Question for those that have or currently are running advanced timing

[99LRDblaster]

I was curious as to what your setups were and what changes you made in terms of fuel and how it worked out for you. I've somewhat been toying with the idea after seeing many reports of the how supposedly "conservative" the stock timing is from Yamaha......which makes sense in a lot of respects for reliability/cooling purposes. I'm not sure I would opt for the 4 degree change like most do, but probably just go a little more conservatively and go with a 2-3 degree change. What causes the increased heat build up that I tend to hear all the time with advanced timing....assuming you are not having pre-detonation.....Is it simply the microsecond extra where deflagration occurs within the combustion chamber or what? The idea simply struck some curiosity in me, and I figured if it's conservative as is....supposedly, then I might as well look into a minor change in timing if it can prove to be beneficial.

 

[mac2mac]

Thats what I been asking for the longest time . One person said go +3 if your running completely stock .+4 if you have any thing upgrade on your bike.... I'm thinking the same as you , I don't want to go max and mess up the way it runs but I do have a ricky stator plate I want to use. I had it on for years now... Ricky Stator I think you can take off your stock parts and put it on here. but I would get the 75w stator like I did Ricky Stator then you can add a ground and a Rectifier/Regulator Ricky Stator and a battery for HIDS....lol ... or you can drill out the stock , someone was saying its in this forum how to

 

[hudack]

for your motor with the 170 something compresion i would not sugest it you were already haveing problems with detonation someone else could probley chime in with some more info but thats my 2 pennies on it

 

[hudack]

Thats what I been asking for the longest time . One person said go +3 if your running completely stock .+4 if you have any thing upgrade on your bike.... I'm thinking the same as you , I don't want to go max and mess up the way it runs but I do have a ricky stator plate I want to use. I had it on for years now... Ricky Stator I think you can take off your stock parts and put it on here. but I would get the 75w stator like I did Ricky Stator then you can add a ground and a Rectifier/Regulator Ricky Stator and a battery for HIDS....lol ... or you can drill out the stock , someone was saying its in this forum how to

if you make a thread about this im sure you would get the answer you want
just saying

 

[Awk08]

timing is dangerous power, < straight from a factory yamaha race team engineer
add in a shaved head, which, in itself advances timing by lowering the plug further into the cylinder and your flirtin with disaster, just my opinion, some guys luv it
i'd rather stay reliable and spend the money i woulda wasted when pistons fry, on other go fast goodies

 

[super noober]

freek and battbike both have thier timing turned up +4 and lots of us have seen thier bikes run in person and its quite impressive. they have not had any reliability issues at all with the timing in addition to redesigned heads, stroker cranks or anything. but like awk said to each his own but when i get my head adn lightened flywheel back i will be advancing my timing but im going more than the norm muaahahaha I:I

 

[99LRDblaster]

timing is dangerous power, < straight from a factory yamaha race team engineer
add in a shaved head, which, in itself advances timing by lowering the plug further into the cylinder and your flirtin with disaster, just my opinion, some guys luv it
i'd rather stay reliable and spend the money i woulda wasted when pistons fry, on other go fast goodies

I'll agree it's dangerous power if done improperly. I don't really see how a shaved/milled head advances the timing. Whether your raise or lower the head, the plug still sparks the same time. With a shaved head, it would actually be more like retarding the time in my opinion. The whole benefit of advancing the timing is sparking the plug 4 degrees(or whatever) earlier, so the the fuel has more time to combust and ideally can achieve maximum/better combustion figures around TDC which in turns provides more force to push down on the piston. If you have a shaved head, this would actually....in my opinion...."retard" the timing per se since you have decreased the distance to the head at TDC so when the plug fires on stock timing, there is even less time for the air/fuel mixture to combust as you have increased compression and shortened the distance(with a stock chambered milled head) for the air/fuel mixture to deflagrate. At least that's how I am seeing it.

