First Post 1976 KZ900 Sports Bike Build

gres6121 wrote:

Okay I don't believe there is a go to thread for this and I understand I might upset people for not liking the old school style/respecting it.. There are plenty of modified "Z's" on here . But I want to create a bike using the stock 76 kz900 bike and building with anything that does not require huge fabrication and stay relatively cheap. Max $3k for everything. That will depend mainly on your skill levels and willingness to learn I want to save original parts and not mess with it too much in case I want to go back from time to time.

I want to extend the swingarm a bit and put longer suspension on it to make 12* angle on swingarm(I've read this is what is desirable on newer bikes) If you intend to fit a later front end then "jacking up" the back in combination with a shorter front end and smaller wheel will most likely result in a bike which is unstable at speed and steers like a shopping cart !! and increase tire width to a 170 This will require an off-set gearbox sprocket. I want to use gs1100 swingarm or maybe longer as it has no fabrications needed. The longer shocks will need a reposition or I could do monoshock(?) advice on this is appreciated You said you didn't want to get into a lot of "fab" a mono-shock requires just that and correct positioning of the lower mount to ensure the "rising rate" geometry is correct . I don't know the drawbacks of this. I'm 230lbs and probably want new shocks like 412 progressive's as not to break the bank. Different wheel needed? Sprocket 10mm needed to clear tire with chain now?

Front suspension.... I have a weeping seal on the stock forks and wouldn't mind going to different forks if I don't have to do major fabrication. I don't want to grind out any of the original parts to take the steering rod/shaft out of the lower triple tree The stem is a "press fit" so not sure what grinding and welding you are referring to ? The only welding I am aware of would be modifying the steering stop to suit a different lower tree. I heard zx6r or some newer forks work easily (there are many pitfalls with a front end swop so don't fall in the trap of thinking it's easy - any 600 super sport forks are significantly shorter than your stock forks and require modification to work correctly) and just require grinding to remove lower triple of original forks and weld to new ones? Don't know where you hear this but there is no welding or grinding involved if done correctly I might just buy a new set and modify those parts instead. Ive read Old Mans PDF on this a bit(doesn't mean I understand all of it) but can take references to that.

Newer ignition system dyna 2000 is for what but better destination of fuel? Please explain a bit on this maybe. Electronic ignition definitly has benefits over the "points" set but but a "Dyna S" is probably more that adequate given the overall budget you are looking at ($3k will soon evaporate)

I've gotten the carbs cleaned and jets replaced but want to tune them correctly because I either A ran bad fuel and can't the title without them dying(also throttles high when applying clutch coming to stop which I think all points to running lean) or B guy never tuned correctly and I need different jets/one clip lower on (jet rod) e clip. I have aftermarket exhaust 4-2 and don't know if re jetting is needed like the jump from 4-4 to 4-1 exhaust. There are guys here like Zed1015 that can advise on this but will need more detail EG: what filters are you using

I'm also going to repaint it and will not paint over OEM stuff. New tank and panels if I do anything. Anyone know ideas to provide better lighting to tachometer and speedometer without taking apart gauges? Maybe a simple hole drilled and run electrical? 

Anyone have electrical manual or any manuals for working on them? There are a full set of FSM in the file base here on the site

Finally I get a clunking noise then at idle which I think it bolts on starter needing to be tightened. Goes away though when I pull clutch in. I will be checking spark plugs soon to check if ran lean.  Possibly a worn clutch basket or carbs need syncing

I enharited bike from great uncle and don't want to do him wrong but he said he doesn't care what I do and it is my bike now. Planned on getting exhaust cerakoted desert grey or something and front forks redone and electroplate them golden/desert if too much fabrication is needed for fork swap. Color now is original diamond brown. 

I'm up in the air and am up for anything when it comes to ideas. Want sportier and newer functionality. Am electrical engineer and can do any pi/Arduino mods. 

1. Start with swap to gs11 swingarm and see how that feels.
2. Just repair front fork seals for now.
3. MSD upgrade
4. Exhaust recommendations? 

1. swingarm angle on newer bikes do what seems like a lot of anti squat swingarm angle 12* or more. I don't really see the need for it because of the acceleration you would get on this engine unless I went to the 29mm makunis or something different sprocket sizes for more low end power, right? But I could easily do a bit more by extending shocks by 1-2". I like the slightly positive swingarm angle when on a stand but why is this a bad idea? Loss of stability in the front? Is it a bad idea to just put on a larger gear sprocket in the rear for more low end performance?  I'd lose top end speed or what else? Strain on engine?
2. I have the 4-2 off and am debating just refurbishing them with cerakoted black/maybe grey on the mufflers and electroplating the headers along with the front fork tubes to be golden. Can you just put chrome instead of doing nickel to avoid silver look? I've heard nickel is the reason for the silver but don't know if chrome will still add that. I want a protective layer to prevent dicolor over years. Maybe I should just cerakote instead. I was told it has 1900 F heat resistance but I don't know if it will last on the headers. 
3.  I've noticed a couple things with my carbs last year when I rode it and this year started getting into it to address them and hence Im now looking into my options. When coming off a throttle and pulling the clutch, engine revs high and Ive never fully have been able to come off the choke. I'm chalking these up to my carb not being tuned properly. This year I can't get the bike to throttle without it dying. I've either A ran bad gas through it or B need it to be tuned correctly. I had a Kawasaki guy in my town Spokane WA to rebuild the carbs when I first got the bike and it ran well. I pulled them off this year and I spected them and I think He used new/cleaned stuff well so I don't think He did anything bad. I want to tune them myself though. I'm going to inspect the spark plugs and see if I was running lean or something. 
4. I also hear a clunking noise from the engine that goes away when I pull the clutch in. I think I've read that this is the starters bolts coming out slightly and need to tighten it up. (Confirmation?) 

gres6121 wrote:

I guess I should start with formulating a plan. 

