Final drive gear ratio

[Guest]

I'm trying to determine the final drive gear ratio on my 82, GS850G. Mine indicates a higher rpm than it should at speed and I'm trying to figure out if it's the tach or some PO has replaced the final drive with one that has a different ratio. Any ideas?

Thanks guys........

[Nessism]

There are only two final drive ratios, and your bike has the lower of the two (higher rpm).

Both tachs and speedometers are often inaccurate. Using a GPS is a good way to check the speedometer. The tach can be checked with an electronic tach or by calculating the rpms@ speed.

This might help...

[tom203]

Check your speedometer with a decent gps .

[Steve]

You say it's "turning higher than it should", what RPM are you seeing?

As Nessism's chart shows, you should be seeing about 5000 at 70 mph.

.

[bbjumper]

Gear ratio

The tach does bounce around a bit but 5600 @ 70 mph would be the average and compared to traffic on the freeway my speedo is within a couple of mph but I'll check it with a GPS this afternoon.

Thanks

[Buddy]

Clean and lube your tach cable. If that doesn't take the bounce out you might have to replace it. You might also spray some lube in the tach through the cable hole. I've had to do that in the past. Then you can better tell whats going on.

When the cable drags it acts like a spring, slowing down and storing energy, then releasing with a burst of speed. The tach is seeing that burst thus a higher than normal reading.

Buddy

[jimfj]

i own a tach that will makes the bike run at 5700 rpm at 70 and I own another that makes the bike run at 5000.

Its your tach, not the bike.

Do the above maintenace and if that doesnt work you will have to find another. I ran around frustrated for three weeks thinking something was wrong with my bike.

Good Luck.