But first, a few points:

• I know many people like clear fuel lines because you can see through them for troubleshooting fuel flow;  I even used to like them for the same reason.  But now I never use them because over time they get hard and brittle, and easily loose their seal when jostled, sometimes at the side of the road, sometimes just while riding.  Even if you take the extra insurance step to use mini clamps, the seal can fail in time.  On the other hand, if you use a reputable brand rubber fuel line you will not have these problems, and you won’t need clamps.
• I change my fuel lines and filters every year when I return the bikes to use for the riding season.  But even if I lived in a year-round riding climate, I’d still change them yearly.  It only costs about $10 to replace it all, and you don’t have to worry about clogged filters, rotting lines, etc.
• Never use paper-element fuel filters.  It’s not a lawn mower.
• Plastic inline fuel filters get softened by fuel over time, and can bend to the point of restricting fuel flow if you’re not careful.  So be careful.

Supplies list:

• 1 early model KZ750 Twin
• 1 package of 1/4″ x 24″ fuel line (Good Year, Prestone, or whatever is at your local auto parts store)
• 2 inline 1/4″ brass-element mini fuel filters (I get them from z1Enterprises.com whenever I’m ordering something else, but you can probably get them at any bike shop)

When the KZ750 was designed, apparently the engineers never thought we’d have to worry about fine rust particles in the tank or inline fuel filters to compensate.  Silly engineers.  As a result, if you run without inline filters, installing fuel lines is an easy, intuitive breeze.

However, since this is the real world, most of us do have to worry about rust, and we do have to use inline filters.  And because of this, we have to do crazy, creative things in order to have room to accommodate the filters… and not cause them to bend and shut down fuel flow as they soften from extended contact with fuel… or melt from contact with the back of the engine.

And this is why I’ve written this post;  My goal was to find the best way to run the best fuel lines with the best fuel filters.  Oh, and for me, “best” means “best possible at the least reasonable expense”. 

So we start with my garage plan chicken-scratch drawing on the back of a dirty envelope to help convey my design layout:

Pathetic Diagram of Petcock, Fuel Lines, Filters, Carbs

So, we start with one package of reasonable brand fuel line.  I’ve always used Good Year line in the past, but this time AutoZone had Prestone.  Whatever, it’s 24 inches of 1/4 inch inner-diameter standard fuel line.

Package of Reputable Brand 1/4" x 24" Fuel Line

As the design drawing above indicates, cut the line into four pieces as follows: 4″, 4.5″, 5″, and 10.5″ (or whatever is left).

Filters and Fuel Lines, Cut To Size

Assemble the parts so that the natural curves in the hose works in your favor, so that when assembled, the filter will be stressed as little as possible.  I’m not sure if you can tell from the pic, but the curves are opposite.  Here is the assembly order:

Left: Petcock -> 10.5″ hose -> filter -> 4″ hose -> Left Carb

Right: Petcock -> 4.5″ hose -> filter -> 5″ hose -> Right Carb

Assembled Fuel Lines And Filters

Assembly Step 1:  Connect the right line to the right carb.  I hope you have small hands, it’s tight in there.  You may have noticed in the pics that I have the tank sitting up on a wooden block for space.

Step1- Right Line To Right Carb

Assembly Step 2:  Complete the right line connection to the right output of the petcock.

Step2 - Right Line To Petcock

Assembly Step 3:  Now feed the left side line assembly in from the right side, around the throttle cables and connect.

Step3 - Left Line To Petcock

Assembly Step 4:  Finally, bring the line around and behind the other right side line, to connect to the left carb.

Step4 - Left Line To Left Carb

Here’s a finished view.  Note that the filters are spaced offset from each other, they are not bent or stressed, and the lines and filters are not touching the engine.  And hey, don’t hassle me about how dirty the engine/carbs are, or that there are old hornets nests that I’ve never cleaned out…  It’s a working man’s bike and that’s how I like it to look… 

Final View

One additional caveat though…  If you use the original stock ’76 – ’78 side covers, you will have to cut away a bit of the cover to accommodate the fuel line running where it was not intended to be.  But if you do it with a nice, smooth arc, it doesn’t look out of place.

Side Cover Cut-Away

I hope that helps!

The O-Ring(s)

Unlike *normal* motorcycles, the KZ750 Twin requires a crazy figure-8-shaped o-ring for the oil chamber cover.  The hands-down best thing for this is to get an N.O.S. o-ring for this, since nothing else fits as well.  But in a way, you have and alternative, giving you 2 main options for replacing the o-ring:

1. Kawasaki o-ring Part # 92055-084, which I’ve seen listed for anywhere between $10-$20 in various places around the ‘Net
2. The o-ring included in Fram Filter CH6014 (see below)

The Filter(s)

I have always read (and you might have too) about quality challenges in certain manufacturer’s oil filters.  But I’m not going to spend big bucks for expensive filters either.  So, I have decided to mitigate any concerns, and regularly alternate oil filters between each change.

