Help & FAQs    Search BCF    Members    Groups    Events Calendar
Resend my activation email : Register : Log in 
BCF: Bike Chat Forums


Ignition advancer.

 Reply to topic
Bike Chat Forums Index -> The Workshop
View previous topic : View next topic  
Author Message

Kawasaki Jimbo
World Chat Champion



Joined: 09 Oct 2015
Karma :
PostPosted: 19:55 - 12 Oct 2019    Post subject: Ignition advancer. Reply with quote
Someone with a ZX7R has written in to Practical Sportsbikes (October) saying they have a DynoJet Stage 1 tune (like my 6R) and a 4 degree ignition advancer. Wassat? And should I get one?
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

stevo as b4
World Chat Champion



Joined: 17 Jul 2003
Karma :
PostPosted: 00:09 - 13 Oct 2019    Post subject: Reply with quote
Yes you should if you have a skimmed and flowed cylinder head, and you run on super unleaded or race fuel.

In essence it does nothing for peak power on a std engine, just moves the torque delivery around favouring low down response. If you run high octane fuel then advancing the part throttle timing might get you something worth having. But an ignition advancer rotor is old school and vastly inferior to a fully programmable ignition. The thing on a four stroke bike is that unless you've been into the engine for serious tuning, then a tunable ignition map won't really make much difference to performance on a std bike. Your better off just messing with fueling for exhaust and intake modifications IMO.
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

Easy-X
Super Spammer



Joined: 08 Mar 2019
Karma :
PostPosted: 12:00 - 13 Oct 2019    Post subject: Reply with quote
stevo as b4 wrote:
Yes you should if you have a skimmed and flowed cylinder head, and you run on super unleaded or race fuel.

In essence it does nothing for peak power on a std engine, just moves the torque delivery around favouring low down response. If you run high octane fuel then advancing the part throttle timing might get you something worth having. But an ignition advancer rotor is old school and vastly inferior to a fully programmable ignition. The thing on a four stroke bike is that unless you've been into the engine for serious tuning, then a tunable ignition map won't really make much difference to performance on a std bike. Your better off just messing with fueling for exhaust and intake modifications IMO.


Purely for educational purposes, what does advancing the timing do, as a general concept?
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter
 Back to top
View user's profile Send private message You must be logged in to rate posts

Riejufixing
World Chat Champion



Joined: 24 Jun 2018
Karma :
PostPosted: 12:20 - 13 Oct 2019    Post subject: Reply with quote
Easy-X wrote:
Purely for educational purposes, what does advancing the timing do, as a general concept?

It makes it go bang earlier.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Bhud
World Chat Champion



Joined: 11 Oct 2018
Karma :
PostPosted: 12:50 - 13 Oct 2019    Post subject: Reply with quote
Pinging is the main risk involved, and it can be exacerbated by hotspots in the cylinder head and on the piston crowns. I did it to my XJ600 after I'd had the head off and removed all the carbon deposits, and it made a noticeable difference. It's a common mod for those bikes. However, they aren't bikes that people worry about unduly...
 Back to top
View user's profile Send private message You must be logged in to rate posts

weasley
World Chat Champion



Joined: 16 Oct 2010
Karma :
PostPosted: 14:01 - 13 Oct 2019    Post subject: Reply with quote
Riejufixing wrote:
Easy-X wrote:
Purely for educational purposes, what does advancing the timing do, as a general concept?

It makes it go bang earlier.


If by “earlier” you meant “later”, then spot on.

The spark normally goes off some time before top-dead-centre (TDC), meaning that the the combustion starts as the piston is still moving up. This means that the first little bit of effort put out by the combustion is actually working against the engine, but eventually the piston moves past TDC and the bulk of the combustion happens during the down-stroke.

If you have a higher compression and use more knock-resistant fuel (higher RON) you can get away with advancing the spark so it happens later, meaning more of the ‘bang’ goes into pushing the piston down rather than slowing it down.
____________________
Yamaha XJ600 | Yamaha YZF600R Thundercat | KTM 990 SMT | BMW F900XR TE
 Back to top
View user's profile Send private message You must be logged in to rate posts

Riejufixing
World Chat Champion



Joined: 24 Jun 2018
Karma :
PostPosted: 15:36 - 13 Oct 2019    Post subject: Reply with quote
Riejufixing wrote:
Easy-X wrote:
Purely for educational purposes, what does advancing the timing do, as a general concept?

