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A65 Timing gears and valves #660667
07/14/16 7:40 pm
07/14/16 7:40 pm
Joined: Oct 2013
Posts: 41
MOTHERWELL NORTH LANARKSHIRE S...
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FLYNN54 Offline OP
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FLYNN54  Offline OP
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Posts: 41
MOTHERWELL NORTH LANARKSHIRE S...
I had a look through the forum and cannot find a response to this specific question so..
Can anyone confirm please that the following is correct regarding checking the valve/gear timing on the A65. I took the timing cover off today to fix an oil leak and the usual happened – the idler timing gear came away with the cover. Before I put the said idler timing gear back in the right way around - the following question came up. Is this the correct sequence to set the timing gears?
The engine is set at TDC. Tappets set to .15”. Plugs out, timing disc fixed to drive side rotor. Timing side -The crank end gear dot is then lined up with the idle gear’s right hand side timing mark and the left hand side mark ( on the idler gear)is positioned so it will mesh (turning anti –clockwise)with the cam timing gear’s single timing mark as it turns ( clockwise). Idler mark at approx. 10o’clock and cam gear mark at 2 o’clock. The left hand side inlet and exhaust tappet arms are just starting to drop and the valves starting to open inside the head. Push rod ends rising. Right hand tappets arms rocking slightly
When the crank gear is turned 360 degrees and its mark lined up with one of the two timing marks on the idler gear, the cam timing gear’s single mark (dot) is then facing away to the left on the gear at approx. 8 o’clock position. The right hand set of tappet arms are then dropping, valves opening inside head and push rod ends rising. Left hand tappet arms rocking slightly.
Basically then -which set of marks controls which set ( side) of valves ?
Is this sequence correct? Is there something I have missed? The timing gears require a bit of “jiggling” getting them to mesh. Bike is 71 reg A65L fitted with Pazon ignition.
Footnote. I am going to try Loctite anaerobic sealant on the inner timing case faces and oil pipe union as I am disappointed with the “new gasket” I fitted last time it was apart (kick start ratchet sticking – still is on and off). Second leak from “new stuff” (SRM sump filter gaskets).
Sorry about the long question. The two manuals I have are vague to say the least (one shows the gears upside down!!) I don’t want to mistime the gears.
Best regards and thanks in advance ( ?) from John.

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Re: A65 Timing gears and valves [Re: FLYNN54] #660678
07/14/16 8:49 pm
07/14/16 8:49 pm
Joined: May 2013
Posts: 4,839
Rotherham - S. Yorkshire
Allan Gill Online happy

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Allan Gill  Online Happy

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Rotherham - S. Yorkshire
I always use the lobe centre figure. With stock cam the motor should be at 98.5° ATDC when the inlet cam is at full lift.


beerchug
Re: A65 Timing gears and valves [Re: FLYNN54] #660679
07/14/16 8:55 pm
07/14/16 8:55 pm
Joined: Nov 2011
Posts: 126
Northern Ireland
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B31 Ally Offline
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Northern Ireland
John, I have no experience of an A65 whatsoever but here is a ball park explanation on valve timing which will work on 99% of four stroke engines. If your not a mechanic then you may not grasp what im saying, the fact your asking about valve timing I would assume your not a mechanic but that's not a bad thing, the fact your asking means you know valves have to be timed, a lot of people don't even know that simple fact and end up with a piston hitting an open valve with the inevitable result of a cylinder head having to be removed to fix the bent valves.

Set number 1 cylinder at TDC and install the valve timing gears for that cylinder that leaves the two valves in the open position at the same time, that means as you have the piston at TDC the exhaust valve is closing and the inlet valve is opening. This is what is known as the valves rocking because both of them are moving at the same time. Give the engine one complete turn and install the ignition timing wheel so the engine fires at around TDC or ever so slightly before TDC. Both valves are now closed as the engine is on the compression stroke and about to fire. Your engine will run at this stage but it will need tweaked.

I have timed hundreds of engines like this for people to get them running, my claim to fame back in the 80's was timing a Jaguar V12 engine this way for a guy who knew nothing about timing an engine and worked at it for nearly a week and couldn't get it running, after I was at it for a few minutes, first turn of the key and away it went! It doesn't matter if it is a single cylinder four stroke lawnmower engine or a V 12, the principal is exactly the same on a cylinder, the valves must be rocking with the piston at TDC and the same cylinder firing at the next complete revolution of the crank at TDC.
Hope this helps.

Re: A65 Timing gears and valves [Re: FLYNN54] #660685
07/14/16 10:56 pm
07/14/16 10:56 pm
Joined: Aug 2001
Posts: 4,433
Owego, NY, USA
Mark Z Offline
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Mark Z  Offline
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Posts: 4,433
Owego, NY, USA
Fortunately, on an A65 it's simple. From where the timing marks on the idler pinion and crank pinion align, you should only have to rotate the engine a couple of teeth to align the opposite mark on the idler pinion and the mark on the camshaft pinion. From recollection, I guess this would be the 8:00 and 4:00 scenario. Frankly, I never knew there was any other way that the marks could line up. The marks on the idler pinion are 180 degrees out, so it makes no difference which way the idler pinion goes in. Rotating the crank 360 degrees does nothing; the crank and pistons position is identical on each revolution. And there's only one mark on the camshaft pinion, so...


