Engine Trouble Recently Rebuilt engine won't start

[FurryOnTheInside]

What is a compression test. 60psi ????/ What do you do, plug in an aircompressor to your engine?

Haha, no. Google it!

 

[SpeedBoi]

Hey guys just got back from camp.

So I ended up rebuilding the engine with all new gaskets and using seal-all on everything bc I was desperate. Anyways the compression test still didn't work and the bike wouldn't start so ethier my compression test sucks and something else is wrong or it is leaking somewhere else. At this point I highly doubt that the gaskets are the problem. Maybe I installed my piston rings incorrectly and I am getting blow by resulting in no compression? again highly doubt this but any input would be helpful. I am pretty confident fuel and spark are not the issue because I checked those thoroughly before realizing compression was the issue.

Any things that I should check/checks I can do would be helpful. I am out of ideas so I'm left to the mercy of these forums to save me from buying a new engine. Thank you all again for all your help

 

[crassius]

what does the compression gauge read? If right at about 25#, then a seal has gone bad.

 

[SpeedBoi]

Compression test reads around 50 psi, how could I check that it is the crank seals that are leaking?

 

[crassius]

that's a hard reading to guess from - could still be a seal that is just leaky rather than blown, or could be any gasket

I'd also look at ends of crank to see if a main bearing is bad and allowing crank to move up/down in seal.

 

[gary55]

Why did you rebuild it, and what did the cylinder look like. That's super low compression and it won't run till it is brought up.

 

[SpeedBoi]

The seals look fine to me, I’m having a hard time finding a way to turn the engine over so I can try and see/hear where the leak is coming from.

When I rebuilt it I drilled balance holes in the crank and installed new bearings. Not sure what you’re looking for when you ask what the cylinder looked like but I can slide it off right now and take some pictures

 

[gary55]

Undo 1 of the mag. wires, put a socket drive in a drill and spin the engine with the socket on the rotor nut. With the clutch locked you should be able to do this and find your leak. The cyl. question was about scoring.

 

[SpeedBoi]

Alright I’ll try this, are there any other reasons for low compression besides gaskets and seal?

 

[gary55]

Alright I’ll try this, are there any other reasons for low compression besides gaskets and seal?

Scored cylinder walls. Warped head not allowing for proper seal.
View media item 60713