2 Questions. #1. Transmission shifting weird sometimes. #2. Starter clutch ??

[lvin4jc]

Ok, well if you haven't read one of my posts before, this is a 1979 CB750K and I am a first time bike rider/not really mechanic. I got my license last week so i've been riding the bike to work as much as I can.

#1. The transmission isn't 100%. What I mean is that sometimes between 2-3 or 3-4 it pops into what feels like neutral (obviously it's not) then even when I lift up on the lever it is stuck in the last gear I was in. I re-shift and everything is fine. This morning I had some trouble shifting to neutral, it wanted 1 or 2 but didn't want to give me neutral.
That's really it, no popping out of gear or anything. And again i'm a first time rider. I find that this bike is easy to shift quickly and the engine's power just makes me want to do so. Maybe the 2-3 3-4 problem is just me shifting too quickly and I need to slow up a bit?
Also, in the process of rebuilding the starter clutch I filled and drained the oil a couple of times (long story) and it seems like my bike transmission might like to be a little over full, just a little. Anyway that's the only variable I can put together. When it's a little over full the transmission seems to shift better, is that a thing?

#2. And far less important. I pulled the cover off of the starter clutch and found the three bolts to be very loose. I thought great, I don't need to install the rebuild kit (I would have if I had know how easy it was to do at the time) so I tightened the bolts and put it back together. It worked much better but still failed maybe 2 out of 10 times. So I pulled it back apart and rebuilt it with the vintage CB750 kit. Now it works 9 out of 10 times but every once in a while, maybe worse in the cold, it fails. The only other thing I had heard was worn teeth on the gears. I looked at mine twice and they looked really good to my eye, no scratches or anything, good looking sharp teeth. What else could that be? Could it also be oil related?

Thanks guys, i'm really, really enjoying riding this wonderful bike!

 

[amc49]

Maybe oil type, that can add to starter clutch issues. The gears have nothing to do with it, only the clutch itself. The 3 bolts come back loose if not loctited.

The shift forks bend from lackeys forcing them, then you have shifting issues. Can be the linkage too, there is a mod that makes them shift much better but only if the forks are not bent or worn. Go to the CB1100F.net site, sign up for free and go to technical documents and download the Motorcyclist magazine article on the mod.............

 

[lvin4jc]

Maybe oil type, that can add to starter clutch issues. The gears have nothing to do with it, only the clutch itself. The 3 bolts come back loose if not loctited.

The shift forks bend from lackeys forcing them, then you have shifting issues. Can be the linkage too, there is a mod that makes them shift much better but only if the forks are not bent or worn. Go to the CB1100F.net site, sign up for free and go to technical documents and download the Motorcyclist magazine article on the mod.............

I will do that right now. I don't suppose you get to see the forks unless you take a lot of stuff apart do you?

I know this is a very loaded question, but... What oil do you use in these?

Ok, I just read the article. I guess it helped put my mind to rest quite a bit that this happened even when they were new. On the way home tonight I put a little more oil in, less than a 1/4 quart. I also took my time shifting and I only had one missed shift. This bike is used as a cruiser so i'm not racing around or anything. I think if the bike and I can learn one another it might not be a big deal. But if it gets annoying the procedure doesn't look too hard either. Maybe if it rains for a few days straight or something. It looks like the missed shifts don't hurt anything or make anything worse in the gearbox, is that an accurate statement?

Thanks again for the help!

 

[amc49]

Add them up and they do, it's cumulative damage, it rounds the ends of the synchro dogs to where the gear begins to fly into neutral by itself under load.

If you got the problem I would be modding NOW, not hard. Once it 'gets annoying' you will have gone too far as the flying out of gear comes up next.

You have to split engine cases to get to the forks.

The starter clutches do not like modern automotive oils which have 'friction modifiers' to replace the zinc removed due to EPA regs. They work TOO well and why the clutch has trouble locking to stay locked. Drop back to zinc oil like motorcycle specific stuff and the clutches work better. Look for like JASO approved stuff, thinking Valvoline makes one but be ready for the price. It's high. Since such a small market EPA allows that since intended for bike but they did command a price increase to lower purchases of it. You're paying to pollute in essence.

The oil is in reference to starter not trans, trans does just fine with either one. It will change nothing in shifting. Don't overfill, the oil is for both engine AND trans, and too high will make engine burn oil.

 

[Blakhawk]

I've found that preloading the shifter results in fewer missed shifts. Also, you don't have to squeeze the clutch lever to the bar. It only takes about half its travel to disengage, and that makes the shift quicker and smoother, but YMMV.

 

[DYNO RYNO]

Ok, well if you haven't read one of my posts before, this is a 1979 CB750K and I am a first time bike rider/not really mechanic. I got my license last week so i've been riding the bike to work as much as I can.

#1. The transmission isn't 100%. What I mean is that sometimes between 2-3 or 3-4 it pops into what feels like neutral (obviously it's not) then even when I lift up on the lever it is stuck in the last gear I was in. I re-shift and everything is fine. This morning I had some trouble shifting to neutral, it wanted 1 or 2 but didn't want to give me neutral.
That's really it, no popping out of gear or anything. And again i'm a first time rider. I find that this bike is easy to shift quickly and the engine's power just makes me want to do so. Maybe the 2-3 3-4 problem is just me shifting too quickly and I need to slow up a bit?
Also, in the process of rebuilding the starter clutch I filled and drained the oil a couple of times (long story) and it seems like my bike transmission might like to be a little over full, just a little. Anyway that's the only variable I can put together. When it's a little over full the transmission seems to shift better, is that a thing?

#2. And far less important. I pulled the cover off of the starter clutch and found the three bolts to be very loose. I thought great, I don't need to install the rebuild kit (I would have if I had know how easy it was to do at the time) so I tightened the bolts and put it back together. It worked much better but still failed maybe 2 out of 10 times. So I pulled it back apart and rebuilt it with the vintage CB750 kit. Now it works 9 out of 10 times but every once in a while, maybe worse in the cold, it fails. The only other thing I had heard was worn teeth on the gears. I looked at mine twice and they looked really good to my eye, no scratches or anything, good looking sharp teeth. What else could that be? Could it also be oil related?

Thanks guys, i'm really, really enjoying riding this wonderful bike!

Look at the bushing n the center of the big starter clutch Gear mine was worn out and falling out I had Same exact symptoms took me twice find it it will allow the gear to wobble slightly when it needs b held tight and true I found one used on the bay 22.00 my prob is my gear doesn't want slide back on by hand I may have to come up w an installer tool hope this helps

 

[DYNO RYNO]

Look at the bushing n the center of the big starter clutch Gear mine was worn out and falling out I had Same exact symptoms took me twice find it it will allow the gear to wobble slightly when it needs b held tight and true I found one used on the bay 22.00 my prob is my gear doesn't want slide back on by hand I may have to come up w an installer tool hope this helps