Topic: The CB550 downdraft port project

[754]

Speedracer, Keep up the good work.. Guys like you move things ahead..

 Myself I have a small shop and have had my hand in a lot of projects.. really wild stuff being built around here, like

 8 sec 1/4 snowmobiles..

 125 mph single v-8 boat...

 wild 4x4's tilt levelling cabs, rear steer, huge clearance, etc

 Wild bike engines..85 hp 250 80 + hp H-D singles, Sportster with Downdraft Carbs in the middle of the tank.. stuff like that.

 Go for it its a lot of work but it will pay off..

 754..

[paulages]

Any volunteers?

chris-- if i can ever wrap up my 714cc project i'll have no need, but i have a couple of spare 550 engines laying around i was considering doing something with one in the meantime, because my current one is leaking oil like a mother#$%*er. also, i have enough frames and spare parts laying around to build up something around another motor easy, so i'll always be a donor recipient if you get the downdraft or anything else going!

gimme a call sometime--you should come see where my project is at.

[FunJimmy]

Chris

How are things progressing? Have you had time to come up for air yet?

Just checking in

Cheers
FJ

[Bill/BentON Racing]

Speedracer Go for it!,Damn I'm jealous,If I pull my Pops Head anytime soon I will post,opened up might be a decent way to describe them,I call them a work of art,they are big time noticeable esp next to stock head.Your project is awesome your head,TG's cylinder,who knows?Bill

[turboguzzi]

Hei Bellcow

would sure be interesting to know how is Spedracer's project going, the posts here are from more than one year ago

my downdraft project thread is another one:

http://forums.sohc4.net/index.php?topic=19554.0

[Bill/BentON Racing]

TG,just checked your downdraft post,how cool,I bet you did sleep well when you finished this up.I love 750's but give me a track and I want CB500/550.You said your class was 500cc's.Do you use a 500 or 550 bottom end,I switched to 550 for clutch arrangement and cases.Good Luck,Bill,Did anyone do anythig with CB650 heads? 

[turboguzzi]

I will sleep even better once I finish adapting the 29's to that head 

I am using a 500 bottom end for no better reason than that's what I have..... 500/550 parts are not that easy to come by here in italy. 550 should be indeed better.

There are quite few threads in the forum regarding tuning around 650 parts, check paulages posts and threads, he OWNS that niche.

If you are planning to race the thing in vintage, make sure to check the regulations to see what allowed and what not before deciding to use a 650 head.

TG

[Bill/BentON Racing]

TG,you deserve a 550 bottom end,we have not discussed tranny mods,what have you done? I will look for you a 550 bottom end,I think I have a 500 or 550 thats stuck from sitting.I think shifting would be improved,I used a 9 plate Action Fours kit,ran total loss,no rotor,bump start,could remove starter clutch and kickstart shaft etc.Tell me more.Bill

[turboguzzi]

Hei bill

Done all that, removed everyhting + undercut the dogs. It made a huge difference to shifting, really good now, so at the moment I am not in a hurry for a 550 bottom, though I would really love to calmly build myself a second motor with all my learnings.

I will add today a big post on gears, let's see what you have to say on the subject...

TG

[Bill/BentON Racing]

Cool,did you undercut the gears yourself ? What RPM's do you turn? I installed 86 electronic tach off GSXR750 in 86.Went thru a few stockers,they didn't like 13,000RPM+.Bill