1974 KZ400 Cafe Racer Build

diggerdanh wrote: I have VM30s on my 76 KZ400. I run 25 pilots, 230 mains and the stock 3.0 slide. I have a pair of aftermarket mufflers on it too. So we are in the same ballpark.

I noticed what you said about getting rid of the slight stumble with the 2.0 slides. I do have just a slight stumble there too. I tried the 2.5 slides a while back but the bike ran like junk. Perhaps though it was because they were not "real" Mikuni slides, the supplier milled 2.5 slides from a 3.0 slide. So perhaps I should get a real pair of 2.5 or 2.0 slides and try again.

Hi Dan,
I'm surprised that the 2.5 slides didn't work well with your VM30s, even if the slides were milled rather than real 2.5s. With mine, knowing that the VM32s take a VERY big gulp of air on a little 400 when whacking the throttle open, I knew that the stumble I had needed a bigger jump than just ,5, so that's why I went to the 2.0s straight from the 3.0s. Kinda the same with the main jets. I had 200s in it and after reading the plugs, I knew 210s would be a waste of time, so I went straight to the 220s and still it's just a hair lean. 230s are going in tomorrow and I'll do a riding video. I did one just before dark with my phone clipped to the top of my jacket, but I forgot to reverse the camera, so it's just a black screen with 5 minutes of engine sounds. (Which is still pretty cool if you ask me.)

This is going to sound silly of me to ask, but when you put the 2.5 slides in, did you perhaps put them in reversed? As in the air cutaway pointed toward the motor instead of the pods? As thorough as I am, I've done that a time or two over the years and then wondered briefly why the bike ran poorly before realizing my mistake.

I would say get the 2.0 slides. If they make the mixture too rich just off idle, you can always sell them off and buy the 2.5s. On the other hand, are you sure what you have is a "lean stumble" and not a "rich burble"? 25 pilots seem a little big for the 30mm carb on the stock 400, assuming it's stock and not ported, Boyer ignition, etc. Since the motor ran worse with the smaller cutaway slides, that tells me that it wanted more air rather than less air, so I'm thinking you might be too rich off the bottom. Just food for thought.

KZCafeChickNJ wrote:

750 R1 wrote:

KZCafeChickNJ wrote:

750 R1 wrote:
You're never too old to do a rider training course....

YOU'RE never too old to actually add something to a thread, nor learn the difference between "you're" and "your". I ignored your first snide remark, but had to put you in your place after this one. YOU'RE welcome.

What's with the panties in a knot attitude ...? I definitely know the difference between you're and your, I was in a hurry to go out and just added that comment without proof reading, I have no idea of what you mean about any "snide remark", whilst I HATE grammar nazi's online, I think THEY'RE petty, I'll let it slide this time as it seems YOUR poor mood is attributed to a complete misunderstanding. I'm 10 years older than you and am no fan of typing , I stink at it, I grew up when spelling was important and value it thanks. On topic, I would recommend rider training courses to anyone that rides, especially people either getting back into riding after a hiatus, or someone who doesn't know how to brake correctly, as it is in your case, I'm surprised by the sheer amount of people I've come across online that rely mainly on their under performing rear brake, I would be dead by now if I rode like that. That is NOT an insult, its a fact. Recently I watched in horror as a guy in his 40's on a Harley locked up his rear brake and slid into the back of a car towing a boat, the leg of the boat motor split his chest down the middle, he got up and sat next to a tree and died in front of me and my son, it was horrible to watch, It wouldn't have happened if he knew how to brake properly, I later found out the deceased guy was a child molester so the story had an upside, strange but true...!! My brother and I have been riding bikes since the late 1970,s, I didn't even have a car license until I was 40, just bikes, My bro bought a new bike recently {CBR1000RR} after not riding for about 10 years, the first thing he did was go do a rider refresher course, NOT because he can't ride, because its a great place to get back YOUR feel for the road without any obstacles, no idiots to look out for that are trying to kill you, and a clean surface to practice your skills, including proper braking technique. I haven't ridden since having major surgery a while ago, I have 5 bikes in my garage and once I get the 750 Kawasaki back on the road i'm doing a refresher course, I also like riding on the track, so it kills two birds with one stone, I can go as hard as I like and no one gets hurt. I've owned over 40 bikes and worked in a very reputable bike shop I can assure you, I know how to ride, but I'm still doing the course, I did get it cheap because I know the rider trainers. I hope I've explained myself clearly, I meant no offense, I'd love you to point out how my comment was offensive because Texas's comment is 100% correct and I just agreed to give assurance ..?

