Topic: My first classic bike

[UGly]

Hey all,

Long story short, had to sell me bike to go to college, finished and moved from east coast to the west, scraped together some cash and bought my first classic honda, 1978 CB750F SuperSport. Im new to this, but I would like  to learn this bike inside and out. That being said I may have some dumb questions, However I am very thorough with searching online, so it will only be things I absolutely cannot find an answer for, like this:

I went out to do some maintenance/pull of some stuff and noticed an oil leak which seemed (keep in mind dont know my ass from my elbow about these bikes) to be coming from the carbs? also there was a little pool of oil in the air filter box. just wondering if this is something normal with these bikes or if somethings wrong. I have attached a picture and any help would be greatly appreciated.

[ekpent]

Take a whiff of that stuff and confirm if it may not be gasoline leaking from the carbs. If it is oil you may have a leaky head gasket and other weeping in that area. Are you turning off the petcock.   Welcome bye the way       Eric

[jessezm]

Also could be oil from your crankcase breather hose, which I think is routed to your airbox to burn off extra emissions.  *I think...

[ABikeNamedTrouble]

Just to throw out another possibility:  Check your cam chain tensioner bolt/nut.  If it's missing, you'll get LOTS of oil leaking out.  If it's simply too loose, tightening it up and/or replacing the washer should seal the leak.

You'll be one of the lucky ones if you can find and seal every oil leak.  You'll get better at tracking them down as you go along .


And, of course, welcome!

[Duke McDukiedook]

Could be a leaky Oil pressure sensor, I have to replace mine VERY soon due to mega leaking from it.

And just to clarify, a 1978 Honda CB is considered far from classic, by most motorcycle enthusiasts it is considered a vintage bike. Classic and vintage are two VERY distinct things.

[Hinomaru]

Hey all,

Long story short, had to sell me bike to go to college, finished and moved from east coast to the west, scraped together some cash and bought my first classic honda, 1978 CB750F SuperSport. Im new to this, but I would like  to learn this bike inside and out. That being said I may have some dumb questions, However I am very thorough with searching online, so it will only be things I absolutely cannot find an answer for, like this:

I went out to do some maintenance/pull of some stuff and noticed an oil leak which seemed (keep in mind dont know my ass from my elbow about these bikes) to be coming from the carbs? also there was a little pool of oil in the air filter box. just wondering if this is something normal with these bikes or if somethings wrong. I have attached a picture and any help would be greatly appreciated.

Welcome to the forums.
 
Ideally, you shouldn’t have any oil pooled in the airbox. If your ‘78 750F is bone stock, then there should be a factory crankcase breather system installed. It does require a bit of maintenance as shown in the factory service manual. Could be the source of your problem?
 
(click on image for a larger view)
 

[SurfinBird]

Welcome UGly. I was in the exact same boat as you about 6 months ago, I have the exact same bike as you (same year, same model), never worked on a bike before and a billion questions. 3 months later and a bunch of post I now have a daily driver. It still needs work, but, it runs well enough to get me around. You'll be riding in no time with help from this forum.

As for your problem, I can't help, but someone will.

[ekpent]

Forgot that there is a lot of extra plumbing on the newer bikes. Good post as usual Hinomaru.

[UGly]

Thank you for the help and all the welcomes. As for the issue, the petcock was off, and if it was leaking it seemed like it was gas from that bottom screw on the carb in my original picture. im hoping it was there before from when i ran it 3 days ago maybe? i know on cars gas+carbs=danger, not sure about bikes. and if it is gas how would it get into my air box?

@ekpent Took a whiff, i think your right about the gas, i was confused by consistency/color cause it mixed with engine grime haha

@DukieFrankenkit apologies for the mixup i'll (hopefully) keep that in mind from now on! the last thing i want is to seem disrespectful.

@SurfinBird thank you, that makes me feel a lot better about this project

p.s. I've attached a picture of the beauty, she's rough but with a little TLC I believe she can be road worthy, and hopefully someday soon ill have the time/money/skill to build her into a cafe.

