Topic: CB750 Supersport Questions!

[christopherk]

So, unfortunately I sold my 550 to buy a certain American made motorcycle. Fortunately, the deal fell through and I was able to pick up this bucket of bolts, 1975 CB 750 Supersport. I'm the second owner with less than 5000 miles. It has the 836 top end and Kerker exhaust. Couple questions for the gurus:

1.) It has this HUGE rear sprocket. Like, wheelie on every gear change huge. I want to take this thing on the freeway at a low RPM. I'm 5'11'' @ 150 lbs, and combined with the exhaust and 836, low end won't be an issue. What gearing should I shoot for?

2.) It came with pod air filters. I hate pods with a passion (ran them on my 550 ugh) and want to run an airbox. Will this work with the exhaust and top end? Can I drill holes in it? Sorta new to the whole airbox scene.

I'm sure some of these topics have been covered, I wanted to show off the bike a bit

[christopherk]

Pictures weren't showing up!






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[Jerry Rxman Griffin aka MuthaF'er]

You didn't say what HUGE means to you. I know what it means to me 

Stock is 17:48. 5000 rpm at 70mph. 18:48 = 75mph @ 5000 rpm IF you have stock size tires.

If the pods are dialed in leave them alone. They can be difficult to dial in but they can have benefits.

A stock airbox will work fine with 'whatever' exhaust you have (Kerker) BUT you're gonna have to play with the jetting! Again, if the pods work, leave them alone.

If you don't want it performing as good as it is now why cut holes in a stock airbox?!

Again, if it ain't broke don't fix it! You could be opening a big can of worms vs a big can of whoop ass. 

Oh yeah, looks nice! Congrats 

[seanbarney41]

So, unfortunately I sold my 550 to buy a certain American made motorcycle. Fortunately, the deal fell through and I was able to pick up this bucket of bolts, 1975 CB 750 Supersport. I'm the second owner with less than 5000 miles. It has the 836 top end and Kerker exhaust. Couple questions for the gurus:

1.) It has this HUGE rear sprocket. Like, wheelie on every gear change huge. I want to take this thing on the freeway at a low RPM. I'm 5'11'' @ 150 lbs, and combined with the exhaust and 836, low end won't be an issue. What gearing should I shoot for?

2.) It came with pod air filters. I hate pods with a passion (ran them on my 550 ugh) and want to run an airbox. Will this work with the exhaust and top end? Can I drill holes in it? Sorta new to the whole airbox scene.

I'm sure some of these topics have been covered, I wanted to show off the bike a bit

1.) ...doesn't look that huge in the picture, how many teeth?(better check the front sprocket too)  If it does wheelies period, and you are around or under 6k rpm at 70mph, learn to live with it, 'cuz you got one bad ass 750.  I forget what tooth count is stock for the f, but if it is +/- 1 or 2 just learn to live with high revs.  If it's in good shape and properly maintained ride it on the freeway all day long.  It's what makes Hondas special.
2.) Yes it will run fine with an airbox, just might require some reverse jetting.

[Hon3ybadger]

That's a virgin compared to what I bought. Seriously nice my friend!

[david 750f]

That looks close to a stock rear sprocket. Count the teeth, should be a 48 tooth sprocket.. perhaps the front sprocket has been replaced with a smaller one?
Pull the rear crankcase (sprocket) cover off and count the teeth as well.

Part #1 in the parts diagram.

http://www.motogrid.com/pages/OemParts#/Honda/CB750F_A_(76)_MOTORCYCLE%2c_JPN%2c_VIN%23_CB750F-2000003_TO_CB750F-2022317/STARTER_MOTOR_%2b_CRANKCASE_COVER/CB750F-76-JPN-A/2Y133920E13392010A

[70CB750]

Good looking bike!

As suggested, count teeth and use a sprocket calculator to check on rpms:

http://www.sohc4.net/cb750-faq/indexphp/sohc4-gearing-chart

[madmtnmotors]

..doesn't look that huge in the picture, how many teeth?(better check the front sprocket too)  If it does wheelies period, and you are around or under 6k rpm at 70mph, learn to live with it, 'cuz you got one bad ass 750.

To "wheelie on every gear change" I would expect a sprocket so large that the chain guard would not fit. I have never been able to lift the front tire, my rear tire always breaks loose first leaving a black streak on the pavement...



and on the seat!   

[Airborne 82nd]

Want to see video of said wheelies or it didn't happen. 

[Hon3ybadger]

Want to see video of said wheelies or it didn't happen. 

+1

[christopherk]

They happened i swear 

Does the stock 750 airbox work on the supersports, or do I need a model specific one?

[Hon3ybadger]

Not sure about the airbox but those socks belong in the 80's

[Stev-o]

Want to see video of said wheelies or it didn't happen. 

+1

+1....have "sox" use his iphone for something other than texting

[andrewk]

A few minor differences among air boxes, but you should be able to use a K or F air box, pre-77 without much issue.  Main differences are how the lid attaches (wingnuts on bottom or a bolt through the top) and the air intake configuration.  If you decide to put the stock box on, don't drill holes in it unless you want it to run like sh*t.  A K&N drop in filter is available, I'd recommend it not for performance but rather for service life.

If this bike runs good, like with tan plugs, crisp throttle response and a quick fall back to idle, consider leaving the pods.  Very few people go through the trouble to completely sort a tune, but if it's sorted, you might be making some steps backward.