 

[slickerthanyou]

I have seen the above blasty's with the timing advance and they surely didn't have any problems, and screamed!
I don't understand enough about it to use it, but I was told not to use this, so I listen to those who know more about it than me. I'd be willing to learn if we can get some insight into this...

 

[99LRDblaster]

for your motor with the 170 something compresion i would not sugest it you were already haveing problems with detonation someone else could probley chime in with some more info but thats my 2 pennies on it

Yea, I was, but I'm running mixed gas with 110 octane now and it's all good now. I:I

 

[99LRDblaster]

I have seen the above blasty's with the timing advance and they surely didn't have any problems, and screamed!
I don't understand enough about it to use it, but I was told not to use this, so I listen to those who know more about it than me. I'd be willing to learn if we can get some insight into this...

The core premise is fairly simple. Essentially, your air/fuel mixture deflagrates before TDC in order to make the fuel burn/combust. It does this before TDC because it takes time for the air/fuel mixture to deflagrate while the piston is moving up towards the head/TDC. If the plug sparked right at TDC, you would have very little force/power since the air/fuel mixture would be deflagrating while the piston was already on it's way down...essentially just bouncing off the deflagration of the air/fuel mixture instead of actually going through a higher compression combustion state where the combustion will DRIVE the piston down. The whole premise of power/force production is maximizing the force of the piston on the downstroke. With advancing the timing EARLIER than stock timing, you ignite the plug whatever degrees earlier which allows the air/fuel mixture to deflagrate earlier which may or may not improve maximum combustive efficiency. For example, let's just say the Blaster's stock timing doesn't achieve this(hypothetically). It puts out power/force, but it may not be OPTIMAL, therefore if you spark the air/fuel mixture earlier, it gives more time for the air/fuel mixture to deflagrate MORE completely. Greater deflagration equals greater/improved combustion.........thereby increasing the force on the piston driving downwards and increasing the power to the wheels. I:I

EDIT: Advancing timing is dangerous if done improperly for one simple reason. If you advance the timing too much and the air/fuel mixture deflagrates and pushes back down on the piston BEFORE it reaches TDC, this proves to be catastrophic on engine internals and power will decrease. You want to have the flame front during deflagration start at the head from the spark of the plug and then push down on the piston AT or AFTER TDC, not before. Imagine being hit in the face.......now imagine being hit in the face while running at somebody full speed......that's basically what it's like for the piston when the timing is advanced too far and the flame front comes down and punches the piston before TDC/while it is still moving upwards.

 

[99LRDblaster]

Also, as a side note for those of whom have done the mod with timing, what changes did you see. One thing I hear a lot is it increased bottom to mid power, but takes away from top end........which doesn't make sense to me. Now, it's an ENTIRELY different situation, but typically with ECUs in cars, the ECU typically advances timing more at higher RPMs for the increased speed the engine is moving, so you would presume that advancing the timing on the Blaster would help out top end the most, but doesn't seem to be the case for whatever reason.

 

[Blaner]

ok, going back a few essays, you mentioned that you dont understand y shaving the head increases running temps, this is simply because of the increased compression, more pressure = more heat as the fuel and air particles are more densly packed and colliding with each other more frequently, friction causes heat and friction is the result of pressure increases here.

I have the 4degree mod and after my last rebuil last year june i ran the bike for a week on stock timing. I did max speed runs and pulled 63 on a slight downhill (my test street) i then quickly advanced the timing and did more top speed runs, i found NO increase in top speed BUT the initial pull off power was better. HOWEVER, i have found that i do not have complete piece of mind about the running temp, i feel its too hot and because of that, i am going to turn it down to about 2 degrees over stock.

Id like to get a IR heat gun to experiment with it. But on the same note, could richening the jetting help to cool the motor better with 4degree timing?

 

[99LRDblaster]

ok, going back a few essays, you mentioned that you dont understand y shaving the head increases running temps, this is simply because of the increased compression, more pressure = more heat as the fuel and air particles are more densly packed and colliding with each other more frequently, friction causes heat and friction is the result of pressure increases here.

