ADVrider

Go Back   ADVrider > Bikes > Old's Cool > 2 smokers
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 05-24-2012, 03:23 PM   #1
Reino OP
Gnarly Adventurer
 
Reino's Avatar
 
Joined: Nov 2011
Location: namibia
Oddometer: 206
Eh? calling all knowledgeable 2smokers, brace your self .. 3d ignition questions!

In the next 3 years i would probably have gathered enough money to start my project (don't ask its a secret till its done).In the meantime i am doing research especially on 3d ignition maps, but so far i have not yet found a collection of 3d maps or good explanations on what happens under load in 3d maps.I am replacing the cdi on my 250sx with a system that can do anything so it would be a shame not to use a 3d map.

my questions:

1-is a 3d map worth it

2-what happens under load

3-how would a 3d map look like (i am well informed about 2d maps)

I live in Namibia (just above South Africa) so because of my time zone i would probably take a while to respond.
Reino is offline   Reply With Quote
Old 05-25-2012, 02:14 PM   #2
Reino OP
Gnarly Adventurer
 
Reino's Avatar
 
Joined: Nov 2011
Location: namibia
Oddometer: 206
so no replies, well thanks anyway .

Can someone just answer one of my 3 questions?
Reino is offline   Reply With Quote
Old 05-25-2012, 07:33 PM   #3
Ever Onward
Time Killer
 
Ever Onward's Avatar
 
Joined: May 2011
Location: Past the point of no return
Oddometer: 706
Best to ask these questions over on a Honda RS board or a Yamaha TZ website.

Its a very complex tech question. Far beyond a simple ignition advancer. Way beyond my grey market 2 stroker knowledge, sorry.
Ever Onward is offline   Reply With Quote
Old 05-26-2012, 02:18 AM   #4
Reino OP
Gnarly Adventurer
 
Reino's Avatar
 
Joined: Nov 2011
Location: namibia
Oddometer: 206
thanks for the reply, around 2 o'clock this morning i found a guy by sheer luck on the interwed that may be able to answer my question.
Reino is offline   Reply With Quote
Old 05-26-2012, 04:48 PM   #5
Shocktower
Beastly Adventurer
 
Shocktower's Avatar
 
Joined: Jul 2009
Location: Oregon City Orygun
Oddometer: 9,450
Dam n00bs , good luck with that, I had no idea WTF he was talking about, if it does not have points whats the points
__________________
Alexa Drew Nov 9 1995- Oct 28th 2004 Miss you baby


'08 KTM 530 EXC
79 RD 400 Daytona
Shocktower is offline   Reply With Quote
Old 05-27-2012, 02:58 AM   #6
Reino OP
Gnarly Adventurer
 
Reino's Avatar
 
Joined: Nov 2011
Location: namibia
Oddometer: 206
good points .

Reino screwed with this post 05-27-2012 at 03:36 AM
Reino is offline   Reply With Quote
Old 05-27-2012, 11:34 AM   #7
hrcs90
Adventurer
 
hrcs90's Avatar
 
Joined: Mar 2011
Location: SW Montana/Northern Wis
Oddometer: 27
I think load is going to be pretty hard to determine on a 2 stroke. I would maybe look at tying into a knock sensor.
hrcs90 is offline   Reply With Quote
Old 05-27-2012, 01:19 PM   #8
Reino OP
Gnarly Adventurer
 
Reino's Avatar
 
Joined: Nov 2011
Location: namibia
Oddometer: 206
The load i am referring to is throttle opening which is measured by a tps in % or vacuum by the map sensor in pascal.

ignition curves for cr500 below

http://i870.photobucket.com/albums/a...396/graph9.jpg

A 2stroke ignition sees most advance in the early parts of the rpm range (30 degrees) to get the exhaust temp high to maximize scavenging and drops after max torque to something like 9 degrees btdc to maximize over-rev, this is for a 2d map of coarse but you get the point.

