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| Matt G. | Mar 2 2009, 07:17 PM |
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I think your valves should hold 125 psi. However, your method of testing them doesn't make any sense. If by "valve adjustment ports" you mean the breather cover, you put 125 psi into the crankcase and NOT the combustion chamber, so the air was probably leaking up through the rings and out an open valve. Was the crankshaft positioned such that both valves were closed? I'd apply 125 psi through the spark plug hole with the piston at top dead center (TDC) and see if you still have air coming out of the exhaust and carb. (Basically, you need to perform a crude 'leakdown test') If you do, it's time to pull the head and remove the valves and see if they (and the seats) are worn. I had an 86 that would start hard and run like crap at WOT. I replaced and rebuilt the carb and changed the whole ignition system to no avail. It made the same weird noises that you are describing. When I removed the valves, I found out that both were completely worn out on the seating surface. The seats were fine. I bought 2 new valves, ground and installed them, and it fixed the problem. I would also make sure that your carb float is adjusted per the manual (which you better have by now :) ). The backfiring may be a valve sticking, which is another problem on top of worn valves. I'd check the guides while you are in there too... Here's a place with reasonably-priced aftermarket and OEM parts: http://tewarehouse.com/ I have purchased from them several times. |
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| Same old problem · IH Cub Cadet Tractors | |
