Author Topic: 1973 Honda cb750K3 Clutch Replacement. (Read 517 times)

BenelliSEI · « **on:** February 13, 2026, 01:14:36 PM »

My 1973 cb750K3 developed an annoying clutch judder over the past few season. When taking off from rest, the clutch does not engage smoothly, but snatches a bit. Not smooth at all. A few extra revs helps, but it’s annoying. My wife rides this bike and she complains about it too…..

So today I decided it was time to dig into it.

BenelliSEI · « **Reply #1 on:** February 13, 2026, 01:15:48 PM »

Here’s a neat way to keep the cover screws.

BenelliSEI · « **Reply #2 on:** February 13, 2026, 01:26:52 PM »

Pulled the clutch apart and didn’t really find anything. Nothing loose or broken. All the clutch plates are between 3.45 to 3.50 mm thick, well above the min. suggested of 3.10 mm. Metal plates are all flat and smooth. They do have a bit of staining and all “dimples” on the faces are long gone, but smooth and zero warp.

Looking more closely I discovered an odd set of clutch springs (the ones on the right in the photo). They measure 3.45 to 3.50 mm free length which is a LOT more than the min of 30.5 mm. I pulled out a few spare sets (used) and they are all at least 3 or 4 mm shorter! The wire size on the tall ones measured only 2.50 mm vs. the stock ones at 2.85 to 2.90 mm. Noted the gasket was smeared in silicone, so I am not the first person in here…… Those springs are for sure not original equipment.

BenelliSEI · « **Reply #3 on:** February 13, 2026, 01:30:52 PM »

Curious what you think? Suggestions?

I have a new set of fibre plates and a really nice set of metal discs that are very clean and still show the faint dimples you see on new ones. Probably going to put those in and use middle set of stock springs that all measure about 32 mm free length. Anything else I should check?

Kelly E · « **Reply #4 on:** February 13, 2026, 03:20:24 PM »

I use a Roloc scuff pad in the die grinder to clean up both sides of used steels before reinstalling.

Mark1976 · « **Reply #5 on:** February 13, 2026, 03:23:40 PM »

The only time I've encountered what you're describing (with honda's) is when aftermarket fibers (and sometimes springs)have been used. The honda fiber plates are way more tolerant of fanning/slipping of the clutch than most of the aftermarket alternatives. I've used the honda clutch plates with the barnett springs, and that combination works well for me. The barnett fibers if abused enough will do exactly what you're describing, they'll hook up fine, they just won't like being fanned. The only other stock clutch that I ever had that would chatter was my 78 z1r. New steels, new fibers, new clutch...

BenelliSEI · « **Reply #6 on:** February 13, 2026, 03:25:34 PM »

Quote from: Kelly E on February 13, 2026, 03:20:24 PM

I use a Roloc scuff pad in the die grinder to clean up both sides of used steels before reinstalling.

Will do. I have a realy clean, “newish” set I will probably use. Really curious what everyone thinks about those weird tall springs I found in there. First I thought they might be a “heavy duty” set but when I measured the wire diameter, not so much.

BenelliSEI · « **Reply #7 on:** February 13, 2026, 03:27:58 PM »

Quote from: Mark1976 on February 13, 2026, 03:23:40 PM

The only time I've encountered what you're describing (with honda's) is when aftermarket fibers (and sometimes springs)have been used. The honda fiber plates are way more tolerant of fanning/slipping of the clutch than most of the aftermarket alternatives. I've used the honda clutch plates with the barnett springs, and that combination works well for me. The barnett fibers if abused enough will do exactly what you're describing, they'll hook up fine, they just won't like being fanned. The only other stock clutch that I ever had that would chatter was my 78 z1r. New steels, new fibers, new clutch...

First time I’ve ever opened anything on this bike. I’ve had it for +14 years but it runs so well I leave it alone. Regular oil changes, tires, fresh brake fluid every 4-5 years, and probably 2 X “3,000 mile tune ups”. This Honda has finished every Ganaraska 250 event since 2011. My wife uses this one occasionally so need it to be smooooth!

I’m probably going to do just as you suggest. New fibre plates, super clean steel discs, and a nice set of stock springs that are well over the min. free length.

kyle750 · « **Reply #8 on:** February 13, 2026, 03:37:21 PM »

I like the way you keep track of your clutch cover screws. Very neat and tidy.

