Clutch siezed

[Mikep328]

Went to the bike today to take a short ride and after warming up a bit, got on, pulled in clutch lever and selected 1st.  Bike immediately lurched forward and stalled.  Clutch discs/steels had obviously seized.  I have seen this on cars when clutch discs got wet and then sat for a period of time but don't understand how it can happen on a clutch submerged in oil!

It was no big deal - did the same thing I have done with car clutches in that situation.  I put the bike in the highest gear, pulled the lever in to "disengage" the clutch, applied the brakes and then engaged the starter which immediately freed the clutch.  I then went out on a short ride in the rain.

I can't figure out how the clutch plates can seize while in an oil bath!  It  had not been ridden in about 6 weeks.  I had done work during that period with the engine running/bike in neutral but had not used the clutch/changed gears at all.

[Johnwebley]

Most of the sohc bikes suffer the same,

The clutch is pressed together by the springs, and the plates just stick,

No rust,

I suggest before the ride, kick it over with the clutch pulled in till they free up,

Or,ride it more often,

Don't worry, just learn how to deal with it

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[McCabe-Thiele (Ted)]

My old XJ900 clutch would stick every winter - I would start it up on the stand, engage 2nd or 3rd gear rev it to about 3k then holding the throttle apply the footbrake - worked fine for the many years I owned her.

I think Johns method using the kick start is kinder to the drive train.

[TrickyMicky]

Went to the bike today to take a short ride and after warming up a bit, got on, pulled in clutch lever and selected 1st.  Bike immediately lurched forward and stalled.  Clutch discs/steels had obviously seized.  I have seen this on cars when clutch discs got wet and then sat for a period of time but don't understand how it can happen on a clutch submerged in oil!

It was no big deal - did the same thing I have done with car clutches in that situation.  I put the bike in the highest gear, pulled the lever in to "disengage" the clutch, applied the brakes and then engaged the starter which immediately freed the clutch.  I then went out on a short ride in the rain.

I can't figure out how the clutch plates can seize while in an oil bath!  It  had not been ridden in about 6 weeks.  I had done work during that period with the engine running/bike in neutral but had not used the clutch/changed gears at all.

Everyday occurence with most bike clutches unfortunately. With all due respect I would not use the starter motor to free it off, that's asking for expensive trouble. I use either of the other suggestions, ie. kick start or engine running then rear brake. Many years ago my bike was off the road for about 5 years, and believe me that clutch was well and truly stuck I did not fancy a dismantling job, so I discovered that if you remove the dipstick the edges of the plates are visible.  The clutch lever on the handlebars was lashed into the open position, and gentle use with a flat screwdriver the plates were separated whils turning the engine over a bit at a time with the kickstart, and yes, it worked. My 48 year old clutch plates are still operating well. (And sticking!!!)

[Mikep328]

Seemed odd - the bike sat for 5 months while we were in the USA and the week I got back here I rode it - no sticking clutch.  Then it sat for 4-5 weeks and had a sticking clutch.  I don't understand the dynamics!    One of those mysteries, I guess! 

[Athame57]

Seemed odd - the bike sat for 5 months while we were in the USA and the week I got back here I rode it - no sticking clutch.  Then it sat for 4-5 weeks and had a sticking clutch.  I don't understand the dynamics!    One of those mysteries, I guess!

Could it be the oil you were using?

[Mikep328]

It was the same oil - I had changed it last November before we left the UK; didn't change it when we arrived in late April and no sticking clutch at that time.  Hard to believe the oil would be fine after 5 months and then go "bad" 5 weeks later.

I'm not particularly concerned that it happened since it's easy enough to "fix" when it occurs just wanting to understand it; I like knowing why something happens! 

[taysidedragon]

It was the same oil - I had changed it last November before we left the UK; didn't change it when we arrived in late April and no sticking clutch at that time.  Hard to believe the oil would be fine after 5 months and then go "bad" 5 weeks later.

I'm not particularly concerned that it happened since it's easy enough to "fix" when it occurs just wanting to understand it; I like knowing why something happens! 

It could be some contamination in the oil after riding it compared to clean, new oil before?

[McCabe-Thiele (Ted)]

Coild it be connected with the age of the clutch plate material, I fitted new plates when I rebuilt my 400, clutch did not sick in the last two winters?

[Mikep328]

Can't see how the oil could get contaminated in a couple of short rides - still looks clean on the dipstick - same as out of the bottle.

Clutch discs are old, I assume, maybe original. Bike only had 14,000 original miles based on MOT records/rebuild info.  No record of them being replaced when the engine was rebuilt in '22.  There are receipts for everything else done to the engine so I'm sure if the clutch discs had been replaced there would be a notation for that. 

That being said, clutch works great. It engages smoothly and there is no slippage at all.  So as doctors say nowadays, "We'll monitor and note any changes!" 

[Johnwebley]

I recently replaced the clutch plates, fibre only,

After that, the clutch worked well,

But after 500 miles or so, the plates seem to bed in,had to adjust the lifter etc,

I assume the plates became smoother,

I also noticed as the clutch got used, the sticking got slightly more apparent,

So the better the surface, the more likely to stick

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[Mikep328]

It's interesting that, from reading posts, this seems to be not uncommon.  But I don't recall it being a problem on any motorcycle I have ever owned and I've owned a lot of them, including 4 SOHC Hondas over the years.  One motorcycle sat in a garage for 2 years between starts and it didn't have sticking clutch plates. 

[Athame57]

It's interesting that, from reading posts, this seems to be not uncommon.  But I don't recall it being a problem on any motorcycle I have ever owned and I've owned a lot of them, including 4 SOHC Hondas over the years.  One motorcycle sat in a garage for 2 years between starts and it didn't have sticking clutch plates.

Nor me! I've certainly had the opposite, my new CB250N developed clutch slip within about nine months of dispatch riding, and a second hand one soon did the same.

[Mikep328]

I rode a bit over 50 miles today.  When I went to the bike this morning, the clutch was sticking again.  Not as firmly as previously but I couldn't easily roll the bike with it in gear/clutch lever pulled.  A heavier attempt and it broke loose.  Since it never did that last year with different oil, I now think the oil may be the issue.  Contrary to most advice here   I used full synthetic motorcycle oil.  The oil that was in the bike when I bought it (per receipts) was the semi-synthetic 10W40 from DSS.  So...I'm thinking I'll drain the almost new synthetic oil (Grrr...) and install the semi-synthetic!  Oh well. it's what I get for not following the advice of folks more knowledgeable re these 400s!

No shifting/sticking issues during the ride but had some (luckily) minor motorcycle excitement (see my "gear lever" post)

UPDate a few minutes later...now thinking straight mineral oil rather than semi/syn.

[Athame57]

This is my oil of choice.  It's meant for classic bikes in the first place.