Author Topic: why SOHC over DOHC? (Read 11194 times)

jason41987 · « **on:** September 06, 2012, 02:40:28 PM »

this has probably been asked a lot.. but of the two honda CBs im looking at ones a SOHC CB350, the others a DOHC CB450... why would many people choose the SOHC engine over the DOHC engines? whats so bad about the DOHCs? is it just aftermarket?... also, what woould you say about the CB360 engine vs the CB350s, both seem very similar

lucky · « **Reply #1 on:** September 06, 2012, 02:48:58 PM »

The CB350 and the CB360 are almost identical.
The CB450 was a break through motorcycle design.
It had torsion bar valve actuators.
It put HONDA on the map as a serious motorcycle to contend with the Brits and HD.

SOHC has less parts.

The DOHC has more parts but has greater intake area and better valve angle
in the cylinder head, allowing for a better piston design.
The valves are smaller and can rev higher.

The early SOHC engines had a 14:1 fuel air ratio mix.

The modern SOHC or DOHC has a 65:1 parts air to one part fuel ratio with direct injection! And some have varible valve timing Too.

Magilla · « **Reply #2 on:** September 06, 2012, 03:58:57 PM »

Old school or should I say olds cool.

Fritz · « **Reply #3 on:** September 06, 2012, 04:07:59 PM »

Quote from: lucky on September 06, 2012, 02:48:58 PM

SOHC has less parts.
[..]
The DOHC has more parts

Well, at least you don't need rocker arms in a DOHC. On the other hand, you don't need to take the camshafts out to adjust the valves on the SOHC.

Quote

The early SOHC engines had a 14:1 fuel air ratio mix.

The modern SOHC or DOHC has a 65:1 parts air to one part fuel ratio with direct injection!

I thought, everything below 12:1 and above 14:1 will be difficult to ignite. These are not diesel engines

lucky · « **Reply #4 on:** September 06, 2012, 04:41:48 PM »

Quote from: Fritz on September 06, 2012, 04:07:59 PM

Quote from: lucky on September 06, 2012, 02:48:58 PM
SOHC has less parts.
[..]
The DOHC has more parts
Well, at least you don't need rocker arms in a DOHC. On the other hand, you don't need to take the camshafts out to adjust the valves.

Quote
The early SOHC engines had a 14:1 fuel air ratio mix.

The modern SOHC or DOHC has a 65:1 parts air to one part fuel ratio with direct injection!
I thought, everything below 12:1 and 14:1 will be difficult to ignite. These are not diesel engines

The CB450 still had rocker arms.

But many modern DOHC engines have no rocker arms.
But not all of them require removing the cams.

jason41987 · « **Reply #5 on:** September 06, 2012, 05:09:59 PM »

so.. whats the better engine? a 350s SOHC, 360s SOHC, or the 450s DOHC engine, and why do you feel its better?

phil71 · « **Reply #6 on:** September 06, 2012, 06:00:15 PM »

the cb 450 had rocker arms huh?

bjbuchanan · « **Reply #7 on:** September 06, 2012, 06:12:48 PM »

A lot of the time it really just becomes a mass preference. The smaller bikes don't, atleast i think, have the same rift in opinion like say a dohc750 or sohc750.

People kinda latch on to what they prefer, whether it be an era or model of something.

Also the 80's bikes started to get more plastic-ey, more like modern. The 70's you just take off the blinkers, change the seat and paint it and you have a vintage looking bike without the vintage price tag, less reliability, more expensive parts etc..

Most of the time it is just what everybody comes to love, just the right lines, power, reliability and ease to work on

The dohc is the choice i would personally go with. more power, solid bike

jaguar · « **Reply #8 on:** September 06, 2012, 06:23:31 PM »

are we talking about 350 twins or 350 four cylinders?

The 450 is a twin only. Has torsion beam operated valves
Either way the Cb450 twin is a much better bike.

Its more powerful and faster. Partly due to the more modern DOHC and partly due to being a physically larger motor in a not much bigger bike.
Down side is it shakes to all hell, more to do with crank firing angles then anything cam related
the 350 four, is turbine smooth

Want a "middle" weight bike? CB400F

jason41987 · « **Reply #9 on:** September 06, 2012, 06:50:01 PM »

im only interested in some of the two cylinders i think.. so im looking at 350s and 450s for the most part

im curious though if you can dress up a 450 or 350 to look like an old CB77?

