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Followup To
Question -
i may have asked this question before but never got your answer but i own a 1978 kz 1000 ltd and need to know what jets i should use. at the moment the bike is stock with 2 into 1 pipes and k&n filters. i believe i am getting to much fuel because my plugs get black from carbon and the bike floods easy.as far as jet changeing what would you use.
Answer -
Hi Edward,
Carb tuning is not easy. I cannot explain the specific jets needed for your LTD's carbs, but I may be able to help you find a close jetting set-up.
You'll likely buy several sets of jets and spark plugs before you're done tuning. You can clean and reuse plugs and jets.
You'll need a float gauge or Vernier calipers for measuring float heights. I'll need to know float heights before tuning. Do know how to take the measurements? Do you have access to carb synchronizing tools? Let me know so I can give you resources for obtinaing these tools.
I'll need to know cylinder compression of each cylinder. Are valve clearances within spec? Valve clearances and compression must be within service limits before carburetors will work properly ("Very Important").
I'll need to know how many "turns out" each fuel screw is adjusted to.
I'll need to know the sizes of all jets currently in use, and clip positions on jet needles.
Are the needle jets worn? You'll need to measure the inside diameter of each jet to check for wear. These openings wear in an oblong shape from the jet needle riding in and out of them. When they wear, they allow excessive fuel to pass resulting in excessive fuel consumption and fouled plugs. Check this and let me know.
As I said, carb tuning is a bit involved. There's a lot to check. Do the best you can and try and answer my questions. We'll get it close.
Respectfully,
Mark Shively
thank you Mark but you now have me in a area that i have no idea about as far as valve clearances and such. as i mentioned before and i don't know if it will help but i was told that i am getting to much fuel and that is why my plugs are fouling out and i also know that i have 120 jets and the book calls for 107.5. i was hopeing you would say try 110 or so but now i see it is more involved. do you think or know of anywhere that rebuilds these type of carbs. i wouldnt be able to handle this job myself
AnswerEdward,
I gave you the worst case scenario to help you understand what's involved. As a tech, I would know the above intel before doing the work in my shop. Taking the time to check valves and compression actually saves time and money in the long run. It's fruitless to tune carbs when the engine is in poor condition.
You can simply change to smaller jets and note performance changes. Read spark plug colors to learn if smaller jets are needed. You may have to change main jets 2-3 times until you get desired performance.
If the changes produce undesirable results, check the things I've mentioned and repair accordingly.
Send me an email:
mshively1@woh.rr.com
I'll return numerous files on carb tuning, cleaning, synchronizing, and more. (Free email services such as Hotmail and Yahoo do not receive large files.)
Respectfully,
Mark Shively
