- Posts: 794
- Thank you received: 194
Highway gearing
- The Milkman
- Offline
- User
You say you have no problem riding around town in 5th gear. Unless you live somewhere with higher speed limits in town than the usual 30 to 35 mph, you are dropping the rpms down to somewhere between 2000 and 2500 rpm if not lower.
That's putting quite a bit of strain on the engine especially heat wise. I went up to a 17 front sprocket on my 78 650 and according to the speedo and tach, I get 10 mph per each 1000 rpm in 3rd gear which I usually run in town which gives me 3000 rpm and plenty of power for most hills.
I am putting a 38 tooth rear sprocket on if the damned weather ever warms up enough to make it comfortable enough to work out in the garage so I'm not freezing my arse off. I'm doing that because I do most of my riding out of town where the rpm's will be higher. I'm hoping to ride the bike down to Pa. from here in Maine this summer and it will save some gas money. But, at a cruising speed of 65 to 70 on I95 I'll still be in the 5000 rmp range which in my opinion is optimal for these engines.
Like I said these are just my opinions.
Ride safe.
78 650-C2, Stock engine, Jardine 4-2 Exh., 17-38 sprockets, dyna ignition and coils, coil wiring mod, carb mod.
Please Log in or Create an account to join the conversation.
- davenkids2001
- Offline
- User
- Posts: 150
- Thank you received: 2
I estimated that I increased my fuel economy by about 1MPG. Again, not much but it gives me another ~4 miles per tankful, which has come in handy when we're burning fumes "up north" looking for a gas station. Last year on one trip we frantically searched for gas for fear of running out. When we finally found gas near Mackinaw City I put nearly 3.8 gallons in my tank, which was rated at 3.7 gallons! That extra few miles of range really saved out butts!
Another benefit of lower RPM's is the reduction of 'buzz' in my arms (back, shoulders and arse) that can take a toll over a long day of higher-speed riding.
It all depends on what you want, your riding style and your weight. Since my bike is used primarily for touring around with my wife, fuel economy and wear on our bodies take precedence over speed and torque. Also, my wife and I aren't big people (together we only weigh about 260# soaking wet) so we really don't need too much lower end torque.
There is a cost associated with whatever you do...another MPG or two is great but may takes years to offset the cost of the new sprocket, depending on how you ride. For me, it is the reduction of RPM buzz that is of primary importance, but the extra MPG helps too. Next time I change sprockets I may increase my front sprocket a tooth to 17...but only if it is a cost effective change and it can benefit my old arse!
That's my 1%
Dave and Janet
Great Lake State
1979 650SR
Please Log in or Create an account to join the conversation.
- seanof30306
- Topic Author
- Offline
- User
- Posts: 606
- Thank you received: 2
My chain broke, and the sprockets were worn, so they had to be replaced; so doing so was routine maintenance. My only real cost here that needs to be recouped is the cost of the second, 17t front sprocket. 20 bucks.
These bikes were geared to deliver a balance of performance and economy; they were the sport bikes of their day. I'm not interested in performance nearly so much as I am in economy on my daily commute. I bought the bike to save money and decrease my carbon footprint.
Lowering the gear ratio from 2.63:1 to 2.35:1 is not, in my opinion, too extreme. It's like adding another gear to the transmission (which it should have, anyway. Every 600 made today, which all have similar bore/stroke ratios, have 6 speed transmissions). It's like the second overdrive every manual Corvette, Camaro and Firebird has had since 1995. Both 5th and 6th are overdrive.
Regardless of where the engine operates most efficiently, since I began short-shifting the bike and loafing at lower rpms in-town on flat streets, I have seen an increase in gas mileage, and the oil shows no signs of heat wear when I change it.
"That @#$%!!! KZ650"
79 KZ650 B3
Dual front disc brakes
Z1R 18" front wheel
Pumper carbs w/pods
MAC 4-1 w/ drilled-out baffle
Dyna S ignition w/ Dyna Green coils
WG coil mod
'81 CSR charging system
17/41 gearing
Please Log in or Create an account to join the conversation.
- Kingcobra
- Offline
- User
- Posts: 86
- Thank you received: 0
Please Log in or Create an account to join the conversation.
- seanof30306
- Topic Author
- Offline
- User
- Posts: 606
- Thank you received: 2
I've been running an 18 tooth front sprocket for months now and I didn't need to remove the u shaped guard either. still plenty of torque and power even on hills in top gear.
That's interesting. My experience was just the opposite. I had to slip the clutch like crazy to get it to launch, and it had no torque in top gear. The slightest hill required a downshift.
Maybe it's my size; I'm 6'5" and 290.
Wait, you didn't say anything about the rear sprocket. I was running 18/40 for a gear ratio of 2.22:1. If you're still running the stock 42 tooth rear sprocket, that's 2.33:1. My 17/40 comes out to 2.35:1, so maybe that's it.
"That @#$%!!! KZ650"
79 KZ650 B3
Dual front disc brakes
Z1R 18" front wheel
Pumper carbs w/pods
MAC 4-1 w/ drilled-out baffle
Dyna S ignition w/ Dyna Green coils
WG coil mod
'81 CSR charging system
17/41 gearing
Please Log in or Create an account to join the conversation.
