Replacement master cylinder question

[Cbraun]

OK so after another thread i asked about rebuilding the old master cylinder, i opened it up and the cylinder was pitted so I've decided to replace it. now i'm finding replacement's for around $150-180 on ebay 5/8 - 15mm bores. The one i'm looking at from Wilwood is only $80 but the only problem is that the bore is 1/2 instead of 5/8.
Will this cause a major problem with the dual caliper setup on the front?
Here is the specs for the new caliper

http://www.wilwood.com/MasterCylinders/MasterCylinderProd.aspx?itemno=260-11866

[Pat Conlon]

Yes, things will change, your brake lever will have a harder, shorter pull.

You are going the wrong way. You want a (axial) master cylinder with a smaller bore, or at least the same bore diameter as stock, not larger.

Our FJ1100/1200 master cylinders are also 5/8" (16mm) bore. They work ok with the stock single/dual piston brake calipers, however when upgrading to the superior R-1 blue spot calipers, better modulation and a lighter lever pull is achevied when using a 14mm or 15mm master cylinder.

[hein]

Pat, I think your math skills are slipping. 1/2 inch is smaller than 5/8. However the 1/2 is 12.7mm and is probably too small causing too much lever travel.

Hein

[Pat Conlon]

Oops, correct you are....Thanks!  I should know better than to post while watching football.

Yes, 1/2" will give you a longer pull with softer lever....probably too long (?) I don't know for sure. It looks that the FJ600 single piston calipers are smaller that the oem single piston calipers that came on my '84, so maybe the 1/2" would ok? I have no experience with the FJ600 brakes.

To be safe, I would stay in the 14/15/16mm range.

Thanks again Hein.

[edit] a follow up check on the microfiche shows the FJ600 sharing the same caliper piston and brake pads as the '84-'87 FJ's....so based on that, I'm sure a 1/2" dia. master cylinder will be too small.
http://www.partzilla.com/parts/detail/yamaha/YP-26H-W0045-11-00.html

[Cbraun]

Ok. thanks for the info. Hopefully after i get this all fixed i can ride it this spring.  

Another question :/ How hard is it to rebuild the speedometer? mine just stopped working ;/

[FJmonkey]

Ok. thanks for the info. Hopefully after i get this all fixed i can ride it this spring.  

Another question :/ How hard is it to rebuild the speedometer? mine just stopped working ;/

http://www.fjowners.com/index.php?topic=5718.0

[Dads_FJ]

Ok. thanks for the info. Hopefully after i get this all fixed i can ride it this spring.  

Another question :/ How hard is it to rebuild the speedometer? mine just stopped working ;/

You did check the cable itself correct?

[billwest]

I bought a master cylinder off an FJR1300, to go with the blue spot calipers I have on there.  Huge improvement all around.
I did the same with the clutch master cylinder.