KZR's Bikes of the Month for 2024

Got Any Ideas?

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09 Jun 2024 18:02 #900529 by Buffalo515
Replied by Buffalo515 on topic Got Any Ideas?
Tested float functionality with bowls off and they stop/allow fuel as they should. 

Have a few tiny cracks on the brim of some of the diaphragms. Don’t think it would prevent bike from starting and idling though. Also they operate fine when I blow compressed air through inlet passage, so should be fine. 

This couldn’t be something electric, timing, or elsewhere right? Since it has started a few times and idled for a couple seconds. 

At this point I kindve feel like I am missing a sneaky vacuum leak somewhere. 

Travis
Maryland
1981 GPZ 550 -gone
1984 GPZ 550
1985 GPZ 550

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09 Jun 2024 20:01 #900530 by F64
Replied by F64 on topic Got Any Ideas?
Yeah, put a timing light on it. You could have something electrical failing.

81-KZ440-D2.
Louis Dudzik's GM HEI ignitor conversion installed 2015 s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html
Motogadget m-unit blue installed 2017.
LIC, NY

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17 Jun 2024 16:17 #900904 by Buffalo515
Replied by Buffalo515 on topic Got Any Ideas?
I got the bike to run and idle. Any input of throttle and it dies…i unless I have the choke on then it will rev. The revs will hang a bit with the choke on like this. 

Tried blocking off part of filter unit with rag but didn’t help. Tried removing filter entirely but didn’t help. Nothing allows me to rev it. 

Been through the pilot passages over and over again. They are clear. 

Vacuum leaks don’t seem present, as no rpm change spraying starter fluid all over intakes/intake side of carb. 

Plugs are all sooted and a little damp except one that is just little bit damp. Spark is good in all plugs.

Travis
Maryland
1981 GPZ 550 -gone
1984 GPZ 550
1985 GPZ 550

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17 Jun 2024 18:01 - 17 Jun 2024 19:29 #900906 by F64
Replied by F64 on topic Got Any Ideas?
You could run a hotter plug. At least they won't foul.

Try vacuum syncing.. I had really bad rpm hanging when my carbs were out of sync. I saw that you bench synced but you may have some cylinders not breathing the same so try a vacuum sync

You may also verify your cam timing and spark timing are correct.

81-KZ440-D2.
Louis Dudzik's GM HEI ignitor conversion installed 2015 s3.amazonaws.com/gpzweb/Ignition/GPZgmHEImod.html
Motogadget m-unit blue installed 2017.
LIC, NY
Last edit: 17 Jun 2024 19:29 by F64.

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24 Jun 2024 15:55 - 24 Jun 2024 15:56 #901262 by Buffalo515
Replied by Buffalo515 on topic Got Any Ideas?
I appreciate everyone contributing their input! But I think I’ve reached a point of about walking away from the bike for a few weeks lol. It will start, idle quite nicely for maybe 10-20 seconds then cut out. Any tiny throttle input kills it. 

I put new intake boots in with new o-rings. I cleaned the internals once again….I promise all passages are very clear. 

I checked timing chain. It was off a few teeth but setting to correct position did not help. 

Brand new filter housing and filter.

I had hopes of trailering the bike with me for a TN mountain trip this week but looks like the bike and trailer are staying home.  

Travis
Maryland
1981 GPZ 550 -gone
1984 GPZ 550
1985 GPZ 550
Last edit: 24 Jun 2024 15:56 by Buffalo515.

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  • Scirocco
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  • Never change a running system
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24 Jun 2024 18:27 - 24 Jun 2024 18:31 #901272 by Scirocco
Replied by Scirocco on topic Got Any Ideas?

I checked timing chain. It was off a few teeth but setting to correct position did not help. 


 
This "few teeth" off the cam timing can minimal bend some valves with a compression loss and un-sync carb vaccum.
Do yourself a favor and make a real statement strong compression, leak down and vaccum sync test!!!
Your testing and diagnosis work around like look and feel is bullsh** and gives you only some vaguely probably wanna be or could be results.
 
Last edit: 24 Jun 2024 18:31 by Scirocco.

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28 Jun 2024 18:54 #901472 by 1kz4me
Replied by 1kz4me on topic Got Any Ideas?
I’d say we’re assuming a lot here. First I agree with others that 7mm seems like a lot I’m i
used to 3mm. But I haven’t taken one of these apart. I’d say your not cleaning the carbs right or good enough. I like dipping carbs in chem dip for awhile, not overnight. Then I use a bunch of little brushes I have, some are torch tip brushes, other are gun brushes I even use a toothbrush. Gotta make absolutely sure everything port passage is clean. Not just blowing with air and saying you feel air out the other end. There are multiple passages within the carb some even act like Venturi to siphon fuel as air screw is adjusted. 

but you lost me when you said cam chain was off a few teeth, really wow, that’s kinda important. 

good luck 

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30 Jun 2024 04:34 #901524 by Rolf1976_KZ900
Replied by Rolf1976_KZ900 on topic Got Any Ideas?

I appreciate everyone contributing their input! But I think I’ve reached a point of about walking away from the bike for a few weeks lol. It will start, idle quite nicely for maybe 10-20 seconds then cut out. Any tiny throttle input kills it. 

I put new intake boots in with new o-rings. I cleaned the internals once again….I promise all passages are very clear. 

I checked timing chain. It was off a few teeth but setting to correct position did not help. 

Brand new filter housing and filter.

I had hopes of trailering the bike with me for a TN mountain trip this week but looks like the bike and trailer are staying home.  
 
If you can get it started and it dies when snapping  up throttle it is a true sign that fuel level is to low.Only 1mm too low will make this happen.
If the timinchain has jumped 1 thooth you will get low compression if you was lucky no damages to valves.
try to rise the fuel level a little

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