won't idle low=too much timing?

[usefulidiot]

I am not sure how old the ATD is. I suspect it is ok since it ran great a few weeks ago. Ed Strain rebuild the armature and has a good reputation so for now i'm going to work on the assumption that the mag is fine and the problem is operator error (me). My local guru (Wes Scott Cycles) re-assembled the mag for me and tested the spark etc and reported it to work great. The points, while being a giant pain in the butt to fit a wrench in to adjust...appear to be good. None of the excessive sparking that was mentioned and they are not corroded. I just got home and waiting in the mailbox was the degree wheel, shaft, and piston stop so now i have the tools to accurately check and set the timing. That is the next order of business. Hopefully i'll be able to report back that the problem is fixed. Thanks very much for the ideas so far

 

[Kansas Bad Man]

You can get real close on the timing with a K1, small screwdriver, small cresent, lead pencil, piece of cellophane off a pack of cigarettes, spark plug wrench

and a Vincent with a rear stand B or C With a magneto and a buddy.

 

[Magnetoman]

Ed Strain rebuild the armature ... (Wes Scott Cycles) re-assembled the mag for me and tested the spark etc and reported it to work great. ... for now i'm going to work on the assumption that the mag is fine

The fact that one guy rewound the armature, and a different shop that does general repair work assembled it, means you shouldn't hold on to the assumption too strongly that it is fine. While your refurbished magneto might be fine, I would suggest as you proceed to try to sort out your problems that you don't have it too far in the back of your mind that this refurbished magneto has not been eliminated as a possible culprit.

 

[Magnetoman]

You can get real close on the timing with ...

I don't have the figure handy, but it should be pretty easy for you to find (or for someone else to post) how many mm BTDC a Vincent engine should be when the points open. A machinist's ruler fits down the spark plug hole and it is easy to determine TDC and the correct no. of mm BTDC accurately enough to get the timing within better than 2 degrees.


I'm not arguing against degree wheels and piston stops since you can do even better with them than is possible with a ruler. But, a ruler is quick and more than good enough to get the timing set close enough for the engine to run quite well.

 

[Kansas Bad Man]

1/ 2 inch to 5/8 inch, depending on fuel, the lower the octane number the closer to the 1/2 inch.

 

[cinquecento]

you've seen this , right? lifted from elsewhere with credit at the bottom. I'm a 34deg full advance BTDC man m'self but that's with a Comet, do a search for posts there are some very interesting first hand practical experiences here. You'll need to do metric conversion yer'self.
Degree travel down bore in inches :
0 -------- 0.000
1 -------- 0.000
2 -------- 0.001
3 -------- 0.003
4 -------- 0.005
5 -------- 0.008
6 -------- 0.012
7 -------- 0.016
8 -------- 0.021
9 -------- 0.027
10 -------- 0.033
11 -------- 0.040
12 -------- 0.048
13 -------- 0.056
14 -------- 0.065
15 -------- 0.075
16 -------- 0.085
17 -------- 0.096
18 -------- 0.107
19 -------- 0.120
20 -------- 0.132
21 -------- 0.146
22 -------- 0.159
23 -------- 0.174
24 -------- 0.189
25 -------- 0.205
26 -------- 0.221
27 -------- 0.238
28 -------- 0.255
29 -------- 0.273
30 -------- 0.292
31 -------- 0.311
32 -------- 0.330
33 -------- 0.350
34 -------- 0.371
35 -------- 0.392
36 -------- 0.414
37 -------- 0.436
38 -------- 0.458
39 -------- 0.481
40 -------- 0.504
Tom Gross 9/1/10

 

[Magnetoman]

You'll need to do metric conversion yer'self.

I carry an appropriate metric ruler in my toolkit, on the back of which I've taped timing measurements of every British bike for which I could find data (the print is tiny, but I also carry an eye loupe in the toolkit). It's not that I don't love the English system of measurement, but it's a lot easier to determine TDC on an engine to a tenth of a mm with the ruler, then add that number to that the timing spec. for the engine, to determine where BTDC needs to be, than it is to quickly and accurately add, say, 13/64" to 7/16" to help someone set his timing when kneeling on the side of a muddy road in the rain as cars whiz by.

p.s. note in the above table that the difference between, say, 34-deg. and 33-deg. is 0.021", i.e. 1/2mm. It is easy to determine the positions of the piston at TDC and BTDC to better than this, which is why the ruler method works just fine. Even if you have the world's best protractor and TDC-Locator in your garage for setting the timing to the nearest 0.0001 deg., it's unlikely you will have those instruments with you on the road. If you do need to set the timing of your engine while on the road you will be quite happy to be able to do it to the accuracy a ruler gives you.

 

[usefulidiot]

I've seen that chart or a similar one on thevincent.com. I dont know why i didnt think to use a machinists ruler..i have one and do amateur lathe stuff. I just scribed TDC on a piece of drill rod while sighted visually along the top of the plug thread then transferred i believe it was .392 (35degrees) and sighted that along the top plug thread as the piston went down. The ruler probably would have been a lot more accurate haha. I'll find out when i get a chance to go and check the degree wheel vs what i did.

 

[Kansas Bad Man]

What works for me, 65 o nitro, 45 o alcohol , 42 to 38 o gas. Some would say to much lead, then others would say not enough. that's why I own a water brake.

 

[bmetcalf]

I use a spoke and nipple trimmed to a length suitable for my thumb to fit between the nipple and the head bracket at TDC. I have filed a notch at 1/2" BTDC*. After dropping it into the chamber one time, I added a wire loop to avoid that. Luckily, it is magnetic.

* Based on the above chart I will use my timing disk and see where 34 deg falls.