Tuning Issues

Schwany said:

Ignition timing with "reluctant help". Thanks that made me laugh.

Looks like you got it under control, but an alternative in the future if something points at the ignition.... Get a TriSpark ignition from Greg and static time it by yourself without the "reluctant help" using one of the things shown below and old piston height measuring methods to find 29 degrees BTDC. I wrote up the procedure and verified it all with a degree wheel. It might be considered taboo by the more enlightened, but it works if there is no other easy way to get it done.


I use Autolite APP3924 plugs in my Norton engine. Easy to find smaller 5/8" wrench resistor plug. Never have trouble starting the motor hot or cold.

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I made a butterfly degree wheel for my T100 out of cardboard and a computer print out pasted onto it. It runs off the end of the cam. The degrees are a bit different since the cam turns at half engine speed. The T100 has one thing going for it. It has a centering hole in the case so you can find the TDC detent in the crank. I was able to strobe the T100 using my makeshift degree wheel and a pointer. It's a first kick starter now.

I was thinking about doing this to the Norton. Using a dial indicator to find true TDC and checking if the degree graduations on the case are accurate. My poor old eyes are so shot I was having trouble locating the timing marks in that hole.

Big_Jim59 said:

OK, It's better. I screwed the air screws out only 3/4 as at starting point and I set the idle up a bit. I changed plugs from Autolite AP64 to Autolite 63 (I couldn't locate and Autolite AP63s) It took it for a ride and got it hot. Noticed that the farting and popping on a close throttle is gone. I dialed the idle down and it runs nice and takes gas well when bliping the throttle. The true test came later. I let it sit in the garage for three minutes and it fired off. I let it sit for another 15 minutes and again it fired off.

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Once you're completely happy, if your air screws are still 3/4 turn out, start looking for an air leak which could just be worn slides. Anytime I have to go less than 1-1/4 out I fix the problem and there always is one.

Can't say for other setups, but Tri-spark ignition, Premier carbs and no chokes installed, the bike should start and idle when cold at about 700 rpm reliably and once warm that will increase to about 1100 rpm. There should be no hesitation when blipping the throttle from 0 to 1/8 turn when warm. The air screw will be 1-1/4 to 1-1/2 turns out. It should start on one kick warm or cold.

When warm, gravity is what determines to tickle or not. If it has sat long enough for the pilot circuit to drain back into the bowl, it may be tough to start without a tickle. However, since when warm the kick is more productive, there's much more of a chance of starting without a tickle than when cold. Also, when warm, a tickle is more likely to flood so, I will give one kick without a tickle and if it doesn't fire, then tickle but not overdoing it.

Big_Jim59 said:

My poor old eyes are so shot I was having trouble locating the timing marks in that hole.

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To make it much easier to see, paint the raised area around the mark black or red and then either scratch the paint out of the mark or paint white in the mark. Then you need someone on the throttle and to get down with your eye level with the opening in the primary case. Since I have trouble getting down that low, I work the throttle and have a more flexible person down looking - they only need to say which side of correct the mark is on.

marshg246 said:

To make it much easier to see, paint the raised area around the mark black or red and then either scratch the paint out of the mark or paint white in the mark. Then you need someone on the throttle and to get down with your eye level with the opening in the primary case. Since I have trouble getting down that low, I work the throttle and have a more flexible person down looking - they only need to say which side of correct the mark is on.

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Funny you should say this. I press ganged my son-in-law (the one with the good eyes and small frame) to crawl on the garage floor and site the timing mark. He said all looks good but I still wonder about the advance curve built into the unit.