akira 
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Bike: 1985 cb700sc
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« on: November 13, 2011, 08:17:45 AM » |
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I am quite disappointed with my 1985 CB700sc mpg. I drive it to work daily on a 50 miles round trip mostly freeway and cruising around 75 mph: the average mpg is 37. Is it normal? On the same trip, my two V65 mpg are around 46 and my three v45 are around 48.
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twoone60
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« Reply #1 on: November 13, 2011, 08:28:43 AM » |
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I get around 45-47 on my 120 mile round trip to work. About 40 miles at 60 and 80 at 75-80. It still has the stock pipes and air filter with no mods.
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Brittles
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« Reply #2 on: November 13, 2011, 08:50:54 AM » |
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I'm getting arround 45 mpg. Maybe your running a little rich.
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John
'84 CB700SC
'04 XL1200C
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tomb raider
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Life is Good !!
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« Reply #3 on: November 13, 2011, 12:03:37 PM » |
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There not as good as the newer NH's.. I get about 50 on my 92 and 30+ on the 700s. Ok with me, it's my Rocket Ship...
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Jimbo
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twoone60
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« Reply #4 on: November 13, 2011, 12:08:36 PM » |
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it's my Rocket Ship...
Might have something to do with 30mpg......
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Bad Boy
Riding outside the box
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'02 Honda VFR800A
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« Reply #5 on: November 14, 2011, 12:20:39 AM » |
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37 is a little low, but face it these bikes are getting old, maybe a little tired. It may not be running 100%. Could be one of dozens of things a bit out of tune.
I get between 40 and 50 depending on how I drive. Mine is an unusually low mileage very good condition example of a 700S.
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Where am I going and why am I in this hand basket?
_
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Laminar
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« Reply #6 on: November 14, 2011, 08:14:34 AM » |
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I am quite disappointed with my 1985 CB700sc mpg. I drive it to work daily on a 50 miles round trip mostly freeway and cruising around 75 mph: the average mpg is 37. Is it normal? On the same trip, my two V65 mpg are around 46 and my three v45 are around 48.
If you're the kind of rider that pulls 46mpg on a V65, I'd suspect the Nighthawk needs a bit of refreshing - check compression, plugs, clean carbs, air filter, final drive oil, etc. |
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It's not what it is, it's what it does.
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muttstang
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« Reply #7 on: November 14, 2011, 08:23:59 AM » |
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Mine gets around 35-40 mpg at best. But I'm 250 lbs and that doesn't help much. I think a big part of the problem is that the engine is designed with such a high power band so it is not as efficient in the normal operating range as an engine that is designed to pull max torque in the normal operating range.
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1985 CB700SC always a project in process! Cams re-timed ;)
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KarlJay
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« Reply #8 on: November 16, 2011, 07:13:29 AM » |
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Mine gets around 35-40 mpg at best. But I'm 250 lbs and that doesn't help much. I think a big part of the problem is that the engine is designed with such a high power band so it is not as efficient in the normal operating range as an engine that is designed to pull max torque in the normal operating range.
Interesting, I wonder if the cam time mod would increase the MPG? I just did a complete go-thru on mine and did the cam-time mod. I also checked the MPG on several tanks before the tear-down. I'll be posting the results as soon as things get worked out. It's got a valve leak problem on cyl #3 BTW, my average MPG over several tanks was 30!! Got 40 on an out-of-town trip once. Otherwise 30! |
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muttstang
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« Reply #9 on: November 16, 2011, 07:32:57 AM » |
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Mine gets around 35-40 mpg at best. But I'm 250 lbs and that doesn't help much. I think a big part of the problem is that the engine is designed with such a high power band so it is not as efficient in the normal operating range as an engine that is designed to pull max torque in the normal operating range.
Interesting, I wonder if the cam time mod would increase the MPG? I just did a complete go-thru on mine and did the cam-time mod. I also checked the MPG on several tanks before the tear-down. I'll be posting the results as soon as things get worked out. It's got a valve leak problem on cyl #3 BTW, my average MPG over several tanks was 30!! Got 40 on an out-of-town trip once. Otherwise 30! depends on how much throttle you give it ;) I know on cars, an aftermarket exhaust is suppose to increase your mpg but a lot of people lose mpg's because they are on the throttle more so they can hear their cool exhaust..... |
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1985 CB700SC always a project in process! Cams re-timed ;)
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MOPARJOE
Mopar Joe and MR. NH-S
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« Reply #10 on: November 17, 2011, 01:43:57 PM » |
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I've had mileage all over the place with these (700-S) bikes; anyhwere gfrom 33-47mpg, It all depends on the bike, and a LOT of variables. I would look towards tune-up, and other easily adjustable items, and I'll bet you get it up to at least 40mpg pretty easily.
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jerjohn
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« Reply #11 on: November 17, 2011, 03:13:50 PM » |
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Im with muttstang on this one. I was worried that my 750 was getting awful mileage but then again im heavier than most riders (260) so im pretty sure thats the reason.  Just goes to show the best performance mod one can make is lose wieght. |
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2000 Nighthawk 750
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TDC71
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« Reply #12 on: November 19, 2011, 08:19:17 AM » |
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I'm in the 40-49 range depending on throttle. 49 if I keep her at 65mph and below. 40 ish if I'm taching it out a bit.
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Mad_Marv
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« Reply #13 on: December 02, 2011, 02:23:12 PM » |
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Got 19,000 miles on the hawk...
It does 42.35 mpg @ 75mph
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tomb raider
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« Reply #14 on: December 03, 2011, 07:52:52 AM » |
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ON that bike path you go 75 mph,  |
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Jimbo
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« Reply #15 on: December 03, 2011, 08:13:02 AM » |
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43-45 mpg commuting.
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akira
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Bike: 1985 cb700sc
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« Reply #16 on: March 29, 2012, 05:11:03 AM » |
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OK guys, I bought a 86 CB700sc with 90K miles and busted starter chain but good carburetor for $250. Take out the carburetor on the 86 and put it on my 85 with bad mpg. After 3 fuel tanks, the average mpg is 45!
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fordh247365
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« Reply #17 on: March 29, 2012, 09:58:18 AM » |
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Sounds like you found the major problem.
My mileage the other day on " a take it easy mostly highway trip" of about 77 miles was 51.3 mpg.
I checked it yesterday on my 48 mile round trip to work and it was 44.7 mpg . I had to get on the throttle pretty good a few times merging into traffic, plus all the stop, start, slow down ,speed up, waiting at traffic lights and people turning off .
I weigh in at about 230, plus full gear and a little tank bag with a few items in it (didn't have the tank bag on the highway trip, just on work commute). I think driving conditions and habits do have drastic effects on mpg.
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1985 Nighthawk S , 2008 Nighthawk 250,2011 Honda PCX
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