KZ engine trouble

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27 Jul 2006 07:15 #65114 by vikfelix
KZ engine trouble was created by vikfelix
Was out riding my 81 305 csr last weekend when the engine died on me at a stoplight. After that it wouldn't start. Let it sit for about 10 min. and it started back up but ran really rough. So I cleaned the carbs, checked the timing and advancer, compression(125 on each cyl) and valve clearance(which was good), but it still runs poorly. The left cylinder spark plug is a tan color, but the right cylinder is black and wet. The right cylinder also back fires alot with flames popping out of the exhaust sometimes(it has shorty mufflers on it).
Sorry this is so long. Any ideas on what to do next?
Thanx!



Post edited by: vikfelix, at: 2006/07/27 16:05

Post edited by: vikfelix, at: 2006/07/27 19:34

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28 Jul 2006 14:00 #65470 by BARNEYHYPHEN
Replied by BARNEYHYPHEN on topic KZ engine trouble
Think I'd start with new plugs. Disconnect plug wires from coils and plug caps, if possible, trim wires slightly at both ends and reattach. Clean all plug related electrical connections before reassembly. tart, ride then report back.

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28 Jul 2006 14:23 #65475 by Biquetoast
Replied by Biquetoast on topic KZ engine trouble
BARNEYHYPHEN wrote:

Think I'd start with new plugs. Disconnect plug wires from coils and plug caps, if possible, trim wires slightly at both ends and reattach. Clean all plug related electrical connections before reassembly. tart, ride then report back.

I agree. If symptom recurs, try reversing the spark wires to see if the problem goes with the wire. Then you know it's the coil or spark-related on the one side.
If not, well then we go down a different road...

(1.) '75/'76 KZ400D - Commuter
(2.) '78 KZ750B3 Twin - Commuter
(3.) '78 KZ750B3 Twin - Commuter
(4.) '75 KZ400D - Sold
kz750twins.com

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28 Jul 2006 19:14 #65538 by vikfelix
Replied by vikfelix on topic KZ engine trouble
Ok, put in new plugs, same thing, switched the coils, same thing(this rules out the wires and boots cuz I switched them with it to). Switched the condensors, same thing. While testing I noticed it backfires thru the carb and it is now blowing white smoke out the exhaust excessivly at times when running. After I stop it, it smokes out the carb and exhaust! This is all only on the right cylinder, the left seems to run fine. Think I roasted the engine?? Any more help would be appriciated.

Thanx alot guys!!

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29 Jul 2006 00:27 #65596 by donthekawguy
Replied by donthekawguy on topic KZ engine trouble
Sounds like you might have a busted ring or bad head gasket. It should be too hard to fix.

Rathdrum Idaho
1971 Kawasaki g3ss
1972 Yamaha R5 350
1965 Suzuki Hillbilly
1964 Yamaha 125

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29 Jul 2006 04:17 #65605 by Biquetoast
Replied by Biquetoast on topic KZ engine trouble
donthekawguy wrote:

...It should be too hard to fix.

Somehow, I think that's a typo...

(1.) '75/'76 KZ400D - Commuter
(2.) '78 KZ750B3 Twin - Commuter
(3.) '78 KZ750B3 Twin - Commuter
(4.) '75 KZ400D - Sold
kz750twins.com

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29 Jul 2006 04:48 #65608 by trippivot
Replied by trippivot on topic KZ engine trouble
the cylinder has loaded up with unburned gook.
sounds carb related
re set the float on the right side and let it all burn off.

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29 Jul 2006 18:51 #65762 by vikfelix
Replied by vikfelix on topic KZ engine trouble
All right, latest update. Checked float levels and adjusted, let it run awile and now she idles like a dream. Checked the plugs and they now look good. Put it all back together and she started right up and idles great. Then I took her for ride and once I get going it starts to sputter and backfire and wont get up over 20mph(no smoke though). Got home and the bike still idles great. I checked the carb sync and they still are all good. One question though, I'm using an old set of automotive vacuum gauges and homemade adapters to sync the carbs, they do flutter a bit but I think I can get them pretty close. Would out of sync carbs cause this many problems? Thanx alot guys!
jk

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29 Jul 2006 19:04 #65773 by Biquetoast
Replied by Biquetoast on topic KZ engine trouble
vikfelix wrote:

...Would out of sync carbs cause this many problems? Thanx alot guys!
jk

I don't think so, not if it idles that well.
The thing about 20mph... is that about 3500rpm? Is this where you are off the pilot jets and on to the main jets? Sounds like you got some gunk in there. You might have got some of it out in your last adjustment. Do you use filters on your fuel lines?

(1.) '75/'76 KZ400D - Commuter
(2.) '78 KZ750B3 Twin - Commuter
(3.) '78 KZ750B3 Twin - Commuter
(4.) '75 KZ400D - Sold
kz750twins.com

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30 Jul 2006 19:51 #65976 by vikfelix
Replied by vikfelix on topic KZ engine trouble
Allright, took the carbs apart and dipped them this time(vs just spraying em). Set em up, went for a ride. Idles good, Runs good at high speed, but hesitates in between. Is there a way to adjust this out? I'm not real good with Keihin carbs, I've only worked on Mukuni's in the past. Thanx for any help!


jk

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