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305 running rough at low rpm
- Rustyhama
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It always runs pretty rough from cold but lately it's become very 'surgey' down at low revs, it's a bit of a pain to ride to work when it's obviously not happy. It's only a 10 minute ride which I don't think suits it well either.
I cleaned the carbs again last night, I removed the tube under the secondary main for the first time. They were both partially blocked with crud so it was good to get them clean. Everything thing else was clean and in good condition - diaphragms are new etc.
The one thing I need to replace is the carb intake boots. They are cracked and in pretty bad condition. I've tested them many times by spraying carb cleaner on them but I never get an increase in revs so not too sure.
Yes I am running pod filters and I know that makes me a dick but cafe racer style is what got me into motorcycles and KZ's in particular so I have to live with them now. I'm running bigger main and secondary main jets, pilot is stock. It runs fine with the throttle open so it's really just the pilot circuit I think.
Any thoughts or suggestions?
Hama
'82 KZ305-B1 Cafe Racer
'80 Z750E project
www.dotheton.com/forum/index.php?topic=59260.0
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- redhawk4
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Is there definitely no other source for pistons and rings, items from another model or the like? perhaps someone knows. For example a KZ650 is 62mm bore as opposed to 61mm on the 305, but I have no idea if the pistons are remotely the same.
1978 KZ1000A2 Wiseco 1075 kit
1977 KZ650B1
1973 Triumph Tiger TR7V
1968 BSA Victor Special 441
2015 Triumph Thunderbird LT
1980 Suzuki SP400
Old enough to know better, still too young to care
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- SWest
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- 10 22 2014
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Steve
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- Rustyhama
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Hama
'82 KZ305-B1 Cafe Racer
'80 Z750E project
www.dotheton.com/forum/index.php?topic=59260.0
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- TexasKZ
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Fuel level could be the culprit.
The sealers you used on the boots MAY have worked, at least where the sealer is. They could still leak where the carbs mount. It doesn't take much of a leak to screw up the low speed mixture.
Ignition timing will not affect the mixture, but it should be checked anyway. Once you have eliminated all other possibilities, what remains, no matter how improbable, will be the answer.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
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- Rustyhama
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Hama
'82 KZ305-B1 Cafe Racer
'80 Z750E project
www.dotheton.com/forum/index.php?topic=59260.0
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- SWest
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Steve
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- Rustyhama
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Hama
'82 KZ305-B1 Cafe Racer
'80 Z750E project
www.dotheton.com/forum/index.php?topic=59260.0
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- jdvorchak
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Those numbers, 6 and 9, would be enough to cause a lean condition in every RPM range.Rustyhama wrote: I have checked the float bowl levels with the clear tube test. It's supposed to be 1.5-3.5mm below the join. My right carb is at 6 left at 9, when I get time, probably in the new year, after our family camping holiday, I'll sort that out and double check the valves. Meanwhile she's parked up. Have a good Christmas everyone!
Don't fix it until it's broken.
John
83 KZ550M1
83 KZ1100LTD
Also own:
2010 Harley Ultra Classic Limited, 2008 Harley low rider 71 CB350/sidecar
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- Rustyhama
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Luckily I re-read my post from late last year re the float levels. When I took them off the bike 1 was fine the other was at about 9mm. They are both perfect now at about 2mm. I rechecked the valve clearances. The intake valves were a little tight so I adjusted them. That got it running better but still surgey at low RPM. So tonight I decided to check the timing. I rotated the mounting plate about 2mm clockwise (I think that would retard it slightly) and that made it much smoother at lower revs. I took the mounting plate right off so I could inspect the timing advancer - I think this could be part of the problem. Both sides of the mechanism are floppy and the whole thing feels loose. I would expect it to feel much firmer to hold the timing steady until the RPM increase sufficiently for it to start to rotate. It looks worn where the springs attach and where the tangs meet the notches in the shaft. Can anyone confirm that this should be firm? Does anyone have any tips on refurbishing these or does it need to be replaced?
Cheers
Hama
Hama
'82 KZ305-B1 Cafe Racer
'80 Z750E project
www.dotheton.com/forum/index.php?topic=59260.0
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- undiablo
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Kawasaki KZ 750/4 LTD 1981
Kawasaki KLR 650 2011
Argentina - Buenos Aires
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- SWest
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Steve
kzrider.com/forum/2-engine/600671-ignition-timing#703561
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