I have the 4degree mod and after my last rebuil last year june i ran the bike for a week on stock timing. I did max speed runs and pulled 63 on a slight downhill (my test street) i then quickly advanced the timing and did more top speed runs, i found NO increase in top speed BUT the initial pull off power was better. HOWEVER, i have found that i do not have complete piece of mind about the running temp, i feel its too hot and because of that, i am going to turn it down to about 2 degrees over stock.

Id like to get a IR heat gun to experiment with it. But on the same note, could richening the jetting help to cool the motor better with 4degree timing?

I know why compression adds heat.....dumb question on my part though as increasing the combustive force will translate into higher compressive force so one in the same I guess with advanced timing.

I'm one in the same with you though. I'm thinking only 2-3 degrees unless I can find some other reason to go with more/less timing than that. According to the Clymer, ignition timing is 16*@3000rpms......obviously non-adjustable(be nice if it was). Now compared to other things I've seen in the past this SEEMS conservative on timing, but I haven't done the math, nor do I actually know if it's conservative or not, so one of these days I might have to bust out the old TI-83 and spend an hour to figure out if timing advancement up to 18-19* would help out with my individual setup. If I went up to straight 110 octane I could probably get away(ballpark guess) with 6* simply because the gas would deflagrate slower.

 

[sicivicdude]

Alright, here goes...

Awk is talking about increasing timing by shaving the head. The spark plug sparks in relation to crankshaft position so unless you change the stator plate (do a timing mod) the spark plug will spark at the same time each time. But, you have to remember what the crankshaft is doing while it's also telling the ignition system when to spark, it's moving that piston (or face as you made the analogy) upwards as well.

Now imagine the face analogy, if you're getting punched in the face and you're worried about timing.... don't you think changing the position of the puncher would have an affect on the punchee? Lowering the spark plug by shaving the head by 2mm on an engine with 57mm of stroke is like advancing the timing 1.5 degrees (or something like that) even without touching the timing plate...

Also, the reason timing has less of an effect on the top speed or top end of a 2 stroke is because of the maximum volumetric efficiency of the top end with a given expansion chamber.

2 strokes are naturally self limiting because the efficiency of the cylinder drops dramatically as you get out of the tuned range of the head pipe.

If you were only worried about power at top end, you'd order a drag pipe with specs tuned to 10,500 RPM and run +6-10 degress of timing advance. Then the timing advance would work at those high RPM's.

Also, the CDI box on the blaster has it's own timing advance which moving the timing plate may have an adverse affect on which cannot be characterized so easily. The CDI box might be dead on the money as far as advance goes above 4K rpm but be a little "off-tuned" at lower RPM's. Moving the timing plate forward 4 degrees gets the timing right where the stock timing is wrong but it actually over-advances at the upper RPM's making the timing not "optimized" at the upper RPM range. I don't know for sure, but it's definitely a possiblity.

 

[99LRDblaster]

Alright, here goes...

Awk is talking about increasing timing by shaving the head. The spark plug sparks in relation to crankshaft position so unless you change the stator plate (do a timing mod) the spark plug will spark at the same time each time. But, you have to remember what the crankshaft is doing while it's also telling the ignition system when to spark, it's moving that piston (or face as you made the analogy) upwards as well.

Now imagine the face analogy, if you're getting punched in the face and you're worried about timing.... don't you think changing the position of the puncher would have an affect on the punchee? Lowering the spark plug by shaving the head by 2mm on an engine with 57mm of stroke is like advancing the timing 1.5 degrees (or something like that) even without touching the timing plate...

Also, the reason timing has less of an effect on the top speed or top end of a 2 stroke is because of the maximum volumetric efficiency of the top end with a given expansion chamber.

2 strokes are naturally self limiting because the efficiency of the cylinder drops dramatically as you get out of the tuned range of the head pipe.