I’m sure there are other filters than the ones I list below, but I’ve arrived at a certain pattern of use over the years, and for better or worse, here it is…  For me, there are 3 basic options:

1. Fram CH6013 – $7.28 – This is the filter that is listed for the KZ750 Twin on some parts sites.  It does fit.  It does work.  It includes 2 o-rings: an o-ring for the oil bolt that you *can* use, and a large round o-ring that you can fling at your buddy, or toss right in the garbage.  It does *not* include the figure-8-shaped o-ring.  I typically do not buy this model.
2. Fram CH6014 – $6.95 – Same filter as the CH6013, and the same small o-ring for the oil bolt, but this one *does* contain what I would call an “attempt” at a figure-8-shaped o-ring that you can actually attempt to use.  Being frank here, you can make it work, but it is not easy, because it is not perfectly shaped.  But you can get it in place and get it sealed with a little patience.  And it may just be the last hope to find the figure-8-shaped o-ring when I have bought up all the N.O.S. ones from eBay…  Did I just write that…?  I typically buy these and alternate them with the Emgo ones below…
3. Emgo 10-24400 – $3.80 – No o-rings.  And you’ll like it.  I typically buy these and alternate them with the CH6014 above.

I have bought these in the past at various places, including the links I provide above, as well as some of the places I list on my “Misc. Vendors” page.  Then there’s eBay, of course…

By the way, I’m not affiliated with any of the links provided… and make no promises regarding them… and prices were valid at the time of this post.

Good luck!

On one 750, I had a complete stock exhaust system, with rotted out ends.  This bike pulled like a freight train; waaaaaaay better than the other 750 that was otherwise identical except for a non-crossover system with Jardine Classics (that breathe very well).

So when I replaced the rotted stock system, I made sure to retain the stock headers and crossover, but replace only the rotted mufflers.  Unfortunately, I didn’t take pictures or notes of that work on that bike.  However, I finally got sick of the power difference between the two bikes, and decided to add the crossover to the other bike as well…  And *this* time, I got pics…  So here we go…

First, the parts.  Besides a complete stock exhaust system to be cut up, you need a few things:

Replacement mufflers…  I chose some MAC tapers, that I got from Dennis Kirk “Scratch and Dent” for chump change:

Optionally, fiber wrap (because in my case, the pipes are cosmetically challenged):And the stainless steel straps to hold the wrap in place:And the high-temp paint to 1.) paint the pipes after sanding and before wrapping and, 2.) paint the wrap after it dries (from wetting during application):And of course, muffler clamps (again, from Dennis Kirk)…  you don’t want your mufflers to fall off do you? Or leak…:First, you have to cut the stock mufflers off the stock headers.  Inside the pipes, underneath the chrome and the outer pipe of the double-wall pipe, there is a gap between where the inner-wall of the header pipe and the baffle in the muffler almost meet up.  This is where you cut.Looking inside the now-cut-off muffler, you can see how close I cut next to the baffle pipe, just catching the edge of it:Here’s the whole carcass:But now here’s where you approach the main catch of this whole thing.  At this point, you have to clean up the left-over bits of the muffler that are still welded to the header pipe.  But, once you grind all that off, you have to keep going; because the clean pipe is actually about 1 9/16 inches.  This means that your 1 1/2 inch slip-on does not yet fit.  So, grind, grind, grind, and let me tell you; this pipe is no soft metal…  Here’s what it looks like ground down to about 1 1/2 inch:Then, if you haven’t already at this point, it’s time to optionally apply the fiber wrap.  You need to sand the pipes, paint them with the high-temp paint, let that dry, apply the wrap (wetting it along the way), let the wrap dry overnight and/or in the sun, and then paint the wrapped pipes again, this time to seal it from the elements.  Here’s a look at the wrapped, but as-yet un-painted headers:…and a close-up of the top strap in action.  Note that I started at about the place where the pipes clear the head; you don’t want to start to close to the beginning, or you can’t get the header clamp in place.  Also note that at the start of the wrap, you wrap it *under*, so the loose end is not exposed: …and here’s the other end, where you really need to fold the end of the wrap under before strapping it down… I did a sloppy job, but it won’t be visible… :Okay then!  So in summary, here’s the requisite “before” pic, with the rusty, non-crossed-over headers, and Jardine Classics:And here’s the “after”, with the picture taken right before the first ride:And Did I mention they smoke like CRAZY when you do this?  Oh yeah… make sure that when you take your first ride, you stay in motion, or you will be bathed in the rising noxious smoke of the baking paint and fiber… Anyway, here’s the “after” taken right after the first 15 minute ride, with the freshly wrapped pipes still smoking… :And a little closer view of the pipes:And another pose:And finally, once from the rear:

