suspected leaky manifolds.

I finally got to run my kz1000st today. First I started it up and let it run on the choke for about 3 seconds and shut it off. I did this to check which cylinders are firing, I found #1 exhaust to be cold,#2 hot, #3&4 almost as hot as #2. Next I started and ran it for a few minutes to warm up, If I hold the rev at a steady 3-4k it will pop thru the exhaust like its running out of fuel, The bike idles OK at 1000 but I suspect only on 3 cylinders. whacking the throttle open at low revs will cause it to die, doing the same at 3000 rpm sounds very crisp and strong ( very mean sounding bike with 4-1 exhaust). the bike has fresh Wiseco 1045cc 10.25-1 pistons and head redone, 380 lift cams, dyna coils, compression is 165lbs X4, valve clearance is .005"-.006" on all, carbs are clean, fuel level set and bench sync done. I can't really do much with the fuel system untill spring when it warms up- I hate working with fuel in a sealed up shop, I could however re&re the mainfolds without creating a fire hazzard.
So, am I better off to just buy new manifolds or try to seal up the existing ones?

Thanks.
Don

spark plug caps might be bad also tighten main ground wire. Hope this helps

peter1958 wrote: spark plug caps might be bad also tighten main ground wire. Hope this helps

The ground connection is clean and tight, the coils, wires and caps are all brand new.

Thank you for the thoughts.

yw will have another nolson ice and ponder

If the carb holders are leaking they really should be replaced. Try this (if possible) - warm the engine up so it is fully up to normal operating temperature. Temporarily set the idle as low as possible (under 1k rpm). Spray carb cleaner around the mating surfaces between the cylinder head and carb holders and around the joint where the carbs attach to the carb holders. If the idle changes (engine may stop running) you have a leaky carb holder. Keep in mind that for this test the lower the idle the better because that causes more vacuum to be applied to the carb holders since the engine cannot suck much air past the slides. If they are leaking it is much better to replace them than to try to seal them up. I ran this test and found mine were leaking badly even though they looked great from the outside. They had very fine cracks on the mating surfaces (nearly invisible to the naked eye), and when I ran the test the engine stopped running. I replaced them (this was 8 years ago) and I really could not believe the improvement in the idle. I've had no idle problems since. Ed

650ed wrote: If the carb holders are leaking they really should be replaced. Try this (if possible) - warm the engine up so it is fully up to normal operating temperature. Temporarily set the idle as low as possible (under 1k rpm). Spray carb cleaner around the mating surfaces between the cylinder head and carb holders and around the joint where the carbs attach to the carb holders. If the idle changes (engine may stop running) you have a leaky carb holder. Keep in mind that for this test the lower the idle the better because that causes more vacuum to be applied to the carb holders since the engine cannot suck much air past the slides. If they are leaking it is much better to replace them than to try to seal them up. I ran this test and found mine were leaking badly even though they looked great from the outside. They had very fine cracks on the mating surfaces (nearly invisible to the naked eye), and when I ran the test the engine stopped running. I replaced them (this was 8 years ago) and I really could not believe the improvement in the idle. I've had no idle problems since. Ed

Yeah.... I should just order up some new ones. Its too cold and windy to test them outside and I can't be running the bike and spraying carb cleaner inside my shop.


Thanks.
Don

Another version is using Propane as a leak detector, as the EPA has mandated formulation changes in spray on carb cleaners, and other volatile cleaners:


(Using An UNLIT Propane Torch For Vacuum Leaks)

Ingested WD40 also smokes from the exhaust, besides effecting rpm change.

Good Fortune!