Forum

[Creaky45]

Just been reading Scotty's reply to Stalling at Idle. My problem was finding the exact position of TDC because there is a point when the piston does not appear to move but the crankshaft will move to and fro, maybe 6 degrees which would mean your timing could be out either way 3 degrees.I use the cheap Hitchcocks TDC finder. Klutz says to use a Dial Gauge which I don't have. I imagine that would be the best. Anyway how do you make an index mark on the stater (or thereabouts). Have you any photos? I presume you mark the TDC, 32 marks on the outside diameter of the roter. What are your other figure for? To my knowledge, .8mm BTDC is 10 degrees and 8mm is 32 degrees so these plus the TDC mark are all that is required. Is you 'clear plastic' the Hitchcocks alternator gauge (as I have one) and what has that to do with anything? Yes I am running points and the gap is spot on. I realize a wider gap will advance the spark if widened after the timing is set. Also if the timing is a little out at idle it will still only be that same amount out at high revs. What degrees do you think pinging would occur? On my noisy 2006 standard Bullet it would be hard to hear anyway. After all this I still think the old fashioned way of ping timing while riding is as good as any if you're careful and the cigarette paper between the points works just as well as watching the ammeter. Trouble is I don't smoke anymore. I leave that to my bike.

[PeteF]

Just get the timing in the ball park and fine tune it by how-it-goes/ping/kickback.

[ric]

If you're using a dial gauge then set the points to fire on full advance 9.5mm before TDC. This takes into account the angle of the plug hole and the use of modern fuel. To be honest you'll be very lucky to get anywhere as close as 3 degrees using a pencil down the plug hole.

[scotty]

Hi tdc mark is across both rotor and stator plastic strip 1 inch by 8 inches cut from shirt box or similar.you slide it between stst and rotor lining the tdc mark on strip with tdc on rotor then mark at 21mm from that for your 32 btdc. Its the mark on rotor that moves with strobe.will take a few pics as I have a few spare alt assys probably will have to enlist scalybacks help with the post. When motors running rotor mark will move towards 32 btdc mark if out slacken points plate and turn it til marks line up.

[Creaky45]

Ric, That's what I wanted to see, your photo. I bought one of those discs but when I saw it only had a small hole in it I contacted Mr H who said it is used statically on the timing side. No good to me as I wanted to use a strobe. So I enlarged the hole and bolted it under the rotor nut like you did. You have fixed an index mark to the bolt hole in the centre. Very clever. I will try that and give it another go. However without a dial gauge it won't be easy to find the exact TDC. So you say 9.5mm using a dial gauge (vertically) in the same as 8mm as per Mr H.s TDC tool as it is on an angle, correct? (very tricky geometry to work that out).Looking forward to Scottys photos as I still can't figure out what he is doing.

[Gwilly]

Creaky have a look here, i know its for electronic ignition but it shows you how to find TDC using a degree disc..

I shouldn't get too hung up on exactitude as there is so many variables on points ignition due to drive and component wear, points gap etc that as Pete suggests fine tuning is better done by ear out on the road...


http://www.hitchcocksmotorcycles.com/pi ... -08-17.pdf

[ric]

Creaky45. No, 9.5mm through the plug hole is not the same as 8mm, it actually works out around 34* but on the standard bikes running 95octane fuel it does work very well.
Instead of chasing TDC, once the gauge is fixed to the rotor why not go for 15mm before with your TDC tool and note the degree readout, turn the engine and find 15mm after tdc, note the degree readout again and split the difference which is where TDC will be found. The further you measure from TDC the more accurate a reading can be obtained.
Even better would be to use a hard stop. Imagine a very long reach plug that the piston would make contact with, at some point when moving up the cylinder it will come to a hard stop. Take a reading, turn the engine backwards until the piston rises back up the cylinder and stops again. Take the second reading, split the difference and the reading between the two will be as near as needed as accurate as that obtained with a dial gauge. Obviously needs to be something that's not going to fall apart on piston contract or damage it either. Unfortunately totally useless method if you have a sprag clutch!

[Creaky45]

Gwilly, I don't know why I have not seen that PDF before. I don't have Boyer ignition but that article is very good and I will follow it up. And Ric, you have cleared up a question I had from Scotty's reply. This is all very interesting stuff but what it comes down to is take Pete's advice and suck it and see. Yes I do have a sprag clutch and I can still turn the motor backwards slowly because the starter motor will turn backwards but I usually unbolt it and leave it hanging out.