Mikuni CV BS34 lean but rich?
- otakar
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74 Z1-A stock
76 KZ-900 Totaly stock vice MAC pipe
77 KZ-1000A stock
78 Z1-R 100%MINT 500 original Mi.
78 Z1-R Yoshi 1103 kit stage 1 cams Yoshi pipe. Etc
79 KZ-1300 (1400)
80 KZ-1300
81 Scratch built GPz1150R
82 KZ1000
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- Patton
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jga2z wrote:
Am I beating a dead horse?I rechecked the coils, 2.6-2.7 ohms primary 12.3K ohms secondary, batt voltage @coils, will jump 5/16-3/8 air gap on all 4.
Doesn't this seem like it should work?
To move on from ignition I need this question resolved.
Clymers says coil specs are 1.8-2.8 pri, 10.4K-15.6K sec, and I saw a post which said air gap test should be about 1 cm.
Can I move on to fuel/carbs?
Visually observed fat blue sparks across the plug tips likely evidences acceptable ignition. Am thinking the ignition timing isn't owner adjustable on this bike. However, may verify proper function of the timing advancer by watching the timing marks under a strobe-type timing light to confirm it's moving quickly back and forth as rpm is varied by blipping the throttle. The advancer might require lubing or both cleaning and lubing.
Should perform a compression test AND assure all valve clearances are within specs BEFORE addressing the carbs.
Good Fortune!
1973 Z1
KZ900 LTD
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- otakar
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74 Z1-A stock
76 KZ-900 Totaly stock vice MAC pipe
77 KZ-1000A stock
78 Z1-R 100%MINT 500 original Mi.
78 Z1-R Yoshi 1103 kit stage 1 cams Yoshi pipe. Etc
79 KZ-1300 (1400)
80 KZ-1300
81 Scratch built GPz1150R
82 KZ1000
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- Polar_Bus
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1)ALWAYS perform simple tests FIRST ! My #1 test is compression. You need all 4 cyl around 125 psi min and all within 10% of each other. You would be amazed at how many people think they have ignition issues when they really have a "bad hole" (low compression in one cyl)
2) Try to isolate weather you have an ignition problem or a fuel problem. Don't attempt to diagnose and or "guess repair" both systems at once.
No doubt running issues on older bikes can be a frustrating PIA, and I have had my share of ghost PIA issues, but my point is simply crack a beer, take a breath and try to systematically approach each diagnostic test.
Bikes:
'84 GPz1100
'06 HD Fatboy
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- jga2z
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That looks pretty good.
I know that valve clearance will change cold to hot, but since it's not running yet It would have to be a cold check. Given the compression results I might skip that for now.
Back to the carbs?
currently 1982 LTD1000 UNI dual throat pods, MAC header Supertrapp muffler. Shoei fairing.
The good old days: 1977 KH 400 triple, 1978 KZ650B all the basic mods, My avatar a 1980 LTD 750, ditto on the mods
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- Polar_Bus
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jga2z wrote: OK the compression test shows #1 150, #2 155, #3 155, #4 150. on a cold (wet) engine
That looks pretty good.
I know that valve clearance will change cold to hot, but since it's not running yet It would have to be a cold check. Given the compression results I might skip that for now.
Back to the carbs?
Compression is good. Back to carbs. You comment you need to keep the choke on for the engine to run, and you also comment #3 and #4 seem to not be firing. Kawis fire 1-4 and 2-3 so with this i'm tossing out the idea of a bad coil. If you had say 1-4 cylinders not firing ,now that a good sign the approiate coil is suspect. I am really thinking you have a #3 and #4 fuel starvation issue. Simple test first crack the bowl drain for carbs 3 and 4, make sure you have a stead flow of fuel out the drain hose. It really sounds to me like you have a plugged #3 and #4 pilot jet circut...
Bikes:
'84 GPz1100
'06 HD Fatboy
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- Motor Head
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- FIX UP YOUR BIKE RIGHT AND CHEAP
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Have you properly set your fuel levels in your carbs with the clear tube method?
What about Sync, do it on the bench first using a round paper clip or wire for a gauge. Set all 4 butterflies the same. Turn your pilot screws the same # of turns out, like 1 1/2 for starters. Get it to run on all four, then a running dynamic sync once up to temp. You can make a Manometer if you don't have one, or maybe borrow one.
What does the plugs look like, wet on the cylinders that are not running, or dry?
1982 KZ1000LTD K2 Vance & Hines 4-1 ACCEL COILS Added Vetter fairing & Bags. FOX Racing rear Shocks, Braced Swing-arm, Fork Brace, Progressive Fork Springs RT Gold Emulators, APE Valve Springs, 1166 Big Bore kit, RS34's, GPZ cams.
