Twinpot Brake upgrade on 78 Skunk

[jabcb]

The Ninja MC is a 14mm (aka Ninja 250) if you use one or 5/8" (aka bigger ninja, concourse etc) if you use two...

Does this Vintage Brake chart still make sense? http://www.vintagebrake.com/mastercylinder.htm


What is the master cylinder ratio for the single disk + 14mm Ninja 250 MC?

[The1970's]

I see EBC offers their pro-lite rotors for the CBR900RR. Do aftermarkets fit the GS wheels also?

[salty_monk]

Does this Vintage Brake chart still make sense? http://www.vintagebrake.com/mastercylinder.htm


What is the master cylinder ratio for the single disk + 14mm Ninja 250 MC?

Without doing a lot of measuring I can't say... but the stock is 5/8" and the stock Kawasaki is 5/8" and both feel ok. The Stock 250 is 14mm (as is the twin piston KLR) and the stock Suzuki single is also 14mm.

[salty_monk]

I see EBC offers their pro-lite rotors for the CBR900RR. Do aftermarkets fit the GS wheels also?

They fit as much as the stock ones do... that's to say all of them need drilling / spacing correctly. I have fitted a few sets of EBC

[hannibal]

A question about clearances from the caliper bracket to rotor: How does this look? This is with a 40mm bolt on all three fork mount/bracket positions. Is this what you guys are running? In the first pic, I'm concerned about the lower fork mount to caliper bracket bolt shown without a nut. The second pic shows the same lower fork mount bolt without a nut and the caliper bracket bolts.





rotor clearance.jpg

[hannibal]

Second pic

[salty_monk]

2nd Pic doesn't show but it looks completely normal. After you put a nut on there you should have in the region of 1/8th inch of clearance (3-4mm).

By the way I wouldn't run a washer under the bolt head if you are using 40mm bolts (same as stock - 40mm bolts, no washer) - use a bit of blue loctite on the thread. We should be able to see the end of the bolt poking through on the back of the caliper in your picture & I can't (then I looked closer & appears that you're using a washer).

The bracket is steel in any case so it's basically already a giant washer...

(also looks like your speedo drive is not located right in that first pic or you didn't fit the dust shield yet as I see a gap).

Cheers,

Dan

[hannibal]

Thanks Dan. Here's the second pic:
bracket clearance.jpg

You're right. I had a regular washer and lock washer on the two caliper bracket bolts.

The lower fork mount has the Kawa bolt which is a bit shorter (36mm or 38mm?). If I use a 40mm bolt with washer and lock washer, I have the same amount of thread sticking out the back as with the plain Kawa bolt. Without a washer, the 40mm sits REALLY close to the buttons on the floating rotor.

I feel like I should be using at least a lock washer on all three of these.

And yes the speedo drive was just thrown on there. It's upside down and missing the dust shield. I'm checking everything upside down with the new dual disc lower forks bolted to the fender and the wheel sitting on the forks.

One more question about the floating rotors. I read that the buttons should spin freely. Mine don't which means they need a good cleaning. Is this a job for PB Blaster or WD40?

[salty_monk]

Hmm the Kawi bolts I've had are all the same. Just make sure you have at least 1mm of thread out the back and 3-4mm of clearance between the two & you should be fine.

They don't spin until the get hot.. just make sure they are clean

I use blue loctite rather than a lock washer.

[The1970's]

Just wanted to share a pic of my new setup. Single caliper with a Honda Blackbird rotor.

20181002_231641.jpg

Only problem I ran into was I bought a caliper listed for an ex500 but it was in fact for the 250 so it was a right hand caliper and the bleeder is at the bottom. I got it bled off the bike just to test everything and it is working great. Although I will order the correct one.

Does anyone have a template for the area of pad that needs to be chamfered? Otherwise I'm thinking of letting my used pads wear a little so I can make a template that others can follow.

Thanks again Dan for putting this kit together. Everything bolted up beautifully

Edit: one question I forgot to ask is that the blackbird rotors have arrows on them indicating a direction. Is this important at all? And also should I be using the factory lock rings on the rotor bolts or loctite?

[johnod]

What chamfering?

[The1970's]

What chamfering?

When converting a single rotor GS with the single rotor salty_monk kit the brake pads overhang the rotor slightly and require a chamfer to avoid wearing a lip into the pads

[salty_monk]

NOTE: THIS ONLY APPLIES TO SINGLE SIDED APPLICATION WITH A 310mm BLACKBIRD ROTOR (CBR1100XX)

When you line it up with the rotor it's fairly easy to see where the overhang is. Nobody has ever laid up a template though - that's a great idea. Some pics of the pad once done would help too. I don't think I have any good ones.

It's approx 3mm-4mm in from the edge from memory.

The chamfering stops the rotor from wearing a step/lip into the brake pad over time (1,000's of miles) which could be at risk of jamming up on outside edge of the rotor or breaking off & getting caught between the pads & rotor.

It's annoying that the left calipers are harder to source than the right ones! Would be much better for our purposes if the left was used on the Ninja 250! They can provide a good source of parts for an older left caliper though as pistons, bracket etc are the same.

[johnod]

Ah, ok thanks, dual caliper here, that's why it didn't sound familiar.

[salty_monk]

Yep, not an issue with the Dual caliper & CBR or GS550 solid rotors.