Author Topic: Timing  (Read 427 times)

Offline Oggers

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Timing
« on: June 18, 2021, 01:39:02 PM »
Sacrilege perhaps, but is there any merit in the following as a temporary substitute for dynamic timing with a strobe.

Warm engine
Hold at 3500 or so rpm
Move stator plate round ACW or CW - by a small amount until the position is found where the revs max out

Bike is 66 Triumph T120 with Boyer. Seems to run fine but may benefit from a small refinement in the timing.



 

Offline Rex

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Re: Timing
« Reply #1 on: June 18, 2021, 04:21:04 PM »
Dunno about the "revs max out" part as correct timing is a little more complex than that.
Back in the days when the nature of fuel was changing and the "stars" system was replaced by merely unleaded, some used to advocate timing by "ping" namely adjusting (advancing)  the timing until it was just heard to ping when steaming up a long hill then retarding a gnat's pisser until the ping no longer occurred and locking it up at that setting.
Seat of the pants stuff, and relies on the rider knowing what pre-ignition sounds like. I'd stick to conventional methods myself.

Offline Oggers

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Re: Timing
« Reply #2 on: June 18, 2021, 04:40:49 PM »
Rex

Sort of what I was getting at. I don't have a strobe and I have had a little success before  - moving the plate ACW/CW a smidge -  and using basically similar methodology of letting it rip up a nearby long hill in top and seeing if it performs any better - or not - within reason of course.

I've often though that there are too many variables on individual bikes to be able to set dyanmic by the book - so to speak. Hence the above method which may be more attuned to my particular bike's foibles and variations. 

Offline R

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Re: Timing
« Reply #3 on: June 18, 2021, 11:41:04 PM »
I don't have a strobe

I think thats called prevaricating about the bush.

We could spend thousands of hours discussing alternatives, or just get one. !
Its only a few gallons of petrol worth ...

Offline TGR90B

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Re: Timing
« Reply #4 on: June 19, 2021, 10:55:31 AM »
According to Boyer you need a strobe lamp to set the timing. About twenty quid on Ebay.
Getting grumpy, but not as grumpy as mini-me.

Offline iansoady

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Re: Timing
« Reply #5 on: June 19, 2021, 01:26:46 PM »
You can set it up statically with the provided holes in the base plate. I always felt that revving my Commando on the stand to 4,000 rpm, apart from being antisocial, was a tricky thing to strobe anyway with the bike and engine leaping all over the place. I used to do much as Oggers originally suggested and didn't find any problems. Old bikes and modern fuels are likely to require advance quite different to what is specified anyway.
Ian
1952 Norton ES2
2008 Yamaha X-Max 250

Offline R

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Re: Timing
« Reply #6 on: June 20, 2021, 12:23:34 AM »
Old bikes and modern fuels are likely to require advance quite different to what is specified anyway.

I've never timed my bikes to anything other than the specified timing.
Nor had any indication that I need to do otherwise ?

Albeit older machinery has an advance/retard lever that you can fiddle with.
But modern fuels generally don't need retarding for poor quality fuels,
since that no longer exists ???

Offline iansoady

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Re: Timing
« Reply #7 on: June 20, 2021, 09:59:34 AM »
Petrol with ethanol tends to burn more slowly potentially requiring more advance; contrarily the lack of TEL requires less advance. The specified advance figures even for a relatively modern bike like this would only be a starting point for me.
Ian
1952 Norton ES2
2008 Yamaha X-Max 250

Offline R

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Re: Timing
« Reply #8 on: June 20, 2021, 10:34:45 AM »
And how would you judge that it needs any different timing to what was specified ??

I can't recall any time recently that I've even heard an engine pink or knock ?
Old classics tend not to have sky high compressions, so modern go juice is SOOOO much better than petrol of old ...

Offline Oggers

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Re: Timing
« Reply #9 on: June 20, 2021, 03:47:03 PM »
Ian

Quote
You can set it up statically with the provided holes in the base plate. I always felt that revving my Commando on the stand to 4,000 rpm, apart from being antisocial, was a tricky thing to strobe anyway with the bike and engine leaping all over the place. I used to do much as Oggers originally suggested and didn't find any problems. Old bikes and modern fuels are likely to require advance quite different to what is specified anyway

Static is very easy, and yes agreed about the difficulties setting dynamically. As it was set, it was not a million miles from static. I gave it several blasts up my (very convenient) mile long hill, and now set it a smidge advanced over what it was. Initially I set it retarded from what it was, and oddly, I thought it was down in power a tad. Certainly not as crisp when accelerating.

I realize I should get a strobe nevertheless. 

Offline Rex

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Re: Timing
« Reply #10 on: June 20, 2021, 04:51:38 PM »
I can't recall any time recently that I've even heard an engine pink or knock ?


Unless someone's been fannying with the timing, then that's as it should be. No-one's going to fill up with XYZ pump petrol and get pre-ignition purely down to the brand/grade of petrol.