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post #1 of 27 (permalink) Old 08-23-2005, 09:07 PM Thread Starter
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High Fuel Consumption

I bought a '99 Honda CBR600 F4 back in 8th of this month. And there's a little maintenance issues that needs to be done. For example, replacing the front tire and changing the oil. Also when the speed drops below 20 mph, the front brake fades in and out, it grabs and then it lets go every 1/2 second.

Anyway, my question is I'm not sure why, but the bike is really burning a lot of gas. Most of my riding is in town with few traffic stops, so far haven't done any freeway riding with the CBR. Mostly I stay in 3rd or 4th gear, and sometimes 5th for few minutes on long stretch of road. Mostly I let the bike cruise at 5-6K rpm and occasionally let it fall at 4K rpm during braking. When accelerating, I don't usually take it above 8K rpm, mostly run it at 7K rpm before shifting up.

So with all that said, I'm getting 80-90 miles out of 3.7 gallons of gas before it hits the reserve, that's about 21-24 mpg.

The bike itself seems to run fine, carburetes well, no hesitation on starting it up. Once I notice white smoke coming out of it when it was cold and gave it some throttle. But that's about it, I never need to use the chole to start it up. There's no hesitation in any of the gears or rpm, and it pulls quite smoothly.

The rear tire is practically new, and like I said, the front tire needs to be replaced, it's pretty bald.

The bike seems stock, no aftermarket stuff, even the OEM license fenders is still there.

So I'm just scratching my head about what could it be? I get even better gas mileage on the SV and my car.

Here are few pics:

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post #2 of 27 (permalink) Old 08-23-2005, 09:13 PM
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maybe its the gears your cruising in? i ususally get 200 ish...out of it..and still drive hard sometimes
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post #3 of 27 (permalink) Old 08-23-2005, 09:24 PM Thread Starter
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200 on full tank, what gear? it seems odd for my bike, but no freeway riding either. like I said, I usually stay in 3rd and 4th pending on traffic.
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post #4 of 27 (permalink) Old 08-23-2005, 10:25 PM
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You mentioned you feel your front wheel grabbing. Take your bike out and go about 55, and then squeeze your brake. Do you feel a pretty strong vibration?

I'm guessing one or both of your front discs are warped, and your brake calipers are dirty. This will drag your mileage way down. The rear brake caliper is even more prone to dirt-induced dragging than the front. Take a two-mile ride without using your rear brake and then touch the rear rotor. Is it hot?I also expect you could use new plugs, and your air filter could stand a good cleaning. How's the chain. Dry, worn, or too tight will also make your bike drink gas.

These are all relatively minor things which you can easily fix yourself. If you're not used to working with brakes, you should either get a manual, and let the fellas & ladies out here help you through it, or let the shop do it.

If you go the shop route, make sure they know you want the calipers thoroughly cleaned. Be a good idea to change the pads also if your wallet will stand it.....Hope this helps...

PSI looked at your pics and the bike looks stock, clean, and well cared for, so just check out those things above and you should be in good shape...

Last edited by Rundog; 08-23-2005 at 10:28 PM.
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post #5 of 27 (permalink) Old 08-23-2005, 11:16 PM Thread Starter
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Thank you. Ya, it's exactly as you described it, on high speed, the brake does work pretty well, but I get this really strong ringing vibration through the bars, and no matter how hard or soft I brake, it 'feels' like the forks are compressing tight. It vibrates strongly every time. Also I'm not sure if it's normal, but there are some minor vibration through the bars when cruising.

I'll see if the rear disc is warm tomorrow, but when I had to repair the rear tire, the dealer mechanic said the rear needs brake pads. I know it does because I experienced fade. And when I got back from the dealer, it seemed the wheel was mounted tighter than I had before. Chains seem fine, but probably needs lubing, but it seems there's not much slack.

I can probably take care of the brake pads, but what happens when brake discs are warped? Anyway to fix it?

