Topic: New clutch doesn't like 5th gear

[Jul]

Hey all, I have a strange issue.  I have a 750K6 which has recently been rebuilt- pistons, bored cylinders, new clutch plates, you name it.  It was really pricey and took a long time, so I'm vexed by the current problem.  I've only had the bike back for about 50 miles, so I want to make sure I'm not doing damage or I want to hear that it just needs to be broken in. 

The bike shifts and acts totally normal until I try to shift into 5th gear.

I can shift into 5th gear without using the clutch pretty much fine.

If I do what I consider normal shifting... it goes into false neutral.  By normal shifting I mean: 1. drop throttle and pull in clutch lever.  2. tap the gear shift up, moving foot off of gear shift after tapping. 3. add throttle and release clutch.  If I do this I hit the false neutral 95% of the time.  I've tried both authoritative taps and gentle taps to no avail.  Most of the time if I go into the false neutral I can tap the gear shift up into position and enter 5th gear, but it then tends to pop out.

If I follow the procedure above, but keep my foot in the up position while releasing the clutch it seems to shift into 5th very regularly and not pop out.  I have never had to do this to shift into 5th before, however, and I have had the bike for about 8 years and 35,000 miles.  Something is amiss.

My mechanic took it for a ride and says he doesn't notice anything, but I know I'm not imagining things.  He races 750's, has a few himself and works on classic bikes in general, so I figure he knows what he's doing, but this is a little weird.

Any advice greatly appreciated...

[MCRider]

Do you know how the trans performed before you did the work?  Sounds like a bent shift fork to me.

Oh poop, I just reread it, worked fine before. No clues from me. Was trans work done, was the bottom end opened up or just the top.?

[Jul]

Hey Ron,

Yeah, the clutch worked just fine before, but since we were doing pistons & cylinders we decided to just do everything.  I'm not sure what you mean by opening up the bottom end, unless you mean splitting the case.

The issue is a little better after riding all day, going from 4th to 5th to try to figure it out.  It seems much more likely to happen if I push the gear shift hard.  It will still sometimes pop out of 5th gear...

[MCRider]

Hey Ron,

Yeah, the clutch worked just fine before, but since we were doing pistons & cylinders we decided to just do everything.  I'm not sure what you mean by opening up the bottom end, unless you mean splitting the case.

The issue is a little better after riding all day, going from 4th to 5th to try to figure it out.  It seems much more likely to happen if I push the gear shift hard.  It will still sometimes pop out of 5th gear...

Yeah, open the bottom end, split the case, same dif. Answer is no eh?

Something like that doesn't fix itself...usually. Popping out of gear = bent shift fork 99% of the time. Popping out of gear will wear down the dogs that are engaging the gear, and such behavior will only make the symptom worse over time.

4th to 5th is the easiest shift. Never heard of a problem there. But it is what it is.
Hope I'm wrong. 

[dave500]

did the end float get altered at the basket?

[MCRider]

did the end float get altered at the basket?

I was trying to think what else could be wrong. Something like that. Or the shift drum moving around. But he wasn't in the bottom end. Changing the clutch discs, if that's all it was, wouldn't disturb the basket. I think.

[Jul]

Yeah Ron, the case was split.... sounds like that offers some possibilities....

Dave, I have no idea if the end float got altered at the basket... in fact, I don't even know what that means. 

Alas, I'll do the timing & valves and change a tire, but haven't generally wanted to get into doing things like pulling the motor & doing clutch work.

Though maybe I'm gonna have to...

[MCRider]

Yeah Ron, the case was split.... sounds like that offers some possibilities....

Dave, I have no idea if the end float got altered at the basket... in fact, I don't even know what that means. 

Alas, I'll do the timing & valves and change a tire, but haven't generally wanted to get into doing things like pulling the motor & doing clutch work.

Though maybe I'm gonna have to...

The clutch itself is completely accessible from the outside. I'm not sure if the endplay Dave refers to is. I'm not sure if that even exists. Or a problem with the shift drum either. We're (or at least I am) in WAG area here.

Since the cases were split that begs the questions, were the trans shafts removed? Was the shift drum removed? It is pegged in place by the neutral switch. Is that OK? Again WAG from me.

[Jul]

Thanks for the WAG-ing.  Totally appreciated.

The neutral switch has been slightly wonky but mostly functional.  A couple times since the rebuild it has seemed like it didn't want to work and first gear was hard to find.  This has happened twice, maybe three times over a full 100 mile day of playing with the gears a lot.  I can't say that this never happened in the past, but probably not 2-3 times in a day.  At this point I might be a little too observant.  The switch is about a year old, as I replaced that myself last Summer.

[Jul]

Could it be the wrong plates?  The mechanic mentioned that he had the plates for the clutch as he was going to put them in his bike, which I think is a '78 or at least an F.  I have a 750K6.  I seem to remember something about 5th gear being a little different on those models.  He mentioned something about "higher performance in the top end," and I wonder if that has us off.

Starting to wish I'd just decided to get in there myself, between the price, the delays and another issue.

[MCRider]

Could it be the wrong plates?  The mechanic mentioned that he had the plates for the clutch as he was going to put them in his bike, which I think is a '78 or at least an F.  I have a 750K6.  I seem to remember something about 5th gear being a little different on those models.  He mentioned something about "higher performance in the top end," and I wonder if that has us off.

Starting to wish I'd just decided to get in there myself, between the price, the delays and another issue.

My first hand knowledge drops off after K2. After that, I know what i've learned (or think I've learned) second hand. The later bikes, Fs only I think F2 and F3 had a lower gear ratio at top so it would keep pulling with vigor v the Ks. I can't see how swapping clutch plates could affect that but you never know. The gear and the plates being distant. Thing to do is check a parts fish and see if the part numbers are the same. My bet is no diffference.

Do you know how to look at parts fiche? If they are different, clutch repair/swapping discs is easy.

Nice thing is you can get into the gearbox itself witout removing the top end. Could be done on a Weekend, other than the diagnosis and obtaining parts. So 2 weekends.

I'll repeat, as you asked in your first post, if its popping out of gear, you are doing damage to the engagement dogs each time it jumps out. So use whatever technique makes for a positive shift, till you get it sorted.

[ekpent]

Go to a parts fiche from an online seller/dealer and carefully compare the K6 clutch to all the ones before it. I think you will see the K6 has a variation in the clutch plate set up than the earlier ones.Those pics and part numbers will be helpful for you.