GS750 cams on GS1000

[Wraith]

I've herd that the GS750 cams fit and are a higher lift than the GS1000 cams?
Can anybody tell me if this is right please

Thanks W.

 

[hampshirehog]

One of the 750 cams (exhaust i think) has a tad more duration if my memory serves me correctly - no more lift.

 

[Nessism]

Cam specs are in the factory service manual. You might want to download both and compare. I believe the lift is basically same for the 750 and 1000, and the 750 has a very minor amount of extra duration (6 degrees). Think you would be sorely dissapointed if you made the swap thinking you will pick up extra power.

 

[tkent02]

Try it and see for yourself.

I heard it works, but I've never tried it.
The 850 uses the 1000 cam, and it sure doesn't run much like a 750.

 

[salty_monk]

Isn't the 850g / 1000g Cam different from the 1000E Cam anyway?

 

[49er]

850's use the 1000 cam profiles. They have higher lift than the 750 cams, but aren't quite as aggressive in their duration and timing.

 

[Wraith]

Cheers all for your input
I've just got some 750 cams off ebay very cheep so when they come I will have a look and next time I do a service on the 1000 have a look at swoping them and see how it gos

Thanks agane for the repliys
W.

 

[Nessism]

From the factory Suzuki service manuals

Valve lift - GS750, 850, 1000, 1000G, 1100G (ALL SAME)
Intake - 8.0 mm
Exhaust - 7.5mm

Cam Timing
GS850GN('79)/GS1000(all)/GS1100G - ALL SAME (BASELINE)
GS850G('80+) - Intake timing retarted 10*
GS750 - Intake +4* duration, Exhaust +8* duration

Bottom line: GS750 cams are hotter, late 850 intake tuned for torque

 

[TeamDar]

From the factory Suzuki service manuals

Valve lift - GS750, 850, 1000, 1000G, 1100G (ALL SAME)
Intake - 8.0 mm
Exhaust - 7.5mm

Cam Timing
GS850GN('79)/GS1000(all)/GS1100G - ALL SAME (BASELINE)
GS850G('80+) - Intake timing retarted 10*
GS750 - Intake +4* duration, Exhaust +8* duration

Bottom line: GS750 cams are hotter, late 850 intake tuned for torque

You are correct. The 750 cams have more duration and they all have the same lift. However, if the late 850 intake cam is retarded 10 degrees it would provide more top end and less torque due to the loss of some dynamic compression by closing the valve 10 degrees later. If you were to advance the intake cam 10 degrees then you would add torque but with a loss of peak horsepower. Advancing the intake cam also adds to the overlap duration which adds torque but didn't make the EPA happy. This is why all GS motors react well to advancing the intake cam to 105 or 106 lobe center. They are usually around 114-118 lobe centers from the factory from my experience. Dar

 

[Nessism]

You are correct. The 750 cams have more duration and they all have the same lift. However, if the late 850 intake cam is retarded 10 degrees it would provide more top end and less torque due to the loss of some dynamic compression by closing the valve 10 degrees later. If you were to advance the intake cam 10 degrees then you would add torque but with a loss of peak horsepower. Advancing the intake cam also adds to the overlap duration which adds torque but didn't make the EPA happy. This is why all GS motors react well to advancing the intake cam to 105 or 106 lobe center. They are usually around 114-118 lobe centers from the factory from my experience. Dar

Good information. Thanks for the correction. Just assumed it was for torque, didn't think about it. Wonder why the 850 is the only bike to get this later timing if emissions were the reason?

 

[Wraith]

Cheers for that, that's very helpful

 

[Wraith]

And just cause I'm scratching my head now...
Anyone care to expand on the effects in these motors on power and torque etc (and differences between) having a longer duration - so valve is open for longer before and after a given 'standard' point - and a retarded valve, opening later than the 'standard' given point but for a shorter time than the first lot (as opposed to a higher lift cam, where the value could be open for the same time or a shorter time, and open before or at or after the given point)...
Saves me asking Mrs W to go and get her tuning books out (though it might shut her up for a bit - or, at least, until she decides to start explaining it to me :-$).