Topic: What rpm's is a cb350f running at say 60mph?

[Seyser]

Next week I will be the new owner of a red 73 350f and am just wondering what kind of rpm's the motor is running at cruising speed? Is it possible to put a bigger sprocket in the front and if yes, where is the best place to pick one up from?

Iv never rid a 350 four before and am just trying to gauge what kind of a treat im in for
Thanks
-Jeremy-

[Uncle Ernie]

I'm going to guess about 6K.

[Suke]

You are definitely in for a treat! I just got a '73 350F Four a few weeks ago, and it's a blast! I took it for a nice 20 mile ride today and rode very smooth. I haven't gotten it up to 60, but it rpms around 3 to 3 1/2 around 40+ mph. Post some pics once you get the bike. Enjoy!

[Seyser]

6k rpm's wow thats right up there, has anyone ever geared these bikes up so the cruising rpm will be lower?

[Bob Wessner]

I would do some research if I were you before you altered the gearing in any way. The smaller displacement engines do their thing best when spinning up some decent RPM's and the engines are designed to take it. Honda has lots of experience on engines like that. I seem to recall they raced a 6 cylinder 250! I bet that thing did some spinning. I would have loved to have seen the insides of that engine design.

[Seyser]

Yea I was just reading about the 250/6 that honda raced in the earlier days, it seemed like a pretty amazing machine. I was just hoping that i could add a tooth in front to try keep the rpm's alittle lower. Im not all that big at 5'10'' 160lbs so hopefully it will pull without a problem.

Im just so anxious to get this thing, im just counting the days, only 5 more!!!
-Jeremy-

[Suke]

I'm about the same size as you and it's definitely quick enough to get you where you need to go, as well as handles extremely well. I took the MSF course in April, and this bike is easier to control than any of the bikes I rode during the course & exam, which were the Rebel and the Suzuki GZ250. My guess is that you are just looking at the pictures of your bike while counting down the days. I'm sure it's going to be worth the wait.

[loonymoon]

Hi! Best of luck with your 350F. Mine is great fun, and yes 6000rpm at 60mph is right in top gear (5th). I have been up to 80ish (8000rpm) on mine but don't normally go too fast. It gets there quite quick but you do have to rev quite hard. You can tell when you're in top  as the rpm is 100x the speed eg. 5000rpm at 50, 7000rpm at 70 etc. The red line is 10,000 so has plenty to play with. I always find that I keep trying to change up when I'm already in top though - I think that's why they put another gear on the 400/4.

Enjoy - it's a GREAT BIKE

[Gordon]

Seyser,

You can certainly do that if you want to, but with that size engine you will lose a significant amount of pulling power on the low end, like when starting from a stand-still.  The 350 doesn't have much low end torque to begin with, either.  Also, cruising at high speeds at a lower RPM, you will find you are constantly down-shifting when going up even the slightest hill or hitting a head wind to compensate for the lack of torque. 

I have had a 350F and a 400F, and can definitely say the hardest part in the beginning was getting used to the high revs, but these bikes were made to cruise around town at above 4K rpm, and don't even get into their power until about 6K.  They were geared to exactly match their power output and any changes will result in a noticeable compromise on one end or the other.   

[Seyser]

Thanks guys for all the great input! Im just so used to riding my dads 99 magna 750  so Im just curious what this 350 will be like, Im not comparing the two as that would be apples and oranges but Im just really eager to see what its like. I know what you mean about having to downshift and thats kinda what I figured would happen if i were to gear it up.

I like how on the magna, it just cruises at a low rpm and has enough torque to just pull it along that way...but im sure the CB will be a fun machine!!!

One last thing...Anyone have a MAC exhaust on their 350F? Im just wondering how it sounds?
Thanks
-Jeremy-

[cb650]

My 360 twin ran at 5k @60.  I went 1 tooth biger on front and 1 size bigger on rear tire and now its about 4600.  Still has some pull too.  Went over the mountains last weekend and did fine for size and load.



                            Terry

[Uncle Ernie]

Terry, I'm no expert on gearing, When you changed the sprockets as you describe, what differnce did you notice?

Jeremy, little engines rev higher. Most people lug their engines in general- cruiser types being the exception. If you love your 350, you need to show it by wringing it out like a dishrag that should have hit the laundry weeks ago. It won't even move under 4000rpm! A Harley is blowing up at those revs. Spank that puppy! You absolutely can not make it cry unless you baby it. I cruise on the freeway at 6K. If I'm diddling around town I'll go down to 5K. In general, you need to shift a lot to stay in the powerband. Jeremy, where IS that powerband? It starts at about 5K and goes up through about 8K. You're getting delivery of a little puppy that wants to play, not a draught horse. Two words here; Ya Hoo.

[cb650]

Terry, I'm no expert on gearing, When you changed the sprockets as you describe, what differnce did you notice?

.

Ah rpms went down.     MPG went up a little.



                      Terry

[Salem350F]

Check out a thread I started about CB-350F sprockets, It is on page 5 of the Tech Section “Chains and Sprockets CB-350F” May 29th.

I am going back to the stock configuration, my drive chain is way out and no more adjustment, I think the PO tried to do what you are talking about.  I am not sure what is the advantage to the minor RPM decrease; Mr. Honda designed them to be best all around.  I ordered the stuff from Dennis Kirk and hope it comes before the weekend so I can get it installed to ride safe.

I am getting the bike registered tomorrow. I Spent some time getting it in condition, carb rebuild, comp;ete tune up, some electrical work, getting the ugly king and queen seat and the Harley sized rack off.  I have only sneaked out on back country roads with the configuration as in the post it was running @ 4000 rpm at 35-40 mph in 3rd gear( my memory might not be perfect). I am a fairly light rider , it took a while to get there.  I agree with a previous contributor that these engines are meant to breath not be lugged.

If it would help you I will take it out and make exact notes of speed and RPM  before I change everyting over to stock.  Let me know soon, because as soon as the parts get here it is going into my shop.

Hope this helps

[dusterdude]

in 1981 i had a 350 twin that revved about 1000 rpm for every 10 mph,i remember doing damn near 6 grand at 60 mph.never hurt the bike at all,although it is a bit buzzy.

[Seyser]

Salem,

No you dont have to make any notes but thanks for offering. So your guna replace your sprockets with the original configuration? Is the rear sprocket that you have on there good? Id mabey be willing to buy it from you as it seems to be 2 teeth smaller than stock.

-Jeremy-

[CRP_III]

I just got my CB350F it has a rattle I don't like but pulls my 6'3" 240lb frame up and over litte hills and hits 60 at 6k no problem.  I am having a blast on it.

[Salem350F]

HI! Further report on the CB-350F sprockets.  I had the bike out for the first time with the correct registration.  I will tell you that I am glad that I made the decision to go back to stock.  This gearing keeps you way below the power band.  I have a steep windy hill, one way home to my house that you need to start from a stop.  Being an Old Yamaha RD-350 rider, it acted exactly like a two stroke, because I couldn’t get the revs up to the power band. When I would try to shift up the revs would drop down below 3000 and lug along, down shift to keep going but had to crest the hill at about 15 before I could shift up. 

I also run a CB 450 twin and the 350 four are two entirely different animals.  Is this your first bike?  I would run it a while and see how you like it, if you are used to bigger bike that will lug a little like the twins do this will be different

If you live in the flat lands somewhere this might be perfect for you.  The sprockets I have aren’t too bad, when I get them off I can send you a picture, If you want them just cover the postage and you can have them.