Topic: 305 Super Hawk

[jaguar]

Just a project right now.

[jas67]

Just a project right now.

I can't wait to see what you do with it!

Wow, that frame looks WAY better than the stock Honda one.     Do you know the weight difference between the two?

[grcamna2]

Who built it jag ?

[jaguar]

Yetman was a frame builder in MA.

It is crazy silly light!
Frame is 8 pounds vs 30 for stock.

http://www.motohistory.net/news2011/news-feb11.html

[jas67]

Yetman was a frame builder in MA.

It is crazy silly light!
Frame is 8 pounds vs 30 for stock.

http://www.motohistory.net/news2011/news-feb11.html

Thanks for the link, that was an interesting read.   I'd seen pictures of Yetmans before, but, didn't know the history.

At less than 1/3 the weight of the production frame, that is pretty amazing.
And, that was with low-carbon steel.    If someone where to copy that frame design with thin wall double-butted chrome-moly, I wonder what they could get the weight down to?    Of course, at 8 lbs, that would be diminished returns.    The fork would potentially be the next place to try to lose some weight.

[CycleRanger]

Yetman was a frame builder in MA.

It is crazy silly light!
Frame is 8 pounds vs 30 for stock.

http://www.motohistory.net/news2011/news-feb11.html

Fascinating article!

[grcamna2]

Yetman was a frame builder in MA.

It is crazy silly light!
Frame is 8 pounds vs 30 for stock.

http://www.motohistory.net/news2011/news-feb11.html

I would think for racing only.

[carnivorous chicken]

OK,thanks Jay. Do you know if the CB77 Superhawk had more HP than the CL77? both 305cc.. just wasn't sure.

I believe -- but am not 100% -- that the CL77 was essentially the same engine but was geared down for more low end power and slower top speed.

I've got my first CB77 project, but it's in line for now -- need to get a few things out the door first.

[grcamna2]

OK,thanks Jay. Do you know if the CB77 Superhawk had more HP than the CL77? both 305cc.. just wasn't sure.

I believe -- but am not 100% -- that the CL77 was essentially the same engine but was geared down for more low end power and slower top speed.

I've got my first CB77 project, but it's in line for now -- need to get a few things out the door first.

I was 16 when I got my CL77 and went from my Dad's little CT90(who never had the time to ride it anyway)up to  that 305,Yeah !
Then I read Cycle World and they just got finished testing the Yamaha RD350A and I felt 'A Need for Speed' so i sold the CL77 after installing a new fuel tank w/ rubber knee pads(it was 1974 so the new tank was very available from Honda  ,and other things like the oem 2 into 1 resonator w/ rubber gasket,etc. and the new owner was real glad to take it off my hands.. I Should have kept that bike,I would have saved Lot's of $ on spark plugs 

[jaguar]

Yetman was a frame builder in MA.

It is crazy silly light!
Frame is 8 pounds vs 30 for stock.

http://www.motohistory.net/news2011/news-feb11.html

Thanks for the link, that was an interesting read.   I'd seen pictures of Yetmans before, but, didn't know the history.

At less than 1/3 the weight of the production frame, that is pretty amazing.
And, that was with low-carbon steel.    If someone where to copy that frame design with thin wall double-butted chrome-moly, I wonder what they could get the weight down to?    Of course, at 8 lbs, that would be diminished returns.    The fork would potentially be the next place to try to lose some weight.

Plan to let a frame builder I know have the frame for a bit and see about making replicas in moly.
These are really race frames.

[SKTP]

Love it

[HondaMan]

That 'Hawk is a cold-cock copy of my first "big" Honda! It was the late '67 and '68 models only that had the "blended" seat (we called it the "nut uncracker" seat, compared to the earlier type). After I rode it from 1969 to 1971, I big-bored it to 337cc/10.5 CR with Rocky Cycle components and went racing. It would touch the ton after the mods, and I rode it 20k miles in the next 2 years after that, riding it to "run whatcha brung" races, there and home. When I came to my [first] 750K1, my [first] father-in-law fairly begged me for the 'Hawk, so to appease the [first] wife, I sold it to him. Big mistake, still miss that 'Hawk. One of the most civilized midsize bikes Honda made!

[bill440cars]

      Nice Looking Super Hawk There. I had gotten myself a '66 CB72 Hawk, when I got stationed in Northern Japan in the Air Force, after I could not a Super Hawk there, to buy. I had hoped to be able to someday, get an actual CB77 305 Super Hawk some day. A few years back, I started getting a little money together and started buy parts and components, to build myself one, as I couldn't seem to come up with the bucks to buy a whole bike, at one time. I Started off with a CB77 Parts bike, that wasn't all there and had a CA77 motor in it. I got to where, I could start mocking up what I wanted it to look like. Then, unknown to me, my Close Friend (Locally) had also wanted one and knew what I was trying to do, bought a Super Hawk that he would go through and keep for a while, then set me up, in a trade, that would leave Me with the one he had gotten. Oh, I knew he had it, but I had no idea what he was up to. Still got those parts and such, that I was gonna build and I still plan on building one, only, it won't be stock. There will be some deviations.

