Topic: New clutch chattering

[Dunk]

I put a new clutch in my CB750 K5 recently. new frictions, steels, and springs. Soaked in dino oil for about two hours, run with synthetic.  Both are JASO oils. When letting the clutch oil slowly or slightly dragging it at a stop it'll chatter, but not with a quicker release or a bit more RPM. Any thoughts on why it might be chattering, how to fix it, or if it'll just wear in? Replaced because it slipped a littale in higher gears at higher RPM. No slipping now. No drag, goes into gear with a slight clunk or totally silent if holding the clutch a few seconds before shifting into first.

[newday777]

So only at low rpm is when it chatters? Twist the throttle a bit.

[PeWe]

The clutch arm outside clutch cover might have too much play?
Release clutch cable from that arm and feel how much play it has.
Probably easier to release the nut, tighten the screw until it stops, release screw 1/4-1/2 turn out, lock with nut.

I have noticed that this play need to be adjusted again when clutch is assembled with fresh oil. Let it run warm, and adjust again.

[Translations]

Does it chatter when idling or when you pull the clutch? from what ive heard its pretty common and mine chatter a bit as well sometimes when in neutral but goes away when it revs? I installed a complete Cycle X kit with stiffer springs and two washers underneath each and it made it much better.

[desertrefugee]

Chatter typically refers to rough as opposed to smooth engagement - not idling noise.  Totally different.

I'd run it a bit to see if it settles down.  Maybe run it a little hard.  ('course that's just me...)

[Medyo Bastos]

There was a service bulletin for this using a gl1000 plate.


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[cooldrum]

I'd suggest going through the 3k mile tune up process just to be sure.  I just changed the frictions, steels, springs on my K4 and installed a new clutch cable.  Then I went through everything else and did a vacuum sink and it runs and pulls well.  Running Dino oil with 34k miles.  I have the normal clutch rattle from time to time at idle, I set the idle up just a bit to smooth it out.  All the little things add up for a smooth runner. 

[Dunk]

At least six weeks now of daily riding on it, ~35 miles per weekday, less or none on weekends. At least 50% stop and go. Chattering seems to be slightly less severe but it still very noticeable, or maybe I'm getting used to it. Can't be good for primary chains, feels like they're slapping around when it chatters. I try to rev just high enough when getting moving that it doesn't chatter. Been slow letting clutch out when shifting it higher gears, let it slip a little to let things wear in and oil get between plates.

I'm wondering if I should take it out and drill the extra holes in the basket. More oil through the clutch would probably result in less chatter. It definitely feels like less range of motion in the lever from disengaged to fully locked. Cannot drag the clutch at all without chatter. New aftermarket frictions and steels from vintagecb750, soaked in Rotella T4 initially and using Rotella T6. Now that I've got used to it it's not too difficult to avoid chatter gets tedious in traffic. It won't slip under load, but this is my daily rider and the chatter is getting old.

[scottly]

Try switching to non-synthetic oil like the Rotella T4, or a motorcycle oil spec'd for use with a wet clutch like Spectro.
PS I did drill the holes in the basket on my K1, and I really didn't notice any difference in the clutch, but I never had a problem with chatter to begin with.

[newday777]

Are you trying to take off in low RPMs?
Are your carbs synced in?

[MauiK3]

My K3 750 chattered a tiny bit when new, it went away quickly.

[Dunk]

Nearly a year later I figured it out. Spark plugs were terribly fouled probably misfiring at low RPM under load and I hadn't checked my chain adjustment in too long for a daily rider so that was pretty sloppy which made it feel worse. New plugs, cleaned and lubed chain, and chain adjusted to 3/4" and the chatter is virtually gone. Runs much better and clutch rattle is reduced. These plugs were iridium from 2015, they worked great but probably got fouled during my jetting attempts that were too rich.

Still need to dial in jetting. Feel rich just cracking into it at 2k-3k RPM low load, stumble. Running 40 slow, 110 main, needle 4th groove from top. Stumble goes away rolling into it after fuel petcock is turned off for a bit. I'm thinking just raise the needle clip 1 groove might do it. Need to stop being lazy and pull the carbs.

