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Discussion Starter · #1 · (Edited)
hi all,just finished up a new bsa build...soooo far everything seems good,but.......having a problem setting the points and timing,so far ive set the points to .015 gap,by rotating the cam lobe with the mark to the plastic foot on the points,making the adjustment then rotating to the lower set of points and doing the same,i then inserted the tdc tool in the crank and the right side(points side)valves and piston are in the compression stroke,but the bottom set of points are open to proper gap,and the top set open ever so slightly,but not the top set as the haynes maual says,at this point i was trying to set the static timing,just to get it running to strobe it,if anyone can supply sum help it would be greatly appreiated,i just cant seem to figure out what im missing here,i do have spark in both cylinders and it does pop and backfire thur carb and exhaust
 

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Put the TDC tool in the crank; then put a small piece of wood or metal down the plug hole until it touches the piston; remove TDC tool; with the rear wheel off the ground and the transmission in 3rd or 4th gear, nudge the rear wheel backwards just enough so that the piece of wood on the piston drops down slightly (say 1/4"~1/8") and put a mark on the wood; now rotate the engine a bit further backwards until the points for that cylinder are closed; put a piece of thin cellophane between the closed points (CD wrapper type cellophane works well); now, slowly nudge the tire forwards (normal rotation) with your foot while pulling gently on the cellophane with one hand and holding your homemade timing marker in the other; the points should release the cellophane when the the line on the timing marker lines up. That should be close enough for the bike to run okay. Once it's running, strobe time it at the crank to be sure it's correct.
When static timing (no advance) it's going to fire just prior to TDC.

Remember, if the points' rubbing blocks are old and worn it may not be possible to get both the timing and points gap correct on both cylinders. You may have to close the points gap up a bit to get the timing on.

And yeah, when all else fails, try switching the plug leads!
 

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bsa points camshaft was a design fuck up from day one

the cam is supported only at one end so any wear in the bearings or cam will manifest itself with the points end of the cam having undesired movement, the effect of this is to put variations in timing

long term its better to go for electronic ignition as they are effected far less by this than points
 

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The whole advance assembly can also run quite a bit out of true due to the steep taper angle...the slightest piece of dirt on the taper can have it wobbling around like a hula dancer. The advance mechanisms are also subject to considerable wear on the shaft, even though they will run sort'a-kinda OK with them like that. I'm not a big fan of EI, but in some cases it can be less expensive to change over to electronic that to repair/ replace the points points and coil set -up.
 

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Discussion Starter · #7 ·
thanks for the help guys,im going try your suggestions today,ill give a update,above is some pics of my build,as you can see im soooo close lol
 

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Discussion Starter · #8 ·
hey glider,thanks for the info,gotta nuther question though........after going through what you describe to do and the cellophane does not release,what adjustment do i do?maybe i shoulda just went with the EI,LOL THANKS
 

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went you finally get tired of fussing with the antique technology of those points and worn out advance mechanization you could get an electronic ignition and do a 10 minute install once and never have to fuss with it again.
 

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Mcdonnella: If you can't get the cellophane to release when it should, you have to move the points rubbing block closer to the cam, or move it more in the opposite rotation to the cam (so it opens sooner).

If the points are already moved to max in the opposite direction to which the cam moves, and they still don't release the cellophane when they should, loosen the points screw and move the points very slightly towards the cam. That it, increase the points gap.
In other words, you may have to compromise with the points gap to get the timing right.
An EI setup will eliminate all this, but EIs need a good battery and points will do fine even if your battery is going south.

Tony: Funny take on EI, I run EI on one of my Bonnies and my A65 but when I recently acquired a nice stock Bonnie with points I re-discovered that old 'centrifugal-advance feel.' The bikes feel different — like they're supposed to — with the old style advance. I'd almost forgotten that feeling, you know, kinda like the way that old girl friend made you feel.

Nice as the EI is, due to its more complex advance curve, I think it homogenizes the traditional power feel of the bikes and changes their character. Perhaps it's just my imagination, but the stock set up feels better, it gives the bike that authentic 'Triumph punch.'
 

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Remember, you have two adjustments: one moves the points left or right. This is what you set the timing with. The other adjustment is for points gap, it moves the points closer or further away from the points cam.
Ideally, you set the gap with one and the timing with the other. But on a fifty year old bike that who knows who has been messing with over the years, things aren't always ideal.... That's why you may have to try slightly different points gaps to get the timing to come in.
As long as the cellophane lets go more or less where it should, the engine will run pretty good.
Also, be sure to move the points cam with the rear wheel--don't put a wrench on the points cam! You can also turn the engine over with the crank on the left side of the engine, problem is, then you have to be in two places at the same time!
And of course, set gap first, timing second.
 
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