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Author Topic: "La Pastinaca" CB450 498cc Big Bore Engine Built By DWMS Racing!  (Read 66141 times)

Offline joeyputt

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #40 on: Jul 26, 2011, 13:41:11 »
Brothers it has already started so go ahead and have the discussion here if you like, I felt it coming! Hahahaha! I have just seen a lot of technical discussions turn into differing opinions and ending with hurt feelings and I did not want that for Brother Habanero52's thread but I am sure everything will stay cool here!

Brother Rip-It-Up this engine is getting custom reground cams and the racing coil spring conversion with titanium retainers so there will be no torsion bar system. The parts have been ordered and should be here soon! I will post photos of the conversion as I install it.
« Last Edit: Jul 26, 2011, 13:50:37 by joeyputt »
Joe - Owner/Operator of DWMS Racing World Class Engine & Motorcycle Building www.dwmsracing.com

Cylinder Head Porting Sale! http://www.dotheton.com/forum/index.php?topic=56203.msg637024#new

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Offline Swagger

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #41 on: Jul 26, 2011, 14:23:51 »
It's funny, I prefer the idea of coil springs....I really do. But Honda raced lots of bikes with torsion bars and I've found no account other than those of guys trying to sell.....coil spring conversions.....that say they are needed. Not trying insinuate anything about anyone selling them, just what I've heard. Torsion bars hold our cars up too.
Now, would 35-40 year old torsion bars merit replacement, you betcha but I'd run fresh torsion bars with a fairly stout cam and feel pretty good about it.
.....there's no way that little rice cooker is going 100m/h when the work need to get up to those speeds includes a big fuck off fairing shaped like a giant cock. ~Staffy

Weiner tetanus is nothing to scoff at. ~JustinLonghorn

Offline joeyputt

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #42 on: Jul 26, 2011, 14:58:23 »
Brother Swagger I like the torsion bar system as well, if for no other reason than its uniqueness and a lot of guys cut a tooth off of the bar to give them more torsion for high rpm engines and they work fine however they will not work with the stem on these particular 5mm valves so to use these valves you have to use the spring conversion kit with them.

The spring conversion is also not quite as easy as most would think, there is a certain amount of valve stem heighth that is required to prevent spring bind and attain proper spring pressure.

Take a look at the valve comparison photo on page four of this thread and you can see the difference in the valves, I guess if you really wanted to you could machine a custom retainer for use with these valves to retain the torsion bar system but the valve is also shorter for use with lash caps so you would probably run into clearance issues with them as well.
« Last Edit: Jul 26, 2011, 15:22:46 by joeyputt »
Joe - Owner/Operator of DWMS Racing World Class Engine & Motorcycle Building www.dwmsracing.com

Cylinder Head Porting Sale! http://www.dotheton.com/forum/index.php?topic=56203.msg637024#new

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Offline Swagger

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #43 on: Jul 26, 2011, 16:15:38 »
Aw yes, those Kibblewhite valves......gooood stuff that. They're taller too aren't they?
.....there's no way that little rice cooker is going 100m/h when the work need to get up to those speeds includes a big fuck off fairing shaped like a giant cock. ~Staffy

Weiner tetanus is nothing to scoff at. ~JustinLonghorn

Offline Habanero52

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #44 on: Jul 26, 2011, 16:38:29 »
Mr. Swagger, would you mind expanding, for may edification, on the Kibblewhite Valves comment?
Habanero52
Speed cost....How fast do you want to spend?
Follow the dream.
Why does life get in the way?

Offline teazer

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #45 on: Jul 26, 2011, 17:19:23 »
Teazer I get what your saying about leaving the valve shrouded to help prevent cross flow during the overlap. However if you where to do serious work to a 450, and I understand he's not taking this one that far, You would want to fix the poor scavenging correctly. It does appear to be, although hard to tell from the pic's, alot of unshrouding around the cylinder sides of the valve that could easily be cut back.
 
I seems to me that the "linear" torsion bar springs are the problem here. I would imagine there would be a bit to be gained by both the 5mm valves and by retrofiting the motor with progressive springs "beehives" would be ideal allowing a custom grind cam with better ramp geometry.
 
Thanks for the article Joey, It does help shed some light to the weak points in the design.
 
Lingo, there's alot of good articles floating around on the web about head porting that would give you some good insight. Without a flow bench and ton's of experience I wouldn't do much more than deflashing and smoothing the ports, smoothing the chamber to eliminate hot spots, and a good valve job. The biggest mistake most people make is taking out too much metal destroying the flow velocity.
 
I think a good discussion on cam geometry and port work would be beneficial to all if someone wants to start a new thread. I think we have jacked Joey's enough. lol

Shrouding on this type of head is not necessarily what you think it is and unshrouding does not necessarily create the flow improvement you might have expected. The flow problems come from two places, general shape of the port and the small short turn radius. David Vizard and AG Bell among others have written books and articles on the subject of port shapes.

If you read the article on what Kenny Augustine did with Todd Henning's head you would have seen the raised floor in the exhausts. That improves flow and also provides anti-reversion which prevents exhaust reverse flow along the floor of the port.

Offline joeyputt

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #46 on: Jul 26, 2011, 20:20:33 »
Also notice that Augustine and Henning chose the spring conversion as well for their Daytona winning engine.

Just so there is no confusion here, I mentioned earlier that I like the torsion bar system and I do so mostly for its uniqueness however this should not be interpreted to read that I like them better than the spring conversion as when I have a choice I will choose the spring conversion every time without question. 

Joe - Owner/Operator of DWMS Racing World Class Engine & Motorcycle Building www.dwmsracing.com

Cylinder Head Porting Sale! http://www.dotheton.com/forum/index.php?topic=56203.msg637024#new

Facebook https://www.facebook.com/joe.dwmsracing

Offline Swagger

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #47 on: Jul 26, 2011, 20:24:57 »
Joey and Mr. Habenero, don't sweat it fellas....the "Kibblewhite comment" was really just what it appears: Let's have a peek.....

Aw yes, those Kibblewhite valves
<generally implying that I'd forgotten about that part of your build>

......gooood stuff that.
<'cuz ya know....they don't suck or anything>

They're taller too aren't they?
<well.....they are....right?>

No hidden subtext, I promise. :)

As to the torsion vs. coils comment....also not meant to stir the pot.
I must be typing on the grouchy keyboard today? haha...
« Last Edit: Jul 26, 2011, 20:27:37 by Swagger »
.....there's no way that little rice cooker is going 100m/h when the work need to get up to those speeds includes a big fuck off fairing shaped like a giant cock. ~Staffy

Weiner tetanus is nothing to scoff at. ~JustinLonghorn

Offline joeyputt

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    • dwmsracing
Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #48 on: Jul 26, 2011, 21:02:15 »
Brother Swagger we all love you man! All is well!

I have been assembling the internals and am getting ready to put the cases back togethor so I will be back this evening and will add some new photos!
Joe - Owner/Operator of DWMS Racing World Class Engine & Motorcycle Building www.dwmsracing.com

Cylinder Head Porting Sale! http://www.dotheton.com/forum/index.php?topic=56203.msg637024#new

Facebook https://www.facebook.com/joe.dwmsracing

Offline Habanero52

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #49 on: Jul 27, 2011, 12:54:25 »
No problem Mr. Swagger!!!!!
I appreciate your comments and your clarifications.
I want everyone to enjoy the thread that Joey has created for this project.
I know that the project's outcome will be memorable to all. :)
 ;)
Habanero52
Speed cost....How fast do you want to spend?
Follow the dream.
Why does life get in the way?