Opinions needed - Strength of KZ440 Frame

I have an early '80s KZ440 project bike. A pic of it is in my new member post...

It's currently stripped completely down, but it was just a belt drive roller sans seat, tank, and carbs when I got it.

I'm not sure which direction I want to go with the project build, either a street tracker or more of an adventure bike.

Now, when I say adventure bike, I'm not talking hard core off road. I just want a bike that is elevated a bit and has more suspension travel than stock. The narliest it would see is a gravel road or fire road. I have no plans to race it or jump it. I'm too old to try that on an old street bike.

My stock fork measures 35" tip to tip unloaded and the axle is at the end of the fork tube. The 2008-present KLR650 forks are leading axle and measure 37.5" OAL with the axle about 1.5" up from the bottom. I'm planning to run longer shocks in the rear to bring the bike back to proper rake.

Is the stock frame strong enough to handle the extra weight of the larger forks? I will have to determine the proper offset for the triple clamps so the trail isn't screwed up too much... and I'm planning to run the stock KLR hub/disc but with a 19" rim instead of 21".

Do the KZ440 frames need any bracing for mild unpaved road duty?

TIA

- BMF

BoilermakerFan wrote: Is the stock frame strong enough to handle the extra weight of the larger forks?

This strikes me as an odd question. The frame is not supporting the forks; the forks are supporting the frame.

Do the KZ440 frames need any bracing for mild unpaved road duty?

With the type of off-road riding you described above, the stress on the frame shouldn't be any greater than what it would see on a bad section of pavement.

Also if you go with significantly longer shocks, keep in mind that you will be changing the geometry of the final drive (be it belt or chain). The longer shocks will place the rear sprocket/pulley farther below the countershaft sprocket/pulley.

Nerdy wrote:

BoilermakerFan wrote: Is the stock frame strong enough to handle the extra weight of the larger forks?

This strikes me as an odd question. The frame is not supporting the forks; the forks are supporting the frame.

Do the KZ440 frames need any bracing for mild unpaved road duty?

With the type of off-road riding you described above, the stress on the frame shouldn't be any greater than what it would see on a bad section of pavement.

Also if you go with significantly longer shocks, keep in mind that you will be changing the geometry of the final drive (be it belt or chain). The longer shocks will place the rear sprocket/pulley farther below the countershaft sprocket/pulley.

Thanks Nerdy.

I guess my verbiage about the weight of the new fork on the frame wasn't correct. I guess I meant the longer length and added weight causing any additional stress to the head tube.

The shocks won't be significantly longer, The forks are 2-1/2" longer, but the axle will only be about an inch lower... so I will only need shocks that about 3/4" to 1" longer to maintain the stock rake and keep the trail in check.. I may end up moving the shock mounts too to gain a little more travel while not changing the swing arm angle significantly.

Are you planning on swapping forks or the entire front end?

KLR650 fork tubes are probably bigger in diameter than the KZ440 & you'll need to check if there are steering bearings that will mate the KLR triple to the frame. see All-balls-racing fork conversion page & the ohio cafe racers fork tube conversion chart.

martin_csr wrote: Are you planning on swapping forks or the entire front end?

KLR650 fork tubes are probably bigger in diameter than the KZ440 & you'll need to check if there are steering bearings that will mate the KLR triple to the frame. see All-balls-racing fork conversion page & the ohio cafe racers fork tube conversion chart.

Martin

My initial plan will be to swap the entire fork with KLR triple clamps and a stem swap (or custom stem if that is required), but if that screws up the trail too much I will have to machine custom triple clamps. I believe the KLR stem is much longer than the stock KZ440 stem. The 2008-2017 KLR tubes are 41mm. I don't have a KLR front end yet so a lot of this is up in the air. The other set of forks I'm considering are Suzuki DZR400 forks, but the motard upside down version... Either way, I'm figure I'll either need a custom stem or custom triple clamps. If I get lucky and the KZ440 stem will press into the KLR triple and the trail is fine, then that would be awesome, but I'm not counting on it.

I'm also looking into a monoshock swingarm conversion for the rear, but I'm wanting to stick with a rear drum brake, I have a spare KZ650 rear drum hub. The hub will take either the belt drive or a chain sprocket so I can swap to a chain if I need to. This is all TBD right now... I'm in the research and planning stage of this build. The stock 440 frame just screams Scrambler/Adventure bike without needing too much fabrication, so that's the direction I want to go.

The engine will get a single carb conversion, C5 Ignition, and custom long tube 2-into-1 exhaust to maximize the torque.

I think I would go to Kz400 wire wheels. They are probably lighter, but more importantly, you can get an 18" rear wheel to get a tiny bit more road clearance, especially if you are going to put on tires for dirt/gravel.

