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Nicholaschase29
Guest
why would that cylinder fire while the valve was held open a tad and now it doesn't run when it's seated?
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86turbodsl
Guest
I don't think it was ever running.
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Guest
Guest
How cheap are you? You can spread a little lapping compound on the valve through the spark plug hole, attach a drill to the valve stem, and start spinning.
This is considered a cheater job when done with the head removed, and I've never heard of anyone doing it attached, don't know where the compound will go...
Grinding paste will shoot up the valve stem / guide; then you've got extra work. DON'T DO IT!
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86turbodsl
Guest
Ok, now I dont know what's going on anymore.
Did the cranking compression test :
#1 - 137 psi
#2 - 115 psi
#3 - 125 psi
#4 - 127 psi ---> the "cold" cylinder.
The exhaust pipe on #4 was cold enough I could comfortably hold my hand on it.
I have verified spark too. #4 wire with plug sparks strongly when laid on valve cover.
Carbs are fresh rebuilt.
Any ideas? Bueller?
I tried revving it up around 5-6000 rpm and didn't get any heat out of the #4 cylinder then either. I figured that would be enough to get it onto the main jet if the idle circuit was plugged.
Did the cranking compression test :
#1 - 137 psi
#2 - 115 psi
#3 - 125 psi
#4 - 127 psi ---> the "cold" cylinder.
The exhaust pipe on #4 was cold enough I could comfortably hold my hand on it.
I have verified spark too. #4 wire with plug sparks strongly when laid on valve cover.
Carbs are fresh rebuilt.
Any ideas? Bueller?
I tried revving it up around 5-6000 rpm and didn't get any heat out of the #4 cylinder then either. I figured that would be enough to get it onto the main jet if the idle circuit was plugged.
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G
Guest
Guest
Is the spark plug wet?
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86turbodsl
Guest
Ok, now I'm baffled. All it did was sit for a couple days. Now I have it firing on #4.
Ran it till it warmed up, LOTS of backfiring.
Reran the compression test on #4, it was about the same.
Did it fix itself? Seems so. Maybe a stuck float bowl valve?
Only thing I can think of is I put it on the center stand tonight rather than side stand.
But the funnel I was using has always been at least 8+ inches above the floats.
But as far as this thread goes, it SEEMS to be fixed. Perhaps the valve didn't burn because it
wasn't firing on #4 for a time? One things' sure, the valvetrain is a LOT noisier. sounds like spinning bearings now.
My guess is do a carb sync next and try and get the AWFUL idle mixture settings correct.
It's got a nasty bog then rev at idle. Doesn't really get responsive until you get it up around 4K rpm.
Still doing tons of popping in exhaust and a bit of fire in the vacuum line to petcock.
Mixture screws all set about 3.5 turns out.
Ran it till it warmed up, LOTS of backfiring.
Reran the compression test on #4, it was about the same.
Did it fix itself? Seems so. Maybe a stuck float bowl valve?
Only thing I can think of is I put it on the center stand tonight rather than side stand.
But the funnel I was using has always been at least 8+ inches above the floats.
But as far as this thread goes, it SEEMS to be fixed. Perhaps the valve didn't burn because it
wasn't firing on #4 for a time? One things' sure, the valvetrain is a LOT noisier. sounds like spinning bearings now.
My guess is do a carb sync next and try and get the AWFUL idle mixture settings correct.
It's got a nasty bog then rev at idle. Doesn't really get responsive until you get it up around 4K rpm.
Still doing tons of popping in exhaust and a bit of fire in the vacuum line to petcock.
Mixture screws all set about 3.5 turns out.
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G
Guest
Guest
wait a minute... you do have the airbox installed, air filter in place, and the cover on, right???
This bike will NOT run in a usable way without all of the above installed.
This bike will NOT run in a usable way without all of the above installed.
And if you have then you have got dirty carbs. Your compression numbers are fine.
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86turbodsl
Guest
Airbox in place, new K+N filter, fresh foam seals on both end caps, new airbox boots and carb boots, new orings.
Carbs were completely disassembled and soaked in berrymans multiple times for over 24 hrs, then removed from the cleaner and sprayed with carb cleaner and all orifices were cleared and sprayed/soaked. I followed the guides.
All new o-rings putting it back together.
Floats set with digital caliper. Even made a bowl screw with tube to double check float heights assembled. (only used it on one bowl though as I set all the floats the same height and the one I checked was EXACTLY at spec with fuel in it.
Carbs were completely disassembled and soaked in berrymans multiple times for over 24 hrs, then removed from the cleaner and sprayed with carb cleaner and all orifices were cleared and sprayed/soaked. I followed the guides.
All new o-rings putting it back together.
Floats set with digital caliper. Even made a bowl screw with tube to double check float heights assembled. (only used it on one bowl though as I set all the floats the same height and the one I checked was EXACTLY at spec with fuel in it.
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twotimeGSr
Guest
I had a #2 cyl that was cold and it was because the float was sticking up. I had a quick bench test done (bowls removed) and the guy showed me that the float did not always spring back "down" after being pressed/tapped "up"... shutting off the gas. He told me how to tweek it and it warms right up now.
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hoyterb
Guest
Does it still have points type?If so change the condensor on 1-4 point set.Ask me how I know>:-s !
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86turbodsl
Guest
Still has points. Brand new points and condensers from Z1, gapped and ignition timing set via timing light. Spot on.
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86turbodsl
Guest
Epilogue:
My homemade manometer didn't work, wasn't tall enough, so i just played it blind and fiddled with the sync screws blind. It runs SIGNIFICANTLY better now. It's just amazing how big a difference. I've still got a ways to go, but it's much much better. very crisp and idles about 1200. Hangs up a tiny bit on a big rev, but will eventually come down. My carb clamps are full closed, do those stretch? Do I still have a bit of leaking air with it hanging a touch? Or could it be the slides being slow?
My homemade manometer didn't work, wasn't tall enough, so i just played it blind and fiddled with the sync screws blind. It runs SIGNIFICANTLY better now. It's just amazing how big a difference. I've still got a ways to go, but it's much much better. very crisp and idles about 1200. Hangs up a tiny bit on a big rev, but will eventually come down. My carb clamps are full closed, do those stretch? Do I still have a bit of leaking air with it hanging a touch? Or could it be the slides being slow?
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TheCafeKid
Guest
If you've gotten the wrong clamps they'll close all the way without being tight. Maybe you got some for a later model head with CV carbs (bigger diameter) maybe you've got airbox side clamps on it. Try to find the correct ones. They should tighten up before being clamped all the way. Also I saw you did the usual, did you replace the intake boot Orings? What are your fuel and air screws set at? Sounds a bit lean still..the VM carbs will dry up for whatever reason faster than the CV carbs I've found (maybe the overflow vent?) and it's common for a float to hang shut...a tap on the bowl or two with a heavy-ish handled screwdriver usually frees it up.
With a KN in box filter you may find it needs the screws set a bit richer (or the air screw alone backed off a bit).
With a KN in box filter you may find it needs the screws set a bit richer (or the air screw alone backed off a bit).
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86turbodsl
Guest
Yes, I replaced the orings too. everything really. It's got CV's on it, so i've only got a mixture screw. I started at 3.5 turns out, and it was popping. I've got them out about 4 turns now. Might need a touch more. Screws look pretty far out though. I really don't like the mikuni floats setup though. Leaky, my funnel will run dry after I shut it off. I have to run the engine out of gas almost so it won't flood over time.
