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1979 CB750k no 6th gear

KageLewis

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So I recently bought a 1979 CB750k and it is my first street bike, but I'm having some troubles with it, with nearly 40,000 miles i wasn't surprised it needed a little TLC but I need some help. I can't seem to get it into 6th gear, I've looked around at other forums and tried their ideas, such as adjusting the clutch lever and making sure the shifter has enough room to fully engage and what not, but to no avail. Im sure I'll have to open it up but I'm not familiar with these bikes so I would like some help diagnosing this problem. Thanks
 

KageLewis

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The you're right, I don't believe normal cb750 editions do have 6 speed transmissions, but the cb750(k) does, multiple websites confirm this as well as the casting on the side of the engine/tranny on my bike
 

amc49

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Wishful thinking. Thinking maybe a couple later models do but I can positively tell you no '79-'83 does, they are all 5 speed. A couple of 900-1000 models of the C are dual range meaning essentially 10 speeds but beyond that nothing. The K is the plainest model there and nothing special about them. If anything would have gotten a 6 speed it would be the F model which was the high-perf model.

I've had bunches of the early DOHC apart, I have every single trans part in memory just about. If you have the dual range trans I believe it's marked on the side but that is not a K or a 750.
 

dirtdigger

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The you're right, I don't believe normal cb750 editions do have 6 speed transmissions, but the cb750(k) does, multiple websites confirm this as well as the casting on the side of the engine/tranny on my bike

Send a couple photos of your bike and the markings on the side covers so we can help you identify your bike.
 

KageLewis

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I tried to post this earlier but it looks like it didn't work. Sorry for wasting your guys' time, I could have sworn I saw 6 speeds on my bike but when I looked earlier today it showed you were right and I only have 5 gears, it didn't help that that website was kinda misleading in confirming my misconceptions. Thank you though.
 

amc49

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I can definitely tell you that bike picced there never had 6 speed, 5 only. The page is wrong. All early DOHC used the exact same trans design with minor differences and it had the extra sub-transmission bolted on side of case in place of the countershaft sprocket to make the high/low transition to 10 speeds.

Here, an 1100F DOHC engine using same exact trans.............

https://imgur.com/PD66tdC

Count across the gears there, you have 5 total on both shafts, the only configuration that trans ever came in.
 

leo750k

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I have a 1980 CB-750k and although it does cry for a sixth gear, it is a 5 speed. I have been thinking about increasing the number of teeth on the final drive sprocket by one.
 

leo750k

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Sorry I probably have my descriptions wrong, I meant 1 tooth to the small sprocket. But after reading one of your other comments, I will most likely leave it like Honda designed it. This is my first motorcycle, but I have been running 4 cylinder Japanese motors all my life, and you are right the worst thing you can do to them is bog them down. There is just less stress on the whole motor and drive train when allowed to run thru the entire rpm range.
 
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