GS/GSXR 16V Valve Lift/Diameter

[posplayr]

EDIT:
Lift=(Max-Min)*1.52 keep units consistent.

The GS rocker ratios vary, due to production tolerances, but the COMMON figure is 1.516-1.526.
Ray.

EDIT: Note even though the 83 GS1100ED Factory manual specs say the cams are 7.0mm and 7.0mm, the cams typically installed are 7.5/7mm (Int/Exh).

EDIT: 83 GS750E cams are (7.5 mm intake and 6.5 mm exhaust) as per the manual.

Here is a tabulation of valve lift/diameter from the official Suzuki manuals as well as Webcam and Megacam websites. Let me know if i screwed something up. I tried to be careful.

 

[posplayr]

cross link more info

http://www.thegsresources.com/_forum/showthread.php?p=1199657&posted=1#post1199657

 

[headsbikesmopars]

Jim,
I used an '81 GS1100 EX intake cam in my sons '81 GS750EX. This is with porting and backcut valves with stock 23 and 20 mm valves. His bike is a strong performer and pulles very hard from down low to red line. It also has a V&H four into one with the 530 drive chain conversion. Rejetted stock carbs, with factory airbox. Very happy how it turned out. A very reliable and good running street bike that will pull right up to the 140 mark (calculated). Thanks to Bill, (Chef) for one of the carbs..and tuning help. That.. saved the day.

Terry

 

[posplayr]

Jim,
I used an '81 GS1100 EX intake cam in my sons '81 GS750EX. This is with porting and backcut valves with stock 23 and 20 mm valves. His bike is a strong performer and pulles very hard from down low to red line. It also has a V&H four into one with the 530 drive chain conversion. Rejetted stock carbs, with factory airbox. Very happy how it turned out. A very reliable and good running street bike that will pull right up to the 140 mark (calculated). Thanks to Bill, (Chef) for one of the carbs..and tuning help. That.. saved the day.

Terry

Terry,
I have to also report that the 1100 head you did for me with 28mm stock 1150 valves and your street port job has plenty of mid range, runs cooler and gets better gas mileage than expected. I'm basing this on comparisions between Bill and my bikes. Of course it has not always been an exact comparision but as a general rule the head work has improved my machine all around. It also has a very distictive sound kinda like a jet .

Anybody looking for some reasonable head work give Terry a call. He will do right by you.

http://www.thegsresources.com/_forum/showpost.php?p=999223&postcount=29

Jim

 

[headsbikesmopars]

Thanks Jim..
Glad to help. Your head (on my bench) flows about 10 feet (cfm) better than a stock 1150 head. Should be a good performer. The 'most flow with the smallest port'... (street) Hold onto that rack for me..I am out of town now but will be intouch next week. thanks buddy.

Terry

 

[posplayr]

Thanks Jim..
Glad to help. Your head (on my bench) flows about 10 feet (cfm) better than a stock 1150 head. Should be a good performer. The 'most flow with the smallest port'... (street) Hold onto that rack for me..I am out of town now but will be intouch next week. thanks buddy.

Terry

Just for some more background when Terry and I discussed my head, he could have made it flow 110-115 CFM, but I opted for stock OE parts (28mm intake valves) and with some mild but skillful porting; he increased the flow in the head by about 20% from stock.

In the figure below you can see the comparison of flow with the stock head and then after the port work. The intake side went from 27mm (stock 1100) to 28mm (stock 1150) so there is a step change in increased flow. In comparison see the difference in flow rate in the exhaust due just to Terry's port work.

My objective was to get the 1100 to be about 10 hp faster than a stock 1150 with an 1100 head. I also have 1166 cc, Web cams 0.340 and jetted (145 mikuni) 1150 36mm carbs. If you recall, Suzuki discovered in 1982 that there were consistent measureable differences in ET for bone stock bikes. They tracted it down to variations in production machine work tolerances in the valve seat area. Tightened tolerances in the seat work is another part of why the 83 1100ED is faster than the prior 1100's.

Except for running at 10K ft and being jetted for sea level the bike runs very well.

P.S. the X and Y labels are reversed CFM is on the vertical axis.

 

[londonboards]

Pops - thanks for that but how do any of your numbers relate to the measurements I have made?

What do I need to do to identify what I have?

Greetings

 

[posplayr]

Pops - thanks for that but how do any of your numbers relate to the measurements I have made?

What do I need to do to identify what I have?

Greetings

Lift=(Max-Min)*1.52 keep units consistent.

The GS rocker ratios vary, due to production tolerances, but the COMMON figure is 1.516-1.526.
Ray.

 

[Rob S.]

...If you recall, Suzuki discovered in 1982 that there were consistent measureable differences in ET for bone stock bikes...

July 1982 Cycle World road test of the 1100e:

"The only other engine changes were performed in the valve area. Suzuki noticed during the past two years that, while all GS1100s were fast, some were slightly faster than others; some owners complained of having riding buddies whose GSs were faster than their own. These slight differences in performance were attributed to small inconsistencies in factory machining around the valve seats. A quality control program was then started to make sure each cylinder head was machined up to blueprint specs in this critical area."