if the washer is still there it will catch on the slightly protruding edge of the old washer. ;)
I poke badgers with spoons.

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Re: no oil returning to the tank

Postby willowbedone » Wed Dec 12, 2018 6:50 pm

Thanks for that I will check

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Re: no oil returning to the tank

Postby willowbedone » Fri Dec 14, 2018 5:08 pm

Guess what I checked for the washers and none top or bottom just loads of silicon sealant The person who built this engine really knew his stuff!!
Ordered new parts today .Just got to fit clutch time the mag fit the Barrell and head

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Re: no oil returning to the tank

Postby SPRIDDLER » Fri Dec 14, 2018 6:26 pm

Dear, dear! Looks as though your oil pump problem was a blessing in disguise.
Make sure you pull the head down square and stop if the base of the p/rod tubes touch the c/case or you will crush/split the bottom flanges. There should be a 1 to 2mm gap when the head is fully tightened down and you should be able to move them........

Pushrods should move a tad (640x480).jpg


Check that the threaded blind holes for the rocker box bolts do not have muck at the bottom (a 5/16" BSF tap clears them nicely). If they have muck (old gasket material etc.) at the bottom the rocker bolts will feel tight but will be stopped 'early' by the muck before the rocker box gasket is sufficiently compressed. This is very often the reason for oil leaks occurring between the rocker box and cyl head and stripped threads in the head as folk keep tightening the bolts in an attempt to stop the leak.
Sorry to nag but you've already had some costly work done........... ;)
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Re: no oil returning to the tank

Postby willowbedone » Sat Dec 15, 2018 4:35 pm

Thanks again Neville all advice is appreciated.i must admit I am as they say measure twice cut once on all I have done so far I cannot believe the things that were done on the last rebuild

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Re: no oil returning to the tank

Postby Pharisee » Sun Dec 16, 2018 9:31 pm

willowbedone wrote:Thanks again Neville all advice is appreciated.i must admit I am as they say measure twice cut once on all I have done so far I cannot believe the things that were done on the last rebuild


We've probably all been there!! The previous owner(s) of the G80S I bought a couple of years ago was a real shocker. I'm still finding and putting right all the bodges he called 'restoration'.

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Re: no oil returning to the tank

Postby willowbedone » Tue Dec 18, 2018 5:05 pm

I wondered why the clutch centre nut was finger tight Now I know why tighten it up and the clutch jams solid Another problem to sort :headbang:

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