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Author Topic: Coffee Shop KZ650  (Read 2913 times)

Offline flip_rip

  • Posts: 44
Coffee Shop KZ650
« on: Jan 11, 2017, 16:03:59 »
Hey Guys!

Starting a new thread for my KZ650 project. The idea behind this one is to create a very minimal KZ650 that is at home cruising down to the local hipster coffee shop with a lady friend on the back, or ditching that idea and hitting the canyon roads balls out and getting its lean on! I want it to look sick in any location, whether its DTLA or in the hills above Malibu, or at full lean on The Crest. The overall look I guess is a bit of cafe and tracker vibes, with an emphasis on road performance.

I am really picky about how a bike rides, and I want this one to strike a balance of performance on the twisties but not be too uncomfortable to ride up the coast to SF. It needs to be versatile and I for sure want to take it out on date nights.

The NX is almost finished and I think that will turn into my dual sport/lightweight baja adventure bike, and will hopefully have a vintage supermoto wheel setup in the near future. So the KZ is more road mannered.

The PO had visions of making this bike some kind of cafe racer and has since stripped out most of the handle bar controls and did a whole bunch of weird wiring things. Also it doesn't run and has no spark...but for $500 with a clean title and registration until Jan 2018 I feel like I'm doing okay.

I'll be keeping it super minimal, so no turn signals, no brights (just one bright headlight setting), no air box, hidden battery, ideally some trick hidden switches for the kill/starter.

I'll chop and loop the frame and de-tab as needed, but I would like to keep a version of the stock duck tail, I really like how that looks.

Up in the air right now are wheels/tires. I though about maybe taking the rear rim and lacing it to the front hub and doing either an 18f/18r wheel setup with a 18x2.15 in front and 18x3.5 rear, or going to an 18x2.15 front and a 17x3.5 rear to gain that better tire selection. I'm also not opposed to keeping the stock 19/18 wheel tire setup, but there seems to be only one or two sets of sticky tires in those sizes.

I'll rebuild the front forks with calibrated spring rates, and will upgrade the rear shocks. I was thinking of going a tad longer with these to give it an agressive stance, but not take away from how it handles.

Lightweight is a goal, but not a rule. I'd like to keep it quick and lively and shave some weight, but I'm not looking to drill speed holes in everything haha.

First up is replacing the whole ignition system to the DynaS and green coils and upgrading to a 3 phase reg/rec unit. Then a manual cam chain tensioner (the chain is rattling in there and I'm really hoping its not more than just a bad auto tensioner). Then I'll remove the head and do a full port and polish job with new valve guides and seals and seats, and shim accordingly. All but cylinder 4 have compression above 175psi, cylinder 4 is at about 125psi. More detective work lead me to leaky valves, hence the head work. I'll probably skip the full top end rebuild for now, as it only has 17k miles on it. Of course a carb rebuild and jet is on the list, but recently finding more info on the Keihin CR29s has me pretty intrigued....I just know know if I want to drop $1000 extra on it yet haha.

New paint, LED lights, a hella black magic headlight, new gold chain, sprockets, gauges, pegs, Renthal bars, fork brace, and a custom seat will round out the package.

As always, photos for days of everything will follow this and hopefully I'll leverage insight from fellow KZ riders here!

Oh and I was able to put this bike into the back of my Trooper without a ramp haha! Its already been and adventure with this thing!
« Last Edit: Jan 17, 2017, 01:19:14 by flip_rip »

Offline doc_rot

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Re: Coffee Shop KZ650
« Reply #1 on: Jan 11, 2017, 20:48:22 »
 17 wheels have more of a tire selection and are going to be lighter which has a big effect on accel/decel, but you give up ride height on a bike that needs it.
18 wheels will keep ride heght and can be pretty light if you get aluminum rims. The rear rim is drilled for the drum brake and the angle of the spokes will not work for the much smaller front hub. It's best to get a rim drilled specifically for you. But if you found a rim for a similar sized hub you could probably make it work with custom spokes. Personally I think the bigger wheels, while being a little heavier, look great on these bikes and if you plan on really getting it leaned the ride hieght is important. You will find the limit of the bike before the limit of the tires with a mild engine. if you are replacing both rims I would go with a 18/3.5 rear and a 18/2.15 front. Running a 130/80/18 rear and a 100/90/18 front using BT-45

If you want to upgrade the chassis I would do so in this order of importance:
Shocks
Cartridge emulators in the stock forks
Stiffer swingarm/ oversized close tolerance pivot
Close tolerance engine mounts.
Braced frame
Fork swap