Kannika refinished my K1 gear shift cover a long time ago and this is how I kept track of the screws

Clearly one system is the work of a professional

BenelliSEI · « **Reply #9 on:** February 13, 2026, 08:43:24 PM »

Quote from: kyle750 on February 13, 2026, 03:37:21 PM

I like the way you keep track of your clutch cover screws. Very neat and tidy.

Kannika refinished my K1 gear shift cover a long time ago and this is how I kept track of the screws

Clearly one system is the work of a professional

Whatever works is a good solution.

Hopefully using fresh parts will solve my problem. Time will tell.

BenelliSEI · « **Reply #10 on:** February 14, 2026, 07:44:43 AM »

One thing I forgot to mention….. I’ve seen people struggle to remove the main clutch cover. Usually because someone has been over zealous with some horrible sealer. First, use a hand held impact driver to loosen ALL the retaining screws and remove. Got them ALL?

Assuming you have the chrome top cover off and the clutch cable removed, loosen the lock nut on the centre clutch actuating mechanism. Use a good size flat blade screw driver and turn the clutch adjuster IN. Easily pushes the cover away from the engine cases without any beating or banging.

BenelliSEI · « **Reply #11 on:** February 14, 2026, 12:19:30 PM »

Built up a clutch stack using new fibre plates and the best set of metal discs I had in my spares. Found a new lock tab, and decided to use a set of more std. looking springs that are all about 32mm on free length.

BenelliSEI · « **Reply #12 on:** February 14, 2026, 12:23:08 PM »

Somewhere I have a clutch basket locking tool I made, but not today! Stick the bike in 2nd gear and wind the back brake up tight on the rear adjuster. Easy way to torque up the centre nut and 4 X little bolts for the basket.

BenelliSEI · « **Reply #13 on:** February 14, 2026, 12:25:25 PM »

Fresh gasket and new case screws finished the job. Too bad it will be months before I get to test it!

Kelly E · « **Reply #14 on:** February 14, 2026, 05:33:57 PM »

Nice work buddy.

I've never had to replace the steels on any of the various bike clutches I've done. The Roloc scuff pad to clean them up has always worked out great with no grabbing or weird stuff, just nice smooth operation.

HondaMan · « **Reply #15 on:** February 14, 2026, 05:49:55 PM »

Quote from: BenelliSEI on February 13, 2026, 01:30:52 PM

Curious what you think? Suggestions?

I have a new set of fibre plates and a really nice set of metal discs that are very clean and still show the faint dimples you see on new ones. Probably going to put those in and use middle set of stock springs that all measure about 32 mm free length. Anything else I should check?

They look like the springs from the K6/F0-3 clutch (and the K7/8). Their increased force causes the cork plates to squish out the oil that is supposed to be soaked into the cork, and the result is ALWAYS a judder-ing clutch in city traffic. I've lost count of how many of those instances I've "fixed" by reinstalling the original springs again. This was common up to the K4 when the 'slpiiper' to plate was added, along with the damnable dual-steel, inner-sprung plates where the rivets always work loose and made the whole gearbox "jangle" at idle speeds.

HondaMan · « **Reply #16 on:** February 14, 2026, 05:52:40 PM »

This also reminds me: what often caused the owner(s) to install "stronger springs" was that they were using incorrect oils, with detergents in them, which would foam in hot city traffic and stop-and-go around 40-50 MPH situations. This foaming made the clutch slip, every time. I also "fixed" many of those by just changing their oil. Twice, about 300 miles apart...

BenelliSEI · « **Reply #17 on:** February 14, 2026, 06:22:41 PM »

Quote from: HondaMan on February 14, 2026, 05:49:55 PM

Quote from: BenelliSEI on February 13, 2026, 01:30:52 PM
Curious what you think? Suggestions?

I have a new set of fibre plates and a really nice set of metal discs that are very clean and still show the faint dimples you see on new ones. Probably going to put those in and use middle set of stock springs that all measure about 32 mm free length. Anything else I should check?

Thanks for this. I put everything back to what should be in there, so I’m thinking it should be fine. As I said earlier, not only were the springs long but the gauge was far less than stock. Strange.

