Topic: Honda cb350f top speed

[Scooterhead]

After completely rebuilding my bike I and curious as to what is the expected top speed
I recond my engine set valves set the point and timing and the tuning is now somewhere near
I have tan spark plugs at idle and full throttle,and I have 150 psi compression on all cylinders
I have seen Honda specs saying that the top speed is around 98 mph but can acheive about 80 to 85 mph which is probably about 8k rpm in 5th gear,is the claimed top speed correct or optimistic

[carnivorous chicken]

I think 98 is optimistic on the part of the Honda engineers. I've had a 350F for 20 years, and don't ever run it flat out. It'll hold 75 easily, and do 80 just fine with a little more to give. Doesn't really answer your question, but maybe downhill with a tailwind you could top out at over 90...

[TwoTired]

Is the bike in stock configuration?
Tires?
Sprockets?
Intake?
Exhaust?

Are you in tuck to minimize air resistance?

I could get to 98 with a stock 305 Honda, but only in tuck.  I weighed 145 lbs at the time.

[grcamna2]

Aw come-on,according to member JWilde we can spin up a CB350F to 85mph in 2nd gear !   

[MoMo]

Aw come-on,according to member JWilde we can spin up a CB350F to 85mph in 2nd gear !   

That's right, Bill.  I still plan to race against him with my 400 Seca, which has been clocked faster than 85 in 2nd              Buy a bridge anyone??

[carnivorous chicken]

Aw come-on,according to member JWilde we can spin up a CB350F to 85mph in 2nd gear !   

I was gonna add that but you beat me to it!

[grcamna2]

Aw come-on,according to member JWilde we can spin up a CB350F to 85mph in 2nd gear !   

I was gonna add that but you beat me to it!

lol    one might wonder how high he was..

[Scooterhead]

Bike is completely stock apart from the guy I bought it from fitted 4 to4 stainless exhausts without baffles(loud)
What am i missing here it's a total recond engine new piston rings etc.struggle to get more than say 82mph but that wasn't tucked in
Oh and I am about 105 kg

[TwoTired]

Probably needs bigger main jets for that pipe.

[Deltarider]

In tests they usually gave the top speed 1. sitting upright and 2. nose between the meters (and sometimes 3. riding two-up). Makes a big difference.

[Steve_K]

I would also question whether the speedometer is accurate.  40 years ago speedos sometimes were off when new. I recall my 350 twin had trouble breaking 80 mph on the speedo. 
Steve

[TwoTired]

I would also question whether the speedometer is accurate.  40 years ago speedos sometimes were off when new. I recall my 350 twin had trouble breaking 80 mph on the speedo. 
Steve

Very good point about speedometer accuracy.  My 305 was 3 months old when I did my max out runs.  But, it was 98 indicated, right in front of my face.  Very slow to rise after 95.

I would think a 4 cylinder 350 would do at least as well.

[scottly]

IIRC, the redline for a 350 four starts at 10,000 RPM. Try taking it up to redline in forth gear before upshifting.

[Dracon]

 Another possibility could be as simple as power to weight ratio. You currently way just over 230 pounds and I'd be willing to bet the average weight of the Japanese test subject in the 1970's was closer to 160 pounds. If you lost 70 pounds I bet you could  get a decent amount faster than what you are now.

Please don't take this to say that I think you are overweight or should lose weight,  I know nothing about you, your height, your build, or anything… just that the average weight of the test subject when the top speed was taken was probably less.

[grcamna2]

Probably needs bigger main jets for that pipe.

I'd like to see the spark plug color,if white in the center porcelain I'd richen-up the main jets considerably 

[flybox1]

Probably needs bigger main jets for that pipe.

+1
75s are too small.  try 78s(if you can find them) or 80s

[BomberMann650]

The horsepower gain/weight reduction diet is something everyone oughta try at least once.

[flybox1]

The horsepower gain/weight reduction diet is something everyone oughta try at least once.

I religiously drop 2lbs before every ride 

[BomberMann650]

The horsepower gain/weight reduction diet is something everyone oughta try at least once.

I religiously drop 2lbs before every ride 

It's 14# per horsepower ain't it? 

[flybox1]

The horsepower gain/weight reduction diet is something everyone oughta try at least once.

I religiously drop 2lbs before every ride 

It's 14# per horsepower ain't it?

FML....I though it was 14hp per lb!   

[TwoTired]

The horsepower gain/weight reduction diet is something everyone oughta try at least once.

I religiously drop 2lbs before every ride 

It's 14# per horsepower ain't it?

Depends on how fast you want to change the inertia of the mass.  And the rolling resistance, and the air drag.


Here's a chart mapping the HP needs vs speed of a Honda 350 Motorcycle.

[Scooterhead]

Can't quite make it out
How much horse power for the claimed 98mph then

[robvangulik]

Can't quite make it out
How much horse power for the claimed 98mph then

About ten HP more than Honda claims it has   

[markreimer]

My 74 350F topped out in a full tuck with no wind (or maybe even a minor tail wind) at about 95 according to my speedo. It was probably exaggerating the speed, but a friend riding with me figures he was going about 155km/h, which is 96mp/h. I weight 150lbs and had a little 6" wind screen I was tucked behind. With a bike this small, weight and aerodynamics really matter! The second I lifted my helmet above the screen my speed would drop by 4-5 mp/h. If I sat up straight, I'd drop a good 10 or more.

Eventually I had to rebuild the engine due to excessive oil burning, found two pistons with heavy scarring on the sides. Hone, new rings, valve job, and my top speed was actually LOWER than before, despite even compression. Then my #4 cylinder gave up the ghost and filled with oil. Still haven't gone back into the engine to fix whatever happened.

[Scooterhead]

I was tucked in today and got 85 mph I weigh about 107 kg
I did a plug chop as well the first one is at full throttle and the second is at idle
Here is the pictures ,what are your opinions