Topic: Greetings from the Bay Area by a CB750K1 owner

[scrambler]

Dear All, I registered here as I became a CB750 owner in December. I bought this bike for commuting while I`m working on my project bike which happens to be a TX750 Yamaha. By now not much have left to do on the Yamaha, so I`ll start restoration on the K1 soon. The Honda is in good condition for the age, it`s an early 1971 bike with HM300 mufflers and the small tail light. It was painted black back in the seventies, apart from that and the headlight with the chromed fork ears it`s all original. The engine probably needs to be rebuilt because it`s leaking oil here and there, has some chain rattling, some transmission noise in 5th gear and I think it should be stronger. The plan is to restore it back to original. I`ll post some pictures soon if I can. (I already tried but didn`t go through the moderators probably.)

[MD]

Welcome from NE MN,

Yes we like pictures but you have to post 5 times before you can add them to the site.  Another option is to link to the picture from another web address.

-MD

[Kevin D]

Hi scrambler, and welcome from a K1 rider in SE Michigan.
Lucky you with the 300 pipes, mine rusted out quickly.
Some oil seepage is par for the course and there are many threads here detailing how to counter leaks, and a Hondaman book is a terrific resource. My own is pretty good 12? years 20000? miles post rebuild.
I don't recall seeing a black CB with the stock gold stripes but I think that would be a winning combination.
Pictures also need to be less than 2mb.

[scrambler]

Thanks, Kevin! The leakage is quite substantial, I keep a piece of cardboard underneath the bike in the parking lot It leaks gas too, probably one of the float valve is shot, it`s not leaking when the engine runs though. I don`t like the black paint too much, it`s quite good quality though, but I want to get it repainted to one of the original color. I haven`t picked the color yet, originally it was ruby red, but that`s the most common and boring color, I like the candy blue (?) a lot more.

[scrambler]

Ok, cool! I`m getting to there!

[scrambler]

Getting close to the five posts, I mean.

[scrambler]

I guess I`ll repost this thread in the project section with pictures, so you can take a look at the bike there. Thanks, Greg

[Johnie]

What do you mean ruby red is boring    Hey welcome to the board. Looking forward to your pics.
Johnie
WI

[scrambler]

You`re right, I`ll reconsider. Dammit, now I have to pick 1 out of 3 options...

[Johnie]

LOL...good answer 

[Johnie]

These bikes commonly have a head "weep" which is usually not that drastic to require a complete rebuild. Once you get the engine cleaned and running you can watch it and see how bad it is. Some other leaks would be the shifter seal and neutral switch on the bottom of the engine. You would benefit by getting the CB750 rebuild manual from member Hondaman. It will be a valuable resource for you from wheel bearings to steering head to brakes, etc.

[Kevin D]

It leaks gas too, probably one of the float valve is shot, it`s not leaking when the engine runs though.

Mine has done that too, but it's much better since I polished all the float hinge parts with 400 grit.
Also replaced two brass floats that didn't float, and one float valve that wouldn't seal.
Rebuilt petcock, new 5.5mm fuel line.

Welcome to the 47 year old MC bug list.

But this bike has never let me down. I'm contemplating a 350 miler tomorrow if only the weather will cooperate.

[scrambler]

Kevin, 83000 miles, that`s impressive, how can I search for pictures of your bike? Johnie, I will have to take a look into the engine because of the noises anyway, the clutch is toast too, it has not much power, does around 10 miles a full tank gas and I want to repaint the frame so the engine has to come out. I`ll measure the compression in the cylinders first. I also have a K3 that I bought before this with seized engine but other than that with good inner parts, I`m planning to use that as a donor. Many parts inside the engine are interchangeble, I believe..

[Johnie]

Which bike you want to see? I have a build thread on the red, gold, blue / green and orange. Currently have a build thread going on my 69CB750KO in the project section.

[scrambler]

I think I came across your K0 project here, but happy to see your other threads, I`ll look into them.  Actually I meant Kevin`s 71 CB750 K1 83000 mi Original Owner bike, just curious to see a bike with such a high mileage.

[scrambler]

Yes, I`ve been following your thread about the sandcast, I can`t search for your other project threads though. I can only search for posts.

[Kevin D]

Scrambler, there is a gallery, you can add photos. I have a few photos on the last page of the member gallery. Look for the gallery tab towards the top of the page.
I think Johnies collection is a lot more impressive. He has a whole flock of motorcycles to keep in fine running order, I have only one, so it gets a few miles. But there are other bikes around here with many more miles.
My CB is mostly survivor, rusted out 300's replaced with 341 takeoffs in 1974?, disgusting faded paint redone 10? years ago, and getting 45-48mpg.

[scottly]

I bought this bike for commuting while I`m working on my project bike which happens to be a TX750 Yamaha.

I hope that is one of the later TX 750s, because the 1972-early '73 ones were crap!! I sold mine decades ago in the Bay Area; sure hope it's not the one you're working on!!

PS You can attach pictures directly to your post, even on the first post; the restriction is on links to photo sharing services.

[Johnie]

scrambler...here is the Honda blue / green project thread you were looking for:

http://forums.sohc4.net/index.php/topic,131103.0.html

[scrambler]

Haha, no, it`s not, it`s from 73 with all the constructional failures that contributed to its horrible reputation. I think i managed to fix them all by now, I`m planning to start it this weekend after an almost 40 years break.

[scrambler]

Thanks Johnie, perfect, these will keep me busy for a while

[scrambler]

Looks great! I kind of started tio like this color. Does it make a big difference to hook up the 341 mufflers instead of the originals in terms of loudness? My HM300 mufflers are pretty loud, they give me a tingle in the ears after a long ride. Are the silencers inside interchangeble? As far as I know the 341s are much longer, the mufflers themselves look identical though.

[scrambler]

I uploaded a few pictures of the CB in the project session, FYI.

[Johnie]

You are correct scrambler. The 300's are louder than the 341's and the pipes fit on either bike.

[Kevin D]

The 300's and the 341's have the same footprint and so are interchangeable. The internals are different.... you have the preferred 300's, OE on K0 and K1, so take good care of them.
The diffusers are available and the 300's have a glass pack to further stifle the sound.
I don't know if the diffusers are interchangeable.
My 341's came with the diffusers pulled for more sound, and I like them the way they are. You can quietly sneak out of town or make a screamin exit if you want.
Johnie, do all your CBs have the diffusers in or out? What's your preference?

http://www.yamiya750.com/index.php?main_page=index&cPath=246_251_142_88

[Johnie]

Kevin all my bikes are stock with diffusers. The 300's have a nice throaty low sound compared to the 341's.

[scrambler]

I do not intend to replace my 300s to 341s, just wondering if I could make them a bit less loud by replacing the baffles or adding some additional silencer inside that does not change the outlook of the mufflers.
I came across this picture of the first sandcasts in Cycle world, the inner side of the lowers are flattened interestingly, what kind of mufflers are these? Some prototype?