They look like the springs from the K6/F0-3 clutch (and the K7/8). Their increased force causes the cork plates to squish out the oil that is supposed to be soaked into the cork, and the result is ALWAYS a judder-ing clutch in city traffic. I've lost count of how many of those instances I've "fixed" by reinstalling the original springs again. This was common up to the K4 when the 'slpiiper' to plate was added, along with the damnable dual-steel, inner-sprung plates where the rivets always work loose and made the whole gearbox "jangle" at idle speeds.

BenelliSEI · « **Reply #18 on:** February 14, 2026, 06:23:52 PM »

Quote from: Kelly E on February 14, 2026, 05:33:57 PM

Nice work buddy.
I've never had to replace the steels on any of the various bike clutches I've done. The Roloc scuff pad to clean them up has always worked out great with no grabbing or weird stuff, just nice smooth operation.

I’ll try them on the ones that came out. They are perfectly flat so I will use them again.

MauiK3 · « **Reply #19 on:** February 15, 2026, 07:38:46 AM »

And I really like the look of that bike, clean lines, great color.

BenelliSEI · « **Reply #20 on:** February 15, 2026, 07:49:21 AM »

Quote from: MauiK3 on February 15, 2026, 07:38:46 AM

And I really like the look of that bike, clean lines, great color.

Steve….. That’s the bike I bought for the first Ganaraska 250 “Moto Giro”, 14 years ago. Paid $1000. The owner said it ran for 20 minutes then seized up. It seemed to be OK, but sure enough, after a short ride it ground to a stop! Took me a few days to figure out the gas cap vent was plugged and it was running out of fuel! It was also a horrible shade of rattle can light blue….

Since then, I keep swapping out bits for parts I come across, like the Lesters and Hindle exhaust. The rear fender/lamp is from a ‘71 and the front is 1978. The tank and side covers got done when a hot rodder buddy of mine was painting his Willy’s Coupe black. He hand striped the tank and then clear coated. Both ends have been off for brakes, seals, bushings etc., but the engine has never been out and I’ve never touched the carbs. It just runs great!

HondaMan · « **Reply #21 on:** February 15, 2026, 04:30:12 PM »

Those Lesters are beautiful! They are the only 'other' wheels I'd like for my own, but never have been able to get a set. I was/am either broke when a set came along, or couldn't find them when I had $$. I have a pair in 19" front and 17" rear (for CB750K7) 'snowflake' pattern (as opposed to the 'spoke' look like yours - which I'd prefer to have) and would love to trade them to someone who has the earlier K type 19"/18" pair, but never had any takers.

Yet?

BenelliSEI · « **Reply #22 on:** February 15, 2026, 05:30:21 PM »

Quote from: HondaMan on February 15, 2026, 04:30:12 PM

Those Lesters are beautiful! They are the only 'other' wheels I'd like for my own, but never have been able to get a set. I was/am either broke when a set came along, or couldn't find them when I had $$. I have a pair in 19" front and 17" rear (for CB750K7) 'snowflake' pattern (as opposed to the 'spoke' look like yours - which I'd prefer to have) and would love to trade them to someone who has the earlier K type 19"/18" pair, but never had any takers.

Yet?

I know a guy with an 18” rear. They’re the hard ones to find. I keep pestering him.

BenelliSEI · « **Reply #23 on:** February 16, 2026, 06:07:41 AM »

Quote from: HondaMan on February 15, 2026, 04:30:12 PM

Those Lesters are beautiful! They are the only 'other' wheels I'd like for my own, but never have been able to get a set. I was/am either broke when a set came along, or couldn't find them when I had $$. I have a pair in 19" front and 17" rear (for CB750K7) 'snowflake' pattern (as opposed to the 'spoke' look like yours - which I'd prefer to have) and would love to trade them to someone who has the earlier K type 19"/18" pair, but never had any takers.

Yet?

I ran these for many years on my cb750K8. When I decided to sell it I kept the wheels! I think they were new when I picked them up.

MauiK3 · « **Reply #24 on:** February 16, 2026, 06:45:00 AM »

Great wheels, I wonder what the weight difference is, if any.

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Author Topic: 1973 Honda cb750K3 Clutch Replacement. (Read 517 times)