1980 KZ550LTD C1 Stock SOLD Miss it
1979 MAZDA RX7 in the works, 13B...
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- Patton
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jga2z wrote: ...I know that valve clearance will change cold to hot, but since it's not running yet It would have to be a cold check. Given the compression results I might skip that for now....
Valve clearances are supposed to be measured when the engine is cold.
Because the clearance diminishes as the engine warms and attains normal operating temperature. The specs recognize and allow for this attribute.
Good compression on a cold engine may result when valves are just barely closed with minimal clearance. Then the compression suffers when the engine gets warmer, because the gap disappears and the valve fails to seal as it can't fully close.
Consider, even perfect carbs can't compensate for deficiencies in the other components. For instance, with leaking valves due to insufficient clearance, it's imo a waste of effort to address carb tuning.
Good Fortune!
1973 Z1
KZ900 LTD
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- jga2z
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- 2 wheels good ,4 wheels bad
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I've checked for vac leaks around the intake boots many times with no leaks found.
I now suspect pilot circuits.
Can I replace the 37.5 non-bleed pilot jets with 40 bleed type? I tried to order pilots for these carbs and they sent me the bleed type. I read a post here that it wouldn't matter.
Yes I done the clear line fuel level test, #3 might be a bit high. Bench sync is/was perfect.
I have the plans for the homemade manometer, and will do that when I get it to keep running.
Patton....
I understand that the clearance decreases with higher temps. But this thing only ran real good when it was totally warmed up/hot. As a matter of routine I know the valve lash needs to be checked. I don't think it's an issue right now, but I'll bite the bullet and check anyway. Another potential problem I can't afford to fix.
currently 1982 LTD1000 UNI dual throat pods, MAC header Supertrapp muffler. Shoei fairing.
The good old days: 1977 KH 400 triple, 1978 KZ650B all the basic mods, My avatar a 1980 LTD 750, ditto on the mods
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- Motor Head
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Good that you have gone after air leaks already. Sometimes the leak is small and hard to find/ diagnose.
If it still does not run on a couple cylinders, but you show good spark on all 4. You can swap the coils if the plug wires are long enough, you can swap them just to see if the missfire follows the same plug lead.
But it really sounds as though with all the checks you've done that fuel would be the problem.
1982 KZ1000LTD K2 Vance & Hines 4-1 ACCEL COILS Added Vetter fairing & Bags. FOX Racing rear Shocks, Braced Swing-arm, Fork Brace, Progressive Fork Springs RT Gold Emulators, APE Valve Springs, 1166 Big Bore kit, RS34's, GPZ cams.
1980 KZ550LTD C1 Stock SOLD Miss it
1979 MAZDA RX7 in the works, 13B...
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- WABBMW
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The choke on these carbs is actually an enrichment circuit. Mine will not run well by tweaking it out just a small amount. It needs to be pulled out until it hits the first groove. Now if the weather is really cold, then pull it even further out.
This is a romote idea, but be sure the float vent hoses are properly connected. They are located on "T" fittings running between the 1 & 2 carbs and between the 3 & 4 carbs. On my bike, the previous owner had replaced the tubing and connected the two "T" fittings together with one hose. Nearly drove me to drink before figuring out that the bowls could not vent, and the fuel level could not come up to normal. I doubt this is your problem, however.
I have BS32 CV carbs on my 650 and I found that changing the pilot jets from 37.5 to 40.0 made a big difference in warm-up and low speed performance just above idle. My original main jets are 107.5. the bike runs quite well with these and gets great fuel mileage. 110.0 jets perform a little better, but mileage goes down about 5 MPG. I tried the 112.5 jets but the bike ran OK but "heavy" and mileage was terrible. By "heavy" I mean that throttle response was not crisp.
I agree with your analysis about the coils. They may not be quite as good as some after market ones, but unless there is something wrong with them, the bike should run reasonably well with them.
One more thing, for what it is worth. My bike would idle and run under very light throttle with the air box open, but would not generate any significant horsepower unless the air box had a filter and the screw-on nozzle on top of the box in place. Seemed to need some restriction to suck enough fuel to perform well.
Hope some of this helps. It took me 5 times to get all the passages clean in my carbs. My guess, is that something is still stopped up in yours. Good luck.
Bill Baker
Houston, Texas
1982 KZ650 CSR
2008 Yamaha FZ1
2006 Yamaha FZ1
1977 Honda Supersport 750 four (sold)
1984 Honda Nighthawk 650 (sold)
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- kawastrtfgtr
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(p.n: part number)
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