If you really want to improve braking, look to the front. That is where about 90% of the braking action happens. I use the rear brake rarely. Usually to settle the chassis going into a turn, or if I am slowly negotiating a really slick surface like wet grass.
Two up touring, yes a little rear brake, otherwise I just punish the front.

I couldn't agree more....

For someone who claims to be no fan of typing, that sure was wordy. I know how to ride very well, thank you. My braking method can't be all that bad since I've never had an accident in 30+ years of continuous riding, and I'm certainly no putt-putt cruiser. My "panties were in a knot" (typical sexist male expression) because I'm tired of men like you who discount my wrenching and riding abilities simply because I'm a female and because of their own insecurities. Meanwhile, I can wrench, fabricate and ride circles around 9/10 of the male motorcyclists I've ever been around. I was simply commenting on how weak the rear brake is on this bike compared to all of the others I've ridden. I never said or intimated that I used nothing but rear brake.

Your first post added absolutely nothing to the thread. Almost as lame as saying "+1" (ugh). Texas said it, in a nice way, and I got it. Your add-on post was completely unnecessary. Your second post was clearly snide. "Rider training courses" are for complete newbs. Advanced technique courses are for people like me who already know how to ride very well and have done so on tracks (motocross and road) since my teens. There's a big difference between a newb course that you suggested, and an advanced class, but perhaps they're the same where you come from. Either way, if you have nothing to add to a thread, why not save your keystrokes? (Rhetorical question)

Now, if you'll excuse me, I'm having far too much fun with my beautiful "new" bike to be dragged down into an internet argument with someone half way around the world.

-1

KZCafeChickNJ wrote:

750 R1 wrote:

KZCafeChickNJ wrote:

750 R1 wrote:
You're never too old to do a rider training course....

YOU'RE never too old to actually add something to a thread, nor learn the difference between "you're" and "your". I ignored your first snide remark, but had to put you in your place after this one. YOU'RE welcome.

What's with the panties in a knot attitude ...? I definitely know the difference between you're and your, I was in a hurry to go out and just added that comment without proof reading, I have no idea of what you mean about any "snide remark", whilst I HATE grammar nazi's online, I think THEY'RE petty, I'll let it slide this time as it seems YOUR poor mood is attributed to a complete misunderstanding. I'm 10 years older than you and am no fan of typing , I stink at it, I grew up when spelling was important and value it thanks. On topic, I would recommend rider training courses to anyone that rides, especially people either getting back into riding after a hiatus, or someone who doesn't know how to brake correctly, as it is in your case, I'm surprised by the sheer amount of people I've come across online that rely mainly on their under performing rear brake, I would be dead by now if I rode like that. That is NOT an insult, its a fact. Recently I watched in horror as a guy in his 40's on a Harley locked up his rear brake and slid into the back of a car towing a boat, the leg of the boat motor split his chest down the middle, he got up and sat next to a tree and died in front of me and my son, it was horrible to watch, It wouldn't have happened if he knew how to brake properly, I later found out the deceased guy was a child molester so the story had an upside, strange but true...!! My brother and I have been riding bikes since the late 1970,s, I didn't even have a car license until I was 40, just bikes, My bro bought a new bike recently {CBR1000RR} after not riding for about 10 years, the first thing he did was go do a rider refresher course, NOT because he can't ride, because its a great place to get back YOUR feel for the road without any obstacles, no idiots to look out for that are trying to kill you, and a clean surface to practice your skills, including proper braking technique. I haven't ridden since having major surgery a while ago, I have 5 bikes in my garage and once I get the 750 Kawasaki back on the road i'm doing a refresher course, I also like riding on the track, so it kills two birds with one stone, I can go as hard as I like and no one gets hurt. I've owned over 40 bikes and worked in a very reputable bike shop I can assure you, I know how to ride, but I'm still doing the course, I did get it cheap because I know the rider trainers. I hope I've explained myself clearly, I meant no offense, I'd love you to point out how my comment was offensive because Texas's comment is 100% correct and I just agreed to give assurance ..?