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: A65 Timing gears and valves [Re: FLYNN54] #660712
07/15/16 8:13 am
07/15/16 8:13 am
Joined: Jan 2015
Posts: 166
Pennsylvania USA
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Mike Stillwell Offline
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Mike Stillwell  Offline
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Pennsylvania USA
Mark Z, I did that with mine and wound up with a valve hitting the piston. Luckily I was slowly turning it by hand and didn't bend anything.

The marks on my motor apparently don't mean anything. frown

I set the engine at the given spec for intake opening @.015"
Set the cam so the intake valve is open .015" (Dial indicator on pushrod)
The idler gear slipped right in.
I then turned the engine over and checked the rest of the valve events against the spec for my cam.

Re: A65 Timing gears and valves [Re: FLYNN54] #660725
07/15/16 9:16 am
07/15/16 9:16 am
Joined: Aug 2001
Posts: 3,861
argyll. scotland, uk
gavin eisler Offline
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gavin eisler  Offline
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Posts: 3,861
argyll. scotland, uk
There have been some camshafts made with the pinion key way cut in the wrong place. This messes up the factory markings.

If the head is on its safest to check with just one push rod installed, less chance of piston clash, fit a degree wheel ( establishing TDC first, then onto valve timing), set the valve lash at 15 thou then time to book figures, now fit the other push rods and check timings of all valves, within a degree or two of book figures all round means you are good to go.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: A65 Timing gears and valves [Re: gavin eisler] #660740
07/15/16 12:21 pm
07/15/16 12:21 pm
Joined: Jan 2015
Posts: 166
Pennsylvania USA
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Mike Stillwell Offline
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Mike Stillwell  Offline
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Joined: Jan 2015
Posts: 166
Pennsylvania USA
Originally Posted By gavin eisler
There have been some camshafts made with the pinion key way cut in the wrong place. This messes up the factory markings.

If the head is on its safest to check with just one push rod installed, less chance of piston clash, fit a degree wheel ( establishing TDC first, then onto valve timing), set the valve lash at 15 thou then time to book figures, now fit the other push rods and check timings of all valves, within a degree or two of book figures all round means you are good to go.

That's the problem I had.
I had the head on but no rockers installed
With the dial indicator in the pushrod I turned the cam until it moved .015" then turned the crank to 51 degrees BTDC and slipped the idler gear in

This worked out well for me, hope it helps.

Re: A65 Timing gears and valves [Re: gavin eisler] #660911
07/17/16 12:04 am
07/17/16 12:04 am
Joined: Aug 2001
Posts: 4,433
Owego, NY, USA
Mark Z Offline
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Mark Z  Offline
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Joined: Aug 2001
Posts: 4,433
Owego, NY, USA
Originally Posted By gavin eisler
There have been some camshafts made with the pinion key way cut in the wrong place. This messes up the factory markings.


I guess this is another one of those areas where I've always been extremely lucky.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: A65 Timing gears and valves [Re: Mark Z] #661283
07/19/16 5:10 pm
07/19/16 5:10 pm
Joined: Oct 2013
Posts: 41
MOTHERWELL NORTH LANARKSHIRE S...
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FLYNN54 Offline OP
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FLYNN54  Offline OP
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Joined: Oct 2013
Posts: 41
MOTHERWELL NORTH LANARKSHIRE S...
Update - Success !!
Many thanks to you all for your assistance and suggestions. As suggested I downloaded a timing wheel and timed the valves to the figures given in the manual. I used the end of a Vernier gauge to find TDC and cross referenced TDC and the ignition point on the rotor mark (number 2)and crank plug. The pazon instructions are a little vague in giving the exact degrees of advance/retard so I set the “points”plate to 5 degrees. I will strobe time the engine later after a double check over. As Frankenstein would say "it lives" - as the bike proceeded to walk (on its stand) down the drive on a racing tick over. Cue – huge grin. Thank you all again. Regards from John.

Re: A65 Timing gears and valves [Re: FLYNN54] #703193
07/29/17 12:20 am
07/29/17 12:20 am
Joined: Aug 2012
Posts: 611
Oregon
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Dana_twin Offline
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Posts: 611
Oregon
Hello reviving this old thread I have a question pls see pic, the intake valve lobe for #1 cylinder ie the LH cylinder is the lobe shown on the far right of the pic attached here, correct? regards

[Linked Image]

Re: A65 Timing gears and valves [Re: FLYNN54] #703201
07/29/17 12:45 am
07/29/17 12:45 am
Joined: Aug 2012
Posts: 611
Oregon
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Dana_twin Offline
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Dana_twin  Offline
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Joined: Aug 2012
Posts: 611
Oregon
tah nickL


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