Ok guys I just rebuilt my 440. New cylinder, piston, rings, base gasket, and dual port muffler. Also put a new tank and handle assembly. When I got it all back together it cranked and ran fine. I ran it for about 5 minutes at low rpms just to get a good heat cycle. after it warmed up I began to adjust the idle screw and L carb screw just to get it idling properly. During this time it died and would not start back up. I put the compression tester on it and it was only 105. I then did a pressure test (I know I should have done this before cranking) and it was leaking around the base of the cylinder. I broke it back down and couldn't see anything visibly wrong. I cleaned all of the joining surfaces and turned the gasket over and put back together. Compression still at 105 and pressure test still revealed leak around the base of cylinder. So here are my questions. Should the saw crank and run at 105 compression? Would the leak itself cause the low compression or with me running it with that leak (for only 5 minutes) have possibly caused damage to the piston/rings/cylinder? Any advise is greatly appreciated.
MS440 rebuild now low compression
- Thread starter hawk910
- Start date
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Aftermarket parts? It probably has huge squish. Does you gauge have a Schrader valve at the very tip of the hose?
put a little sealant"dirko" on gasket. is arrow on top of piston pointing towards exhaust?
Yes, aftermarket parts. Yes, my gauge has a Schrader valve. I checked the gauge on one of my 461s and it read 155 so I don't think it is the gauge.
Here is the kit I purchased.
Attachments
Yes, arrow is pointing toward exhaust.
After market parts... careful of sources, cheap isn't always good enough
I use oem on all rebuilds. never a problem. plug off decomp
I pluged it off on pressure test. Are you saying to plug it off permanently?
The gasket leak will have no affect at all on compression. You have a problem with the topend.
That’s what I thought. Thank you for confirming that for me.
test
Check rings in to cylinder bore and see how much ring gap you have, measure with a feeler gauge.
Steve
Steve
drf255
BAD CAD
Aftermarket is always a gamble. Gotta check everything upon assembly. The price of OEM includes the quality control aspect.
Like said above, after you check everything, add dirko to the base and mounting pad. You have to check squish, and you should check with and without the gasket.
Like said above, after you check everything, add dirko to the base and mounting pad. You have to check squish, and you should check with and without the gasket.
Beer Gut
A Fine Pilsner
Dido. Check squish, you may want to just seal and leave gasket out. Curious to here your numbers
Beer Gut
A Fine Pilsner
None will help if jug is bored to deep. Check squish
Get some caber rings, eliminate the base gasket and seal it with Dirko or The Right Stuff, check your squish shooting for somewhere in the .020 range, cut wood!
If s
If jug is bored too deep would it have run for 5 minutes or so and then stopped running?
If jug is bored too deep would it have run for 5 minutes or so and then stopped running?
Beer Gut
A Fine Pilsner
Yes. Not starting again could be other things. Try it now cold after sitting