I assume you will also be converting to chain drive. It's not very difficult.

loudhvx wrote: I think I would go to Kz400 wire wheels. They are probably lighter, but more importantly, you can get an 18" rear wheel to get a tiny bit more road clearance, especially if you are going to put on tires for dirt/gravel.

I assume you will also be converting to chain drive. It's not very difficult.

loudhvx,

I have a KZ650 wire wheel hub that fits the KZ440. It has a larger drum brake diameter by about an inch over the stock KZ440 alloy wheels. I ditched the alloy wheels as soon as I brought the bike home, traded them for other parts including the KZ650 wire wheel hub. The stock KZ440 wheels have to be the heaviest cast wheels I've seen! And yes, I'm going to look into 18" rear tires. I'm probably dropping to 19" in the front for a better tire selection, but if I find a nice 21" tire then I may go that route.

I'm planning to run the more road oriented adventure/dual sport tires. No knobbies.

I have the belt drive and chain drive rear sprockets. All I would need is the front chain sprocket and chain. If I go with a different swingarm then I'm definitely switching to a chain drive.

I can't wait to see it. My buddy was really into Klr650's for a few years. I puttered around on it and it went over curbs nicely.

The only issue I've found with "enduros" (old school terminology, ha) is that brakes that are designed for dirt are weak for the road, and brakes designed for the road seem to lock up a little too easy on dirt/gravel. I guess some sort of compromise has to be made.

...and yes, all of those Kz alloy wheels are damn heavy.

Good luck on the build!

loudhvx wrote: I can't wait to see it. My buddy was really into Klr650's for a few years. I puttered around on it and it went over curbs nicely.

The only issue I've found with "enduros" (old school terminology, ha) is that brakes that are designed for dirt are weak for the road, and brakes designed for the road seem to lock up a little too easy on dirt/gravel. I guess some sort of compromise has to be made.

...and yes, all of those Kz alloy wheels are damn heavy.

Good luck on the build!

Thanks, I'm really looking forward to the build. Once it gets a little bit along in the build I'll start a build thread. I need to start looking for a tank for it. I have an early KZ440 tank on my KZ650 that was on it when I bought it. I might have knee pockets put into it, or I might look for a little bigger tank. I don't want to go too big or it will become more top heavy. I'd rather carry a couple of spare small fuel canisters low on the saddle bags than have more fuel up high.

Balanced braking is the big reason why I really want to keep the rear brake a drum. Lighter weight and better modulation. The bigger surface of the larger hub will give me more stopping power on the road while maintaining better control in the loose stuff. I've ridden mountain bikes for years so skidding the rear brake in loose stuff doesn't phase me. We actually had a big sandy spot in the parking lot when I took my ABATE class. The instructors deliberately had us emergency stop in a straight line through it. Taught us how to go lighter on the front brake and let the rear lock up.

I'm probably most concerned with getting the spring rates and fork oil dialed in to minimize fork dive but still get enough damping for rough roads. I'm probably going to go with custom Hagon shocks for the rear through Dave Quinn. A local buddy ordered a set for his W650 build and Dave dialed them in for his bike and his weight. They were gorgeous looking too.

My $.02 ... I would brace the frame since it is relatively cheap and simple to do, and more importantly it will most likely help deal with the increase stiffer forks and swingarm inputs to the frame. There is a thread on here somewhere of people bracing their 1000 frames. adapt that to the 440 frame. If you want to go even further, over-sizing the motor mount bolts to remove the factory tolerances and remaking the motor plates out of aluminum plate will help tie everything together to form a more rigid structure. I have done both on my kz1000 and kz750 twin. I haven't ridden the twin yet but the 1000 is much more planted at speed.

DoctoRot wrote: My $.02 ... I would brace the frame since it is relatively cheap and simple to do, and more importantly it will most likely help deal with the increase stiffer forks and swingarm inputs to the frame. There is a thread on here somewhere of people bracing their 1000 frames. adapt that to the 440 frame. If you want to go even further, over-sizing the motor mount bolts to remove the factory tolerances and remaking the motor plates out of aluminum plate will help tie everything together to form a more rigid structure. I have done both on my kz1000 and kz750 twin. I haven't ridden the twin yet but the 1000 is much more planted at speed.

DoctoRot,

Thank you for the tips! I was going to look into bracing/reinforcing the frame, but I hadn't thought about the motor mounts.

- BMF

the motor mount holes are way oversized. I went to 7/16" on the M10 holes and 3/8" on the M8s. On two M8 holes that i tried to ream out the reamer fell through without turning! lots of room for improvement. plus they look awesome, check out the upper mount on my 750 twin. you can make something like this, the inline 4 motors don't have a head mount like this but the twins do.

make sure you get a real good fit-up on the braces and weld it with the motor and swing-arm bolted in to act as a jig..

lots of info here> kzrider.com/forum/5-chassis/294594-frame-bracing?start=120