750 #1:

The starter clutch exploded and seized my engine on my “first” 750 twin first.  I was riding along at about 30mph in town when the engine just rapidly seized and the back wheel locked up.  I got a handful of clutch and rolled to the side of the road.  I pushed the bike home, pissed off.  A week later I got around to checking out why…

It had automatically backed 1 of the 3 mounting allen screws/bolts out (the other two were already loose too), dropped a roller out, jammed against the starter sprocket or something and cracked in half.  I was lucky it wasn’t worse.

This is immediately after removing the assembly from the seized engine. Note the melted screw head at top right. All 3 screws were loose and backing out. The pin and roller had freed themselves and wedged somewhere between the assembly, the starter sprocket and the engine case to cause the engine seizure.

Now from the other side, I hope you notice the housing cracked in half, the missing metal chip (hole in housing in foreground) I recovered (in background).

I just pulled the rotor, removed all the debris, got a replacement starter clutch from a spare KZ400 engine, removed all the pins, springs and rollers (only kickstart now), and reinstalled the *housing* only with RED Locktite on the 3 screws.  So the final difference from stock is that it’s just missing pins, springs, and rollers.  When you push the starter button, it just goes “Wheeee…”

Since I did this bike’s repair first, I naively thought I needed the housing as a spacer (of course, if I had it to do over, I would have left the housing out).  More on that below…

750 #2:

So, shortly after, I was working on my *other* 750 twin;  because I swore I would pull the rotor to examine the state of the starter clutch before that thing saw the road that season.

This time, after I pulled the rotor off, I was looking at what looked like the backside of a starter clutch, still on the starter sprocket.  Lo and behold, it *was* the starter clutch.  The three bolts that mount the starter clutch *to* the rotor had ALL sheared cleanly, separating it from the rotor.  No shattering, no other damage, just a completely free-floating starter clutch. It looks like one of the three bolts was a little worn like it had been grinding like my other bike, but only a little.  I’m sure this would have caused damage in the future…  So I had to get the little bolt bits out of my rotor…

This is where all 3 screws were sheared, and the starter clutch was effectively free-floating in there. How long before one of the screw pieces got free and made it's way toward the crank? Fortunately, we will not find out.

For this bike, I left out the *complete* starter clutch assembly.  This is because (as I mentioned above) I later realized that I do not need the housing as a spacer, but I *do* need the starter sprockets and chain to hold the sprocket steady while running.

IMPORTANT: I got some great advice over on the KTOF about an oil journal that exists on the crankshaft right under the starter sprocket.  Without the starter sprocket in place on the crank, oil pressure might be reduced; by how much, I don’t know.  Since I don’t want *any* reduced oil pressure, I put it in.  And if the sprocket is on the crank, I may as well have the starter chain to hold it steady, and the starter to hold the chain, and the ankle bone’s connected to the….

Conclusion:

Now, all is well.  And I can kick start them forever now.  But do the pics make you cringe?

So is everyone going to go get a gasket (or make your own), a rotor puller (or rear axle), and check them out?

On a related note… If you decide to repair rather than remove, it appears as though Parts N More offers a starter clutch rebuild kit (though I’ve never bought anything from them myself).

Sorry if I sound like an evangelist, folks.  But my engine seizing – even at relatively low speed – might have been my scariest moment in my brief motorcycle history…

My main oil for my KZ750 is Shell Rotella T big jug (though I have been known to thrown in a jug of GTX once in a while).  I use the 15w-40, and as I live in the northern mid-west of the US, I ride only at 32F and above.  If I ever start riding in colder weather, I might switch to the 5w-40 synthetic.  Warmer areas can consider 20w50.  Straight-weight oils generate so much debate that I have decided to avoid them altogether, given the availability of alternatives.

I change my bike’s oil at 1500-2000 mile intervals!  Bikes that share the transmission with the clutch and the… well, the rest of the engine, break down viscosity quickly.  Since it’s only around $13 per gallon, everyone can afford it…

But one of the most important points of all is this:  avoid oil with so-called “enhancements” or “friction modifiers”.  These ingredients can make you clutch slip, and you’ll be wondering why your bike won’t move…

Shell Rotella T