Triumphrat

choppedtriumph · 05-23-2009, 12:49 AM

What is the easiest and most accurate way of finding BTDC without the plunger tool or specialty tools? I just received a new sparx ignition kit and I am having trouble finding the proper setting for BTDC through the crankcase timing plug. There is two notches to look for? How do you know which notch is TDC and BTDC? Any and all help is very much appreciated. Btw.... I have the Haynes manual, and all it shows is how to find TDC.

Caulky · 05-23-2009, 06:01 AM

With a screwdriver in the crankcase timing hole, find the notch for TDC when the RH piston is at the top of its cycle.
Put it into gear...top is easiest I think. (although my gearbox is naff and I can only get 1st and 2nd, at the moment). Turn the rear wheel backwards [carefully, dont jam the driver] until the 38 degrees before TDC [BTDC] notch is found. This is the fully advanced setting.
Presumably you have the fitting instructions here:
http://www.tri-corengland.com/acatal...c_Ignition.pdf
See the alternator picture 10.

It does not really matter if the ignition cycle is 180 degrees out because the sparks are produced on both plugs on every half cycle.

choppedtriumph · 05-23-2009, 12:51 PM

Thanks Caulky! But that 38 degree mark is what I can't find. The only notch I can find is like an engraved deep horizontal line on the flywheel. (I used the small screwdriver and even the mirror method to look for it) Is there suppose to be an actual hole?

Btw... It is a 1977 t140v 750.

GrandPaulZ · 05-23-2009, 01:03 PM

You found the mark, it's a bullet-shaped groove cut.

choppedtriumph · 05-23-2009, 01:53 PM

Thanks GPZ. But is that the TDC notch or the 38 degree BTDC notch? Because I can only see/find one.

GrandPaulZ · 05-23-2009, 02:37 PM

Easy enough to tell; if the notch is aligned, are the pistons at TDC or just before?

choppedtriumph · 05-23-2009, 02:43 PM

Hmmm... Ok, I will have to take a look. And I am guessing I will want the pistons to be just before TDC. Right? Thanks GPZ, I appreciate the help.

Caulky · 05-23-2009, 03:25 PM

It may be easier to open the alternator cover and look at this:

choppedtriumph · 05-23-2009, 04:02 PM

Yeah I tried that, but all I found was a one line indicator or mark . And I have a 77 750 which has the little inspection cap above the Triumph symbol, which has a little nail looking pointer. I will try what you have both suggested and see what happens. Thank you guys for the help!
But one more question (before I go out and start playing with it)... How do you check for spark? By holding the wire close to the plug or something metal, while kicking it over? Or what? Thanks again

Caulky · 05-23-2009, 04:31 PM

I rest the plugs in their caps on top of the cylinder head and kick over.
*You have got 5000 Ohm plug caps I hope?