If you were only worried about power at top end, you'd order a drag pipe with specs tuned to 10,500 RPM and run +6-10 degress of timing advance. Then the timing advance would work at those high RPM's.

Also, the CDI box on the blaster has it's own timing advance which moving the timing plate may have an adverse affect on which cannot be characterized so easily. The CDI box might be dead on the money as far as advance goes above 4K rpm but be a little "off-tuned" at lower RPM's. Moving the timing plate forward 4 degrees gets the timing right where the stock timing is wrong but it actually over-advances at the upper RPM's making the timing not "optimized" at the upper RPM range. I don't know for sure, but it's definitely a possiblity.

Well I'm not running 2mm(~0.080 off) the head, however I kind of get your point. You are saying since the plug sits closer and sparks at the same time on stock timing, that simply because the plug is closer to the piston now, it advances the timing.

However, since the plug sits closer to the piston at TDC now with a shaved head, wouldn't that be the SAME thing as if you RETARDED the timing? Think about it. I'm just going to through out random numbers for comparison.

-Let's say you have the Blaster with stock timing at 16* and the engine is stock and there is let's say 20cm(random #) between the top of the piston at BTDC(plug spark point) and the plug.

Now here are 2 scenarios, that I look at and see 2 in the same....both retarding the timing:
1: You shave the head 2mm and keep stock timing. You now have 18cm(20-2mm for head shave) between the plug and BTDC point of the piston when the spark occurs.
2: You have a stock head...stock everything and RETARD the timing...let's say...4 degrees(random #). You now have 18cm between the plug and BTDC point of the piston since the spark is initiated later(retarded) and the crown of the piston is closer to TDC.

This is why I don't understand how shaving the head advances the timing.

 

[Blaner]

this is an interesting topic, i see your point civic, and am going to go crunch some numbers over this to see whats really going on. this is a very dangerous thing for people to be unclear about

 

[sicivicdude]

It's advancing the timing because the spark event actually occurs before the piston reaches TDC.

If you watch a quartz camera view of the timing event on super slow motion, it's not a clear cut spark and explosion. It's sort of a sizzle at the end of the spark plug and then little bits of fire shoot out everywhere.


Here's a video of a power stroke in a 4 stroke (the timing advance principles are the same however)

As you can see, the timing event comes just before the piston is at the top of it's stroke (advanced means advanced before top dead center). If you moved the spark plug closer to the piston not only would you be concentrating the fuel and air around the electrode which means the flame front needs to move less to consume all of the charge, but the spark plug is "sooner" in the stroke.

 

[sicivicdude]

Timing is a 4D event not just 3D. Think of not only physical placement of the components but how those components are moving in time. So the comparison of equal distances from the piston crown to the spark plug electrode aren't taking into account the timing of the event, only the distance of the event away from one another.

But in your example, retarding the timing 4 deg (or however much you would to get the imaginary 18cm distance) would actually put the timing event closer to TDC and later on in the stroke putting the explosion catching the piston.

Shaving the head to get the 18 cm means that the piston is the same distance away from the electrode but at a different time during the stroke.

 

[slickerthanyou]

The core premise is fairly simple. Essentially, your air/fuel mixture deflagrates before TDC in order to make the fuel burn/combust. It does this before TDC because it takes time for the air/fuel mixture to deflagrate while the piston is moving up towards the head/TDC. If the plug sparked right at TDC, you would have very little force/power since the air/fuel mixture would be deflagrating while the piston was already on it's way down...essentially just bouncing off the deflagration of the air/fuel mixture instead of actually going through a higher compression combustion state where the combustion will DRIVE the piston down. The whole premise of power/force production is maximizing the force of the piston on the downstroke. With advancing the timing EARLIER than stock timing, you ignite the plug whatever degrees earlier which allows the air/fuel mixture to deflagrate earlier which may or may not improve maximum combustive efficiency. For example, let's just say the Blaster's stock timing doesn't achieve this(hypothetically). It puts out power/force, but it may not be OPTIMAL, therefore if you spark the air/fuel mixture earlier, it gives more time for the air/fuel mixture to deflagrate MORE completely. Greater deflagration equals greater/improved combustion.........thereby increasing the force on the piston driving downwards and increasing the power to the wheels. I:I