I let a very good friend of mine ride it, he didn't mention anything about vibration, but he said the brake fade could be due to brake discs being warped and needs a new tire.

Also I heard that the older CBR6s are known for having bad cam-chain tensioners, how would I know if it's disfunctional? Is there long term solution to this?

I'll take some closer shots tomorrow if it helps.

Last edited by Z_Fanatic; 08-23-2005 at 11:51 PM.
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post #6 of 27 (permalink) Old 08-24-2005, 03:58 AM
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Hi Z_Fanatic-

You might also want to double-check your tire pressure to ensure they're not way too low. That could certainly lead to gas-guzzling. I like to start looking for a gas station when my main tank hits about 130 miles or so. I'll have to run it down to empty to see what kind of actual mileage I'm getting on my CBR 600F2 for comparison purposes.

In terms of the cam chain tensioner (CCT) going bad, you'll know because it will sound like a bunch of loose marbles being rattled around in a coffee can. The sound is mostly noticeable from the right side of the engine at idle and then will go away once throttle is applied. It is annoying in nature, but won't be a "code red" situation that needs to be addressed immediately. The best bet is to remove, clean, and reinstall your current CCT while you shop around to get the best deal on a stock CCT or one of the aftermarket manual CCTs that are advertised. Due a search and you'll see lots of threads on this topic (including pictures) and how to do it.

~ Blue Jays ~

Last edited by Blue Jays; 08-24-2005 at 04:04 AM.
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post #7 of 27 (permalink) Old 08-24-2005, 05:06 AM
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Sounds like warped disks are the problem. They would be dragging, so its like riding around with a brake applied a tad. Bad on gas milage. Now the trick is finding out which one is it.
Car disks can be shaved a tad to get a true surface, so long as they are not too warped. I dont know if the same can be done to bike rotors or not. My guess is no since they are so thin.
I'd advise finding which rotor is warped and scoring a replacement on ebay.

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post #8 of 27 (permalink) Old 08-24-2005, 05:34 AM
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man, I beat the ever living crap out of my bike and still get 130-150 out of it. If I am gental, I have squeezed as much as 192 miles out of a tank before pushing the bike half a mile up the breakdown lane to get fuel.
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post #9 of 27 (permalink) Old 08-24-2005, 06:00 AM
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Warped rotor. Guys, be careful how you handle wheels when they're off the bike. It's not hard to warp one of these floating rotors from banging them around while off the bike. It's generally the hub that bends when hit, not necessarily the rotor itself but once done, it's the unit that needs replaced.

You probably won't even need any fancy measuring tools to find the culprit. With the wheel off the ground and a screwdriver held stationary against the lower leg, spin the wheel and see which one is friendly, waving at you.

The fuel mileage may be the result of an overzealous jetting job. Especially when you say that no choke is needed on cold start. If you get a Xmas card from the Saudi royal family, you can be sure of it.

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post #10 of 27 (permalink) Old 08-24-2005, 01:43 PM
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Good tips up above. Still check on the teeth of the small & large sprocket for you might find the prior owner went down one tooth on the front so YES you will use up more fuel, but probably only on the hwys.

You have to realize the sportbikes were never designed for puttering around in the city traffic for that is where a regular riding position bike of nothing larger then 500cc will prove to be the good bike when it comes to fuel use.

When it seemed like fuel prices were high in the late 40s or to the 60s I noted chaps with larger bikes like 500cc to 750cc to even Harley 74OHV would latch onto a smaller bike, for around town, like a 125 2-stroke, to 250cc 4 stroke to even 350cc single 4-stroke & yes AS a 2nd bike.

I used my bikes to & from work so rode anything from 125cc to a 350cc & yes that included the little old Villiers 125cc 2-strokes to the flat opposed liquid cooled 175cc LE Velocette. There simply was no need of a 500 to 1000cc bike when in town town riding. Though these were not LARGE cities like in the States so traffic tie-ups were almost unheard of.

Last edited by Smitty; 09-01-2005 at 12:55 PM.
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