8V Ignition Hopup ???

[posplayr]

A question came up in this thread about swapping ignitors.

http://www.thegsresources.com/_forum/showpost.php?p=1259461&postcount=4

It raises the question if there is not a nearly free hopup for an 8V to use 16V advancer or ignitor with built in curve.

Has anybody done this (Chef thinks he may have done it in reverse; 8V into a 16V ) 8V hop up by putting a 16V advancer into an 8V motor with a few extra degrees of inital advance. 16V has fewer total degrees advance

That really helped my Small block accelerate off the line.

 

[blowerbike]

without knowing the exact degree difference between the 8 and 16v. advancers..
the 16v. likes 34-35 max.
i think the 8v. advancer will add to much total timing.
here is an even cheaper "mod" as the young folks like to call it.
slot the factory timing plate in the front of the holes(to right) to advance the timing for free.
counter clockwise=advance.

 

[blowerbike]

ok i missed what you was saying at first.
if you do that you will lose total advance which is going backwards in performance IMO..

 

[posplayr]

ok i missed what you was saying at first.
if you do that you will lose total advance which is going backwards in performance IMO..

The GS1100E 16V timing seems to be remarkably like the small block Chevy Hi po mod. IIRC

SBC stock is:
4 initial
28 mechanical
-----------------
32 degree total

The SBC Hi po mod was

12 initial
20 mechanical
----------------
32 total (no change)

This is identical to stock GS1100 16V (if i remember the chevy mods, it has been about 35 years.) The big increase in initial advance really helped SBC.
So there is not big improvements to be had in the GS1100 as it is already set with alot of initial advance lest you want to burn pistons.

I looked up the GS1000 and it is

17 Initial
20 mechanical
----------------
37 total

So that is already a ton of advance. However the 20 degree mechanical advance is the same as the 16V . Does that mean all ignitors are swappable as long as you can set initial properly (12 degree vs. 17 degree for 16V v.s 8V)?

 

[cowboyup3371]

I'm trying to follow along here. The mechanical is what you set the timing to when you adjust the chain correct? What is the initial advance you are referring to?

 

[posplayr]

I'm trying to follow along here. The mechanical is what you set the timing to when you adjust the chain correct? What is the initial advance you are referring to?

This is all ignition timing not cam timing. Initial advance is set rotating the timing plate under the ignition cover. The 20 degrees mehanical advance refers to the weights that swing out or the electronic that is built into the ignitor. Sorry that is a poor term in this context but I did not want to invent a new term like dynamic advance.

 

[blowerbike]

The GS1100E 16V timing seems to be remarkably like the small block Chevy Hi po mod. IIRC

SBC stock is:
4 initial
28 mechanical
-----------------
32 degree total

The SBC Hi po mod was

12 initial
20 mechanical
----------------
32 total (no change)

This is identical to stock GS1100 16V (if i remember the chevy mods, it has been about 35 years.) The big increase in initial advance really helped SBC.
So there is not big improvements to be had in the GS1100 as it is already set with alot of initial advance lest you want to burn pistons.

I looked up the GS1000 and it is

17 Initial
20 mechanical
----------------
37 total

So that is already a ton of advance. However the 20 degree mechanical advance is the same as the 16V . Does that mean all ignitors are swappable as long as you can set initial properly (12 degree vs. 17 degree for 16V v.s 8V)?

on the mechanical advance models i believe chef bill said that the trigger plates was the same and the difference was the advancer itself.
on electronic advance models.......
i would believe the same is true as they used to sell timing advancers for 1150's..like they still do for the oil cooled GSXR's and Kats/Bandits.
Hmmmmmmmm........

 

[posplayr]

on the mechanical advance models i believe chef bill said that the trigger plates was the same and the difference was the advancer itself.
Hmmmmmmmm........

Actually Bill was concerned he might have stuck an 8V trigger plate on his 1166 which is what might have contributed to the blow up he had in Nor Cal.

based on the manual the dynamic advance is the same for GS1100 16V or GS1000 8V at least.

 

[TheCafeKid]

Forgive me if I'm way off base here, but before swapping the plate or any of the above ideas, would you not first want to assure that the bike is timed exactly to begin with? I do believe I recall both Terry and others say they've found an otherwise stock bike to be more than a couple degrees off from the factory with regards to TDC/BDC vs the plate markings?? If someone were to just willy nilly toss a different than stock plate or slot the plate without checking would there be the danger of having too much advance and doing some damage?