---------------------------------
'78 KZ1000  Project

'80 KZ750 Twin Project

Offline doc_rot

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Re: Coffee Shop KZ650
« Reply #2 on: Jan 12, 2017, 05:05:20 »
Also I know you didn't ask for this but my only advice for the styling is remove the rear fender and ginormous tail light and just stare at it for a month. Hard to beat that seat/tail for 2 up riding...also side covers aint too bad either...  just saying ;D draw your own conclusions
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'78 KZ1000  Project

'80 KZ750 Twin Project

Offline flip_rip

  • Posts: 44
Re: Coffee Shop KZ650
« Reply #3 on: Jan 12, 2017, 14:26:32 »
Haha I really appreciate the input! This is awesome! We'll have to see on the tail/side covers. I'm for sure not opposed, but I think the seat is a bit thick for my taste haha.

Thanks for the heads up on the wheels. I'm back and forth. At this point it'll be keeping the stock wheels and find sticky tires, or going to exactly what you suggested, aluminum rims, new spokes in the 18x2.15/18x3.5 and go to a full tubeless setup. That will be the lightest setup, but also will take a bit of work. Also I completely spaced the drum brake rear, so the spoke angles and holes will be different. Might need to flip a coin haha.

As for shocks, I have a few options, mostly looking for input on shock length (and in turn ride height). Stock is 13.5, so do I go 14, 14.5? Any experience with this?

I might start looking into a whole front end swap since I'm leaning toward changing the front wheel anyway. That way I can play with the forks, and front wheel at the same time, and maybe even upgrade the braking system. I don't think I need a dual setup, but maybe a larger single rotor and bigger caliper.

Offline doc_rot

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Re: Coffee Shop KZ650
« Reply #4 on: Jan 12, 2017, 17:53:34 »
A fork swap is a easy way to get better brakes, lighter wheels, and better suspension for sure, but there are a lot of factors that need to be considered when selecting new forks/triples. Not to mention quite a bit of modifications that need to be done to do it "right". That was why it was last on my list.
If you want to swap the forks, in my opinion, you need to upgrade everything else as well. The problem is that modern forks are much stiffer and typically shorter. By lowering the front of the bike and decreasing the rake you are putting much more stress on the head stock. So while you have much improved suspension in the front you cant fully utilize it because the rest of the chassis is forced to be much more flexible. If you look at my kz1000 project you can see the great extent I went through to reinforce the head-stock and brace the frame to deal with the load that a stiffer fork and swing-arm would translate to the frame. oversized close tolerance motor mounts to tie everything together are a help here as well.

Again, it really how you see yourself using the bike. if you just want a cool bike to cruise on that's one thing, if you want to improve is functionality that's another. To do a fork swap and get the most out of it you must approach it as a complete redesign. That means considering all these variable at once, wheel/tire size, fork length, fork offset (very important). triple tree height, swingarm length, wheelbase, and shock length.

Stock rake/trail for the kz650B2 is 27°/108mm

Modern Superbikes are usually around 24-25° and 95-100mm of trail. It is inadvisable to go much below these figures.

So to answer your question on the shock length; if you are keeping the stock wheel size, you can go up to a 14.5. it will make the bike a bit more twitchy but it will turn quicker, and it will gain ride height.
If you start changing other variables like the forks and wheels, the shock length must be considered as well, so I would figure out how deep of a transformation you want to go and then decide on shocks.

Also with lightened rotors, sintered pads, and a 15mm brembo MC for the 38mm calipers the brakes on the 650 are pretty good. depending on traction and body position I could "stoppie" my old bike. I just put the same setup on my buddies 650.
« Last Edit: Jan 12, 2017, 18:00:43 by doc_rot »
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'78 KZ1000  Project

'80 KZ750 Twin Project

Online ApriliaBill

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Re: Coffee Shop KZ650
« Reply #5 on: Jan 12, 2017, 22:44:04 »
Here's my opinion, which should mean little, because it's your bike and your $. I don't understand designing a bike that throws every bit of road debris and weather directly at all your hard work. I'm a huge fan of the KZ650 and it's styling. I agree the back light might be a little HUGE, but the fender and tail piece look great, and an abbreviated front fender would look cool. Other than fenders ( I think KZ650 look great stock) I think the middle bike on the right (with fenders) would look great, and yes a tad thinner seat, maybe a small aluminum air lip above the head light.... It'll be interesting to see where you take this project...
"Do not neglect to show hospitality to strangers, for by this some have entertained angels without knowing it."