[Duke McDukiedook]

Oh, no disrespect meant or taken, I was just informing you on the opinion most motorcycle enthusiasts hold on these types of bikes. They are good, vintage bikes- I can say that much. Classic? Eh.

Some would definitely debate whether or not if a sandcast 1969 CB750KO would be considered a classic (usually the holy grail of CB750 enthusiasts), a lot of people would consider that just a vintage bike. Maybe 10 or more years would change that, I don't know.

[HonderCB]

could just be o-ring in your air/fuel adjustment screws, i have one that leaks just like that, too lazy to fix

[ekpent]

Sometimes when a carb may have a float issue or a plugged overflow tube,the little hoses on the bottom of the carb bowl,the gas can fill up and exit out of the carbs both into the airbox and the engine.  PS-How many miles is it showing on the odometer?

[ABikeNamedTrouble]

Welcome UGly. I was in the exact same boat as you about 6 months ago... never worked on a bike before and a billion questions. 3 months later and a bunch of post I now have a daily driver. It still needs work, but, it runs well enough to get me around. You'll be riding in no time with help from this forum.

I feel like you just described 80% of the people here, including myself

[graeme7]

Oh, no disrespect meant or taken, I was just informing you on the opinion most motorcycle enthusiasts hold on these types of bikes. They are good, vintage bikes- I can say that much. Classic? Eh.

Some would definitely debate whether or not if a sandcast 1969 CB750KO would be considered a classic (usually the holy grail of CB750 enthusiasts), a lot of people would consider that just a vintage bike. Maybe 10 or more years would change that, I don't know.

In th UK that would be the other way round. Generaly, with all vehicles, classic would cover anything from maybe the late 50's possibly through to the mid 80's. Vintage would be anywhere from maybe 30's to the 50's and pre 1930's would be veteran.

I think the usage of 'classic' in your terms would be maybe 'iconic' over here.

Pointless info 

[Duke McDukiedook]

Ah, now we are getting into the cultural connotation to the meanings of the words.
I was referring to the US where say something like an Ariel Square Four, Vincent Black Shadow or a 40's Indian are considered classics and Japanese 60's and 70's bikes would be considered vintage.

[graeme7]

Yeah, i figured.
I like hearing the ways different cultures use the same words.

For some (dull) reason i find it interesting.



My cb750 is my first 'older'  bike too. I think there good to start learing on, especialy if like me, your used to cars. The tech is basicaly the same.
I find the best way to learn your bike is to read alot then take it apart.

Have fun!

[Dave K]

Every bike a get, gets a complete clean up and wax, then I get into repairing. It helps me learn it from one end to the other and prevents dirt from getting into anything. Keep a note book handy and write down what you see to do as you clean and polish.

[Gordon]

Welcome, UGly.  

The picture you posted looks exactly like every bike I've had when there was a slight gas leak at one or more of the carbs.  It leaks out, most of it evaporates away, and what's left is the varnish that's sticky and yellow/brown, like cooked oil. 

[Stev-o]

Welcome from Texas!  If the bike is not running great, you might want to consider giving it a full 3000 mile tune up. An oil change my be a good idea too. And check the year made on the tires, if over 8 years old, I would replace them (or if they are dry rotted).

Good luck...

[UGly]

@ekpent There's 14,569 on the odometer

@Dave K Thanks for the great idea, i think ill get one to keep in my toolbox

@Stev-o it was went through, kind of, when i bought it, but i dont feel comfortable if i dont know the mechanic (in this case i do not). Do you have, or know of, a list of all the odds and ends tools i would need to do that tune-up? i know its pretty extensive. thanks

A little history of the bike. the guy i bought it from, it was his friends daily driver. his friend moved away and it sat for a year, his friend said he wasn't coming back and he could have the bike. He took it to a guy who went through the bike and got it running (but i dont know how thorough he was). I know it needs a new front tire, also left rear blinker and mirrors (not sure about Cali state law on these).

Im :fingers crossed: going to the Long Beach Cycle Swap this weekend so hopefully i can find some good deals and be on the road a week from now.

Thanks again to everyone for all the help