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Dellorto SS1 carbs on a CYB77.

CYP77 - Police | Race Bikes | Choppers, Bobbers and Mods
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MotoNut
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Joined: Sat Feb 18, 2012 9:15 pm

Dellorto SS1 carbs on a CYB77.

Post by MotoNut » Sun Feb 26, 2012 8:26 pm

Does anyone out there have any info on putting Dellorto SS1 carbs on a CB77. I am building a CYB bike. I want to use some NOS left and right 28mm Dellorto SS1 carbs I have on my CYB bike. I will be using NOS CYB cams, electronic ignition (the same one from this site) and CYB megaphones. I plan to run Webco valve-springs (I believe they were made by Precision Engineering) unless i can find some better new springs. I also plan to have the manifold-head-exaust ports matched and flowed. I don't know if running larger valves is something I need to do. I am building this bike as a "HOT" tuned cafe bike but I also want it to actually idle and be reliable. ok maybe I'm asking too much? does anyone know or have any info on slapping SS1 carbs on these bikes? Jetting, slide cut etc? you can see my project here

http://motonut.com/CYB77.htm

thanks

teazer
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Location: Midwest US

Post by teazer » Sat Apr 21, 2012 12:57 am

CYB/810 cam is a nice mild cam and shouldn't be too lumpy, though a megacycle street cam might be better. Get a set of R&D or Kibblewhite springs and caps.

CYB megaphones were not much use on a race bike and would be horrendously noisy on the street. You really need baffled/muffled longer megaphones. Check out teh Dusntall copies that Vince Lupo used on his 5 speed 350 kitted bike.

For a mild tune stock sized valves are fine if a little heavy. 350 kit with modern thin rings would be a good addition to your shopping list. Stock pistons are a little heavy if you want it to rev and they have thick heavy rings.

It really all comes down to how you plan on using it. The summer evening ride to local bike night you can get away with almost anything. If you want to ride it more than a few miles and more often than twice a year, think mild rather than wild.

Ports would benefit from a professional clean up for sure but avoid full radiused valve seats.

Vince Lupo
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Post by Vince Lupo » Sat Apr 21, 2012 4:39 am

teazer wrote:You really need baffled/muffled longer megaphones. Check out teh Dusntall copies that Vince Lupo used on his 5 speed 350 kitted bike.
Actually, I did have them on my bike, but that was a few years ago. I've had the Norman Hyde TOGA Gold Star replicas on there for the past few years, and really like them better. The EMGO Dunstalls were okay for the money, but their weakness is in the mounting bracket channel that's on the backside of the muffler itself. I've had three different brackets fracture on the facing plate of that channel, likely due to the inherent vibration of the bike. The TOGA bracket is a different setup and is much more robust. They were discontinued a number of years ago, but I think that British Cycle Supply still has a small supply of them in stock. Beware though -- they are loud muthas.

As far as the carbs go, I went with the Amal 626's and have had great success with them, though they took a while to completely dial them in with the bike and the modifications that I made to the engine (350 kit, port/polish, race valve springs and titanium caps, 5-speed, etc etc etc). With those carbs on a cold morning, I open the petcock, 'tickle' both carbs, push the start button, and it's an instant and constant idle of about 1100-1300 rpms. No coughing nor fighting with the throttle to keep it going, which I understand can be the 'norm' with these cold-blooded bikes.

Goofy question -- with the remote float in those Dell'Orto carbs, would there be an issue with gas flow/fuel level in each carb as you lean the bike in a turn? In other words, if you were in a long left-hand sweeper, could you theoretically starve the right carb of fuel? From what I read about the Amal carbs, the remote floats on the earlier carbs caused some issues in that regard, and the Mk. 1 Concentrics basically solved that problem by having the float chamber directly underneath the body of the carb. I could be wrong, however!

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G-Man
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Post by G-Man » Sat Apr 21, 2012 7:26 am

Vince

Motorcycles are neutral in terms of lateral loading because they lean in corners. Th problem you mention did affect motorcycle engines used in cars or motorcycles and sidecars, which do not lean.

Regardless of that, having a float chamber directly under the jet is better engineering practice but clearly eliminates some of the adjustments that were possible with truly remote float chambers and the ability to mount them on anti-vibration mounts.

G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

bbraun
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Re: Dellorto SS1 carbs on a CYB77.

Post by bbraun » Fri Jun 01, 2012 3:51 pm

MotoNut wrote:Does anyone out there have any info on putting Dellorto SS1 carbs on a CB77. I am building a CYB bike. I want to use some NOS left and right 28mm Dellorto SS1 carbs I have on my CYB bike. I will be using NOS CYB cams, electronic ignition (the same one from this site) and CYB megaphones. I plan to run Webco valve-springs (I believe they were made by Precision Engineering) unless i can find some better new springs. I also plan to have the manifold-head-exaust ports matched and flowed. I don't know if running larger valves is something I need to do. I am building this bike as a "HOT" tuned cafe bike but I also want it to actually idle and be reliable. ok maybe I'm asking too much? does anyone know or have any info on slapping SS1 carbs on these bikes? Jetting, slide cut etc? you can see my project here

http://motonut.com/CYB77.htm

thanks
no info on tuning with dellortos but i spent a lo of time getting my stock for now cb77 racer to start and run at full throttle with the CYB megs. 145 mains 45 idle; open carbs. next i/m putting on the 28mm carbs & manifolds and flat side megs on it plus some suspension mods ( yetman frame). i have nos megs and flat side megs plus one set of replica flat side megs if anyone's interested. other cyb stuff will be going on me cb72 project.

the 305 badly needs a 5 speed and some work on the cyb shifter setup - pedal is too long and not offset like it should be.

anyone using a 4LS front brake that doesn't weigh a ton?

beth
Beth

'64 CB72
'64 CB77/Yetman race bike
'65 CA77
'63 CA72 project
'65 CB160 race bike

'63 CA95

a number of other '60s Hondas

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