Now to your problem......The one thing I keyed on was that you mentioned that air was puffing out of your carbs during cranking. This suggests either cam timing (which you say you've checked.......just keep this in mind) OR that it's possible the engine is cranking backwards! Check THAT just for badness when you're looking things over!
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4 cylinders, 0 compression, help!!
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SPARKSS
I concur that the carbs do NOT need to be open to "create" compression. Engines have developed good compression from allowed idle air for decades!
Now to your problem......The one thing I keyed on was that you mentioned that air was puffing out of your carbs during cranking. This suggests either cam timing (which you say you've checked.......just keep this in mind) OR that it's possible the engine is cranking backwards! Check THAT just for badness when you're looking things over!
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Billy Ricks
Cams may be off by a matter of teeth rather than 180 out. He did say there is evidence the valves hit the pistons. PO may have used the wrong marks on the rotor to drop the cams in.
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Forum LongTimerGSResource Superstar
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Originally posted by Billy Ricks View PostCams may be off by a matter of teeth rather than 180 out. He did say there is evidence the valves hit the pistons. PO may have used the wrong marks on the rotor to drop the cams in.Ed
To measure is to know.
Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182
Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846
Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf
KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection
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smagnusen
Update: Success! -at least mostly. After reassembling the motor and adjusting the timing a cold dry crank gave me over 120 pounds on the first cylinder. That felt good. 3 and 4 show the same but number 2 is only at 25 or so pounds.
This brings me to another question. Strangely I could not get the timing tick on the exhaust cam exactly where it should be at tdc. Clymer shows the #1 tick to be exactly pointing to the gasket surface. It clearly wanted to be either above or below it. Any thoughts? I did notice that the clymer manual stated that the tdc mark was to the "left of the T" mark, and on my bike it is to the right. Are these few degrees out enough to effect the valve timing?
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oldschoolorange
if the engine has kissed the valves there is a good chance one of them is bent, A real quick way to check for a valve seating if you do not have a vacume pump is to tip the head over so the valves are straight up and them pour varsol onto the valves. The varsol will pool and no leaks will be visible if the valves are seating properly
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Forum LongTimerGSResource Superstar
Past Site Supporter
Super Site Supporter- Mar 2006
- 35605
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Originally posted by oldschoolorange View Postif the engine has kissed the valves there is a good chance one of them is bent, A real quick way to check for a valve seating if you do not have a vacume pump is to tip the head over so the valves are straight up and them pour varsol onto the valves. The varsol will pool and no leaks will be visible if the valves are seating properlyEd
To measure is to know.
Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182
Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846
Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf
KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection
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smagnusen
With the head upside down on a bench I put pool of carb cleaner in each valve area and the valves seemed to hold it pretty well. Valve clearances were nil but I did change the shims down a size on reassembly. Think there was some clearance but will check them again.
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oldschoolorange
Originally posted by Nessism View PostEasier way is to check valve clearances. A bent valve will not close all the way thus the clearance will be excessive.
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