KZ900 opinions please
- Kapahulu
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122, 105, 115, 115
I poured motor oil in cylinder #2 and it didn't change the compression.
Also used the morgan carbtune to check the mixture at low rpm's.
I checked the ignition timing (dyna S) and it's okay. Also checked the ignition advancer and it seems to be working fine.
The bike doesn't idle well after first firing up, I can turn up the idle to keep it from dying but then when the motor is warm it idles too high and I adjust the idle down. I bench synced the carbs, have not synced them with gauges yet, will probably do that next.
It has a 4 into 1 pipe, stock airbox with K&N, stock 26mm carbs, pilot jets 15 mains 117.5 needle on middle clip.
The bike looks great and I'd probably like to keep it. I would rather not spend the money for a rebore because I have many other motorcycles to work on. And if I decide to sell this one I don't think I'll get the rebore money back in the sale price. So I'm thinking maybe take the head off and get a valve job by a local mechanic (he's experienced, I know him well). Then maybe get new piston rings.
Will new rings and a valve job put enough life into this motor? If I get it rebored I might have to send the block to the U.S. mainland because the shop that used to bore motorcycle cylinders here closed about a year ago and the local auto shops I called say I have to bring the block in to see if they can bore it. Not confidence inspiring.
Resident experts please let me know what you think.
Thanks, Mike
1978 KZ1000, 1976 KZ900, 1975 H2, 1973 H1, 1973 H2, 1978 RD400, 1977 RD400, 1974 RD350
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- 4TheKZ1000
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did you have throttle wide open on compression check? if not you will get incorrect numbers.
how many miles are on bike? you might do good with a valve job and valve seals.
Those 26mm carbs are very small a restrict the bike.
You would notice a nice bump with a set of 28mm carbs.
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- 650ed
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- Check the valve clearances and adjust if needed.
- Test for carb holder leaks. (let us know if you need instructions) Leaky carb holders absolutely ruin idle smoothness. If there are leaks replace the holders.
- Test the fuel level in the carb bowls using clear tube method and adjust if needed. (let us know if you need instructions)
- Synchronize the carbs using quality gauges or carb sticks. Bench synching will only get you to the ballpark; it will not ensure equal vacuum pull across all carbs.
Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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- Kapahulu
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All four carb holders were replaced when I fixed up the bike a couple of years ago.
Fuel level might be a problem. I have an extra float bowl and I think I'll turn it into a fuel level checker.
I think the next step will be to sync the carbs. I don't think that's going to add much power though, hopefully it will smooth out the idle.
1978 KZ1000, 1976 KZ900, 1975 H2, 1973 H1, 1973 H2, 1978 RD400, 1977 RD400, 1974 RD350
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- Jeff.Saunders
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Also, if the bike has been sitting a while, it's best to get the engine through a couple of heat cycles to free up piston rings as they can gum into the ring grooves.
If the engine has not been apart, it's worth running some SeaFoam or Ring-Free through the fuel for a tank or two - this can help free the rings and also remove carbon on the valve. ...and recheck the valve clearances AFTER 100+ miles of running the SeaFoam or Ring-Free through the engine.
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- KZJOE900
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Current project 76 KZ900 (This was a Vetter model)
76 KZ900
81 XJ550H SECA (Current Project)
82 XJ550R SECA
Past:
86 FJ1200
74 Z1900
72 CB450
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- Kapahulu
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Joe, you're right our bikes sound similar. My KZ900 runs great on the highway, street manners are okay too other than the idle fluctuation from cold engine to warm. My '78 KZ1000 more fun to ride though, it just has more grunt on the bottom end.
I recently fixed the fuel level on my H2. I had the float levels adjusted per specification but the bike didn't run well on the bottom end. A clue was that two carb bowls leaked fuel at the gasket. So I adjusted the floats to get the fuel levels lower. That made a great improvement. H2's don't have a drain screw on the bowl so I don't know what the fuel level is, but the bike's performance is much better.
I have a spare float bowl for a KZ and will hookup a clear hose to it, then check the fuel level for each carb.
1978 KZ1000, 1976 KZ900, 1975 H2, 1973 H1, 1973 H2, 1978 RD400, 1977 RD400, 1974 RD350
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- Z1Driver
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- love the smell of triple smoke
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What do the plugs look like?
Blue 1975 Z1B
Red 2009 Concours 14
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- Kapahulu
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1978 KZ1000, 1976 KZ900, 1975 H2, 1973 H1, 1973 H2, 1978 RD400, 1977 RD400, 1974 RD350
2strokeworld.com
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- Z1Driver
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- love the smell of triple smoke
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Kapahulu wrote: Plug #3 is sooty. The other three look about the same, tan colored. The bike has emgo coils.
If you screw the air bleed screw in or out on #3 carb, any RPM difference? On my Z1 it's #2 giving me a hard time with a sooty plug with the other 3 burning clean. (light tan) I'm going to clean the snot out of carb #2 and see if anything changes.
Last time I sync'ed the carb's I could screw #2's air bleed all the way in or out with no RPM change. the Bike ran good though. I would rather have a rich situation rather than a lean one.
I should recheck the float level on #2 for grins.
Best, Tim
Blue 1975 Z1B
Red 2009 Concours 14
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- Kapahulu
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1978 KZ1000, 1976 KZ900, 1975 H2, 1973 H1, 1973 H2, 1978 RD400, 1977 RD400, 1974 RD350
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- Old Man Rock
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All it takes is little carbon on the valve seats and she won't close all the way thus lower compression measurements. Simple Valve seat lap can clean this up.... Lapping tool and compound at any auto parts store...
As for performance..... carbs, ignition spark/timing, valve clearances, electrical spark can all be associated to under par performance / expectations. Normally with a vacuum leak, she'll pop on ya...
Another review for rich/lean, condition of plugs (base ring, strap, porcelain)....?
Regarding the Morgan color tune, you perform all 3 adjustments/verification's and they came out right...?
1976 KZ900-A4
MTC 1075cc.
Camshafts: Kawi GPZ-1100 .375 lift
Head: P&P via Larry Cavanaugh
ZX636 suspension
MIKUNI, RS-34'S...
Kerker 4-1, 1.5" comp baffle.
Dyna-S E.I.
Earls 10 row Oil Cooler
Acewell 2802 Series Speedo/Tach
Innovate LC1 Wideband 02 AFR meter
Phoenix, Az
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