Lil Red · « **Reply #10 on:** September 06, 2012, 06:51:03 PM »

I dont think it's SOHC "over" DOHC or the reverse...SOHC was where Honda, and by that I mean its where Soichiro and his company, were at, for mass production, at the time when it was developed...I believe, but am not certain that Honda had DOHC F1 car engines in the early to mid 60's. When the 750 sohc came out it was so far ahead of the other bikes engine wise (as a mass produced multi) that they went with the simpler SOHC design just to be conservative, have less moving parts, less machining etc...better reliability? in the massed produced sense...Honda had DOHC moto GP bikes in the early and mid 60's as well. SO from a cost, profit and reliability standpoint they went with the SOHC....These views are just from what I've read...and may or may not be precisely what occured....another opinon of mine is the early like up to 75 sohc's sound like nothing else....the CB400f in particular...I'm biased toward it...the SOHC has since been outpowered and is dated technology...but no other Japanese multi (3 or more cylinders) sounds like it or as good...and as a powerplant what it lacks in the modern sense of power and speed, it more than makes up for in character and soul...to me the SOHC is the only thing that competes with the Euro bikes (of any era) in those categories...The twins CB350,450 maybe even outperform a 350 or 400 four...but in my opinion not by enough to have a twin over the four.

PS either of the bikes, twins or four can have the CB77 look...depends on how many megaphones you put on it...4 into2 2 into 2 CB77 4 into 4 and you get Rc172.

Killer Canary · « **Reply #11 on:** September 06, 2012, 06:54:57 PM »

Depends what you want it for! For me, a 350 twin is for cafe, the 450 is for restoring to stock.

jaguar · « **Reply #12 on:** September 06, 2012, 07:00:19 PM »

why dress a bike up to be something its not?
just buy a CB77 if you like the styling

jason41987 · « **Reply #13 on:** September 06, 2012, 07:17:16 PM »

i cant buy anything until i find one to buy... all i can find within 200 miles of me are CB750s.. ill probably need to post a wanted ad online in a few places

splitt · « **Reply #14 on:** September 06, 2012, 07:44:03 PM »

I've also heard that some just prefer the smooth asthetics of the of the valve cover on the SOHC engines as compared to the double humps on the DOHC's. Just ride whatever you like.

Lil Red · « **Reply #15 on:** September 06, 2012, 07:48:51 PM »

Some of these things are like dog whistles to certain people...the twins have all the right vibes...for me the 4's have the right lack of vibes, yet that certain tingle...Having a Moto Guzzi twin with it's strong vibes...the minute I got on the 400f...it was just other wordly...theres nothing a vertical twins gonna have on a 90 degree pushrod aircooled V-twin...that's what I found when I rode the Honda twins.

jason41987 · « **Reply #16 on:** September 06, 2012, 07:51:02 PM »

i was really thinking of a cafe racer conversion.. nothing that would use permanent, irreversible modifications, swapping handlebars, seat foam, cover, etc would work fine... so CB350/CB450 for the twins, 400F and 550 for the inline-4s, what wuold make the better cafe racer?

Lil Red · « **Reply #17 on:** September 06, 2012, 07:56:13 PM »

You need to ride all of them and make a decision...see what appels to you....you can make a cafe racer out of all of them. Wherever your state of mind takes you....you cant really go wrong...dont forget the 350 four...it's got a personality all it's own...as do the others that you listed.

jason41987 · « **Reply #18 on:** September 06, 2012, 08:05:11 PM »

thats what makes the decision so hard.. all these bikes seem to have their own personalities, and i wont have the opportunity to ride any of them before i buy one

bamabiker · « **Reply #19 on:** September 06, 2012, 08:28:37 PM »

The Honda Twins website has all the info you would ever want about merits and problems of Honda's 350, 360, and 450 twins (and all the other twins). Its a good site, just not as good as this one.

JeffSTL · « **Reply #20 on:** September 06, 2012, 08:43:05 PM »

For me the answer is quite simple. The 1969-76 CB750K is the most beautiful bike ever made and it happens to be sohc. Yes there are other beautiful bikes but the first generation 750k's just say motorcycle to me.

jason41987 · « **Reply #21 on:** September 06, 2012, 08:43:30 PM »

i found a CB450 60 miles from me... ill call the guy tomorrow and see if he can email me some photos of it... $500 and apparently it runs, just needs a carb rebuild and some new tires... if it is as advertised, all be going with that one and pick it up this weekend, start working on it next week

JeffSTL · « **Reply #22 on:** September 06, 2012, 08:46:50 PM »

Also don't chop up or cafe a perfectly good example. If you are looking for a project buy a project bike.

jason41987 · « **Reply #23 on:** September 06, 2012, 08:50:21 PM »

a sub $500 bike that barely runs isnt a project bike?.. $500 is my limit for the bike because im looking for a winter project... man, after listening to that CB400F though.. id love to find one of those, personally not loving the exhaust on them though.. prefer the 550 style exhause (are they interchangable) but that 400F sounds like a supercar

JeffSTL · « **Reply #24 on:** September 06, 2012, 09:02:57 PM »

Well you had posted that while I was typing my post. There are people who take a nice survivor and cut it up and it always pains me. The typical line here is "it's your motorcycle do what you want but...." I'm a stocker, I like how honda made 'em.

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Author Topic: why SOHC over DOHC? (Read 11194 times)