RPM Seems High at Freeway Speed

[ajcasper]

Hi folks. I'm finally back on a GS after almost 10 years.

I have a question. I just picked up a barn find and restored it but it seems that the bike turns an awful lot of RPMs (6500-7000) at 65mph and higher.

So here is the info on the bike. 1982 Suzuki GS650GL with 9400 miles I picked up for 100 bucks with the Windjammer and sound bar on board. Had an airbox fire and was forced to replaced all wiring, battery, rectifier and ignition module. all vacuum and fuel hoses. Full rebuild on carbs with larger jets and individual pods.

Any one else know if this many RPMs is usual or should I be looking for a problem?

It seems weird to me after riding my roommates 4 Madura 1200s that only turn about 3000rpm or less while cruising the freeway.

[cowboyup3371]

My 550 will run 6000 at 70mph on the highway. It should be fine.

[7981GS]

With a shafty, you are pretty much stuck with what you have.
The only thing that will really help is a taller tire when that one wears out.
(yes, someone will just HAVE to mention that very few of the 1100GK's had a very slightly higher rear ratio.)
I believe that yours is 3.09:1
My 850 and 1000 shafties run about 6,000 at 70 also.

Daniel

[tkent02]

The 650 should be 5,000 something at 70mph, slightly lower than cowboy's 550.
Your tach could be reading high, your clutch could be slipping, or someone could have put on a smaller size tire. Probably you are just used to the low RPM rumble of the Madura. Just think of it as a Ferrari, it only sounds right at high RPM. It's a good sound.

[TPL]

I bet it is the tach, I have an 82 850 and the gauges are not accurate, the speedo I cleaned internals and that helped, my tach reads 1800 when the bike is at 1100-1000 idle. Listening to the motor with my ears is more accurate.

[bonanzadave]

Just for comparison my 1100E is turning 4K @ 70mph (in 5th).

[BassCliff]

Greetings and Salutations!!

Hi Mr. ajcasper,

It's great to see another barn find returned to useful existence. Good show!

My GS850GT turns 5000 rpm @ 70 mph (in 5th gear). Adjust the valves, sync the carbs, balance the tires, etc, and yours will be smooth at that speed, no buzzy-ness. Yes, it seems your gauges are a little off. I think your 650 should be similar at speed to my 850.

Anyway, let me dump a TON if information on you and share some GS850G lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[ajcasper]

thanks

Forum, thank you for the replies. Sorry if this is choppy or mispelled; working from my mobile today.
I agree that the tach is off. It works when it wants to. Riffing around on the original rubbber is scary sometimes. Tires are in too good of shape to replace. I think u r right about being used to the low rumble of the Maduras. I loved this website when I had my GS425 years ago. Thank you for the warm welcome. I'll be back and posting to help others out soon.

For now cya later

[1948man]

Original tires? Good tread on old tires doesn't =safe.

[tkent02]

Riffing around on the original rubbber is scary sometimes. Tires are in too good of shape to replace.

Tires that old? Wow, that is seriously dangerous. Haven't you ever had a tire come apart at speed? If they are more than three or maybe even five years old BY THE DATE CODE, don't even think about riding it. In this case, round is not a shape.

[1_v8_merc]

My 650 is at the same rpms.

This appears to be normal on the 650's, from what I've seen.
Many owners have complained of this bike needing a 6th gear.


I'm buying a 2nd bike just for highway riding, cause the rpms are just too high!


Or either that, I needa do the valves again or clutch.

[Steve]

With a shafty, you are pretty much stuck with what you have.
The only thing that will really help is a taller tire when that one wears out.
(yes, someone will just HAVE to mention that very few of the 1100GK's had a very slightly higher rear ratio.)
I believe that yours is 3.09:1
My 850 and 1000 shafties run about 6,000 at 70 also.

Daniel

Yes, the GKs had a taller ratio, but I don't think that final drive will fit on the 650.

If your 850 and 1000 are turning 6000 rpm at 70 mph, you have problems. All three of our 850s are turning between 5000 and 5200 at a TRUE 70 mph (according to GPS). A 1000 should turn just a little bit less than that.

Riffing around on the original rubbber is scary sometimes. Tires are in too good of shape to replace.

If they are original tires, they are NOT in good shape, unless you stick the bike in a museum and DON'T RIDE IT.

This appears to be normal on the 650's, from what I've seen.
Many owners have complained of this bike needing a 6th gear.

The only way to have a GS650 with a 6th gear is to start with a 550 and replace the pistons, cylinders and head. The only problem with that is that you would lose the shaft drive, but some would see that as a "plus".

[BassCliff]

Hi,

Riffing around on the original rubbber is scary sometimes. Tires are in too good of shape to replace.

Have a look at this information: How old are my tires?


Thank you for your indulgence,

BassCliff