GS1100G Cam timing

[GregT]

For the first time in some years I had an 1100G on the bench today.

The owner is an old friend who has had several bikes modified by me over the years. He'd recently acquired a tidy 1100G and naturally wanted it tweaked a bit...as you do.
I was prepared to dial the cams to a known good setting but after a hard look at the bike decided not to.

The std timing appears to be 120 deg lobe center inlet and 100 degree lobe center exhaust.
This led to the question - why ? Why the retarded inlet cam ?

The answer I think lies in the huge ports of the 1100 8V head. To get a good vacuum signal for the CV carbs, the cam is run retarded - relative to the sporty 8V motors anyway.

The only 1100G I'd done previously took a lot of work to get it carburating right - with cam lobe centers I'd use on a hot 1000. Poor vacuum signal IMO - in hindsight.

When you factor in the old carb to head rubbers - and the hard carb to airbox rubbers - it would have become a saga....So the clearances were done and the camchain adjusted
and it was screwed back together.

So my recommendation now - with everything getting old - is to leave the 1100G stock. Unless you're going to fit better carbs eg, RS's or CR's which are much more tunable.

 

[rphillips]

Do you know what the lobe centers are for the GS1000E or G? I'm not familiar with the 8V. Those #'s seem way Hi on intake, & pretty lo on EX. compared to the 16V GS1100 specs.

 

[Steve]

According to my calculations, both cams have 110? centers. :-k

.

 

[Big T]

I think Greg T has mentioned 106 degree lobe centers for chain drive 1000s

 

[GregT]

The 16V 1100's have quite different lobe centers. Std seems to vary more on them than on the 8V engines too. I've measured 16V 1100's anywhere from 115 - 118 for E's and 105 - 110 degrees for 1150's on the inlet side. Exhausts seem to be closer to 110 for the early ones and around 108 for the 1150.

The 8V 1000's are nominally 110/110 - but again you see variations. The "S" versions are the most radical stock with around 100 - 103 inlets and 110 for exhausts.

For what it's worth - my personal preferences are:

8V 1000 and above - hot street and race - 107 inlet, 109 exhaust lobe centers.

16V 1100 or 1150 - hot street and short course roadrace - 106 inlet, 108 exhaust.
Full house long course roadrace and drag - 110 inlet, 113 exhaust.

All are predicated on a decent head and pipe combo.

 

[Guest]

The cam timing on stock motor will vary quite a bit. That is why I degree them in.
degreeing the cams in will not give you more power unless they are way off. Moving the lobe centers below 104 or above 115 will not gain anything. Degreeing the cam will only change what RPM the bike makes it’s peek HP and toque at. The higher the lob center will bring the peek power to a higher RPM. Most factory cam timing is supposed to be 104I/106E or in like the Bandit that was famous for the low end toque is 102i/104e but petered our at 9,000rpm. Which IMO is way to low. I move all stock cams to 105i/107e and aftermarket cam in preformance motors are degreed according to the riders needs. My GS1150 with 1198cc pistons 30/25 valve head with .410/380 cams degreed in at 110/113 was a street ripper and very consistent at the track.
plus if you mill the head or deck any surfaces then you are changing your cam timing.
Oh one more thing I never put both intake and exhaust cam at the same lobe centers I always run the exhaust at least 2 degrees higher.

 

[Guest]

For the first time in some years I had an 1100G on the bench today.

The owner is an old friend who has had several bikes modified by me over the years. He'd recently acquired a tidy 1100G and naturally wanted it tweaked a bit...as you do.
I was prepared to dial the cams to a known good setting but after a hard look at the bike decided not to.

The std timing appears to be 120 deg lobe center inlet and 100 degree lobe center exhaust.
This led to the question - why ? Why the retarded inlet cam ?.

If you got 120 lobe center then it was set one tooth off. 13 degrees per tooth if I remember correctly.
just because it was set at the factory doesn’t mean that it is right.

 

[GregT]

If you got 120 lobe center then it was set one tooth off. 13 degrees per tooth if I remember correctly.
just because it was set at the factory doesn?t mean that it is right.

Timing was spot on the marks and correct no of pins between. Degree wheel on the crank with TDC established separate from the factory marks.
I've been doing this since the early 80's.

I broadly agree with your comments in the other post. Good gains can be made by tailoring the cam timing to put the torque peak where it's most useful IMO.

 

[Guest]

Timing was spot on the marks and correct no of pins between. Degree wheel on the crank with TDC established separate from the factory marks.
I've been doing this since the early 80's.

I broadly agree with your comments in the other post. Good gains can be made by tailoring the cam timing to put the torque peak where it's most useful IMO.

if you have been doing this for 20 years then you know that 120i/100e is way off and factory marks should not be used.

 

[GregT]

if you have been doing this for 20 years then you know that 120i/100e is way off and factory marks should not be used.

Lets be accurate here. I've been doing it for around 40 years. And I'm still surprised at what i find.

The engine in question is low mileage - around 60,000KM. I'd pick some of the valve shims were the originals.
i have no reason to believe that this was not how it came out of the factory.

Have you ever been inside an 8V 1000S ? Checked the timing ex factory on those ? What about the limited edition "Black pipe" GSX1100E and wire wheel Katanas ?
Suzuki have over the years produced quite a few oddities with the cams well outside "normal" timings.

 

[Guest]

Lets be accurate here. I've been doing it for around 40 years. And I'm still surprised at what i find.

The engine in question is low mileage - around 60,000KM. I'd pick some of the valve shims were the originals.
i have no reason to believe that this was not how it came out of the factory.


Have you ever been inside an 8V 1000S ? Checked the timing ex factory on those ? What about the limited edition "Black pipe" GSX1100E and wire wheel Katanas ?
Suzuki have over the years produced quite a few oddities with the cams well outside "normal" timings.

I have seen the timing on factory bike all over the place anywhere from 94lc to 115lc that doesn?t make it right. I would never put it back to those settings. I have never found the factory timing to be correct on the cams or ignition.
no one from the factory intended for the intake to be at 120 lc.
I am building a 1540cc 1150 right now and I am putting my cams in at 111i/114e because I want it to build it?s peek HP at about 11500 to 12,000 rpm. At 120lc your gonna have to spin that motor to 13,000 rpm to get the cam to work right. Say good buy to any bottom end power.

 

[Guest]

yes I have!
I have been inside a lot of different motor. One tends to that when you build race bikes for almost 40 years.