[bwaller]

That Yetman frame is wild! I have been thinking for a few years to build a CB72 race bike. They are nearly hen's teeth it seems, but I have heard the CB72's & 77's shared the bottom end & cylinder head? Can any of you fella's with experience confirm this? If this is the case then it would likely be easier to find a 305 instead.

Man that Yetman would be a cool addition. My good friend Denis Curtis CMRRacing.com could duplicate that easily. I have raced with Karsten Illg of framecrafters.net and they would also.

Those original CB frames are very heavy. If anyone has a parts bike or even an engine that might consider parting with I might be interested. 

[jaguar]

I know of another yetman frame for sale on the east coast.

[bwaller]

Thanks, PM your way jaquar.

[bill440cars]

That Yetman frame is wild! I have been thinking for a few years to build a CB72 race bike. They are nearly hen's teeth it seems, but I have heard the CB72's & 77's shared the bottom end & cylinder head? Can any of you fella's with experience confirm this? If this is the case then it would likely be easier to find a 305 instead.

Man that Yetman would be a cool addition. My good friend Denis Curtis CMRRacing.com could duplicate that easily. I have raced with Karsten Illg of framecrafters.net and they would also.

Those original CB frames are very heavy. If anyone has a parts bike or even an engine that might consider parting with I might be interested. 

    Best I know of, the difference between the 250 & 305, is the bore, like you said. Pretty good amount of stuff on ebay and there is a forum, if you weren't aware, that covers the older ones like that,

http://www.honda305.com/forums/    and there is a part for Racing Talk as well. Lots of good info there and knowledge. You should check it out. There are several SOHC4 folks there, including myself. Like to hear about whatever you do, if you do decide to build on a 250 or 305 too.   

[72 yellow]

My 1966 Super Hawk on the work stand.  Was my dad's.

[jas67]

My 1966 Super Hawk on the work stand.  Was my dad's.

Nice!

[HondaMan]

That Yetman frame is wild! I have been thinking for a few years to build a CB72 race bike. They are nearly hen's teeth it seems, but I have heard the CB72's & 77's shared the bottom end & cylinder head? Can any of you fella's with experience confirm this? If this is the case then it would likely be easier to find a 305 instead.

Man that Yetman would be a cool addition. My good friend Denis Curtis CMRRacing.com could duplicate that easily. I have raced with Karsten Illg of framecrafters.net and they would also.

Those original CB frames are very heavy. If anyone has a parts bike or even an engine that might consider parting with I might be interested. 

The 305 and 250 were the same engines, but for a few top-end differences. They don't seem to swap on the top-ends, though, for reasons I can't remember well enough to itemize at the moment (!) (old mind?). The head on the 250 has smaller valves, and the 305 last production had the largest intake valves, starting in the 1967 versions. One lesson I learned myself the hard way was: you cannot bore these engines as far as the SOHC4 engines (like S12 oversize) because their liners are quite brittle, and will fracture if this is done (sad story, don't ask...). And, the 250 bikes (and I am told, some of the CL77 early ones) had 3-jet carbs with a "power jet" that seriously extended the upper RPM power curve in the 6500+ RPM range. These often made the low end run richer than it should, causing fouled plugs and such, but the torque difference was really noticeable.

The exhaust rockers have a different-sized shaft than the intakes, by just 0.0004" size, that requires you to take notice of where they came from when putting them back together: this is one of the great "secrets" of working on them. If you get one, look for the shop manual entitled "CL72 Scrumbler" (that typo is consistent though the whole book!) which came from Japan in the early 1960s, as this has all the secrets in it that were missing in the later-translated manuals. There is a wealth of info in that one that really cleared up many questions I long had from the other manuals. Also, the springs that operate the points advancer always are sacked and need 1/2 turn cut off them, or else the bike is cantankerous until it reaches about 3000 RPM, a common trait on this bike (250 or 305, both).

[bwaller]

Jaquar has been very kind to send pictures & info, thanks man. I still haven't decided whether I'll build one of these to race though. Good info on the Scrumbler manual, likely incredibly rare.

I finally communicated with a guy I know that races one. He claims getting cranks rebuilt has become difficult, primary chains are NLA, and the 4 spd is a weak point. He races a CB350 as well and claims the CB77 engine is very heavy. He also mentioned that even when his (250) ran well, a 250 Ducati single would run away from it! One can pick up a Ducati for short money compared to what it would take to make a CB72 competitive.

That said in street form these are great to see.

[jas67]

I finally communicated with a guy I know that races one. He claims getting cranks rebuilt has become difficult, primary chains are NLA, and the 4 spd is a weak point. He races a CB350 as well and claims the CB77 engine is very heavy. He also mentioned that even when his (250) ran well, a 250 Ducati single would run away from it! One can pick up a Ducati for short money compared to what it would take to make a CB72 competitive.

At least in street form, a 250 Ducati is about 100# lighter than a CB72 or CB77.

The stock CB72/CB77 frame is heavy, so,  Yetman frame would go a long way towards losing weight, but, yes, the lovely 250-305cc lump is a heavy one.

[bwaller]

Don't get me wrong, these bikes are iconic and very cool.