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Author Topic: KZ-440 stalling while slowing down  (Read 595 times)

Offline greenearwax

  • Posts: 8
KZ-440 stalling while slowing down
« on: Jul 10, 2017, 14:50:46 »
My KZ-440 started having an issue recently where I will be going around 60 miles and when I pull the clutch in and shift down to 1st while stopping the engine will cut out. Then it doesn't start back up either. I had to wait about 15 minutes on the side of the road before trying again, at that point it started right up.

From my very limited experience it seemed like the engine flooded, after doing some research I figure I should try cleaning the float valves?

However after doing some research some people had a similar issue due to engine starvation rather than flooding. If that's the case I should clean the vacuum line, tank vent, etc.

I don't have a lot of experience with small engines but i'm pretty good mechanically and confident in my ability to do any fixes with the user manual and youtube but I could use some advice as to what the problem is or how to tell better.

How do I know if its flooding or starved and what's the best way to go about fixing it?

Offline vwrabbit

  • Posts: 102
Re: KZ-440 stalling while slowing down
« Reply #1 on: Jul 19, 2017, 16:38:58 »
If it's starved, the plugs should show lean.  Pull the plugs and see what they look like.  It does sound like starvation.  The 15 minute wait is probably the bowls filling back up.

https://www.tuningmatters.com/wp-content/uploads/2014/07/spark-plug-lean-rich-optimal-640x360.jpg

Offline greenearwax

  • Posts: 8
Re: KZ-440 stalling while slowing down
« Reply #2 on: Jul 19, 2017, 17:10:04 »
If it's starved, the plugs should show lean.  Pull the plugs and see what they look like.  It does sound like starvation.  The 15 minute wait is probably the bowls filling back up.

https://www.tuningmatters.com/wp-content/uploads/2014/07/spark-plug-lean-rich-optimal-640x360.jpg

I replaced the plugs here a few days ago and when I pulled them they actually looked like it had been running rich, but they very well could have been in there for a decade but ill check the new ones in a bit.
After talking to a few friends my plan going forward is going to be to clean and synch my carbs as well as clean up my points and replace the condenser. I haven't done either before so that should be fun.

Offline vwrabbit

  • Posts: 102
Re: KZ-440 stalling while slowing down
« Reply #3 on: Jul 19, 2017, 17:13:03 »
Are you running the stock airbox still? 

Offline greenearwax

  • Posts: 8
Re: KZ-440 stalling while slowing down
« Reply #4 on: Jul 19, 2017, 17:19:05 »
Yeah its pretty much completely stock.
I'm thinking as the engine gets hot that its causing an ignition issue. The last time it died I pulled the plugs and the spark looked week but it was hard to say because of the sunlight. But I could be totally wrong, I don't have a lot of experience.

Offline vwrabbit

  • Posts: 102
Re: KZ-440 stalling while slowing down
« Reply #5 on: Jul 19, 2017, 17:23:55 »
Look for some 1/4" clear fuel line to run from the petcock to the carb T.  If it's starving for fuel, that line will be dry when it dies.  Easiest way to verify fuel starvation. 

Offline coyote13

  • Posts: 1152
Re: KZ-440 stalling while slowing down
« Reply #6 on: Jul 19, 2017, 17:23:58 »
Check your battery, if it isn't holding a FULL charge it could be dying on deceleration as a result, can cause all sorts of little problems and you end up chasing your tail trying to tune carbs ignition etc on a bad battery.
Half the fun's in the get there...

Offline vwrabbit

  • Posts: 102
Re: KZ-440 stalling while slowing down
« Reply #7 on: Jul 19, 2017, 17:25:24 »
Good call on battery.  That could be a regulator/rectifier issue also if the battery is dying.

Offline greenearwax

  • Posts: 8
Re: KZ-440 stalling while slowing down
« Reply #8 on: Jul 19, 2017, 17:25:48 »
Check your battery, if it isn't holding a FULL charge it could be dying on deceleration as a result, can cause all sorts of little problems and you end up chasing your tail trying to tune carbs ignition etc on a bad battery.

I should've said, I replaced the battery over the weekend, it was kinda flat but now its at 12.75v with the bike off and up to 14v when I give it throttle.

Offline vwrabbit

  • Posts: 102
Re: KZ-440 stalling while slowing down
« Reply #9 on: Jul 19, 2017, 17:29:05 »
That rules out battery then. 