[HondaMan]

The K5 was the first of the 750s to have a different top clutch plate from the rest of the stack.It has wider outer fingers (tabs) than the other plates. Did you install one on the top that was different from the others? If not, it will rattle.

[Dunk]

I did not. The original clutch and the aftermarket replacement both had the same width tabs on all plates, at least none were visibly different. I'd assume the difference would be noticeable. Partzilla lists 22201-300-000 or 22201-371-000 for all friction disks. Source or part# for the outer wider tab friction disc?

If NLA what is the solution? Swap an earlier basket?

[HondaMan]

I did not. The original clutch and the aftermarket replacement both had the same width tabs on all plates, at least none were visibly different. I'd assume the difference would be noticeable. Partzilla lists 22201-300-000 or 22201-371-000 for all friction disks. Source or part# for the outer wider tab friction disc?

If NLA what is the solution? Swap an earlier basket?

I get good ones from PartsNmore.com:

Clutch Plate
#39-1090 | Honda CB750K (1976-1978)

Clutch Plate 1 Piece Required .138" Thickness OEM Ref # 22202-371-000 / 22202-390-000 / 22202-392-000

Make sure your clutch basket has the wider slots for this special top plate, as the tabs are wider by 2mm. The OEM version had slant-cut cork blocks on this top plate, but this pretty much went away by 1990 or so. The idea behind it was to 'soften' the takeoff from a hard start by letting the stack slip just a little in the lower 2 gears. In real life, this let just the top plate wear out too soon, so it was eventually dropped.

[PeWe]

About clutch baskets

Below the earlier my K2 has. All plates the same.
I thought K5 had that one too.



#

K6 with wider outer plate. When ordering clutch plates K6, K7, F1, F2 often written on the package.

Zoom in and you'll see the wider outer outside of the band holding the "fingers". Like grinded a mm or so.

[Dunk]

Found a picture from when I had it apart last time. It appears to the the earlier style basket.

[Tracksnblades1]

Try switching to non-synthetic oil like the Rotella T4, or a motorcycle oil spec'd for use with a wet clutch like Spectro.
PS I did drill the holes in the basket on my K1, and I really didn't notice any difference in the clutch, but I never had a problem with chatter to begin with.

👍 +1..

Rotella is a good one…😇
Vavoline 20w-50 has tested well on the Canadian’s oil test blog…😇
There’s lots of good conventional oils out there.

 We use Case/IH HyTrans oil in our two stroke Honda CR’s transmission. Said good by to the black oil every ride, clutch chatter and grabby jerking when fanning the clutch on the smaller cc bikes.. HyTrans cannot be used in 4 strokes that share common transmission and crankcase oil like the SOHC Hondas…

[Dunk]

Last oil change I used Rotella T4 for most of it after using up the last of T6 I normally have on hand, and had some T4 from back when there was a shortage. The T4 seemed to chatter less than the T6 and helped smooth it out. Changed oil the other day when I did plugs and chain adjustment among other odds and ends, obviously chatter is reduced. I like the sythetic T6. Good for all the bikes, cars, diesel truck, and boat. Easier to just keep one oil on hand, but the T4 did seem to reduce chatter slightly.

I did notice the T4 was not as nice in cold weather (freezing, give or take ten degrees). Took longer to idle normal even after getting decent temp in the head when leaving work where it sits outside all day and idle normal, probably a thinner would be better if running dino oil in those temps. Both T4 and T6 seem to get about the same water/oil white thick sludge just inside the oil cap. I'd love to get rid of that, but I think it's just the nature of riding in the winter, doesn't seem to accumulate in the oil, just on the cap that would be pretty cold even when oil is hot.

I did the extra clutch basket oil holes on my K1 during the rebuild. I didn't notice any difference after, but it had been all winter since I rode it and I changed the clutch anyhow, then another time or two until I got rid of the clutch drag and associated hard shifting.

[Tracksnblades1]

Last oil change I used Rotella T4 for most of it after using up the last of T6 I normally have on hand, and had some T4 from back when there was a shortage. The T4 seemed to chatter less than the T6 and helped smooth it out. Changed oil the other day when I did plugs and chain adjustment among other odds and ends, obviously chatter is reduced. I like the sythetic T6. Good for all the bikes, cars, diesel truck, and boat. Easier to just keep one oil on hand, but the T4 did seem to reduce chatter slightly.

