Building a "virtual" 1000G engine, need some airflow & cam specs

[Guest]

While I'm waiting for my (cylinder ) head to be repaired, I have a software program called Dyno 2000 that lets you build a virtual engine. I was playing around with it today. I found it will not accept a 70mm bore, so I had to adjust the stroke to get the proper displacement for the 8V '81 1000G engine. It has numerous fields to be filled in with actual data.

I got some data from the shop manual and an online site.

Here are the parameters it allows you to input, and what I've gotten so far:
Block
Bore: 71.12 (the minimum, stock is 70mm)
Stroke: 62.12 (stock is 64.8) This yields the indicated 987cc from the reference website.
No. of cylinders: 4

Heads
Cylinder head (general type): Stock ports & valves
Intake valve size: 38mm (from the manual)
Exhaust valve size: 32mm (ditto)

Compression
Stock ration: 9.2:1 (reference website)

Induction
Several options ranging from 300 to 1100 CFM with various manifolds. I used individual runners as the type since there are 4 carbs for 4 cylinders. I need an idea of the airflow the stock carbs are capable of to get this number close.

Exhaust
Again several options, I used small tube headers with mufflers for the 4 into 2 system.

Camshaft
Here is where most of the data is needed. It has fields for:
Type: Stock street/economy (can make a custom profile)
Lifter type: Used solid
How measured (seat to seat or @ .050): Need this info in conjunction w/ below
Intake lift: 8mm (from the manual)
Exhaust lift: 7.5mm (ditto)
Timing (advance/retard): ???
Intake open & close: Need this info
Exhaust open & close: Need this info

It has a math window that lets you enter lobe center, intake centerline, and intake & exhaust duration, if these are known, and it calculates the above numbers.

The program shows you what the engine should be putting out for HP & TQ at various speeds. I know the stock motor was rated at 90 HP @ 8200 RPM and 8.5 kg-m (61.4 foot-pounds) TQ @ 6500 RPM. I have not been able to exactly match this yet, since I can't find the data anywhere and I don't have a degree wheel to do my cams.

Once I have a baseline, I can plug in things like big bore kits as well as better flowing air cleaners or carbs & exhaust.

Thanks for any tips or numbers.

[Nessism]

The service manual has the intake time info. For the carb flowrate, I'd use the lowest - 300 cfm. It's certainly not more than this and you can't go lower.

[GS1000G Shopper]

I've looked through the manual and can't find that info. It is 472 pages, but I've looked at the specs and cam install parts for the various models. Any idea where it is?

Edit
Found this post here. It has the following info for the '81 GS1000G:
Everything I found says the stock duration for my bike is 236 with a cam line of 110.

It looks like my intake is 104 and my exhaust is 103.

[Nessism]

Page 7-18 in the base level GS1000 manual. The G is different though, so you might want to download the manual from Basscliff and see how the specs compare.

[GS1000G Shopper]

Got it, thank you sir. The G manual did not have a different top end inspection page, so I used those numbers of (posting for posterity here):
Intake open: 28 BTDC
Intake close: 68 ABDC

Exhaust open: 66 BBDC
Exhaust close: 26 ATDC

My airflow must be way off, since it shows peak HP of 67@ 7500 and peak TQ of 58@ 5500. I input the 1100 B&S of 72/66 and CR of 8.8:1 and got 67 HP from 6500~7500, and 58 TQ @ 5500.

I had to tweak head, intake, and exhaust flow to get 90 HP @ 7500. This gave me 67 TQ @ 5500~6000. This is about as close as I'll get to the baseline motor's 90 @ 8200 and 61 @ 6500.

Next, I changed the bore to 72mm & stroke to 64.8 to simulate a stock 1100 piston on the 1000 crank, and left the CR at 8.8:1 (it may actually be higher due to a larger volume being compressed depending on the head). I got 94 HP (+4) @ 7500 (93 from 8000~8500) and 71 TQ (+10) from 5500~6000.

I then simulated the $500+ 1100cc aftermarket big bore kit. With a B&S of 73.5 & 64.8 (+3.5mm OS pistons) and a CR increase to 10.25, this results in 104 HP (+14) from 7500~8500 and 82 (+15) TQ @ 5500.

My conclusion is utilizing the 1100 setup on the 1000 crank looks to be an economical method of boosting power and torque. I think my friend tkent02 said as much in another thread, so here are the numbers to back that up.