Offline VonYinzer

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Re: KZ-440 stalling while slowing down
« Reply #10 on: Jul 19, 2017, 17:39:49 »
Sync the carbs and set timing. Adjust the clutch as well. Make sure everything is at factory settings.
Like a river that don't know where it's flowin'
I took a wrong turn and just kept goin'

Offline advCo

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Re: KZ-440 stalling while slowing down
« Reply #11 on: Jul 19, 2017, 18:35:16 »
Leaking needle and seat and/or leaky float can cause this, as well. Old carb on the CT90 has a hole in the float and you have to blip the throttle to keep it running when coming to a stop.
"He broke the mirrors off his Cadillac, 'cause he doesn't like it looking like he looks back."

74 CB360 - Luna - http://www.dotheton.com/forum/index.php?topic=63294.0
82 GS550L - Tracker-ish - http://www.dotheton.com/forum/index.php?topic=67229.0 - Sold
74 XL350 - The Turd - http://www.dotheton.com/forum/index.php?topic=70252.0
Suzuki FA50 "No-Ped" - http://www.dotheton.com/forum/index.php?topic=71189.0
73 Suzuki RV125 -http://www.dotheton.com/forum/index.php?topic=73875.0

Offline greenearwax

  • Posts: 8
Re: KZ-440 stalling while slowing down
« Reply #12 on: Aug 07, 2017, 11:07:56 »
So here's an update on the issue.
I managed to figure out that im losing spark as the engine heats up.
After asking around most people said that that was probably caused by an ignition coil breakdown. after replacing it i'm still having the same issue of no spark once it warms up.
I don't have a totally accurate wiring diagram because apparently my model bike was only made in small quantities? (kz440 g1). and there are differences from the other kz440s such as my bike has a pickup coil rather than points. im not sure what else though. All the comments and help is appreciated! thanks guys!

edit: Im thinking it might be the transistor igniter? not really sure though
« Last Edit: Aug 07, 2017, 11:10:04 by greenearwax »

Offline vwrabbit

  • Posts: 102
Re: KZ-440 stalling while slowing down
« Reply #13 on: Aug 07, 2017, 11:38:19 »
Should be able to find another igniter on fleabay for about $35-50 (if no one has one here), cheaper if you are patient.  I've heard that a 750 twin will work.  Only use one side obviously. 

Offline advCo

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Re: KZ-440 stalling while slowing down
« Reply #14 on: Aug 07, 2017, 12:08:04 »
Your original issue was "stalling while slowing down" or coming to a stop, nothing to do with when the bike warms up. If the coils didn't fix it its unlikely that its an ignition problem.

Here's a free test you can do. Go for a ride and try to reproduce the problem. Right before the issue usually happens, turn the petcock to OFF position, and see if it goes back to normal.

I would check your float height and float valve to make sure they are set and working properly before you keep throwing parts at it.
« Last Edit: Aug 07, 2017, 12:10:07 by advCo »
"He broke the mirrors off his Cadillac, 'cause he doesn't like it looking like he looks back."

74 CB360 - Luna - http://www.dotheton.com/forum/index.php?topic=63294.0
82 GS550L - Tracker-ish - http://www.dotheton.com/forum/index.php?topic=67229.0 - Sold
74 XL350 - The Turd - http://www.dotheton.com/forum/index.php?topic=70252.0
Suzuki FA50 "No-Ped" - http://www.dotheton.com/forum/index.php?topic=71189.0
73 Suzuki RV125 -http://www.dotheton.com/forum/index.php?topic=73875.0

Offline greenearwax

  • Posts: 8
Re: KZ-440 stalling while slowing down
« Reply #15 on: Aug 07, 2017, 12:48:30 »
Your original issue was "stalling while slowing down" or coming to a stop, nothing to do with when the bike warms up. If the coils didn't fix it its unlikely that its an ignition problem.

Here's a free test you can do. Go for a ride and try to reproduce the problem. Right before the issue usually happens, turn the petcock to OFF position, and see if it goes back to normal.

I would check your float height and float valve to make sure they are set and working properly before you keep throwing parts at it.

Ill definitely check the floats next. but I should have mentioned that the issue has gotten worse where at one point it happened while I was cruising at like 5000rpm. Last night it quit when I just let it run in the driveway for 10 minutes so I definitely think its temperature related (that's when I checked spark and there was none). Maybe it was just a coincidence that the first few times it happened it was while I was slowing to a stop. not really sure.

Offline vwrabbit

  • Posts: 102
Re: KZ-440 stalling while slowing down
« Reply #16 on: Aug 24, 2017, 12:16:44 »
Any luck tracking down the problem?