Topic: cb350f on the Hwy

[Ernest]

Just starting to ride this little bike around and I noticed I can drive around the city all day long and It seems like I'm barely using any gas at all.  I take it on the highway though and It seems like I'm burning right through it.  I've got a 25 mile commute to work, I fill the tank up last night, drive it to work and it looks like I went through at least a gallon or more.  I haven't let it get down to empty yet so I'm not sure where that would put the mileage at on a 3 gallon tank but I'm assuming I get around 20 miles a gallon on the Hwy.

This kinda makes sense to me being such a small engine going 60 to 70 mph and pulling 6 k to 7 k rpms it would eat alot of gas but I just wanted to ask and make sure I may not have something wrong with the bike.  Is there a possibility that I have something wrong with the carbs and I'm losing fuel through the overflows at these speeds?  Or does this sound normal for a 34 y/o little 350 that probably shouldn't be on the Hwy anyways? 

thanks

[GroovieGhoulie]

I've ridden my 400F (same carbs) on the freeway some and I've noticed about 40MPG on the freeway, cuffing it hard to keep up.  The throttles are VERY open when I'm riding on the freeway.

Can't think why you're getting bad mileage.

[Tim.]

How 'aerodynamic' are you?

[Bob Wessner]

How 'aerodynamic' are you?

Sounds like a personal question. 

[csiress2]

I have the same bike, 1973, and I ride it about once a month from Orlando to Tampa, about 100 each way, and I get about 48 - 50 miles per gallon.  This is even at 8 - 9 grand.  I'm no mech, but I think something is off on your bike. 
It's a great little bike.  In fact, my dad bought the bike in Northern Indiana and rode it down to Orlando.  He said he was cruising around 8 to 9 grand the whole way down.  I love the bike.  It's my daily rider.  It sure beats my 23 mpg truck.  Thought 23 mpg for an '88 Toyota pickup is pretty good.

Hope you enjoy riding your 350.

Craig II
<><

[Ernest]

Something is definately off if you all are saying you get 40 mpg or more.  I'm only beginning to learn the mechanics on these bikes so it wouldn't surprise me if I had something out of wack with the carbs.  I haven't done a plug chop on it yet so I could be running super rich among other things.

6'3" and 200lbs wouldn't make me exactly aerodynamic and the bike is alittle too small proportionately but I love riding the thing.

Two big chopper guys pulled up next to me a week ago and told me to pull over.  I thought I was going to have to take these guys out and defend my little scoot but they were actually really excited to see one on the road.  One of the guys offered me another cb350f parts bike for $100.  Picked it up on sunday, not in as good shape as mine but has a running engine among other parts.

thanks

[nickjtc]

Two big chopper guys pulled up next to me a week ago and told me to pull over.  I thought I was going to have to take these guys out and defend my little scoot but they were actually really excited to see one on the road.  One of the guys offered me another cb350f parts bike for $100.  Picked it up on sunday, not in as good shape as mine but has a running engine among other parts.

You meet the nicest people when you ride your Honda...

[supersport_CB400F]

A lot depends on exhaust and air filter modifications

[Bodi]

It takes a fairly consistent horsepower to run any unfaired UJM at freeway speed on level ground, they all have pretty much the same atrocious aerodynamics. Whether it's a 350-4 or a CB1100 makes little difference. They should all get roughly the same gas mileage cruising the same level highway at the same constant speed.
I would do a plug chop after a few minutes at cruising speed, I think you'll find something amiss.
A simple tuneup could make a big difference. If the ignition timing is retarded the bike may run great at idle and lower RPM but you'll be wasting a lot of the gas energy just heating up your exhaust pipes because the fire starts too late to get the most out of it at higher RPM.

[mlinder]

motorcycles are nearly twice the drag of autos. averaging .775 drag coefficient.

[dusterdude]

#$%*,i bet my drag is over 1 then.

[mlinder]

#$%*,i bet my drag is over 1 then.

Crap. some other sources put us well over 1.

[tramp]

my old 350 4 got about 45-50 no matter how i drove

[cb650]

My little twin gets 45-55 town or hiway.   Even with the monkey on back.  Mostly ride to work but it has seen 500+ round trips several times.



                Terry

[aptech77]

I have 30MM CV carbs on my 400F and still get 48-54MPG depending on how hard I ride on that tank..... OK OK to much info!

[Ernest]

I just got around 80 miles out of that tank, thats about 27 mpg.

 

A lot depends on exhaust and air filter modifications

I do have a 4 to 1 exhaust on it.  Would that cause it to use more gas than a stock exhaust or a 4 to 2?
Air filter is stock.  I'm pretty sure I have it running too rich also, I imagine it's a combination of factors.

[cmorgan47]

My little twin....

sorry, you lost me there.

[supersport_CB400F]

I just got around 80 miles out of that tank, thats about 27 mpg.

 

A lot depends on exhaust and air filter modifications

I do have a 4 to 1 exhaust on it.  Would that cause it to use more gas than a stock exhaust or a 4 to 2?
Air filter is stock.  I'm pretty sure I have it running too rich also, I imagine it's a combination of factors.

I think once you move away from a stock set up with air\fuel and exhaust then getting the balance back is not an easy job.

[Gordon]

There's no reason to guess if it's running rich.  Pull the plugs and see what they say.