• Welcome to the forum website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Online Forum Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this forum website.

    If you have previously registered to use this forum website, you should log in now. CLICK HERE.

    If you have never registered to use this forum website before, please CLICK HERE.

Pazon Sure Fire

Howard

Well Known and Active Forum Website User
VOC Member
Does anyone else use Pazon Sure Fire (not Smartfire) on a twin?

If so are the timing marks in the right place?

I started at 34 BTDC, that seems to be the norm on modern petrol. That was way to retarded (it started well, but it ran very hot and flat), and it gradually crept up to 40. After Mallory on Saturday, I felt the timing was still too retarded, and yesterday I increased to 43 BTDC ........ No pinging and a significant increase in performance!

I can't beleive it really is 43 degrees, but there's no "easy" way of knowing where it's actually firing.

Help ! ?

H
 

timetraveller

Well Known and Active Forum Website User
VOC Member
A combination of some of our French members and clevtrev produce a nifty litle gadget that fits inside the timing side mainshaft and replaces the big end quill. This carries a degree plate made from a CD or DVD disc and allows one to use a stroboscope on a Vincent while the engine is running. This allows a proper check on the timing.
 

goin michel

Well Known and Active Forum Website User
Non-VOC Member
A combination of some of our French members and clevtrev produce a nifty litle gadget that fits inside the timing side mainshaft and replaces the big end quill. This carries a degree plate made from a CD or DVD disc and allows one to use a stroboscope on a Vincent while the engine is running. This allows a proper check on the timing.

It's Francois Grosset work with the help of Trevor Southwell. Look the last MPH publicity of François (electric-starter and electronic-ignition) and you will have his e-mail (PONTRICOUL@aol.com)

Michel​
 

Howard

Well Known and Active Forum Website User
VOC Member
Thanks for the replies TT and Michel. I'm not really that bothered where it's set to (apart from curiosity) when I get it running at its best, I'll set the piston stop to coincide with the red dot for future setting. I just wondered if other users had had similar discrepancies. The Pazon is a nice simple piece of kit that works well, but it could do with an LED (eg) to indicate when "the points open".

H
 

davidd

Well Known and Active Forum Website User
VOC Member
Howard,

That is a very interesting result. Like Timetraveler I am interested in your final decision. It seems a bit counter intuitive to advance the timing that significantly. It leads one to believe that the charge, with the addition of the quicker burning twin plug ignition, is burning much slower,thus, requiring more advance.

Two things that I think are important with ignition mods: Check the timing with a strobe at least once to verify your settings, and set the timing at least once with a dyno to find out what setting makes the best power. Timetraveler reported Roy Robertson's timing range for his much modified twin to be 18-24 degrees. I have run 19 degrees on my racer for the past five races. I strobed mine and set it on a dyno and I suspect Roy did also.

David
 

Howard

Well Known and Active Forum Website User
VOC Member
addition

OK TT wait til I've reached a conclusion, and I'll have a shot at measuring where it's firing.

David, I'm only on single plugs. Peter Appleton says he's running 40 degrees on a more sophisticated ignition computer and thinks he could go higher, and if the timing marks are right, I've past that and still going.

My thought is, why do conventional systems stop advancing at 4,000 rpm (ish)? Why should the advance be the same at everything over 4,000 rpm? Could it be that there is such a wide range on my advance curve that I can keep advancing it to suit 5, 6, 7,000rpm but not be over advanced at lower rpm? I don't know. All I know is, based on the Pazon timing mark I'm running at 43 degrees, and so far every advance has made a perceptible improvement. Watch this space.

H

ps Just wait til I get to 60 BTDC - that Ged Abrahams won't be coming past me next year !!! ;-)
 
Last edited:

John Appleton

Well Known and Active Forum Website User
VOC Member
OK TT wait til I've reached a conclusion, and I'll have a shot at measuring where it's firing.

David, I'm only on single plugs. Peter Appleton says he's running 40 degrees on a more sophisticated ignition computer and thinks he could go higher, and if the timing marks are right, I've past that and still going.

My thought is, why do conventional systems stop advancing at 4,000 rpm (ish)? Why should the advance be the same at everything over 4,000 rpm? Could it be that there is such a wide range on my advance curve that I can keep advancing it to suit 5, 6, 7,000rpm but not be over advanced at lower rpm.


Yep,

Keep going Howard, you are exactly on the right track, and bear in mind that many of those obsolete and worn ATD's reach full advance at a lot less than 4000 rpm. John
 
Last edited:

Tom Gaynor

Well Known and Active Forum Website User
VOC Member
This comes from a separate discussion with David Dunfey, with the help of an article by Kevin Cameron, copies on receipt of private email.
Gilera and Honda multis, with a thin crescent section combustion space, ran advance of 55-60 degrees. "The burn" lasts twice the advance, so the mixture was still burning 55 deg ATDC. Nortons had much more efficient combustion chamber shapes, so ran 34 deg advance. (The Britton, and the legendary Harley racer "Lucifer's Hammer - wonderful name - ran something like 18 degrees advance.) IF twin plugs were doing any good, then advance would be reducing, because the mixture would burn faster. (This was my point when I started the thread "what advance do you run with twin plugs?" If it isn't LESS than with a single plug, the second plug is doing nothing. No one who answered ran significantly less. Ergo, twin plugs are a waste of time and money. I apologise in advance to anyone running, say, 34 with one plug, 24 with two, who didn't respond.)
So: the more advance one needs, the LESS efficient combustion is. If one is up to 43 degrees with twin plugs, take one plug lead off.
Another consideration is that electrickery is intrinsically lazy: if it is easier to fire one plug than the other, then that's where the current will go. If the "easiest plug" is not the best one from a combustion POV, then one will have to advance the timing to accommodate a slower burn rate.
Which means lower BMEP. Which means less torque. Which does not mean more power.
 

davidd

Well Known and Active Forum Website User
VOC Member
Sorry about the "twin" confusion. It is interesting that you are getting more power by allowing for a longer burn, but the proof is in the numbers. The article that Tom mentions raised some interesting questions about ignition timing. I know very little about advance curves except that modern tuners want to design their own curve, which can be done with many new ignitions. The curves that I have seen for BT-H and Pazon as I remember are fairly traditional. I think they both stop advancing below 3250 rpm. It is another reason why it may be valuable to use a strobe in order to see if the advance is working as one would expect.

David
 
Warning! This thread is more than 11yrs ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.
Top