If you really want to improve braking, look to the front. That is where about 90% of the braking action happens. I use the rear brake rarely. Usually to settle the chassis going into a turn, or if I am slowly negotiating a really slick surface like wet grass.
Two up touring, yes a little rear brake, otherwise I just punish the front.

I couldn't agree more....

For someone who claims to be no fan of typing, that sure was wordy. I know how to ride very well, thank you. My braking method can't be all that bad since I've never had an accident in 30+ years of continuous riding, and I'm certainly no putt-putt cruiser. My "panties were in a knot" (typical sexist male expression) because I'm tired of men like you who discount my wrenching and riding abilities simply because I'm a female and because of their own insecurities. Meanwhile, I can wrench, fabricate and ride circles around 9/10 of the male motorcyclists I've ever been around. I was simply commenting on how weak the rear brake is on this bike compared to all of the others I've ridden. I never said or intimated that I used nothing but rear brake.

Your first post added absolutely nothing to the thread. Almost as lame as saying "+1" (ugh). Texas said it, in a nice way, and I got it. Your add-on post was completely unnecessary. Your second post was clearly snide. "Rider training courses" are for complete newbs. Advanced technique courses are for people like me who already know how to ride very well and have done so on tracks (motocross and road) since my teens. There's a big difference between a newb course that you suggested, and an advanced class, but perhaps they're the same where you come from. Either way, if you have nothing to add to a thread, why not save your keystrokes? (Rhetorical question)

Now, if you'll excuse me, I'm having far too much fun with my beautiful "new" bike to be dragged down into an internet argument with someone half way around the world.

Jesus lady, I've never read so much garbage in one post in my life, you've made an incorrect assumption and then dribbled on with a pile of worthless rubbish, what a load of condescending, possibly feminist crap. I was trying to help regardless of what you assumed..

You said this "I'm thrilled with it! The only thing I'm not thrilled with is the rear brake. I wasn't expecting much since it's a drum, but a 300 lb bike with a 130 lb rider should stop a lot better.." I didn't make any assumptions here, a 300 pound bike DOES stop better, Learn to use the front brake correctly and you'll soon find out. I'm out of here, I'm through wasting my time with a defensive fool looking for anything to be offended by.... sheesh...!!!

Awwww. Your input will be sorely missed. Bye. :kiss:

Very nice build. Apparently you've managed to ride for ~30 years thinking of your front brake as a "helper" to your back brake. You ought to rethink that

The front brake provides 70 - 80% of the stopping power in large part because of the weight transfer when braking. One shouldn't be very surprised to find the rear brake (even a very good one like the one on my bike) doesn't provide very much stopping power.

You state you've been riding for 30 years and "ride circles around 9/10 of the male motorcyclists I've ever been around". However, you also state "I always looked at front brakes more as a "helper" to the rears, but I'm going to adjust my thinking and my riding style "; "I put a few miles on the 650 yesterday and used the front brake a lot more than usual"; and "I'll try it on the 400 today after the valve caps get here." To one reading your postings this means you haven't fully utilized the front brake in the past.

Regarding 750 R1's suggestion about taking a riding class - I thought it was actually good advice and not at all intended to be insulting. If you, 750 R1, or anyone else suggested that I take a training class I would not be insulted, and I've been riding for a bit over 50 years. I might not take the class, but I wouldn't be insulted at the suggestion.

Your comment "I'm tired of men like you who discount my wrenching and riding abilities simply because I'm a female and because of their own insecurities" seems rather bizarre since there was no mention by anyone about your wrenching abilities or any comment that your riding or any other skills were lacking because of your gender.

To this reader your comments seemed over-sensitive and defensive considering the fact that the advice you were given was not intended to be insulting or gender-based. Maybe you should consider the fact that folks on this site actually try to be helpful rather than insulting, but if you blast folks for making reasonable suggestions with which you disagree you may alienate others that might have otherwise offered helpful suggestions. Ed

650ed wrote: The front brake provides 70 - 80% of the stopping power in large part because of the weight transfer when braking. One shouldn't be very surprised to find the rear brake (even a very good one like the one on my bike) doesn't provide very much stopping power.

You state you've been riding for 30 years and "ride circles around 9/10 of the male motorcyclists I've ever been around". However, you also state "I always looked at front brakes more as a "helper" to the rears, but I'm going to adjust my thinking and my riding style "; "I put a few miles on the 650 yesterday and used the front brake a lot more than usual"; and "I'll try it on the 400 today after the valve caps get here." To one reading your postings this means you haven't fully utilized the front brake in the past.

