clutch springs and increased displacement

[Jaydela180]

Engine out of frame and beginning to collect parts for rebuild. Been debating on whether to increase displacement ( specifically je 700 ppositions) my question is whether there is a rule of thumb on what strength of clutch springs are needed. Thanks and happy new year.

 

[XSLeo]

If your clutch is working ok now, I might try it as is. If in doubt, then upgrading the springs is a good first step.
I had trouble with slipping when I added the 750 kit to my 75. It acted about the same with the 75 7 plate clutch as it did with the 82 6 plate clutch. I started by cleaning the steel plates with 120 grit sandpaper, to clean off any discoloration as well as remove any burrs and rough edges. The steel plates are punched out. This leaves a slightly rounded edge on one side and a sharp edge on the other. By removing and slightly rounding this sharp edge the plates slide in the basket with out binding.
This coarse sanding left the surface of the plates slightly rougher, improves the grip on the fiber plates.
I also roughed up the fiber plates a bit. This helped, but it still slipped a bit and got worse after a bit of running.
I found a set of NOS Kibble White 70 lb springs on Ebay and got a set of Forodo plates.
With the new plates and springs, a new worm, mine was cracked, well lubed worm and cable and my clutch works great. The new worm I got from Mike's has a lomg arm with two holes to attach the cable. Use the hole closest to the worm. This position opens the clutch a bit farther, minimizing clutch drag. This makes finding neutral easier.
You can try the hole farther away from the worm, it doesmake the lever pull slightly less, but it doesn't open the clutch as far. This increases clutch drag, making neutral harder to find.
With the worm set this way, well lubed with a well lubed cable I can still pull the lever with two fingers. No slipping, easy to find neutral and adjusted right no cold to hot readjustment needed.
Leo

 

[Jaydela180]

Thanks Leo. I'll address clutch parts as suggested.

 

[weekendrider]

I think the one thing everybody will agree on, is when tuned to run well, the 650 will slip the oem clutch. If you ride that way.
I can't say this spring or another is what you need.
I can say I've seen Mikes "heavy" spring boo'ed more than once.
I have seen multiple thumbs up for 650 Central products.
It seems as if in the fog of my memory I've heard recommendations of the stock springs from another Yamaha model but I may have that confused with valve springs.
If you find an OEM part I'd like to hear about it. My clutch needs help 2. Or I could slow down.

 

[Jaydela180]

Asked Gary at hoos racing about hidden costs of increasing displacement. When asked specifically about springs he said that It would not be necessary. Gonna swap out slightly stronger springs while I'm in there and do as Leo suggested. I'll adjust accordingly after I get a few miles under it.

 

[5twins]

As suggested above, give 3M at 650Central a call. He stocks 3 flavors of springs - mild, medium, and really stiff. Tell him the mods you have in mind and he can recommend the springs you'll need. That being said, every wet clutched Jap bike I ever owned needed new, better (stronger) springs.

 

[scabber]

The Forodo springs and clutches worked fo me MMM 650 central. As far as going to the 700cc. higher compression pistons. On a street bike I would go with the stock compression pistons and spend the money on a good cam and valve springs. Clean up the casting flaws and you are good to go.

 

[hooser]

Asked Gary at hoos racing about hidden costs of increasing displacement. When asked specifically about springs he said that It would not be necessary. Gonna swap out slightly stronger springs while I'm in there and do as Leo suggested. I'll adjust accordingly after I get a few miles under it.

I said that asumming you have good clutch plates now and good spring. I use stock clutch fiction disk and alternate using 3 Vesrah HD clutch spring and never had my clutch slip with my 750. Also make sure your steel plates are good, not 30year old rusty or warped.
We make 70+hp and still do nothing special with our cluthes other then good plates and good springs.

 

[Jaydela180]

I figured you were assuming clutch was operating correctly and in good shape. Hopefully no one mistranslated my translation. But yes, discs well within spec and plates pass warp test with feeler. Springs are new, but nothing heavy duty.