I am anticipating having to check the timing on a friends 600 alt/ mag equiped twin , I don't want to dismantle the bike ,but am pretty sure there is no other way . If left to its own devices it may dismantle itself in time. Moving the engine using the back wheel or kickstart is so clumsy its barely worth while, unless you have developed a refinement ??
I remove the plugs and…
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Can't you just set it up on…
Can't you just set it up on the road? 35 - 45 mph in top gear, open the throttle and listen for pinking, if it's pinking retard a little, if it's not, advance until it does and then retard a tad.
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Hi Bob, The engine is a …
Hi Bob, The engine is a high comp one with twin carbs ,and has been expensively restored but sounds a bit "clanky" on one side , I suspect a varience in the timing side to side ,or it may be carbs out. I'm told it does pink although run on best pump fuel. Backing the timing off does remove the clank but makes it a bit flat. No time to play with it ,but would like to find the issue ,preferably before the big bang.
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Cam Ring Symmetry
Hi Robert; recent jobs with K2FC's has highlighted the lack of symmetry on the cam rings. (between 9 and18 degrees on the last two).
How ever you time it, if the "clanking" is one side you are only going to optimise the setting. Get the cam ring out and checked for 180 separation. That's simple enough to do; get the error corrected or replace with a dialled in cam ring then revert to the road test set up as Bob suggests.
Happy hunting...
Jon
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If it's manual advance, it…
If it's manual advance, it can be set at perhaps 32 but with a mark at perhaps 30. Then it can be tried and adjusted. But not feasible with auto advance. Except by adjusting contact breaker gap. ( Edit...how can you adjust an auto advance mag on the road? Since it's manual, you do have the option to set it further advanced than any book figure and adjust it back with the lever)
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auto advance
does not prevent you setting the timing accurately. Put a wedge of some kind in the atd so that it is fixed at full advance, and then check the points opening point. Check both cylinders.
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My first post did state a…
My first post did state a manual mag. Its clear that no one has found (or invented !) a better way of accurately manipulating the engine movements to check the timing than we have used for years , that is , dismantle the casings , In this instance I don't expect the timing to be wrong on both cylinders , only on the one that has not been checked yet. I will be (very carefully!) using a piston stop to position the engine in the correct place and comparing the points actions. If I were to own a mag bike I suppose I could cut a strobe port in the primary case and use my mains assisted strobe to keep a check on the timing. Back in the day we just set the timing (roughly!) and then used the manual lever to find a sweet spot. Keeping our fingers crossed that the dreaded drive side seize up would get someone else. Not a good plan now with the cost of a rebuild. Shame that a mag design does not allow easy changes to timing (like a distributor has).But back then strobes were not in use. At this time I can only check the discrepancy and advise the owner if its a worry.
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I suppose I could…
I suppose I could temporarily lock the ignition advance in a reasonable setting and drive a wedge of feeler behind the cam ring in the new late position to balance things. But this would make starting even more an ordeal for us old crocks with gammy legs. Its all my fault,should have fixed my van months ago then we would not have to ride these pretty exhibits at all !!.
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I'm still not clear what the…
I'm still not clear what the problem is. Mine has alternator and I have added timing marks at TDC and 30 before TDC using white paint on the rotor and stator. Turn the engine with a spanner to what I want (30 in my case), release the mag taper, set the lever on full advance, turn the mag till it just breaks, and tighten it up. Then check the other lobe (which is OK on mine). I have in the past then checked with a strobe on my white marks.
The only stripping down is the timing cover, and taking out the plugs so it's easy to turn the engine.
On my singles, I pulled the lever to full advance but then knocked it back a touch. Added paint lines on the lever, and set the timing from the book. That allows me to get a little more advance if I want to experiment.
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After some playing with a…
After some playing with a timing rod on both sides and a feeler in the points we think the points cam is not too far out. The clanking has eased ( oil getting where it should be ?) ,however the carbs appear to be a bit unbalanced and with strange fuel levels so that will be on the list when time permits.
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I remove the plugs and either put it into top gear to turn the engine over on the side stand with the wheel propped off the ground, or (if the timing cover is off) put it into neutral and put a ring spanner on the main shaft alternator fixing nut. I try to turn it the right way to get slack out of the timing chains.