Regarding 750 R1's suggestion about taking a riding class - I thought it was actually good advice and not at all intended to be insulting. If you, 750 R1, or anyone else suggested that I take a training class I would not be insulted, and I've been riding for a bit over 50 years. I might not take the class, but I wouldn't be insulted at the suggestion.

Your comment "I'm tired of men like you who discount my wrenching and riding abilities simply because I'm a female and because of their own insecurities" seems rather bizarre since there was no mention by anyone about your wrenching abilities or any comment that your riding or any other skills were lacking because of your gender.

To this reader your comments seemed over-sensitive and defensive considering the fact that the advice you were given was not intended to be insulting or gender-based. Maybe you should consider the fact that folks on this site actually try to be helpful rather than insulting, but if you blast folks for making reasonable suggestions with which you disagree you may alienate others that might have otherwise offered helpful suggestions. Ed

+1
+1
+1


.

650ed wrote: The front brake provides 70 - 80% of the stopping power in large part because of the weight transfer when braking. One shouldn't be very surprised to find the rear brake (even a very good one like the one on my bike) doesn't provide very much stopping power.

You state you've been riding for 30 years and "ride circles around 9/10 of the male motorcyclists I've ever been around". However, you also state "I always looked at front brakes more as a "helper" to the rears, but I'm going to adjust my thinking and my riding style "; "I put a few miles on the 650 yesterday and used the front brake a lot more than usual"; and "I'll try it on the 400 today after the valve caps get here." To one reading your postings this means you haven't fully utilized the front brake in the past.

Regarding 750 R1's suggestion about taking a riding class - I thought it was actually good advice and not at all intended to be insulting. If you, 750 R1, or anyone else suggested that I take a training class I would not be insulted, and I've been riding for a bit over 50 years. I might not take the class, but I wouldn't be insulted at the suggestion.

Your comment "I'm tired of men like you who discount my wrenching and riding abilities simply because I'm a female and because of their own insecurities" seems rather bizarre since there was no mention by anyone about your wrenching abilities or any comment that your riding or any other skills were lacking because of your gender.

To this reader your comments seemed over-sensitive and defensive considering the fact that the advice you were given was not intended to be insulting or gender-based. Maybe you should consider the fact that folks on this site actually try to be helpful rather than insulting, but if you blast folks for making reasonable suggestions with which you disagree you may alienate others that might have otherwise offered helpful suggestions. Ed

Yes, I do admit I was being overly sensitive, and I apologize for lashing out. In my defense, if you were a female in the male dominated world of motorcycling, you'd probably understand. A lot of men see women like me as a novelty; "Awwww, isn't that cute; a woman rider. Oh, she wrenches, too? Adorable!". That sort of thing. Most guys won't actually say things like that, but it's clear that's what they mean.

After all, Ed, it was you who attacked me for wanting to "cut up" a classic bike literally after my first post here on the site. That's the kind of thing that'll make a gal, or anyone, defensive. Those are the kind of non-helpful posts that don't need to be made. If your opinion isn't helpful, keep it to yourself. Texas made a helpful suggestion in his post and did it in a nice way. I got the message and thanked him. "+1"s weren't necessary.

What you guys still might be missing is that the rear brake on this bike is barely there. I'm talking about for average, mundane straight line stops where you're not worried about sliding out the rear end of the bike. Another thing, and this might be where I need a class, but the bike is ultra-light and I'm only 130 lbs, and I don't like the feeling of the bike wanting to throw me forward into and over the bars when I use a lot of front brake. The bike has new fork springs, but no one seems to make a spring soft enough for this bike, at this low weight with such a relatively light rider on it. I'd have to check my records, but I believe the spring rate (lowest available) was for a stock KZ400 (387 lbs) with a 160 lb rider on it. I'm sure if the front end were a bit softer, I'd be a lot more comfortable with putting more front brake into it.