It makes it go bang earlier.

weasley wrote:
If by “earlier” you meant “later”, then spot on ... If you have a higher compression and use more knock-resistant fuel (higher RON) you can get away with advancing the spark so it happens later

Eh? The spark comes further before TDC. Retarding the ignition means it fires later.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Easy-X
Super Spammer



Joined: 08 Mar 2019
Karma :
PostPosted: 18:17 - 13 Oct 2019    Post subject: Reply with quote
Um, so firing at TDC would only be "okay" if the flame front moves at high speed, e.g. Hydrogen. For petrol it takes a little longer so you spark a touch earlier so the point of highest pressure, i.e. the flame front has got to the sides of the cylinder, is just on the downstroke. Have I got that right?

Advancing the timing is sparking earlier and retarding the timing is later?

And where does knock and high octane fuel come into the equation?
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter
 Back to top
View user's profile Send private message You must be logged in to rate posts

misscrabstick
Crazy Courier



Joined: 05 Jul 2013
Karma :
PostPosted: 18:47 - 13 Oct 2019    Post subject: Reply with quote
Weasley said

"If by “earlier” you meant “later”, then spot on."

No, advanced is making the spark happen further before TDC, retarding it is nearer to or after TDC.

Advance means occurring earlier, and retarding occurring later.
 Back to top
View user's profile Send private message Send e-mail Visit poster's website You must be logged in to rate posts

Nobby the Bastard
Harley Gaydar



Joined: 16 Aug 2013
Karma :
PostPosted: 18:58 - 13 Oct 2019    Post subject: Reply with quote
weasley wrote:


If by “earlier” you meant “later”, then spot on.

The spark normally goes off some time before top-dead-centre (TDC), meaning that the the combustion starts as the piston is still moving up. This means that the first little bit of effort put out by the combustion is actually working against the engine, but eventually the piston moves past TDC and the bulk of the combustion happens during the down-stroke.

If you have a higher compression and use more knock-resistant fuel (higher RON) you can get away with advancing the spark so it happens later, meaning more of the ‘bang’ goes into pushing the piston down rather than slowing it down.


Actually, advancing the ignition means the spark happens earlier.

Most ignitions have a method of advancing the ignition as the engine revs incre|se because the bang needs time to propgate. Typically, the spark actually happens before the piston is at tdc. As the engine speed increases the spark has to be earlier as that the propogation of the compustion takes the same length of time . if it wasn't earlier, the bang would happen progressivly after tdc as revs increase, costing power.

most rev limiters actually work by retarding the igntion, stopping the engine from overrevving. If they just cut the spark entirely , fuel mixture would just go down the exhaust and go bang really loudly every time you hit the rev limiter.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050
 Back to top
View user's profile Send private message You must be logged in to rate posts

Riejufixing
World Chat Champion



Joined: 24 Jun 2018
Karma :
PostPosted: 22:13 - 13 Oct 2019    Post subject: Reply with quote
misscrabstick wrote:
No, advanced is making the spark happen further before TDC, retarding it is nearer to or after TDC.

I bet he knows that really, it's just the drink confusing things.

Nice to see you both, by the way.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Riejufixing
World Chat Champion



Joined: 24 Jun 2018
Karma :
PostPosted: 22:15 - 13 Oct 2019    Post subject: Reply with quote
Nobby the Bastard wrote:
If they just cut the spark entirely , fuel mixture would just go down the exhaust and go bang really loudly every time you hit the rev limiter.

....or when you let go of the kill switch, or switch the ignition back on, and a bloody great flame shoots out too. Oh! Is that the time, sorry, must run.... Smile
 Back to top
View user's profile Send private message You must be logged in to rate posts

weasley
World Chat Champion



Joined: 16 Oct 2010
Karma :
PostPosted: 09:16 - 14 Oct 2019    Post subject: Reply with quote
Yep, ignore me, got it right in my head but wrong out loud. As you were.
____________________
Yamaha XJ600 | Yamaha YZF600R Thundercat | KTM 990 SMT | BMW F900XR TE
 Back to top
View user's profile Send private message You must be logged in to rate posts
Old Thread Alert!

The last post was made 4 years, 194 days ago. Instead of replying here, would creating a new thread be more useful?
  Display posts from previous:   
This page may contain affiliate links, which means we may earn a small commission if a visitor clicks through and makes a purchase. By clicking on an affiliate link, you accept that third-party cookies will be set.

Post new topic   Reply to topic    Bike Chat Forums Index -> The Workshop All times are GMT + 1 Hour
Page 1 of 1

 
 You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum

Read the Terms of Use! - Powered by phpBB © phpBB Group
 
Debug Mode: ON - Server: birks (www) - Page Generation Time: 0.10 Sec - Server Load: 0.91 - MySQL Queries: 17 - Page Size: 82.9 Kb