I thought about this topic for a while and realized an expansion chamber's scavenging effect is optimized for a certain temp, so with less load you can effectively increase advance to increase exhaust temp for throttle response. under load you would retard to decrease temp to decrease chance of melting the piston.

this is why i love 2strokes, deceptively complex bastards.

Reino screwed with this post 05-27-2012 at 02:41 PM Reason: forgot info
Reino is offline   Reply With Quote
Old 05-27-2012, 07:10 PM   #9
Ever Onward
Time Killer
 
Ever Onward's Avatar
 
Joined: May 2011
Location: Past the point of no return
Oddometer: 706
Not sure how this will tie into your design theorys, but, sometimes builders use thermal retention pipe wrap on expansion chambers to increase the working temperature of the pipe itself.

You see this on two stroke snowmobile race engines sometimes. No idea the adverse effects if run in a application where it would make the pipe run too hot.

Most also run EGT sensors a specific distance from the piston skirts in the headpipe of the expansion chamber to keep a close eye on how hot things are running, and to help judge if their air / fuel mixture ratio is right at different throttle positions.
Ever Onward is offline   Reply With Quote
Old 05-28-2012, 02:48 AM   #10
Reino OP
Gnarly Adventurer
 
Reino's Avatar
 
Joined: Nov 2011
Location: namibia
Oddometer: 206
Thanks for your input low budget, i am probably going to use a EGT to measure my temp so that i am just under melting a piston at every rpm and load situation under max torque.

I Know the yz250, rs250, tz250 and tzr250 used 3d maps.

But i am still not certain if it is worth while to use a 3d map, at the moment that's my biggest problem.
Reino is offline   Reply With Quote
Old 05-28-2012, 06:18 AM   #11
Ever Onward
Time Killer
 
Ever Onward's Avatar
 
Joined: May 2011
Location: Past the point of no return
Oddometer: 706
Yes, a good quality EGT gauge thats located in the right spot will let you know when things are getting to hot early enough to shut it down before damage.

It reacts very fast, and is a better indicator than a typical engine temp gauge as to whats going on at that moment in the combustion chamber.

Once you have a engine setup all dialed in, and note the EGT running temp at a given situation, you can then use that number as your benchmark for doing further tuning. Like rejetting for altitude differences or temperatures and humidity changes.

You may very well be OK with a 2d ignition and other things than be overly complicated trying to combine the extra variables of the 3d .

Its all rocket science at that point !
Ever Onward is offline   Reply With Quote
Old 05-28-2012, 06:29 AM   #12
Reino OP
Gnarly Adventurer
 
Reino's Avatar
 
Joined: Nov 2011
Location: namibia
Oddometer: 206
i think i should drop 3d map and stick with a 2d one. I have a big test on the 7th next month on centriods and moment of inertia. My time is better spent studding. Afterwords i am going to have a lot of these and do a lot of this and this .
Reino is offline   Reply With Quote
Old 07-28-2012, 05:32 PM   #13
Reino OP
Gnarly Adventurer
 
Reino's Avatar
 
Joined: Nov 2011
Location: namibia
Oddometer: 206
I know this thread is old but, I have my answer.

My assumption was correct. The less load the more advance there is below peak torque the difference becomes less the more you rev the engine.

Finally some closure!
Reino is offline   Reply With Quote
Old 07-29-2012, 08:38 AM   #14
Twin-shocker
Beastly Adventurer
 
Joined: Jan 2012
Oddometer: 1,673
The dynamics of a 2T motor are entirely different to those of a 4T, and unless you have access to a dyno, and have an ignition system which can be programmed, you are going to be wasting time and money with this.
Twin-shocker is offline   Reply With Quote
Old 07-29-2012, 09:11 AM   #15
Reino OP
Gnarly Adventurer
 
Reino's Avatar
 
Joined: Nov 2011
Location: namibia
Oddometer: 206
I am well aware of the differences regarding 2t and 4t. As i have explained in my first post, I am scrapping my cdi with a programmable unit.

I am not going to stop at the ignition side. Also having access to a dyno is not a problem for me.

This is going to be a long term project (3 or 4 years).
Reino is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 05:05 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014