1. Start with swap to gs11 swingarm and see how that feels. Make sure you get a twin shock arm not the mono-shock version (I believe asphalt has one)
2. Just repair front fork seals for now. Also replace "bushes" - given that you are a "big lad" you might want to consider uprated springs and possibly heavier oil . Also worth considering a "fork brace"
3. MSD upgrade I would suggest servicing the mechanical advancer then fitting a "DynaS" and "by-pass relay" (see link for the rational)                               Ignition by-pass relay W - KZRider Forum - KZRider, KZ, Z1 & Z Motorcycle Enthusiast's Forum
4. Exhaust recommendations? It depends what you want, personally I like the "Delkevic" 4-1 pipe like the pic below of Kelly's Ltd (these are sensible money and a good fit) Restoring the Jardin pipes you have will cost more and the Delkevic will look and sound better. Given the rarity of the Jardin system you can probably sell it for good money to someone looking to restore a Ltd to original

Suggestions

1. Rebuild brake callipers and master cylinders with new seals and pistons if necc
2. Fit braided brake lines
3. You could consider upgrading the front brake to twin discs
4. If you want bigger tyres you could have the stock wheels re-built with wider rims (possibly 3x18 and 4.5 x 18) this would mean all the original parts like brakes, speedo drive, wheel spacers etc would all still fit as intended

So a couple questions if anyone can help.

1. swingarm angle on newer bikes do what seems like a lot of anti squat swingarm angle 12* or more. Don't get hung up on "swingarm angles" too much, it's more important that when you are sitting on the bike that the lower frame rails are close to parallel with the road (the angle will sort itself) the modern bikes you are comparing to have "rising rate" suspension linkages which mean the ratio of wheel travel/shock travel changes through the travel of the swingarm. Also a little "squat" is a good thing on launch (the weight transfer to the rear improves traction, no squat = wheel spin) I don't really see the need for it because of the acceleration you would get on this engine unless I went to the 29mm makunis or something different sprocket sizes for more low end power, right? Changing the sprocket ratio's will indeed improve acceleration or top speed depending which way you go (don't over do it or it will be screaming at highway speed) The below link takes the guesswork out of it, you can punch in your wheel size and desired sprocket sizes, the calculator will then tell you what revs will be at different road speeds                                                                                                                                                                                                               Gearing Commander - Motorcycle Speed and Drive Train Calculator v7                                                                                                                                                                                              But I could easily do a bit more by extending shocks by 1-2". I like the slightly positive swingarm angle when on a stand but why is this a bad idea? Loss of stability in the front? A little "rake" is OK but overdoing it will have a negative impact on the steering geometry and stability (as stated above aim for the frame rails being close to parallel with the ground when you are sitting on the bike)  Is it a bad idea to just put on a larger gear sprocket in the rear for more low end performance?  I'd lose top end speed or what else? Strain on engine? There isn't really anything detrimental from changing the gearing, the above link will tell you how much speed you will lose
2. I have the 4-2 off and am debating just refurbishing them with cerakoted black/maybe grey on the mufflers and electroplating the headers along with the front fork tubes to be golden. Can you just put chrome instead of doing nickel to avoid silver look? I've heard nickel is the reason for the silver but don't know if chrome will still add that. I want a protective layer to prevent dicolor over years. Maybe I should just cerakote instead. I was told it has 1900 F heat resistance but I don't know if it will last on the headers. Cerakote will work fine on the headers (that's what I will be doing with mine) if the "prep" is good (surface blasted and cleaned)
3.  I've noticed a couple things with my carbs last year when I rode it and this year started getting into it to address them and hence Im now looking into my options. When coming off a throttle and pulling the clutch, engine revs high and Ive never fully have been able to come off the choke.This is likely the result of "air leaks" if the carb to head rubbers are original is is almost a given that they will be hard and cracked so won't seal correctly. Also check the condition of the vacum caps on the carbs.  I'm chalking these up to my carb not being tuned properly. This year I can't get the bike to throttle without it dying. I've either A ran bad gas through it or B need it to be tuned correctly. I had a Kawasaki guy in my town Spokane WA to rebuild the carbs when I first got the bike and it ran well. I pulled them off this year and I spected them and I think He used new/cleaned stuff well so I don't think He did anything bad. I want to tune them myself though. I'm going to inspect the spark plugs and see if I was running lean or something. 
4. I also hear a clunking noise from the engine that goes away when I pull the clutch in. I think I've read that this is the starters bolts coming out slightly and need to tighten it up. (Confirmation?) As previously mentioned, you say the noise goes when you pull the clutch which would suggest the noise is clutch or transmission related, possibly a worn clutch basket

Sorry I know this is a lot but this is my first bike and I've basically analyzed all I could and just need to start somewhere talking with knowledgable people on these things. Thanks a bunch for the quick responses and recommendations so far, I really appreciate it.  No issue with lot's of questions here (unless they involve tax returns, energy costs, yard restoration etc. If so you are in the wrong place )

asphalt900 wrote:

I don't know how to use the PM system here, big dummy i is. I see you're in Idaho, not that far from Kansas i guess. Call me 816-365-8687 Clay