EDIT: Advancing timing is dangerous if done improperly for one simple reason. If you advance the timing too much and the air/fuel mixture deflagrates and pushes back down on the piston BEFORE it reaches TDC, this proves to be catastrophic on engine internals and power will decrease. You want to have the flame front during deflagration start at the head from the spark of the plug and then push down on the piston AT or AFTER TDC, not before. Imagine being hit in the face.......now imagine being hit in the face while running at somebody full speed......that's basically what it's like for the piston when the timing is advanced too far and the flame front comes down and punches the piston before TDC/while it is still moving upwards.

Alright, here goes...

Awk is talking about increasing timing by shaving the head. The spark plug sparks in relation to crankshaft position so unless you change the stator plate (do a timing mod) the spark plug will spark at the same time each time. But, you have to remember what the crankshaft is doing while it's also telling the ignition system when to spark, it's moving that piston (or face as you made the analogy) upwards as well.

Now imagine the face analogy, if you're getting punched in the face and you're worried about timing.... don't you think changing the position of the puncher would have an affect on the punchee? Lowering the spark plug by shaving the head by 2mm on an engine with 57mm of stroke is like advancing the timing 1.5 degrees (or something like that) even without touching the timing plate...

Also, the reason timing has less of an effect on the top speed or top end of a 2 stroke is because of the maximum volumetric efficiency of the top end with a given expansion chamber.

2 strokes are naturally self limiting because the efficiency of the cylinder drops dramatically as you get out of the tuned range of the head pipe.

If you were only worried about power at top end, you'd order a drag pipe with specs tuned to 10,500 RPM and run +6-10 degress of timing advance. Then the timing advance would work at those high RPM's.

Also, the CDI box on the blaster has it's own timing advance which moving the timing plate may have an adverse affect on which cannot be characterized so easily. The CDI box might be dead on the money as far as advance goes above 4K rpm but be a little "off-tuned" at lower RPM's. Moving the timing plate forward 4 degrees gets the timing right where the stock timing is wrong but it actually over-advances at the upper RPM's making the timing not "optimized" at the upper RPM range. I don't know for sure, but it's definitely a possiblity.

WOW! I have a headache front everyone punching me! i do have a tad bit more knowledge now, still not messin with my sh*t. I can't afford another build anytime soon, I need a T-rock swinger first!

 

[99LRDblaster]

It's advancing the timing because the spark event actually occurs before the piston reaches TDC.

If you watch a quartz camera view of the timing event on super slow motion, it's not a clear cut spark and explosion. It's sort of a sizzle at the end of the spark plug and then little bits of fire shoot out everywhere.


Here's a video of a power stroke in a 4 stroke (the timing advance principles are the same however)

YouTube - In Cylinder Video ( How a 4 stroke engine works )

As you can see, the timing event comes just before the piston is at the top of it's stroke (advanced means advanced before top dead center). If you moved the spark plug closer to the piston not only would you be concentrating the fuel and air around the electrode which means the flame front needs to move less to consume all of the charge, but the spark plug is "sooner" in the stroke.

The spark always occurs before TDC since it takes time for the fuel to deflagrate like you see in the vid when the plug sparks BEFORE TDC giving time for the fuel to deflagrate and cause the expansion within the chamber. I still don't see how milling the head indirectly advances the timing though. What you just described is what will happen when you retard the timing as the plug will spark when the piston is closer to TDC and be "concentrating" the fuel/air mixture. On stock timing, the placement and milling of the head has no effect on when the plug actually fires.....it's fires at 16* regardless.

Advancing the timing does the opposite of what you describe. It gives more space and time for the air/fuel mixture to deflagrate more completely to provide more expansion of combustive gases when the piston reaches TDC to push down.