clutch question for the pros! and more!

[budpat105]

OK, did a complete bearing,seals, bore and piston on my combat( had fears of this but you guys gave me the courage). Starts great. Clutch won't release. I did not take clutch pack apart, I thought it worked when I took the motor apart. I had not rode bike before tear-down due to tank problems. Thanks Paul for selling me a clarke take, looks great. Also does everyone leave spark arrestor in stock pipe? seems like its restricted with it in there and wanting to leak exhaust around cylinder. Also guessing this bike will lack bottom end power and need high RPM riding? I don't think I have ever rode a non-reeded 2 stroke. No pictures until I get completely finished. Hope to make a couple MOVMX races as I am in central IL. Thanks, Bud

[JayLael]

Take a good look at the bushing on the clutch. If it will not release, but loosening the clutch nut makes it release, the bushing is apple cored and effectively too short. I would start there.

[Dale]

Bud,
I run my C/W with the spark arrestor in place as I ride it in the woods as well as on the track. It works well. If your's feels restricted it could be plugged with carbon and needs to be burnt out. When you say exhaust is seen around the cylinder, do you mean escaping around the pipe? If so, that would indicate that the pipe is plugged. The spark arrestor will not cause that.

Also, on your clutch, double check that the thick inner thrust washer is installed properly. It goes on first and with the rounded edge towards the crank bearing. Without it you will have no clutch either.
Dale

[budpat105]

OK, I'll try to get clutch apart this week and post a picture of what and what order I have in there. Also just put the exhaust pipe on a fire and let it burn out? This makes me a little nervous. thanks

[hodakamax]

As for cooking the pipe, type in "cookout" in the search window. There's quite a discussion on that awhile back. Kind of an entertaining procedure, check it out!

Max

[MTrat]

Regarding exhaust pipe 'cookout'; I've had success with this method. 1) take out the spark arrestor 2) pour about a pint of gasoline in the pipe and roll it all around so that entire inside is soaked. 3) stand it up outside with the tail end up 4) lay the spark arrestor on the ground and pour gas over it.
5) burn them out. This will remove most of the oil and carbon deposits.... Repaint with hi-temp exhaust paint...

[hodakamax]

Hmmm, bad idea on the gasoline, Way too dangerous. Just build a wood fire and lay the pipe in it. Flames will come out both ends as the deposits burn. You might weigh it before and after, you'll be surprised how much stuff was in there. Dull red on the pipe is enough, we don't want to burn it up.

Max

Again, NO on the gasoline!

[Bill2001]

How does a stiff oxycetylene flame sound? Something just slightly oxidizing?

Just kidding-- I'll pull the spark arrestor sometime soon. Newly refurbed, it should be OK but I like to putter.

--Bill

[budpat105]

OK, here is what I have when I took clutch apart.The bottom washer looks to be flat and the washer under the nut is dished. Does this look correct? Also enjoyed the wombat cookout, preparing for a combat cookout. Can I hook my timing light to a 12V power supply and clamp on plug wire to time bike, just adjust points to change timing? Thanks Bud

[rlkarren]

Can I hook my timing light to a 12V power supply and clamp on plug wire to time bike

This is what I do. Others will advocate the more traditional method, but I find certain level of confidence when using a timing light that it's correct. You do have to make sure your marks are correct though. They've been known to be off a little sometimes.

$0.02

Roger

[racerclam]

If your timing with a regular auto timing light with advance dial and it don't have a 2 stroke mode you have to divide your reading by 2. My craftsman digital light has a 2 stroke setting

Rich

[Dale]

Bud,
There should be a total of 3 washers. The dished one is the lock washer for the nut.

The second one (on the far left of your picture) is the Inner Thrust Washer. It should measure 30mm OD, 17.3mm ID and is 2mm thick. It is a pressed washer and therefore has one rounded edge and one sharp edge. The rounded edge goes towards the crank bearing.

The third washer is another Clutch Thrust Washer that fits between the Clutch Hub and the Clutch Rotor Gear. It is quite thin (.3mm) and measures 29.7mm OD and 21.6mm ID.

