That's a Point..

Like many of the Coventry makes, Triumph had their roots in the bicycle industry, beginning motorcycle production in 1902.

Re: That's a Point..

Postby Graham B » Thu Mar 11, 2010 11:00 am

Dizzies have a points plate as well don't they? Just making sure before I confuse the man with tech ... :250
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Re: That's a Point..

Postby Tman » Thu Mar 11, 2010 3:22 pm

from TDC does the piston need to be to get 38deg before?
Not a lot, but unless the head's off, it's not much use to you knowing exactly how much. The plugs are angled, so trying to measure vertical distance would be difficult to say the least.
Sure you haven't got the 38 slot in the flywheel periphery too? Some did, you may be lucky.

I've not got the timing aperture in the primary case and cant find me timing wheel.. Don't really want to crack the primary open either.


Don't think you've got much choice there.You can do 19 on the cam wheel, but that still needs some dismantling + a degree disc, and is less accurate.
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Re: That's a Point..

Postby Bill » Thu Mar 11, 2010 6:37 pm

Graham, it's a 66' unit 650, so has side points. I'm not aware of any 650 (unit or pre-unit) with the distributor on the back. :150

Erm, I know it's a little hard to explain what i'm trying to do. The flywheel only has hole for TDC.. Otherwise it'd be plain sailing. :42 I can shove a rod through the plug hole and make a mark for TDC, from that mark I'd want to measure and mark a point for 38deg BTDC.. From there i can lower the piston down to line the marks up with whatever datum im using.. (edge of the plug hole for example). This method works, as i've seen it done.. I just need that measurement.. :153
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Re: That's a Point..

Postby L.A.B. » Thu Mar 11, 2010 9:33 pm

According to various 650 Triumph factory manuals, piston position at 38° BTDC is .415" (10.4mm).

However as your 650 is a 6T model, shouldn't you be setting the timing to 35° BTDC?
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Re: That's a Point..

Postby L.A.B. » Thu Mar 11, 2010 9:52 pm

Tman wrote:
from TDC does the piston need to be to get 38deg before?
Not a lot, but unless the head's off, it's not much use to you knowing exactly how much. The plugs are angled, so trying to measure vertical distance would be difficult to say the least.




There shouldn't be any problem holding a thin timing stick vertically within the angled plug hole.

Tman wrote:Sure you haven't got the 38 slot in the flywheel periphery too? Some did, you may be lucky.


Extremely lucky to find that before '68 I would have thought,- unless the crankshaft has been replaced?
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Re: That's a Point..

Postby Bill » Thu Mar 11, 2010 10:18 pm

L.A.B. wrote:However as your 650 is a 6T model, shouldn't you be setting the timing to 35° BTDC?


Cheers LAB. I'd spoken to me mate and he said 7/16", which is 0.4375.. So only 20 (0.5mm) thou difference. Erm, not too sure about it being 35deg BTDC.. Can't see it making a vast amount of difference. As long as the carbs set up right and i'm not getting any 'pinking'. I can't see a reason why it should be a problem anyway. I'll set it and do a plug chop to be on the safe side though.

Again.. cheers.. :151
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Re: That's a Point..

Postby Graham B » Thu Mar 11, 2010 10:36 pm

Hi Bill

click on my signature link, then on "the revisions are available to view online" and then on Preview. 2/3rds the way through is how I do it. Make up a partial disc like mine and you'll be able to adjust the points pillar bolts with it in situ. Your lines must be 19 degrees apart for 38 BTDC. Use this method for static or strobe timing - strobe is best if you have access to one.

Once you've made up the required parts it means setting the timing is always quick, simple and accurate :250
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Re: That's a Point..

Postby Graham B » Thu Mar 11, 2010 10:50 pm

My information concurs with L.A.B. in that the timing should be 35 BTDC. If you believe the engine to be fairly close to original spec then I'd go with 35
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Re: That's a Point..

Postby L.A.B. » Fri Mar 12, 2010 2:53 pm

Bill wrote:I'd spoken to me mate and he said 7/16", which is 0.4375.. So only 20 (0.5mm) thou difference.



7/16" is 39 degrees BTDC, which was the setting used before the factory changed over to 38 degrees BTDC (for T120 & TR6 etc.).
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Re: That's a Point..

Postby Bill » Fri Mar 12, 2010 7:14 pm

All timed up and running sweet again. Cheers for all the help peeps. Much appreciated. Virtual beers all round :150 :150 :151

Graham. I've drawn up the mini-timing wheel on the CAD and will be cutting a brass one in the very near future. I'll post up pic's when I come to strobe it up. I realise what you say about using plastic, but at the rate it'll be spinning, it'll still chop ye fingers off. :115
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