Recently made a purchase (what i feel is a steal) from a coworker for a 1978 Kz1000 LTD, along with a 71 honda cl100. The KZ he never really did much with besides finished putting together from what a PO had torn down and then just drove around town till putting in storage for a few years. Fastforward to now i was able to fire it up on full choke but the moment choke is off it dies like it starving for fuel. Been cleaning the carbs and trying to eliminate issues as i can seeing how the cold season is upon us up here and wont be able to get it out much. But will continue to work on it and clean it as much as my wife and wallet will allow.
The following user(s) said Thank You: Nessism, howardhb
Hi if the bike has stood a long time the petrol has probably gummed up in the carbs blocking the jets. It would fire on the starter choke jet but as soon as you release the choke norhing being drawn up from the main or pilot jets. An easy fix with a rhin wire and some carb cleaner once they are removed from the bike that is. I found it much easier to warm the intake rubbers first with a hair dryer, makes them flexible and less likely to split when jiggling carbs free. Hopefully you will sort it
Thanks, I have pulled the carbs off the bike and pulled the bowls off along with all the floats and jets and cleaned them all, along with the tank and petcock. But it has the same results and before as fires and runs on choke but dies instantly when it's taken off.
Frustrating. Are the carb sliders set to correct idle gap? With them off the bike slide a bit of wire about .7 of a mill under the slide between it and the base. You should be able to see light shining through as you hold them up. Another thing you could look at are the air mixture screws they should all be at least one turn out from the stop. Make a note of where each one was prior to adjustment, so you can put it back if needed. Are the idle jets blocked? Again just blow through them with a tube. From the pic the airbox is removed, try it in place if you have it may increase the vacuum needed to draw the petrol up the jets. Let me know how you get on.
i have the carbs off again and cleaned the jets again, the slides are up id say 1/16" or 1.5mm i believe so ill lower them. The airbox was off when i purchased it but it came with it as well as a vast array of other spare parts, but i reinstalled when i first started working on it because one of the main thing i picked up from scouring forums in that the carbs hate not have the restrictions from it without other mods and a bunch of adjustments.
Thats true. Keep trying one thing at a time and you will get there. Make a note of how many turns you adjust each slider, so you can restore them to original settings if needed. Hows your compression? While the carbs are off place the palm of your hand over the intake on the cylinder head and spin the engine with the plugs un you should feel a good suction and also if it blows against your hand that means your valves are leaking. Mine did that and i found that the cam had zero clearance so was keeping valve open. Was quite easy to get thinner shims. Hows your spark? Is the ignition timing spot on? All or anything these things together could cause the issue i changed my ignition back to points from electronic i find them much easier to work on. I can detail the timing process here if you need?
i have not checked the voltage or anything like that i have pulled the plugs and they all spark and appear good to the eye but havent actually measure or anything. With the carbs off i turned it over and seem to have great suction with no blow back like your saying, so i am hoping that means the valve and shims are correct. i have readjusted the slides but with work and all have had time to throw them back on yet and test for results yet.
If it starts on the choke then the ignition timing cant be that much off. So with good compression suction and a healthy spark at the correct time then concentrate on the carbs as the culprit. I will be stripping my carbs down too soon as ironically enough after a long ride out it now wont fire up! I suspect flooding and have ordered some float needles from our oriental friends. Funny how fine one day and nothing the next but they are old grumpy things and we put up or sell up i suppose