Topic: CB400F or CB500/550 clutch spring measurement

[Psychonaut]

 I am looking for a measurement of a CB400 clutch spring and a CB500/550 spring. If someone has an extra clutch spring they could measure, I need to know the wire diameter and length.  I would really appreciate it.  The reason is below.


 A quick history of the bike. I just got the bike running two days ago. I bought it two weeks ago in poor condition with not much knowledge other than it started and ran but not above 1/4 throttle. It had sat since 1992 when the other owner sold it to the guy I bought it from. The guy I bought it from put 200 miles on it. The bike has 30,500 miles total. I rebuilt the carbs among other things, runs great now other than I can't get neutral while running.

The PO had a new set of unmarked disks in a baggy, only 6 though and a a package of Barnett springs(mt-10) in a box of parts. I pulled the steels out and removed the thick layer of varnish buildup with 220 paper on a flat surface, put it back together with the old disks. Still won't get neutral while running. I then used the new disks after oiling them and letting sit overnight. I had to use the original thick disk though.  This still drags. I do not know if the I should have 6 thin disks and 1 thick disk or 7 thin disks, I assume 1 thick one as the parts diagram shows a different PN for one of the disks.  I also know stiff springs can cause clutch drag so i did not use the Barnett springs, they are a little thinner on the wire diameter but a little longer (1.480" long, .105" diameter wire).

What should the stock disks be in thickness. My used ones are .103-.105" thick. The new disks I have are .105", I forgot to measure the thicker old one I can measure one later. The springs that came in the bike are 1.240" (31.5mm) long and wire dia is .114 (2.9mm). The length is shorter than what the book says for a 400 but is about right for a 500/550 (min is 1.200"). I don't know their wire diam though.  Does anyone know if these are the right  springs for a 400 or can anyone measure a 500/550 spring? I have read one post of people using othe CB springs and fear that it is possible that the PO might have done something like this. I did not face the steels the same direction. I will do this when I pull it apart again. It is not a clutch adjustment issue. I have tried every point, If I go too far on the release point it will drag more and roll the bike, too little and it will not get any gear without a cluck..  Oil is Castrol 10/40.

Thanks
Clifton

[Psychonaut]

Anyone with an extra stock spring to measure? 

[camelman]

Service limits on the clutch springs are:
400F = 29.75mm
550  = 35.4mm
550F = 35.4mm

I measure the stock springs on my 400f, which are original, and they were at 31.5mm.  I don't know what they are when new, but probably around there.

[Psychonaut]

Thanks so much. Your book is a little better than what I'm going by (Clymer).  Mine are the same as length as yours. Looks like the springs are not my problem.

[Psychonaut]

Does anyone know if the 7th 8mm tall disk should be thicker than the rest? Mine is .119" (3.03mm) thick, the other 6 are .103"(2.62mm) thick. The manual I have just gives one thickness for the 400, .091" (2.3mm) minimum.

[camelman]

That is the "B" plate, and should be thicker.  The way to measure it's wear is to have the entire clutch pack assembled and tightened.  Then, use a feeler gauge to see if the gap between the "B" plate and the clutch center is greater than 0.5mm.  If so, then you need a new "B" plate.

The "clutch center" is the large part that slides into the clutch drum.

Camelman

[Psychonaut]

Problem found. The collar with the flange was behind the basket/flywheel not in front. I should have looked at the book instead of the way it was when I removed it. The way it was I only had about .020-.025"" of disengagement. It seemed too little but I never knew what it should have been. I don't know why I trusted the PO considering the many other problems I have found.

 Thanks again camelman, you helped me rule out the springs and disks.

[camelman]

Wow, I had no idea it would cause that issue. Congrats!