Engine Trouble Recently Rebuilt engine won't start

[SpeedBoi]

I think I figure out what my problem is, when I was reassembling the motor, I sanded down the crankshaft so thaf I could push fit the bearings instead of having to hammer them on. I think this smaller diameter means that the crank is not pressing up againt the seals with as much force. I shall be putting in a brand new crankshaft today, will let you guys know wheter or not it starts

 

[Frankenstein]

Can you pull the shields out of your mag side bearing and crank it without the seal in the mag side and get a reading on the comp out of curiousity? Then pop it in and check the difference? Please? How many times are you willing to take a motor apart lol..

 

[gary55]

What about the exhaust port being open to standard local atmospheric pressure and being the last part to be closed off? Unless there's significant back pressure why isn't most of the pre-pressured air not just excaping? Unless it has something to do with the speed at which one turns the engine over? Gary are you using a drill to spin it? That engine isn't mounted in anything and at your age I don't think you're cranking it over with a box wrench.

Yes I was using a drill wiseguy, and even with my ancient nervous system and age leathered hands I could still feel the air pumping out of the case. The seal was compromised, leaking like hell, and no change in compression. Why isn't the pre pressured air escaping? It is thus the need for expansion chambers. It would seem clear that the 14.7 of atmosphere conastant would be far more relevant when the exhaust closes than the 3 to 7 that equals quickly with three ports wide open at once. Unless someone cares to duplicate my experiment with different findings I'm just going to consider them sound. Whipper snapper.
View media item 61421

 

[Frankenstein]

Yes I was using a drill wiseguy, and even with my ancient nervous system and age leathered hands I could still feel the air pumping out of the case. The seal was compromised, leaking like hell, and no change in compression. Why isn't the pre pressured air escaping? It is thus the need for expansion chambers. It would seem clear that the 14.7 of atmosphere conastant would be far more relevant when the exhaust closes than the 3 to 7 that equals quickly with three ports wide open at once. Unless someone cares to duplicate my experiment with different findings I'm just going to consider them sound. Whipper snapper.
View media item 61421

I understand all that, but it's perplexing that he is finding a specific result out of intuition that your data is yelling in the face of. Being that I am neither of you old folks i don't depend on either answer being correct, I just want to know which one is correct. And more importantly, why?

 

[Detroitbradster313]

Check your timing an magneto make sure its not in backwards.. Sounds like you didnt line the crank position/ timing with the magneto... Loosen carb bowl screw and make sure your floats not off wack and the carb is purged of air. Not starting is one thing from a fuel-spark-timing issue.. not running all together because you rebuilt a motor uneducated is another. Check for spark at night or just hold the electrode in your mouth as you spin the back wheel.. If your hair raises on your head then you have proper spark

 

[Detroitbradster313]

I highly recommend you do so especially when tracking a compression problem as that is the first place to look.

wgood.

You will notice a leak around the gasket parameter of the cyclinder n head. Looks like the leak around your exhaust gasket. Youll see the staining on the block surface

 

[gary55]

I understand all that, but it's perplexing that he is finding a specific result out of intuition that your data is yelling in the face of. Being that I am neither of you old folks i don't depend on either answer being correct, I just want to know which one is correct. And more importantly, why?

Easy peasy. Who's right? I am. How do I know this? Because I conducted the experiment to prove it to myself that a bad crank seal with a compromised bearing seal has no significant effect on the cylinder compression. How do I know that their is no inner seal? 1. You can see light through the bearing when shined into the case. 2. A wire will extend into the case13.2mm's beyond the outer edge of a 11mm wide bearing. 3. I can feel the air coming out of the case through the bearing. I have gone through some lengths to prove myself wrong. As for the why, when you squeeze air it becomes compressed. As for your knowing. The only way for that is to test it yourself. After all you'r the mad scientist here.

 

[Detroitbradster313]

Easy peasy. Who's right? I am. How do I know this? Because I conducted the experiment to prove it to myself that a bad crank seal with a compromised bearing seal has no significant effect on the cylinder compression. How do I know that their is no inner seal? 1. You can see light through the bearing when shined into the case. 2. A wire will extend into the case13.2mm's beyond the outer edge of a 11mm wide bearing. 3. I can feel the air coming out of the case through the bearing. I have gone through some lengths to prove myself wrong. As for the why, when you squeeze air it becomes compressed. As for your knowing. The only way for that is to test it yourself. After all you'r the mad scientist here.

I got $100 on it that he failed to set the magneto/crank postion to tdc or put in backwards or his bowl floats off

 

[Frankenstein]

I got $100 on it that he failed to set the magneto/crank postion to tdc or put in backwards or his bowl floats off

Well currently he still has compression problems, but I'd say that's a definite real possibility during the original problem that started back in June. At this point he's had it apart too much to even make that bet (but he still can be doing that wrong too.)

Easy peasy. Who's right? I am. How do I know this? Because I conducted the experiment to prove it to myself that a bad crank seal with a compromised bearing seal has no significant effect on the cylinder compression. How do I know that their is no inner seal? 1. You can see light through the bearing when shined into the case. 2. A wire will extend into the case13.2mm's beyond the outer edge of a 11mm wide bearing. 3. I can feel the air coming out of the case through the bearing. I have gone through some lengths to prove myself wrong. As for the why, when you squeeze air it becomes compressed. As for your knowing. The only way for that is to test it yourself. After all you'r the mad scientist here.

So any idea why crassius sees this symptom and why replacing the seal will fix the issue? I don't think either one of you are full of crap, so I can't willingly denounce either of you. And no offense, he runs a shop dealing with these and a repair service, so I'm aken to believe he's seeing a pattern here.

 

[SpeedBoi]

I got a crankshaft with an incorrect con rod so it'll be about a week before I can get a proper crankshaft.

Gary, I don't doubt you but at the same time I don't understand what else could be my problem. I have replaced the cylinder/piston/piston rings and gotten all new gaskets to no avail. Where else could the air be coming out of? and what else would cause a compression reading that low?