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Author Topic: "La Pastinaca" CB450 498cc Big Bore Engine Built By DWMS Racing!  (Read 59628 times)

Offline Swagger

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Re: "La Pastinaca" CB450 New photos! Painted the cases!
« Reply #30 on: Jul 21, 2011, 13:37:38 »
Say Flugtechnik...that's pretty....but all you black engine guys....knock it off! hehe
Aw well, we'll be the black engine posse.....(perhaps with a less dumb name)
.....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! Painted the cases!
« Reply #31 on: Jul 22, 2011, 19:58:14 »
Say Flugtechnik...that's pretty....but all you black engine guys....knock it off! hehe
Aw well, we'll be the black engine posse.....(perhaps with a less dumb name)

No fair, my CB450's engine is gold! I want to ride with the cool kids too! Hahahaha! I know...we are not kids, but we are young at heart and that counts right? Hahahaha! Seriously though there are a lot of beautiful black engines around here lately!

Oh well, back to work! Brother Habanero52 ordered new shift forks for the transmission and it will be a few days before they arrive and I can assemble the bottom end so I am working on sanding the engine covers to prepare them for polishing and the cylinder head.

We are converting the valvetrain from the stock factory valves to lightweight racing valves with 5mm stems. Naturally with the stem size change we had to convert the valve guides as well. We got all four valve guides installed in the cylinder head and reamed so here are some photos!

This photo shows the new 5mm valve guides installed in the cylinder head on the intake side.



Here is a photo of the new valve seals installed.



In this photo you can see the difference between the stock intake valve on the left and the new 5mm lightweight racing intake valve on the right! The new valve stems themselves are shorter as well for use with lash caps.



I still need to cut the valve seats and am waiting for a pilot in the new guides size before I can do it. I also want to smooth the combustion chambers a little more but here is a photo of what the valves look like in the chamber.










« Last Edit: Jul 22, 2011, 20:09:33 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

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

Offline Swagger

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #32 on: Jul 22, 2011, 20:14:22 »
Apparently there's some *measurable* power to be had in cutting and blending the ridge between the valves down, especially near the plug. I've seen two dyno sheets that showed around a pony from doing so. Now....I've not seen them in real life nor did I know the guys that built the engine. Just thought I'd toss it out there since you're turning this one up to 11......
.....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 Rip-It-Up

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #33 on: Jul 23, 2011, 21:05:29 »
Nice, I haven't looked alot into internal mod's for these motors. Do you have any links or resources you would mind sharing for parts and stuff?
 
BTW looks like there's a ton of room for unshrouding to be had there. My hand is twitching for a die grinder just looking at those pics! lol! I reaaalllyyy want to play with one of these bikes.
 
Out of curiosity do you have any more pic's of the port's? Did honda leave alot of flashing in there? Haha, sorry for so many questions. I haven't seen any posts with anyone doing much more than a rebuild on one of these. I'm very interested to see what one of these old twins could pick up with some of todays cylinder head knowledge. Correct me if I'm wrong but I think I've heard that they where pretty under rated at 43hp back in the day.

Offline joeyputt

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #34 on: Jul 25, 2011, 17:49:52 »
Brother Swagger combustion chamber and port shapes would be a long discussion and would deserve their own threads I am sure as I know there are a lot of different opinions on the subjects here on dotheton as we have attempted to try and discuss them a couple of times! Hahahaha!

Brother Rip-It-Up I sent you a PM. We have to help you find a CB450 to play with, you would love it! This is an older article that you may enjoy, it is a short read and has some good information- http://www.motorcycle.com/how-to/modifications-to-the-henning-honda-cb500-14679.html

Brother Habanero52 ordered new shift forks for the transmission and they got here today so I can start assembling the bottom end!


« Last Edit: Jul 25, 2011, 17:54:28 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

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

Offline Swagger

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #35 on: Jul 25, 2011, 18:06:00 »
true enough, I'll look forward to you pics.....
.....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 teazer

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #36 on: Jul 25, 2011, 18:10:10 »
You might be surprised how much shrouding those heads need to improve trapping efficiency. I'd just round off the sharp edges and leave it at that.  You don't want too much overlap flow into the exhaust port.

Most older Hondas suffer from constipation.  They have enough intake flow but can't get rid of exhaust gasses effectively.  Squish (quench) was typically too deep to be effective too.  Lots of ways to improve them.

Offline joeyputt

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #37 on: Jul 25, 2011, 19:09:43 »
true enough, I'll look forward to you pics.....

It is not like that Brother! You know I always value your information and enjoy talking with you, I just do not want to get into a large debate (not with you, I know we agree a lot!) over combustion chamber designs and port shapes here as it is Brother Habanero52's build thread. We can start a new thread if everyone would like to try and discuss these issues though and I will join in.

You might be surprised how much shrouding those heads need to improve trapping efficiency. I'd just round off the sharp edges and leave it at that.  You don't want too much overlap flow into the exhaust port.

Brother Teazer that is the plan, as this engine is not going to be on the track I just want to smooth the chambers and ports real nice and I may cc match the chambers after I cut the seats.
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 lingo

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #38 on: Jul 25, 2011, 23:17:23 »
I would really enjoy a discussion of the modifications that can be done to the 450 head to make it breath better. I come from the hot rod world but head work is something that I have never learned. I wouldn't necessarily do it myself but I would like to learn about it.
CB450K3- organ donor
CB450K3- On the road again.

Offline Rip-It-Up

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Re: "La Pastinaca" CB450 New photos! 5mm racing valves conversion!
« Reply #39 on: Jul 26, 2011, 12:05:08 »
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