Should the 850 run better than the 750?

[patj2474]

This is a question for those long time enthusiasts who have owned/ridden multiple GS's...
I own a 1980 GS850G tourer that I bought last summer (my first GS) and a 1982 GS750T I bought a few weeks ago. I really like the 850 and thought it ran fine until I started riding the 750. The 750 has sooooo much more power. Is the 16 valve 750 supposed to be that much more powerful than the 8 valve 850? Here are the particulars about the bikes:

1982 GS750
21,000 mi
Haven't touched the carbs, maybe next winter. Doesn't matter though, this is the one that runs so good. Once that engine hits 3000 RPM it pulls hard to the redline.
Stock air cleaner, stock exhaust, clean air filter
compression is 160+

1980 GS850G
21,000 mi
full faring, bags, and trunk (some extra weight but not that much)
rebuilt carbs (thoroughly cleaned; new needle valves, jets, gaskets, o-ring kits)
New o-rings in the intake manifolds
Stock air cleaner and exhaust
Valves adjusted to spec.
Compression is on the low end, 125-140 psi range. If I recall correctly the clymer manual says it should be 128-170(?).
-other than the fact the values are on the low end, I'm not seeing any other typical symptoms of a tired engine like fouled plugs, oil smoke, hard starts, etc.

So... Any opinions among those who have owned or ridden both? Is the difference due to engine technology, engine wear (compression), or something else?

[Dave8338]

Weight of the bike?

[Roostabunny]

Weight of the bike?

I can tell you that an 850g weighs about 550lbs without luggage - about 50lbs heavier than some of the 1100's. Sorry, can't tell you how much the 750 weighs, just that the 850 is a beast.

[Steve]

Although the 850 is a favorite of many on the board, it also seems to be about the heavaiest with the lowest specific power output.

And, you have further encumbered your 850 with fairing, saddlebags and trunk.

Yes, the 2-valve vs 4-valve technology makes a difference, too. I have not seen numbers for the 16-valve 750s, but the 8-valve 750s claimed 72 hp, the 850s claimed 77 hp. Weight was another issue. The 8-valve 750 were about 530 pounds, but the later 750ES claimed only 478, the 850s were about 557 pounds. Doing the math, that is 7.35 lbs/hp for the 8-valve 750, 7.23 lbs/hp for the 850. Since I don't have hp figures for the 16-valve 750, let's assume the same power. That would make only 6.63 lbs/hp, and since they likely make more power, the figure is even better.

Yeah, the 750 is going to out-run your 850.

.

[BassCliff]

My research shows the 16-valve 750 puts out somewhere around 89hp. Quite an improvement when coupled with the lighter weight. But don't ask me to give up my shaft drive. ;-)


Thank you for your indulgence,

BassCliff

[flyingace]

My research shows the 16-valve 750 puts out somewhere around 89hp. Quite an improvement when coupled with the lighter weight. But don't ask me to give up my shaft drive. ;-)


Thank you for your indulgence,

BassCliff

Amen. This is a bit of an apples to oranges comparison anyway. People who obtain the 850s aren't after performance. They are after smooth and comfortable. The shaft drive alone must weigh an extra 30-40 lbs, and it tells you the bikes purpose is not acceleration.

You are fortunate to have two bikes with different characters. Enjoy each for what it does best.

[SqDancerLynn1]

Here we go comparing apples & oranges. The GS850 was designed as a work horse able to do everything up to a point. The 750 is a preformance based bike

[doctorgonzo]

Glad I have the 1000G though. The weight is similar to the 850G (about 560 lbs dry), but that little extra horesepower helps.

[TheCafeKid]

Im glad i have an 1100G about 30lbs lighter than the 850, and a claimed 98hp vs the 77 of the 850. Same ergonomics as well

[doctorgonzo]

Im glad i have an 1100G about 30lbs lighter than the 850, and a claimed 98hp vs the 77 of the 850. Same ergonomics as well

Think the 1000G is 85 to 88 HP stock. I'm probably low 90's with pods. JUST enough for that heavy ass bike.

[Steve]

My research shows the 16-valve 750 puts out somewhere around 89hp.

478 pounds, 89 hp = 5.37 lbs/hp.
That's a far sight better than the 850's ratio of 7.35. Each 'pony' only has to move about 3/4 of the weight.

.

[hampshirehog]

In it's day though, the 850 was considered a pretty quick bike and a bit 'peppy'. Not the fastest in it's class by any means, but if you had one you definitely had cred.

[patj2474]

Thanks to everybody for the replies!
Good advice and good info.
I love the shaftie and when I have someplace to go it's definitely my choice.
But the 750 sure is a blast just to ride for the heck of it.
I'll quit fretting about a top end overhaul and go back to having fun!
Thanks again.

[doctorgonzo]

Don't know the weight or horsepower, but the KZ1000 was the dream bike of my high school years in the late 70's early 80's. I saw one built into a drag bike back in 83 and man that thing would fly., Course our GS's are just the same engine but better!