The pinion bushing itself should measure 21mm OD, 17mm ID and is 25.1mm in length. This is the one that Jay pointed out that if it has mushroomed that it would cause your problem.
Dale

[Bill2001]

And double-check the safety wire on the seven clutch assembly screws-- viewed from this end the screws are rotating in a counterclockwise direction to tighten, and the pull of the safety wire must be in a direction that tightens the screw, not loosens it.

--Bill

[budpat105]

OK, back to the top! I have studied clutches and read a great post in archived posts! I took clutch completely apart, filed groves out of cage, oiled everything and put back together.Re assembled back on motor, paid special attention to inner thrust washer, pinion bushing is slightly "proud" installed 1 inner thrust washer (had 3??) and clutch works! But-- no free play, it had 2 shims that I removed and still no free play, makes me wonder if I got clutch parts together tight enough. When I was safety wiring it I had "most" of the hole in screw showing, enough to get wire in. Any thoughts on this? I'm not going to quit until I get it right. Thanks Bud

[Bullfrog]

The clutch screws should be tightened to about a "medium grunt" or even a "good grunt" with two hands on a good screw driver. In other words they should be Tight - not just sort of tight. The "no free play" issue was at the clutch lever on the engine, right?

Ed

[budpat105]

correct, no free play at engine with cable off, thanks

[---]

It's possible the clutch plate stack height is not right. Or that something is a bit hung up inside, in which case I would not trust it to settle in, but would verify that it is right before going out riding.

Did you use old discs or new ones? Did you happen to measure them for thickness? Or, do you happen to remember the disc count for metal and fiber discs?

[Bullfrog]

While it is a bit counter-intuitive, when the clutch disks wear down and get thinner, the "body" of the clutch moves "out" (away from the center of the engine) ultimately resulting in no clutch lever free play. So, assuming that the disk and steel plate count is correct in your clutch - we seem to have a pretty strong indication that your clutch disks are worn down and are too thin now. The original clutch disks are listed as being .098" thick - I suspect yours are somewhat thinner than that.

Ed

[budpat105]

There are 5 fibers and 4 metals disc.I did not measure, I did measure springs. When I put it together I noticed wear on the fibers and understand what you are saying about the worn plates causing the free play issue. New clutch plates will be installed, looks like they have been improved over stock. Any secret setups I should know about? Thanks for your help with this.

[Bullfrog]

Did you de-burr the steel plates when you went thru the clutch? Removing those burrs is a critical process for achieving really smooth clutch operation - and it staves off the "washboarding" of the teeth on the inside of the clutch cage.

Ed

[---]

There is a how-to article on Paul's website on blue printing clutches. Look under FAQ's for the tech article list.

[budpat105]

I have my new clutch parts for the combat, my cage has some grooving and filed most out, but I thought that I could put the other side up and have a like new surface for the clutch plates. Can you flip the cage over or does it have a up and down? Thanks

[Bullfrog]

Nope, it can't be flipped. The "covers" at either end fit up against the clutch hub differently - so it is a "one way" part.

Ed

[matt glascock]

Hi Ed, I've noticed the "washboarding" effect you mentioned on the clutch cage on a 95 CW I'm rebuilding. I've blueprinted the new steel clutch plates ala the tech tips page here on the SH site. Do I need to address (dress?) this issue with the cage? Thanks!

Best,

Matt

[Bullfrog]

So you have removed the burr edge from the steel plates - which will allow them to slide inside the clutch cage easily . . . IF there is no "washboarding" of the teeth inside the clutch cage. If there IS "washboarding", then the steel plates can "hang up" in the "valleys" of the washboarding momentarily as the clutch lever is being released. Then when they pop loose, the clutch engages big time (and I hope you had a good grip on the bars). So, yes, BOTH the burr edge on the steel plates AND the washboarding inside the cage teeth needs to be addressed if you want a buttery smooth clutch.
Ed