The only reason I bring it up is to at least make a person who might not know any better that there is a chance they could mess their motor up if they're not paying close attention.

 

[posplayr]

Forgive me if I'm way off base here, but before swapping the plate or any of the above ideas, would you not first want to assure that the bike is timed exactly to begin with? I do believe I recall both Terry and others say they've found an otherwise stock bike to be more than a couple degrees off from the factory with regards to TDC/BDC vs the plate markings?? If someone were to just willy nilly toss a different than stock plate or slot the plate without checking would there be the danger of having too much advance and doing some damage?

The only reason I bring it up is to at least make a person who might not know any better that there is a chance they could mess their motor up if they're not paying close attention.

Yes Josh that is correct, and any time I have a degree wheel on bike I have confirmed the TDC timing mark. Bill infact verified all of this timing marks with a degree wheel (this time ).

On the other hand while none of the marks are perfect and that is part of the design there is enough tolerance to error build up that you can usually just slap OE parts in.

The only question I have at this point is why can't a 1150 ignitor with 20 degrees of advance be put into a GS1100G 8V motor where it will be run with 17 degrees initial instead of 12 as the 16V would want?

The main problem would be the one that Bill discovered which inadvertenly putting an 8V ignition plate into a 16V and using those marks which has an extra 5 degrees of total advance.

Were talking about a 5 degree difference here not a 1 degree possible build up tolerance.

BTW when both Bill and I both degreed in our timing marks there was essentially no appreciable error which would cause us to try and modify the marks.

We also measured for crank twist as well while the wheel was on there. :-\\\

 

[Steve]

Simply adding advance is no guarantee that you will add power.

Only if testing shows that combustion is not complete in time for maximum pressure on the piston should you have to advance the timing. How much should you advance it? Again, only testing will show.

The differences in combustion efficiency between the 8V and 16V engines can easily require different advance amounts and "curves", I would be hesitant to just slap on a different part without substantial testing. You guys go ahead and do the testing for me. :-\\\

.

 

[TheCafeKid]

This is true also. The 16v heads are substantially more efficient than the 8vs. A simple look at the jet sizing on a 16v 1100 vs an 8v will show you. The head on the 8v doesn't flow as well, thus the jets being larger to allow what pull there is to pull more fuel. A 16v has better flow, so the jet size can be a bit smaller as the flow will pull effectively the same (as necessary) amount of fuel...

It's an odd thing... Some jet kits for other later Suzuki models actually have you decreasing jet sizes or slide port sizes...

Bigger isn't always better, just like more advance may or may not be better... Testing would not only be a good idea, were it me, it would have to prove that it was necessary...

 

[posplayr]

OK Guys since this topic is dead, I'll have to start another one of 8V v.s. 16V ignitor compatability

The RPM based advance is the same ; 20 degrees

 

[blowerbike]

a person should always use a degree wheel with any type of "hi-performance" engine improvements.
ALWAYS!
i think Bill would agree with me at this point.

 

[ericoppel]

The Suzuki OEM manual I have for the GS1100GKE states the timing is 13 degrees B.T.D.C below 1500 RPM and 33 degrees B.T.D.C above 2350 RPM (+- 150RPM).

There is no mention I could find anywhere of being able to (or needing to) adjust it in any way.

 

[gearhead13]

This is true also. The 16v heads are substantially more efficient than the 8vs. A simple look at the jet sizing on a 16v 1100 vs an 8v will show you. The head on the 8v doesn't flow as well, thus the jets being larger to allow what pull there is to pull more fuel. A 16v has better flow, so the jet size can be a bit smaller as the flow will pull effectively the same (as necessary) amount of fuel...

It's an odd thing... Some jet kits for other later Suzuki models actually have you decreasing jet sizes or slide port sizes...

Bigger isn't always better, just like more advance may or may not be better... Testing would not only be a good idea, were it me, it would have to prove that it was necessary...

I think the difference in jet size is because of the different sizes of the main air jet orifice on the 8v and 16 cv's.

 

[Guest]

The only question I have at this point is why can't a 1150 ignitor with 20 degrees of advance be put into a GS1100G 8V motor where it will be run with 17 degrees initial instead of 12 as the 16V would want?

:-\\\

Allow me to complicate things.

The 1150 ignitor is 22 degrees, not 20, like the 16v 1100.