Topic: CB450DOHC Question

[bill440cars]

       The thing is, the 450 cam from the factory with torsion bars instead of valve springs in the head. Now I've seen a conversion kit over at M3 Racing. Thing is, the conversion costs $475!

         


         http://www.m3racing.com/products/parts.html#CB450/500



          What I'd like to know, would it be worth it to do this? Mind you, there's no way I could come even close to justifying the cost of their kit! I realize that the old torsion bars have been in that motor for quite some time. Any input on this would be greatly appreciated.
I'm sure M3 has some fine stuff but, they also have some FINE prices too!
         Also, if anyone with info of warming up the 450 motor wants to chime in here, feel free!

                               Later on, Bill    

[bryanj]

All the 450 and 500 twins had the torsion bars instead of coils, considering the way Honda made them rev and that the "Black Bomber" was the top of the line till the SOHC4  why modify, i cant see any problem unless you cut the seat or valve too far and there is no tension on the bar.
Aslso a damn site easier to fit than coils as i remember it

[bill440cars]

All the 450 and 500 twins had the torsion bars instead of coils, considering the way Honda made them rev and that the "Black Bomber" was the top of the line till the SOHC4  why modify, i cant see any problem unless you cut the seat or valve too far and there is no tension on the bar.
Aslso a damn site easier to fit than coils as i remember it

     Hey Bryan.  I just ran across the deal on M3 Racing site and just wondered about the pros and cons of it. I mean, I figured that the stock setup should be good for some pretty good running. I just wondered, at what point would something like that kit be an advantage. I knew that all the 450 & 500DOHC twins had the torsionbar setup and always thought the 450 to be quite a breakthrough motor, when it came out. Myself, I figured that it'd be easier to swap out the torsion bars with replacements rather than convert to coil springs for the valves. I was looking to see if there might be something I hadn't thought of or realized. Thanks for the response Bryan.

                                      Later on, Bill    

[bryanj]

Personaly I think that the coil conversion is used when the valves/seats are altered and the machining aint as accurate as original so the bars dont close the valves propely---No proof on that just my 2 cents.

For a real pain to set up try a Ducati Desmo!!!! All I will say on that is NEVER again!

[bill440cars]

Personaly I think that the coil conversion is used when the valves/seats are altered and the machining aint as accurate as original so the bars dont close the valves propely---No proof on that just my 2 cents.

For a real pain to set up try a Ducati Desmo!!!! All I will say on that is NEVER again!

          You could be right on that theory Bryan. I, personally, like the 450 motor because of the way they perform and the things that were  new to the motorcycling world, when it was introduced. I don't intend to change mine, I was just wondering about the theory behind the change and, if it was because the coil springs were supposed to be better foe high performance, what kind of performance and other internal changes would have been made? It's just an interest I have (for the knowledge only, not application by me).

          I have NEVER had any dealings with doing anything with a Ducati, so I wouldn't have a clue about setting one up. From what you say, I can only imagine.

                                Later on, Bill    

[bryanj]

Lets just say with the ducati heads only on the bench 4 hours EACH and the another day to fit the heads and get it running

[mark]

my 2 cents....

I would opine that once one has fitted the forged pistons and the lightened-polished-balanced crank assembly and the hot cams, that the upper RPM limit would then be the point at which the valves float. Haven't gone looking, but I cannot recall ever hearing of aftermarket stiffer torsion bars for the 450 head.
I'm guessing that, at speed, there is far less inertia in the coil spring/Titanium retainer combo than the stock parts.
It is, after all, a page of race parts.

As for the price..... 4 each valves, guides, 'springs', retainers, 8 keepers... $462 from hondaparts-direct. No big difference there. Not that I would blow $175 for torsion bar assemblies on a stock rebuild.

As for the install....
It looks pretty easy on the head in the pic! 


Happy trails.

Mark

[bill440cars]

        I'd probably be safe to say that I'd never be swapping out the torsion bars for the springs. I mean, those torsion bars seem to be doing the job and for quite some time. IF, and that's a big IF, I was to ever need 1 torsion bar, I'd not be buying 1 new one and I couldn't afford to buy a whole set! I'd just swap out a set from another 450 (or maybe just 1)!

         I'd have to agree with Mark's statement about how easy it looks to set it up on that display head.

                                     Later on, Bill