1978 kz650d (sr) starting/idle problems

hey guys, im having quite the problem with my kz650.

i bought it a few weeks ago, and it took me 50 miles to my girlfriends apt complex and quit. on the way home, it stalled when just idling at an intersection, but started up again. in the parking lot, it died and wouldnt start again. ever since, ive been trying to get it to work. i had run it with old gas, so i cleaned the carbs. i put a new battery in it also.

heres its current condition:

1) it slowly slowly leaks gas out of one of the overflow tubes. i need to replace the needle and seat, where is the best place to get these? carb rebuild kits? also, i noticed when taking apart the carbs that two of the pilot adjustment screws were longer than the other, or really, theyre all the same size, but two of them seemed lopped off at the end by an eighth inch or so and end bluntly. is this really bad?

2) the only way i can get it started is by jumping it with my car (not on), turning the idle adjustment screw (the one that opens up the throttle slides a wee bit on the inside) way in, and giving a tiny bit of throttle. any choke at all seems to kill my chances. then, this is the important part. it will, not surprisingly, start to idle very high. also, it will tend to not decelerate at all if i gun it. so, i reduce the idle with the screw until about 1 rpm. now, when i gun it, it barely barely decelerates. i then leave it alone after it achieves idle again. after a bit, however, the engine starts to accelerate, so i turn the idle screw out a little more. now, when i gun it for a sec, it decelerates, but slowly. then, after maybe 15 minutes of running, the engine accelerates again (on its own, i mean), i reduce the idle down to normal with the screw, and when i gun it, the engine will decelerate almost normally. like, it will take about 3 or 4 seconds to decelerate from 5 rpm to idle. it then runs fine, i can get around town, and im very happy. however, the idle screw is now way out.

now this is the more important part. if i stop it, it will start right back up again great. however, if i let it alone for more than a half hour, the whole process starts over again, and i have to jump it, turn the idle screw way in, and use a little throttle.

it seems that engine temperature affects the idle. however, i would think that i should never have to change that idle screw. if its idling, and i turn the bike off and come back a half hour later, it should start right back up, right? what could possibly change?

3) also, any ideas on how to change the pilot adjustment screws easily? its so freaking hard to get my hand in there, and i have to use a bit for a multihead screwdriver to adjust them. talk about a pain...

sorry for the longest post ever. the local mechanic knows nothing about old bikes, and you guys are my only resource. i tried and tried to search the archives and find a similar situation, but couldnt. thanks for any ideas you have, guys.

jeff

ja347 wrote:

hey guys, im having quite the problem with my kz650.

heres its current condition:

1) it slowly slowly leaks gas out of one of the overflow tubes. i need to replace the needle and seat, where is the best place to get these? carb rebuild kits?

Z1 Enterprises

also, i noticed when taking apart the carbs that two of the pilot adjustment screws were longer than the other, or really, theyre all the same size, but two of them seemed lopped off at the end by an eighth inch or so and end bluntly. is this really bad?

yes, the tip appears to be broken off, probably inside the carb. You may or may not be able to fix this. You may wind up buying ebay carbs.

2) the only way i can get it started is by jumping it with my car (not on), turning the idle adjustment screw (the one that opens up the throttle slides a wee bit on the inside) way in, and giving a tiny bit of throttle. any choke at all seems to kill my chances. then, this is the important part. it will, not surprisingly, start to idle very high. also, it will tend to not decelerate at all if i gun it. so, i reduce the idle with the screw until about 1 rpm. now, when i gun it, it barely barely decelerates. i then leave it alone after it achieves idle again. after a bit, however, the engine starts to accelerate, so i turn the idle screw out a little more. now, when i gun it for a sec, it decelerates, but slowly. then, after maybe 15 minutes of running, the engine accelerates again (on its own, i mean), i reduce the idle down to normal with the screw, and when i gun it, the engine will decelerate almost normally. like, it will take about 3 or 4 seconds to decelerate from 5 rpm to idle. it then runs fine, i can get around town, and im very happy. however, the idle screw is now way out.

These problems could be due to the broken tips

3) also, any ideas on how to change the pilot adjustment screws easily? its so freaking hard to get my hand in there, and i have to use a bit for a multihead screwdriver to adjust them. talk about a pain...

The carbs probably need removal and cleaning. It's easy (I thought it was anyways)

sorry for the longest post ever. the local mechanic knows nothing about old bikes, and you guys are my only resource. i tried and tried to search the archives and find a similar situation, but couldnt. thanks for any ideas you have, guys.

jeff

Good luck !
Kent

Get a manual...it's a starting place. I ebayed one JUST the other day.

You need a good carb going over. Your right, no turning of the Idle screw should be needed once set. Sounds like something is blocking fuel flow.

I will usually need the choke most first start up of the day. Pulling it all the way up and fuel valve to prime if that positions available.