AHRMA Vintage Superbike Middleweight Racer

Oh, and valve sizes:

1979 Kz650-C3:
Intake: 33mm
Exhaust: 28mm

1982 Kz750-E3:
Intake: 34mm
Exhaust: 30mm

Again, margin for error is sky high because I was behind the wheel here.

mark1122 wrote: do some more homework on this one.
make sure your cables will work before u jump in.
i used some ebay parts to make a 1/5th turn throttle. r1's use a shot twist throttle tube. the outer housing looks like the 1 in your pic. i use a cbr1000 exterior with a r1 inner .
a short turn helps , so u dont have to reposition your hand and just makes it feel better on the track. does for me anyways.

Mark - I didn't realize the new bikes also used a 7/8" handlebar?

mark1122 wrote: i would just buy an ebay master from a modern bike. if u can go with a radial master in your class, that would be best . if not, just about any modern master will work. get 1 from a very popular bike, so u can get a replacement lever fast and cheap if u brake 1. i put a zx636 radial master on my cbr track bike. i have a spare master from my cbr if u want a freebee. it needs a bar clamp and lever though.
as for the splitter. the bolt u show is for adding dual lines to a master so u would not need a splitter. i should have a few spares . yours for free if u go that rout.

Yeah, looks like the Magura I have is recommended only for single caliper operation anyways (it was for the 900, but I was able to rebuild the master cylinder that was on it) - it's the 13mm model.

www.pingelonline.com/magura_master_cylinder.htm

I'll shop around for a master cylinder. I think the dual banjo might be the solution too, although it means buying more brake line.

Just to let you know. I have a '78 KZ650 and used the dual banjo bolt set-up at the splitter. One brake line from the MC to the splitter and 2 brake lines (1 for each side)to the calipers. Didn't want as much "spaghetti" at the handlebars with an extra brake line at the MC so I did it at the splitter.

I also used a modern dual caliper MC from a 2009 Kawasaki 650R. The 650R's use 7/8" handlebars so it will fit your KZ650 too. Good luck. Watching your build with interest.

DoubleDub wrote:

mark1122 wrote: i would just buy an ebay master from a modern bike. if u can go with a radial master in your class, that would be best . if not, just about any modern master will work. get 1 from a very popular bike, so u can get a replacement lever fast and cheap if u brake 1. i put a zx636 radial master on my cbr track bike. i have a spare master from my cbr if u want a freebee. it needs a bar clamp and lever though.
as for the splitter. the bolt u show is for adding dual lines to a master so u would not need a splitter. i should have a few spares . yours for free if u go that rout.

Yeah, looks like the Magura I have is recommended only for single caliper operation anyways (it was for the 900, but I was able to rebuild the master cylinder that was on it) - it's the 13mm model.

www.pingelonline.com/magura_master_cylinder.htm
I'll shop around for a master cylinder. I think the dual banjo might be the solution too, although it means buying more brake line.

i have a zx9/12 master on my kz now. i'm switching it out for a r51 master. so it will be available. what is your brake line routing plan? do u have a braided lines now ? the simple way is 2 lines from the master to cals. but u can use 3 with a splitter. cant recall right now if i still have a spare dual splitter? i'd have to look if u need 1.

thats good news that the chambers are the same size. can u swap the cams? i wonder if there are any other cams available. i know a guy that just pulled some cams from his 810 bike that would work. they are fairly hi lift. if interested just shoot me a pm, and i'll hook u up.

One more option for plumbing dual calipers is how I did my bike. I ran a single line from the master down to the right caliper. On that caliper I installed a dual banjo bolt, and then ran a shorter line over the front fender to the left caliper. You can sort of see it in this picture. Works good, and keeps the clutter to a minimum.

Not sure about brakes right now - I'm still trying to feel the whole situation out. The rules state that I can only use 1 or 2 pot brakes calipers. I'd love to find a pair of 2 pot calipers that I could get to work with the Kz650's stock rotors with some kind of mounting bracket, mostly because of cost.

Testa - thanks for the suggestion - that seems to be the way to go. Does there seem to be any imbalance created by putting the calipers "in-line"?

As for the cams, I can definitely swap them around. The Kz750 had the hyvo chain type, but the sprockets appear to be interchangeable. I need to get someone to notch my sprockets to make them adjustable or use the method I saw someone post on here (thanks, Inj!).

However, I'm concerned about putting much higher lift cams in the bike without higher compression pistons, but maybe that's something I misunderstand. Most of the high lift camshafts I see say that they require high comp pistons and HD valve springs.

For example - Webcam - the grind 189 Road Race camshaft states that it requires high compression pistons - and the duration is lower than their hot street cam (118).

I'm not sure what mashup of cams would work best, either. And major head work will likely be out of the picture for the first year due to budget, hoping to make that a year two addition. Just want the engine to be solid and problem free for the first year and focus on bracing, suspension, brakes, and tires.

I can't wait to actually start doing something on the bike, though Should have the front and rear suspension off soon and the engine cases removed. Then we can start playing with welding some bracing in place. I think we'll likely take an initial stab at bracing the swingarm ourselves too.

testarossa wrote: One more option for plumbing dual calipers is how I did my bike. I ran a single line from the master down to the right caliper. On that caliper I installed a dual banjo bolt, and then ran a shorter line over the front fender to the left caliper. You can sort of see it in this picture. Works good, and keeps the clutter to a minimum.

good point Josh. most modded bikes i see, go with the 2 lines from the master. i have never found any info on whether there are any pros and cons from 1 method to the other, have u ?