- Kingcobra
- Offline
- User
- Posts: 86
- Thank you received: 0
Please Log in or Create an account to join the conversation.
- RetroRiceRocketRider
- Offline
- User
- ...bring in the machine that goes PING!
- Posts: 1641
- Thank you received: 29
Lowering the gear ratio from 2.63:1 to 2.35:1 is not, in my opinion, too extreme. It's like adding another gear to the transmission (which it should have, anyway. Every 600 made today, which all have similar bore/stroke ratios, have 6 speed transmissions).....
All the newer inline-4's that I'm aware of do have a 6-speed trans, but most of the V-twins (any given CC size) are still a 5-speed.
And IIRC, Kawi (and just about every other Asian import brand) didn't start adding a 6th gear to their 4 cylinder bikes until after they had eliminated the kick-starters in them.
Please Log in or Create an account to join the conversation.
- seanof30306
- Topic Author
- Offline
- User
- Posts: 606
- Thank you received: 2
Regardless, the point was, going from 2.63:1 to 2.35:1 is not too extreme. All I can say is, I've done it, and so far, the results are very positive.
"That @#$%!!! KZ650"
79 KZ650 B3
Dual front disc brakes
Z1R 18" front wheel
Pumper carbs w/pods
MAC 4-1 w/ drilled-out baffle
Dyna S ignition w/ Dyna Green coils
WG coil mod
'81 CSR charging system
17/41 gearing
Please Log in or Create an account to join the conversation.
- mjg15
- Offline
- User
'80 Z750fx
'81 KZ550A
'81 GPz550's, Too many!
'82 KZ1000R
'82 GPz750
'90 ZR550
Project photo album: s163.photobucket.com/albums/t289/mg15_ph...GPz-ZR550%20project/
s163.photobucket.com/albums/t289/mg15_ph...current=DSC01286.jpg
Please Log in or Create an account to join the conversation.
- seanof30306
- Topic Author
- Offline
- User
- Posts: 606
- Thank you received: 2
Let's try it again. Today, most inline four cylinder street motorcycles of between 499 and 651 cubic centimeters displacement have six-speed transmissions.
There. OK?
The point still is, however, that going from the stock ratio of 2.63:1 to 2.35:1 is not problematic.
On this I am not wrong.
I am not in error.
I am not mistaken.
I have done it to my motorcycle.
I ride my motorcycle.
I know.
In another thread, someone said it was appreciated here when people came back and posted results after posing questions in threads.
That is what I did (What a freaking mistake that was).
Here are the results:
I went from 2.63:1 to 2.35:1.
I have ridden the bike.
I like it.
Going from 2.63:1 to 2.35:1 is not too extreme.
How do I know this?
Because I did it.
Then I rode the bike.
I liked it.
Therefore, in my informed opinion, based upon the most direct experience possible, actually doing it, going from 2.63: to 2.35:1 is not too extreme.
Thank you.
"That @#$%!!! KZ650"
79 KZ650 B3
Dual front disc brakes
Z1R 18" front wheel
Pumper carbs w/pods
MAC 4-1 w/ drilled-out baffle
Dyna S ignition w/ Dyna Green coils
WG coil mod
'81 CSR charging system
17/41 gearing
Please Log in or Create an account to join the conversation.
- mjg15
- Offline
- User
Anyway , what was your change in fuel mileage ? You stated in your orig post that economy was your primary goal .
'80 Z750fx
'81 KZ550A
'81 GPz550's, Too many!
'82 KZ1000R
'82 GPz750
'90 ZR550
Project photo album: s163.photobucket.com/albums/t289/mg15_ph...GPz-ZR550%20project/
s163.photobucket.com/albums/t289/mg15_ph...current=DSC01286.jpg
Please Log in or Create an account to join the conversation.
- seanof30306
- Topic Author
- Offline
- User
- Posts: 606
- Thank you received: 2
Before, it was getting 36 mpg. I was getting about 120-125 miles out of a tank before I'd have to switch over to reserve and start looking for a gas station.
Last week, I rode it back and forth to work 4 times (32 miles each day), and rode it at least 30 miles on my day off, too. I know I got 124 miles from the to-and-from work riding, and at least another 30 miles, which would translate to a 5mpg+ improvement. Won't know for sure until I get my gauges back.
Even if I am getting 40+mpg, that's still not where I think it should be. Lots of guys on here are reporting 50+mpg.
I've upgraded to electronic ignition, the carbs have been rebuilt to (near) perfection, and I hypermile it. If all I end up getting is 40-43mpg, I still have some work to do.
"That @#$%!!! KZ650"
79 KZ650 B3
Dual front disc brakes
Z1R 18" front wheel
Pumper carbs w/pods
MAC 4-1 w/ drilled-out baffle
Dyna S ignition w/ Dyna Green coils
WG coil mod
'81 CSR charging system
17/41 gearing
Please Log in or Create an account to join the conversation.