I do understand weight transfer and I do understand that just like in a car, your front brake is a large portion of your braking power. That's why cars with front discs and rear drums will have the front pads replaced 3 times for every 1 time the rear shoes are replaced. I get all that. What I was saying, and I guess I wasn't being clear, is that the rear brake on this bike is virtually non existent despite the drum being within spec, new shoes and springs.

it might be worth removing the shoes and scuffing the surface up (wire wheel comes to mind)and maybe a scotch brighting to the drum surface to brake any glaze and then put it together and use it a lil.then remove it and look at the surface of the shoes and see if they are making full contact with the drum.
if you have a brake rebuilder in the area they can "arc"the shoes to the drum thus insuring proper contact.
also insure all the brake pivots and metal to metal sliding surfaces are clean.i like to put a light coat of grease on the pivots and sliding areas.but grease in a drum brake is typically a no-no.
hth,ymmv

leon

531blackbanshee wrote: it might be worth removing the shoes and scuffing the surface up (wire wheel comes to mind)and maybe a scotch brighting to the drum surface to brake any glaze and then put it together and use it a lil.then remove it and look at the surface of the shoes and see if they are making full contact with the drum.
if you have a brake rebuilder in the area they can "arc"the shoes to the drum thus insuring proper contact.
also insure all the brake pivots and metal to metal sliding surfaces are clean.i like to put a light coat of grease on the pivots and sliding areas.but grease in a drum brake is typically a no-no.
hth,ymmv

leon

Thank you, Leon. All very good suggestions. We're on the same wavelength for sure. Before putting the rear brake together, I scuffed the new shoes with a red scotch brite and broke the glaze on the drum with 320 sandpaper. I also cleaned and lightly greased the pivot to the point where it rotated silky smooth.

I just finished working on it and road testing it and I found the solution. Since my custom application calls for having the actuator arm on top rather than the bottom, the arm angle was off 2 splines. First I moved it one spline toward the rear and it was a big difference, but not quite there. I popped it off again and moved it one more spline and that did the trick. I also lowered the rear sets to their lowest position, reworked the pedal stop and reworked the pin I made as a spring holder for the brake light switch spring. The rear brake is now functioning as it should in all aspects.

Thanks again for the helpful post.

Good to know it was something simple. Kudos for working it out before you threw some unnecessary money at it. For the extent of your build, it's actually gone pretty smoothly.

Now that you know the rear brake works as intended, I would actually replace the shoes. If you don't know how long they have been on there or what kind of conditions they've been through you might run the risk of the friction material separating from the base and jamming itself into the other and locking up. Not something you want to do at speed. It's just a piece of mind thing, not to mention the newer higher friction options that are available to give it more braking power than was available when it was new.

I for one don't care what you have between your legs, as long as it's not a Harley we'll get along fine.

Feel free to stop by and put some of those mad building skill to use on my sad little GPz which is still waiting for attention.

GPzMOD750 wrote: Good to know it was something simple. Kudos for working it out before you threw some unnecessary money at it. For the extent of your build, it's actually gone pretty smoothly.

Now that you know the rear brake works as intended, I would actually replace the shoes. If you don't know how long they have been on there or what kind of conditions they've been through you might run the risk of the friction material separating from the base and jamming itself into the other and locking up. Not something you want to do at speed. It's just a piece of mind thing, not to mention the newer higher friction options that are available to give it more braking power than was available when it was new.

I for one don't care what you have between your legs, as long as it's not a Harley we'll get along fine.

Feel free to stop by and put some of those mad building skill to use on my sad little GPz which is still waiting for attention.

Thank you. The shoes are new. I just always scuff 'em up a little for a little more bite.

You're right about the extent of my build and only having the rear brake issue and the cracked valve caps issue, which I also figured out yesterday. The new o-rings I bought for the caps were the right part number, but they were too thin. They turned out to be 2.0mm thickness when they should have been 3.0 thickness, so they weren't cushioning the metal-on-metal contact the way they should have been. A quick trip to the Sears Hardware store up in town for the correct sized o-rings and I was all set.

You know what they say about Harleys.... 98% of Harleys ever made are still on the road today. The other 2% made it home. Nyuck nyuck nyuck.

Thanks for the compliment on my building skills. I'd love to help out, but SLC is a long ways from Joisey. :laugh: I would have had this thing done eons ago if a bunch of non-motorcycle, real-life crap hadn't come up. I actually kept tabs on all of the labor I put into this bike; 487 hours from start to finish. In a shop working 10-12 hour days, that only would have been a month and a half, but it took me a year and two months. Oh well... I'm gonna ride the heck out of it til the weather finally turns.