DoubleDub wrote:
As for the cams, I can definitely swap them around. The Kz750 had the hyvo chain type, but the sprockets appear to be interchangeable. I need to get someone to notch my sprockets to make them adjustable or use the method I saw someone post on here (thanks, Inj!).

++Just use a dremmel or a hand file. u only need about a 1/16th extra for the slot.

However, I'm concerned about putting much higher lift cams in the bike without higher compression pistons, but maybe that's something I misunderstand. Most of the high lift camshafts I see say that they require high comp pistons and HD valve springs.

+++ very true. u had best stick to the short duration stock 650 cams.there may be other options too, like maybee gpz?? ask steel.if u use longer duration cams u loose psi which means less torque.

No eBay APP ID and/or Cert ID defined in Kunena configurationWould there be any benefit from using the taller exhaust cam from the 750? I suppose we need to know the duration to really know.

Looks like the early ZX7's (1989-1991 or so) had 2-pot calipers. I might pick up a pair to see if they can be made to fit.



But that will be later on.

Also found this post discussing rotor sizes on the Kz650's from a couple years ago:

www.kzrider.com/forum/5-chassis/273686-k...rotors-compatibility

Thanks for the info, everyone!

Brake line configuration questions/answers from some random dude on some random forum that Google found:

www.m109riders.com/forums/showthread.php...uestions-and-Answers

Ok, 1st of all, there are actually 3 configurations for 109 front brake lines. There is 1 tri-line configuration and 2 dual-line configurations.

1) Tri-line (stock US-spec M109s): one short line runs from the master cylinder down to a "T" distribution block and two medium lines run from the "T" down to each respective caliper.

2) Dual-line (some non-UK foreign-spec M109s): one long line runs from the master cylinder down to the right caliper and a second short line crosses over from the right caliper to the left caliper.

3) Dual-line (high-end sportbikes and what most are running @ the track - aka, racer special): two long lines run independently from the master cylinder down to each respective caliper (true dual-line, as in my how-to).

It doesn't matter which configuration you use, all will have equal pressure in the entire system. The pressure is created in the master cylinder and since all lines are of equal interior diameter, that pressure will be consistent across all lines. The only difference is time it takes the pressure increase to reach each caliper and that difference in time is so minuscule among the 3 configurations that it's virtually undetectable.

So what are the pros and cons of each configuration?

1) The tri-line contains the most parts which makes it the heaviest and most expensive. It has 6 fittings compared to 4 in either dual line system. The distribution block often acts as a high-point for the collection of stray air bubbles (not a problem if you bleed your lines properly). With more lines and more fittings compared to a dual-line, the tri-line has the greater risk of failure. But the tri-line also has many advantages... more parts/lines means that it's less expensive to repair. With only one line coming out of the master cylinder, it's considered by some to be a "cleaner" installation (more aesthetically pleasing). If you decide to do to a larger riser mod, you only need to buy one single, longer short line up top (from the master cylinder to the distribution block) whereas with dual-line setups you'll need to replace the more expensive long line(s).

2) The non-UK foreign-spec M109 configuration is the least expensive, which is sole reason many manufacturers have started implementing this configuration for motorcycle dual-caliper front brakes. It has the shortest total line length and only 4 fittings. It's also the least efficient but we're spitting hairs here. With only 4 fittings and the shortest total line length, it has a lower risk of leaks. With only one line coming out of the master cylinder, it's considered aesthetically pleasing up top, but is arguably the ugliest configuration down at the fender. And you'd have to come up with a mounting/securing solution for the crossover line to install this on a US-spec M109. It's the most difficult to bleed properly, but that's not a big issue.

3) The dual-line racer special is the most efficient, has slightly better performance in terms of feel at the lever (splitting hairs here), is as inexpensive as 2) and is easiest to install and bleed. It's the most expensive to repair, but the likelihood of needing repair over the lifespan of your bike is nil.

So there you have it. The bottom line is that doesn't really matter bro. If you're looking for better braking performance, you'll be happy with any configuration. I've raced sportbikes for decades and I've always been able to feel the slight differences between setups. But on our 700lb+ behemoths, I honestly can't tell between the 3 options. Simply changing from stock rubber hoses to any steel-braided configuration alone is like night and day. If you're primarily concerned about looks, just pick the configuration the looks best to you that's within your budget.

References to follow...

Galfer Brakes
Note 4th paragraph: For Sport bikes, the most common line set up is a dual line kit (pictured here) for the front. It eliminates the stock splitter by bolting both lines directly to the master cylinder with a double banjo bolt and directly routing down to each caliper. This style kit provides a stiffer feel at the lever and allows for cleaner routing.

Russell Performance
Note 2nd paragraph: For many sportbikes with dual front discs, Russell makes what we call a "two line racer special". In these applications, the brakeline kit consists of two brakelines, a double length banjo bolt and the necessary sealing washers. Both lines connect to the master cylinder using the double length banjo bolt and three crush washers, with the longer line going directly to the left brake caliper and the shorter line going to the right caliper. This arrangement eliminates the junction block used in the original three line setup, providing easier brake bleeding, fewer possible locations for leaks, and slightly better braking performance.

Goodridge
Note 2nd paragraph: All our front brake line kits are supplied as two line kits and are the same price for all models. These run two individual lines direct from the master cylinder to the front brake calipers, dispensing with the splitter box and thereby saving on both weight and cost.