Clutch rebuild help

ABSINTHE · Full Member Joined: Nov 05, 2008 Posts: 53

heya guys I am in the process of rebuilding the clutch on my bike its a 1980 special I am finding it a litle hard to find neutral latley and its not the oil and its adjusted properly its just that its done 60 000 kms and I think its worn anyhow what I wanted to know what do you guys recomend I am thinking of doing a thrust bearing as well what I wanted to know is would you do the friction plates only and which would you use standard /hi performance (from mikes xs ) or would you do the steel plates as well or anything else its not a race bike its just a every day sort of bike I want more smoothnes and quality in the long run any tips and such much apreciated thanx a lot

Retiredgentleman · Posted: April 15, 2009, 7:04 pm Post subject: Re: Clutch rebuild help

If you have the clutch apart, you should carefully check all the parts for the correct size and the correct assembly order. This revised drawing was put out by Yamaha around 78 I believe.

Use a micrometer and measure the thickness of the steel and friction plates. Also measure the various washers. Springs can be checked with a vernier. The service manual gives wear limits (78SE) for friction plates ( .106") and normal size (.055") for steel plates

Use the Yamaha service manuals to learn the specs for the year of bike you have.
www.biker.net/650parts_index.html

Apparently the roller thrust bearing can cause grief if its worn excessively. I found it was still .079" (2 mm) on my clutch, so I re-used it.

On my clutch, a PO had left out a washer which had caused a minor rubbing of parts. So, its important to make sure you have all the right parts.

Don't forget that these bikes have 2 settings at the clutch lever to find neutral. Free play at the lever set at about 1/8" when engine cold. After the engine gets hot out on the road, the free play will be much bigger and you can't find neutral. Re-adjust the free-play back to 1/8" and now you have it re-adjusted for the hot engine. There is no one "set and forget" for these clutches, that's just how they work.

ABSINTHE · Full Member Joined: Nov 05, 2008 Posts: 53

oh I know that I am forever playing with the thing and I think its the thrust bearing more than anything else due to the way it is at the lights when in first gear and just idling it seems that it needs to seperate the engine and box more because it feels that it still trying to move forward a litle so I feal its not seperating the plates all the way

ABSINTHE · Full Member Joined: Nov 05, 2008 Posts: 53

oh and thanx for that drawing

ABSINTHE · Full Member Joined: Nov 05, 2008 Posts: 53

so what parts do you think I shoud replace to start off with

Retiredgentleman · Posted: April 15, 2009, 9:43 pm Post subject: Re: Clutch rebuild help

You need to measure the size of the clutch parts. The results of the measurements will tell you if they are worn or not.

ABSINTHE · Full Member Joined: Nov 05, 2008 Posts: 53

ok thanx for that looks like I need a micrometer

yamaman · Posted: April 16, 2009, 3:27 am Post subject: Re: Clutch rebuild help

ABSINTHE wrote:

ok thanx for that looks like I need a micrometer

Probably cheaper to just buy a set of fibre plates!

tacoswild · Posted: April 16, 2009, 5:03 am Post subject: Re: Clutch rebuild help

Should be able to get a digital caliper for around $20. I get a lot of tools at Princess Auto and $19.99 seems to be the default sale price for anything. I recently got a deflection gauge with a magnetic stand that switches on and off for $19.99 and last year a really nice 1/2" drive torque wrench for the same. That's Canuck dollars too.

I have to redo my clutch too, PO had put only five friction plates and four metal discs in there. These are the early thicker plates so that's only two missing but still... ? Oddly it worked pretty good. I've considered those mikes "high performance" plates too but there's nothing to say what's so high performace about them and I haven't heard from anyone who's tried them.

ABSINTHE · Full Member Joined: Nov 05, 2008 Posts: 53

yeah me neither but the price diference is minimal like 2 $ a disc so I was thinking ill do the friction plates steel plates and thrust bearing that should get me going for a while

yamaman · Posted: April 16, 2009, 6:52 am Post subject: Re: Clutch rebuild help

I've raced over 2 seasons with Mikes heavy duty plates & 5 Barnett h/d springs, no dramas!
Though I can't say that wouldn't have happened with std's......

ABSINTHE · Full Member Joined: Nov 05, 2008 Posts: 53

oh and a one piece clutch rod

Retiredgentleman · Posted: April 16, 2009, 12:04 pm Post subject: Re: Clutch rebuild help

An inexpensive vernier is likely accurate enough to measure the clutch parts.

There's 2 ways to work on these bikes. You can just randomly buy parts and hope you replace the ones that are worn. This gets to be very expensive. This also increases the profits of the parts suppliers.

The best way is to measure the parts and determine which ones are badly worn, and only replace the worn parts. This saves you money.

For example: Friction plates, Normal=.118" and Wear limit= .106"
My friction plates measured = .115" , so I re-used them.

Steel plates, normal= .055", My steel plates measured= .054" , so again I re-used them.

Clutch springs, Free length normal=1.363" and Wear limit=1.324",
My springs measured= 1.370 , so again I re-used them.

If your clutch is slipping, you might want to use 3 of the Heavy Duty springs along with your 3 standard springs.

The plates on these clutches don't wear rapidly, but measuring is the way to check them.

The most likely cause that you can't find neutral, is you are not re-adjusting the free-play at the clutch lever after the engine gets hot.

Joseph · Full Member Joined: May 22, 2007 Posts: 767 Location: NY

When I have my bike up on the center stand, not running, put it in gear and hold the clutch in when I spin the back tire by hand the motor spins. is that normal? The clutch seems fine otherwise. The lever has no free play I was considering adjusting the actuator, any suggestions?

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