I did notice the T4 was not as nice in cold weather (freezing, give or take ten degrees). Took longer to idle normal even after getting decent temp in the head when leaving work where it sits outside all day and idle normal, probably a thinner would be better if running dino oil in those temps. Both T4 and T6 seem to get about the same water/oil white thick sludge just inside the oil cap. I'd love to get rid of that, but I think it's just the nature of riding in the winter, doesn't seem to accumulate in the oil, just on the cap that would be pretty cold even when oil is hot.

I did the extra clutch basket oil holes on my K1 during the rebuild. I didn't notice any difference after, but it had been all winter since I rode it and I changed the clutch anyhow, then another time or two until I got rid of the clutch drag and associated hard shifting.

White sludge?

Sounds like you have a cool running oil temperature sohc..
wonder if your oil temperature is breaking 212*..?

Do you run an auxiliary oil cooler ? Thermostatic type ?

[Dunk]

No additional oil cooling factory setup. Unsure of oil temps but in summer I've seen head temps 230*+, maybe nearly 240*+ at hottest spots on a hot day after a hard run. White sludge on the oil cap is every winter after riding in temps from 10*-32*. I figure in those temps even if the oil tank is good and hot the cap will stay pretty cold from the cold air passing over it, and condense any moisture on the inside.

[newday777]

White sludge on the oil cap is every winter after riding in temps from 10*-32*. I figure in those temps even if the oil tank is good and hot the cap will stay pretty cold from the cold air passing over it, and condense any moisture on the inside.

How long are you riding on these winter rides? Sounds like you aren't riding long enough to burn out the moisture in the engine 🙄

[The Lone Builder]

The K5 was the first of the 750s to have a different top clutch plate from the rest of the stack.It has wider outer fingers (tabs) than the other plates. Did you install one on the top that was different from the others? If not, it will rattle.

What was the reason for this change?
Would modifying earlier baskets by grinding that mm off, as PW commented on, and using this later plate be an improvement?

[Dunk]

White sludge on the oil cap is every winter after riding in temps from 10*-32*. I figure in those temps even if the oil tank is good and hot the cap will stay pretty cold from the cold air passing over it, and condense any moisture on the inside.

How long are you riding on these winter rides? Sounds like you aren't riding long enough to burn out the moisture in the engine 🙄

16-18 miles each way, 25-45 minutes typically. Sometimes highway at 65-90 MPH for most of that, other times back roads some stop and go but ending either direction with a good stretch at 50 MPH. I don't think it would get any hotter riding longer than my usual commute. Never checked head temp after running it hard in below freezing temps though.

[PeWe]

The K5 was the first of the 750s to have a different top clutch plate from the rest of the stack.It has wider outer fingers (tabs) than the other plates. Did you install one on the top that was different from the others? If not, it will rattle.

What was the reason for this change?
Would modifying earlier baskets by grinding that mm off, as PW commented on, and using this later plate be an improvement?

You cannot grind an earlier basket to use later wider outer clutch disc. No meaning in that.
Compare construction and fitness. The later clutchbasket fingers look sturdier.

If upgrading clutch, use the later K7, F2 clutch that has a deeper basket than K6, alu hub is deeper to. This to use the double riveted metal disc.

The primary hub same as from K6 with a clip holding the basket on the splined shaft. Good idea to replace cush rubbers inside

My K6 has that later F2 clutch  But that engine need a better clutch, >100whp.

Ratting at idle is rather normal. It disappear when using the clutch.
New and tight primary chains will help too.
Synced carbs and ignition is a must too.
If using points, adjust them with dwell meter so both act at same degree.

Dyna-S the easier way to make 1:4 and 2:3 equal.
Cut adv springs 1/2 wound will help too.
A must on both my CB750 to run well. Ok idle and not advancing too early.

I know one guy with a 100% stock CB750 K2 that runs really nice. No clutch rattling  at all when idling. Carbs and ignition must be bang on.

I must ask him whatvhw had done. If STP in high dose is used.