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Author Topic: '74 CB383 (CB360) - a Mighty Mouse adventure bike  (Read 21503 times)

Offline Finnigan

  • Posts: 1945
Re: '74 CB383 (CB360) - a Mighty Mouse adventure bike
« Reply #50 on: Feb 27, 2013, 16:24:33 »
Are you clearing out the junk or actually removing metal?  Thinking about doing this to mine since i havent assembled it fully yet.

Reason for doing this is better air flow?

Offline Treesus

  • Posts: 69
  • Probably not sane.
    • Half Day Around
Re: '74 CB383 (CB360) - a Mighty Mouse adventure bike
« Reply #51 on: Feb 27, 2013, 17:59:53 »
Actually removing metal.

(Disclaimer to me sounding like I know what is going on: All of my knowledge of this is from reading others' experience and various forums, most of the concrete knowledge from PJ)

The exhaust ports are the main restriction on flow through the 360's engine. As you have probably read, a lot of unaware folks buy 360's and try to put Mikuni VM32s and such on them with resulting headaches. The Stock carbs and intake ports are already a bit large for the stock engine, so boring the cylinders out for bigger displacement helps bring those into a more optimal size for the flow.

I think this is opposite to the 350, which gets help from larger carbs and intake ports. I may be wrong on this, as I've never owned one, but I am pretty sure I've read about that (and it is probably where most people get the notion to do it on 360's).

So I ground off much of the protruding valve guide boss, and opened it up around the perimeter. I would say if you have the head off, definitely do this. Just do it better than I did and go for the D shape.  ;D

Should help exhaust flow more efficiently out of the combustion chamber. I am also making a straight through exhaust set up to help with this.

and thanks, 3DogNate!


~Tree

CB360 Adventure build http://www.dotheton.com/forum/index.php?topic=43834.20

"I think it says in the Bible that there is a time to listen to techno, and a time not to." -Joe Strummer

Offline Finnigan

  • Posts: 1945
Re: '74 CB383 (CB360) - a Mighty Mouse adventure bike
« Reply #52 on: Feb 27, 2013, 18:04:25 »
Good to know!

3dognate do you have any pics i can go off? 

Offline Treesus

  • Posts: 69
  • Probably not sane.
    • Half Day Around
Re: '74 CB383 (CB360) - a Mighty Mouse adventure bike
« Reply #53 on: Feb 27, 2013, 18:10:33 »
Nate just made a comment saying this was a cool project. Not sure if he has porting info?

I would maybe ask PJ or Sonreir if they have any photos of the porting they have done. Or just look at mine, but take less off the bottom and more off the sides.
~Tree

CB360 Adventure build http://www.dotheton.com/forum/index.php?topic=43834.20

"I think it says in the Bible that there is a time to listen to techno, and a time not to." -Joe Strummer

Offline Finnigan

  • Posts: 1945
Re: '74 CB383 (CB360) - a Mighty Mouse adventure bike
« Reply #54 on: Feb 27, 2013, 18:21:28 »
The bottom being the lump where the guide is?

Are you just taking material from the mouth or the opening or all the way in?

Offline crazypj

  • Posts: 12994
  • Split personality, I fake being smart
Re: '74 CB383 (CB360) - a Mighty Mouse adventure bike
« Reply #55 on: Feb 27, 2013, 20:30:00 »
I'll see if I can find pic online (maybe I took some of mine, can't remember)
from combustion chamber, bowl behind valve head fully smoothed out


Intake


Looking for exhaust pic, although if you can imagine exhaust flat where the picture is cut off, that's the 'D' shape, blend into the bowl area
OK, couldn't find a pic so I just took one of head I'm going to work on.
Line is a bit high but you get the idea, maybe 2/3~3/4 the way down
« Last Edit: Feb 27, 2013, 20:52:24 by crazypj »
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline Treesus

  • Posts: 69
  • Probably not sane.
    • Half Day Around
Re: '74 CB383 (CB360) - a Mighty Mouse adventure bike
« Reply #56 on: Feb 27, 2013, 21:10:40 »
Those are great, PJ.

I'm thinking I may go back and work on mine a bit more. Bring that D section to the gasket. Or do you think that would be too much with what I have already done?
~Tree

CB360 Adventure build http://www.dotheton.com/forum/index.php?topic=43834.20

"I think it says in the Bible that there is a time to listen to techno, and a time not to." -Joe Strummer

Offline crazypj

  • Posts: 12994
  • Split personality, I fake being smart
Re: '74 CB383 (CB360) - a Mighty Mouse adventure bike
« Reply #57 on: Feb 27, 2013, 21:22:24 »
 restricting it with a steel 'D' gasket probably won't be a good idea, just open the top half to original squashed gasket size
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline Treesus

  • Posts: 69
  • Probably not sane.
    • Half Day Around
Re: '74 CB383 (CB360) - a Mighty Mouse adventure bike
« Reply #58 on: Mar 28, 2013, 02:57:17 »
Finally back in Anchorage. Went down to Hawai'i for a few days after work to meet a friend. Sitting in the cockpit jumpseat on a return flight from Honolulu to LA, I had an awesome conversation about classic motorbikes with the captain. Turns out he is very close friends with Eddie Lawson and invited me down to ride with them. Said he had a bunch of extra bikes. Sounds like a fun way to get killed.

Anyhow. On to bike progress.


-dropped off the tank and side covers to get paint. Really excited the see them finished, especially after meeting the guy who was recommended to me for the job. His work is fantastic.

- installed new valve guides. Really wasn't much too it. I heated the head to about 200* for a bit, and the old tapped right out. Swapped the circlips, and the new ones tapped right in.

-reamed the valve guides. (Thanks Finnigan)

-dropped the head and +1mm oversized valves off at Alaska Drag Bike to have them seated.


With the oversized valves, will I need to check piston-valve clearance? I did not skim the head at all.
~Tree

CB360 Adventure build http://www.dotheton.com/forum/index.php?topic=43834.20

"I think it says in the Bible that there is a time to listen to techno, and a time not to." -Joe Strummer

Offline Treesus

  • Posts: 69
  • Probably not sane.
    • Half Day Around
Re: '74 CB383 (CB360) - a Mighty Mouse adventure bike
« Reply #59 on: Mar 28, 2013, 03:27:34 »
Also this



reminds me of going to see Barnum and Bailey as a kid.
~Tree

CB360 Adventure build http://www.dotheton.com/forum/index.php?topic=43834.20

"I think it says in the Bible that there is a time to listen to techno, and a time not to." -Joe Strummer