Offline flip_rip

  • Posts: 44
Re: Coffee Shop KZ650
« Reply #6 on: Jan 13, 2017, 19:44:51 »
Haha thanks guys! I really do appreciate the input. I agree with fenders, but I think there is a way to shorten the tail of the bike and still maintain that ducktail feature without it looking like its sticking way out there. I did a very rough chop job of what I'm thinking for the rear. But with a thinner seat. See how its moved up? Tracker style at this point, but it doesn't hang way off there. Since I'm modifying the frame anyways I think I can just slide everything forward and integrate the seatpan to sit a bit further back to accommodate 2 people. I think I like the idea of side covers, but it might look sweet with the short ducktail and no covers too....hmmm need to start chopping metal!

Doc - what rotors/brake setup is that? Is that from an SR? I'd like to keep the stock solo rotor, and have already planned to do an SS line and MC upgrade. Good to know the 15mm Brembo option is out there.
« Last Edit: Jan 13, 2017, 20:29:20 by flip_rip »

Offline doc_rot

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Re: Coffee Shop KZ650
« Reply #7 on: Jan 16, 2017, 02:45:15 »

Doc - what rotors/brake setup is that? Is that from an SR? I'd like to keep the stock solo rotor, and have already planned to do an SS line and MC upgrade. Good to know the 15mm Brembo option is out there.

Its the factory dual brake setup, that is found on the KZ650C/D kz1000B,  the disks have been thinned and drilled by Goddfrey's Garage. The 15mm MC is for dual 38mm calipers. If you keep the single (IIRC its 41mm) caliper you will need a different size master.
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'78 KZ1000  Project

'80 KZ750 Twin Project

Offline flip_rip

  • Posts: 44
Re: Coffee Shop KZ650
« Reply #8 on: Jan 17, 2017, 01:18:01 »
Gotcha gotcha. Thanks for the info! I ended up going with a 14mm MC and a braided line from galfer. I also went a little wild and tore into the bike to figure out exactly why it isnt starting....turns out the PO must have left a spark plug out during a rain storm or something because the inside of the #4 cylinder was very very rusty. So I pulled the head and the cylinder block.

I was able to snag some new old stock KZ pistons and a ring set off ebay for cheap. My other option was to do the wiseco 700 kit, but I want to keep the stock carbs and I think a 700 might be on the upper end of their performance. So now I'm off to find someone to do new valve seats, clean the head and re-hone the cylinders. (most look pretty good, but the cross hatching isn't what i was hoping for)

I also order all new gaskets, a sweet new headlight, clutch pack, clutch cable, grips, a new throttle, pod filters, oil filters, and I decided on my handlebar switch setup for the clean look.

I made the decision to keep the stock wheels and just clean them up. It would be cool to do a smaller set, but I came across the Continental Classic Attacks, and will be putting on a set of those.

Fork rebuild is still on the list (maybe stiffer springs) and for sure new rear shocks with appropriate rates, but I need to get this thing running and on the road before I start making any suspension changes.

There is a ton to do, but I need to finish stripping the frame to repaint it and get the wheels and fork clean and fresh. Then motor rebuild, carb rebuild, make a seat pan, rewire the bike, get some new tires, and the other few odds and ends to get this road worthy! The ideal plan is to have it running by mid feb.

Also my roommate gave me a sweet idea to make the ducktail into some kind of removable cowl to make it a 1 or 2 seater, so I might take on that challenge instead of totally chopping up the rear of the bike. I'll detab it but I don't think I'll do a whole new subframe like on the NX.

So hopefully UPS and Fedex and USPS are good to me this week and I'll have about 50 packages to dive into this weekend!

Photos of how I ended my weekend attached!

« Last Edit: Jan 17, 2017, 01:22:49 by flip_rip »

Offline doc_rot

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Re: Coffee Shop KZ650
« Reply #9 on: Jan 17, 2017, 16:33:49 »
I'm curious to see how those conti classic attack tires end up feeling. I have the conti road attack II on my Aprilia and love them, they are supposed to be very similar.

The reason why the stock seat is so long is to accommodate 2 people. I think where you have the tail sitting right now looks awesome, but you ain't getting two people realistically on a seat that size. In the early iterations of my kz1000 I thought about having two separate seats; one for single and one for 2 up. I ended up scraping that idea because there was too much compromise for me, but ill be interested to see if you pull it off.
---------------------------------
'78 KZ1000  Project

'80 KZ750 Twin Project