Page 4 of 5
Re: Which ignition retard
Posted: Tue Aug 19, 2014 1:21 pm
by rondord
Adam is correct and special x is showing how little he understands two stoke engines.
special x do a search on google for ignition and rpm effect on 2 stroke flame front combustion or something similar, you might learn some thing mate
Re: Which ignition retard
Posted: Thu Aug 21, 2014 10:36 am
by nelson pk
Yep.
To special x, I think you are confusing 4 stroke ignition with 2 stroke.
A two stroke ignition system that advances with revs would be a recipe for disaster! However modern four stroke ignitions do advance with revs.
Even if you did set it safe....say 10 degrees advancing to say 16 or 17 degrees you would get less performance low down than a static set at 16 or 17 so there would be no gains at all.
Re: Which ignition retard
Posted: Fri Aug 22, 2014 5:25 pm
by Special X
So . . . . . . petrol burns at a uniform speed in a four stroke, but in a 2 stroke the petroil mixture senses that the revs are higher, and burns faster and faster as the engine speed rises.
Ok I'm sorry I was wrong, and I bow to your superior understanding of special physics.
Re: Which ignition retard
Posted: Fri Aug 22, 2014 9:19 pm
by jason frost
Re: Which ignition retard
Posted: Fri Aug 22, 2014 9:26 pm
by jason frost
Its about heat, as revs rise power and heat rise, by moving the timing closer to tdc you move the heat into the exhaust and not the cylinder head/ piston and you don't melt the piston.
Re: Which ignition retard
Posted: Fri Aug 22, 2014 10:01 pm
by drunkmunkey6969
Special X wrote:You're absolutely right that variable ignition timing is better than static Adam, but it needs to advance as the revs rise, Rearding as the revs rise is a way of stopping an engine with too high compression, poor head design, wrong squish, etc grenading. A correctly set up motor with the ignition advancing as the revs rise would be the way forward.
Trouble is fashion now dictates that we all need to fit auto retard kits.
Horseshit.
Re: Which ignition retard
Posted: Fri Aug 22, 2014 10:07 pm
by Yanker
drunkmunkey6969 wrote:
Horseshit.
Just slapped mi Wellies on as the waders are in the attic
(also removed any red clothing incase there is any 'Bull' version arround - it does stick you know)
PS maybe the perp should fit one of those 'retard' kits back to front and appraise it for us Luddites?
Re: Which ignition retard
Posted: Mon Aug 25, 2014 10:50 am
by nelson pk
Special X wrote:So . . . . . . petrol burns at a uniform speed in a four stroke, but in a 2 stroke the petroil mixture senses that the revs are higher, and burns faster and faster as the engine speed rises.
Ok I'm sorry I was wrong, and I bow to your superior understanding of special physics.
Tell you what....get a ignition on your scoot that can be mapped. Tell the tuner you want 10 degrees to start off advancing to 17 or 18 degrees..... they mask ask whats the point??? but insist and see how s**t it runs at low revs compared to static at 17 degrees.
Then get it remapped to go from 16 degrees to advance to 23 or 24 degrees at top revs and watch your piston melt!
Go for it, I dare you
Re: Which ignition retard
Posted: Mon Aug 25, 2014 10:52 am
by nelson pk
jason frost wrote:Its about heat, as revs rise power and heat rise, by moving the timing closer to tdc you move the heat into the exhaust and not the cylinder head/ piston and you don't melt the piston.
Bang on. If you retard your timing your egt goes up as more heat goes into the pipe and if you advance, egt goes down as more heat is held in the head.
Re: Which ignition retard
Posted: Wed Aug 27, 2014 11:32 am
by fishi
SIP in Germany, has a nice CDI, too
a blue and yellow one, from HHP
looks very good in quality, anybody knows more about it?