Topic: CB750F Cafe Help!

[noahhalvorson]

I'm converting my 1975 CB 750F Supersport into a cafe bike, and my 4-2 headers don't allow for proper ground clearance or retraction of the side stand. The pipes run side-by-side into side-cut mufflers. I am looking for something readily available for under $400; anything that will improve ground clearance and maximize horsepower. Preferably chrome. Any suggestions?

I'm also thinking of having a port and polish done. Does anyone have a general idea of cost for it?

Does K&N make pod style air filters to fit the Keihin carbs?

As you can probably see, I am trying to tweak the bike as much as possible without tearing into an expensive rebuild, since it's running quite well with only 20k miles and doesn't need it.

Your input is appreciated!

[mikedialect]

MAC is affordable, but I don't hear a whole lot of "I love MAC" either. Generally people seem 'OK' with them, though.

K&N does make pods. Do some searching.

[fuzzybutt]

save yourself some headaches and keep the airbox for the time being. tuning with pods can be a real nightmare. an inexpensive 4 into 1 exhaust is made by mac. spend a bit more and the kerker exhaust system can be had. the quality between the 2 is night and day. also before doing any motor work go and get yourself a dyna ignition and matching coils. that mod in itself makes a huge difference in the way the bike runs.

[jdub]

I have a nice Mac 4 into 1 out in the shop that not being used if you wanna do some trading.

[Sam Green Racing]

Welcome to the forum Noah, you'll find all you need to know on here.

What's your location ?

Sam.

[aj]

the stock 4-1 pipe clears pretty good. check it out. u migh be able to score 1 cheap too.

[noahhalvorson]

Thanks for the welcome and the help.

In regards to Sam's question, I am in Cincinnati. You?

jdub - Thank you for the offer, but preferably, I would keep my old exhaust. It really sounds great and alleviates any backpressure I could suffer. I did some 'research' (really just tipping the bike over until something touched the ground) and found that my pegs scratch before my exhaust ever does. My problem is that my side stand hits the pipes and it scrapes badly when I lean. I have to discover a way to obviate that. I was thinking of pulling the mufflers out, slash-cutting the pipes, and refitting them. (shortened, of course)

Do you really think that the K&N's are such a meager improvement that the box is better? If not, then I don't mind tuning them. I have access to some manometers.

I'll have to do a search for Dyna Coils. I'm not sure which ones made for other Honda models match the CB. My goal was to replace the points with CDI anyway, and if I'm not buying pipes, then I'll have the extra money this winter.

aj - bike looks great! No wobble without that fender brace? I hear that it's necessary.

[aj]

my machinist is making 1 for me ya u do need it. show us some pics. thanks for the compliment.

[noahhalvorson]

Of course, man. Here are some:





Ugly stock bike, but clean. As you can see, the kickstand really is a problem.

I had to repaint the bike quick with rattlecan laquer if I wanted to ride this season, so it doesn't look great. I should have just done flat black until I can afford to give it a professional job. This winter, it's undergoing the transformation to cafe!

[my78k]

I think the reference to the airbox and tuning wasn't so much about carb sync but rather more about mixture. Getting the mix right can be a pain with pods and non-stock exhaust. You will need to play with the jetting to get it dialed in and can be a real pain having to buy abunch of different jets and trying to get them right...

Dennis

[kuyarico]

Check out this thread regarding pods vs. airbox. http://www.sohc4.us/forums/index.php?topic=22036.0
I think that edbiker can attest to the fact that the bike simply runs better with the stock airbox.

[edbikerii]

Using the stock airbox and jetting may be easier, but is not necessarily better.  It is a great starting point if you just want to get on your bike and ride it TODAY.

The stock jetting for my 77 550K was definitely too lean, so the bike ran too hot.  I wasn't happy with that, so I went back to pods and trial-and-error rejetting.  Although I'm pretty happy, I'm not quite finished yet.  For 77 and 78 550 K with the "lean-burn" carbs there was no "generally accepted" starting point, which makes things a little difficult.

For a 750 I'd look to Carpy's advice on jetting with pods and 4-1 as a good starting point.  His customers seem pretty happy with his setup.  See his advice in the old Greenspun archive: http://www.sohc4.us/greenspun/index.php?topic=12848.msg54353#msg54353

And remember, always tune the main jets for WOT first, then worry about the needles and finally the pilots, in that order.  Makes it much simpler, more systematic.

Good luck.

Check out this thread regarding pods vs. airbox. http://www.sohc4.us/forums/index.php?topic=22036.0
I think that edbiker can attest to the fact that the bike simply runs better with the stock airbox.

[noahhalvorson]

Thank you, once more, for the advice. The bike pulls absolutely beautifully through all the gears. Sometimes the throttle responds slowly after completely dumping it at 3500> RPMs, but I suppose that it is to be expected. They like to rev pretty high.

For the extra few HP I'd get, I think the airbox is fine. I already plan to invest in a Dyna ignition, and the pods would set me back so much monetarily that I might not be able to accomplish that.

I actually did scrape a tail pipe today coming around a turn, and I've decided now that I'm going to slash-cut them before the turn out and then just send them to Brown's. They sound wonderful, and restrict the bike very little.

My ultimate goal is to have a good general bike with a cafe look and feel. It's more important to me to have better clearance and clubmans (maybe even rearsets) than to squeeze 5-10 HP out of the engine. I can't imagine that bike standing up, but it could be possible.