77 kz 650 carb problem

Kinda new to this game bought a 1977 kawasaki kz650 going to do a bobber build but I ran into a little issue, I took off the airbox to checkout the carbs turned the bike on and found that one of my carbs is sucking in close to nothing and two feel a little weak and the good one turns off(obviously) when I cover it. My guess was maybe dirty carbs and need redone. Just looking to see if anyone has ran into this problem or if they have clues to a solution???

Sounds like they need to synchronized. You can do it with a homemade manometer.

Is that cylinder running? Check the header pipes to see if all are getting equally hot. Also, should check the valve clearances, could be tight keeping them open.

Have you given it a complete clean and service - set timing, checked plugs & valves, compression etc? I'd give it a thorough clean and inspection. Grab a Service manual and a notepad and start there.

What I' getting at is that what appears to be carbs could be any number of things and at this stage you need to know what's right and what isn't rather than hoping it's all OK and trying to fault find one symptom at a time. A complete service and compression check should take you a full evening and at the end of it you will know your new bike a lot better.

I own one of these too, if you haven't cleaned the carbs....and the PO says they were clean.....or the bike ran great....stop what you are doing and do what Teazer and Deacon said.

Clean carbs, set/check timing (could be that points are out of spec or off) change plugs because they are cheap, and if you need help with doing the valves, its a bit more of a PITA than some of the old bikes, because the shims are under the buckets, I can help you out too.

Thanks for the advise guys, Im in college so kinda sucks on time, but winter is coming up so perfect time to tear shit up.. also thinking about getting it running good and selling to get something smaller, kz650 is a little rough on a 5'5" 140lb guy like me haha

Try to avoid the temptation to tear parts off unless we are talking removing drain plugs to change oil or filter boxes to check a filter. Bikes in bits have a habit of turning into scrap metal with no great value.

If the bike runs, focus on making it run perfectly by doing a complete service. Start by getting it clean and then work through stuff bit at a time. Plugs are cheap to replace and so are plug caps. Fresh oil and fresh gas are a must. Clean the carbs and repeat and then clean them again. What once was considered clean enough will soon be seen as filthy.

Your issue on lack of suction could be more serious, so you might start with a compression test on all 4 pots to see what's up and then check valve clearances. They are not so easy to adjust but are easy to check.

Look at is as a research project. The first step is to determine the current state and that will take a little work. Step two is to determine the desired state - that's where the manual comes in and third step is to work out how to get it from A to B.

sansal10 said:

Thanks for the advise guys, Im in college so kinda sucks on time, but winter is coming up so perfect time to tear shit up.. also thinking about getting it running good and selling to get something smaller, kz650 is a little rough on a 5'5" 140lb guy like me haha

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I hear ya, I'm 5'7" and just a tad heavier than you, that thing sits pretty tall. My lady rides our 77' KZ650 and she's on tip toes, I lowered the seat and changed the suspension a bit and that seemed to work great. And I agree with Teazer on the scrap metal part...especially if time is an issue. I'd maybe consider soaking the cylinders a little too...maybe some Marvel Mystery Oil down the spark plug holes and let it sit at least over night, could be some stuck rings too. I think yamaha makes something called "ring free" as well, I don't know much about it though. If you need help with the valve clearances just ask. We'll help you get it sorted, but you'll need a few hours for it (hopefully you have a shop nearby that still has the shims in the sizes you need) Otherwise Z1 enterprises has them.

MotorbikeBruno said:

I hear ya, I'm 5'7" and just a tad heavier than you, that thing sits pretty tall. My lady rides our 77' KZ650 and she's on tip toes, I lowered the seat and changed the suspension a bit and that seemed to work great. And I agree with Teazer on the scrap metal part...especially if time is an issue. I'd maybe consider soaking the cylinders a little too...maybe some Marvel Mystery Oil down the spark plug holes and let it sit at least over night, could be some stuck rings too. I think yamaha makes something called "ring free" as well, I don't know much about it though. If you need help with the valve clearances just ask. We'll help you get it sorted, but you'll need a few hours for it (hopefully you have a shop nearby that still has the shims in the sizes you need) Otherwise Z1 enterprises has them.

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Thanks for all the advise guys, Im hoping to get it to a shop this weekend or so do get a compression test to see if there's any problems there, really hoping its not and hoping its just dirty and needs adjusted guess got to hope for the best and expect the worst lol...