Leakdown test

[2003225X]

When you guys do them... do you pull all the sparkplugs out or leave the ones in you aren't testing?

 

[h2oskiier30]

I pull them all, because you're going to be testing every hole anyway.That said, it won't affect the results either way.

 

[LakeAnna]

Leave it alone Matt!!

 

[fnshrmaster]

When you guys do them... do you pull all the sparkplugs out or leave the ones in you aren't testing?

Great question!

 

[silverbullet02]

Shouldn't matter should it? You gonna send it to jsre to get hopped up if the leak down is high?

 

[2003225X]

It could have a hole in the block and it wouldn't go there! Lol

 

[2003225X]

Compression is 144 and 145 on all cylinders. 5 cylinders show 3-5% leakdown and 4 cylinder shows 6-8%. 18 hours on motor. Not sure if it will get better, worse, or stay the same for a while. Guess I will keep my eye on it.

 

[Dave Hensley]

Did you rock number 4 at tdc to make sure it was sealed?

 

[2003225X]

No I didn't rock it. Was looking at the gauge and rotated flywheel correct direction until hand stopped moving. Are you supposed to rock them?

 

[h2oskiier30]

Some folks are believers in setting tdc on the port side pistons going counter-clockwise on the flywheel, while setting tdc on the starboard side pistons going clockwise. I'm not sure what the reasoning is, but I've heard several folks say it. I think Lee Sanderson is one of them, but don't quote me on that. I do "rock" them, but that's just checking and double checking tdc...my final "set" is clockwise.

 

[2003225X]

Do you get consistent numbers when your final set it clockwise? I have been told the way to do it is the first way you mentioned.

Unfortuantely, if you look around or listen to different people you will get every answer. There are a group that says leakdown tests are the best one to do. Others say a leakdown test is pointless on a 2 stroke, that thy are meant for a 4 stroke and to do a compression check.

Pick who you want to listen to! LOL

 

[fnshrmaster]

Good info, just bought a leakdown tester. I need a Hensley 280 to try it on

 

[h2oskiier30]

Yes, I've never had a problem getting consistent readings either way. I just figure that true tdc is tdc, no matter how you arrived at that point. I guess the reason I do the final set clockwise, no matter the cylinder, is because that's how the engine sets the pistons. As I said before, I've never seen where it really matters for me...just more of a personal preference thing, I guess.

 

[h2oskiier30]

Good info, just bought a leakdown tester. I need a Hensley 280 to try it on

Put the money on him, and I'm sure he'll put a 280 on you.

 

[Dave Hensley]

Not an expert on this but there should be a slight difference in the way the piston and ring are sealed depending on if it is on compression or power. The piston has a natural rock on either side of tdc and the rod angle combined with any offset in wrist pin bore might cause a difference. Bill Gohr can do a much better job explaining than me. I have seen it on the gauge so it is measurable.

 

[Dave Hensley]

Do you get consistent numbers when your final set it clockwise? I have been told the way to do it is the first way you mentioned.

Unfortuantely, if you look around or listen to different people you will get every answer. There are a group that says leakdown tests are the best one to do. Others say a leakdown test is pointless on a 2 stroke, that thy are meant for a 4 stroke and to do a compression check.

Pick who you want to listen to! LOL

Pull a head and inspect/measure the bores. Head gaskets are cheap vs. the result if there is a problem.

 

[catfish123]

There is a definite difference in readings in the direction the flywheel is rotated on the port and starboard side. It should be rotated in a clockwise direction on the port side, and counter clockwise direction on the starboard side. This is done when achieving TDC.

 

[SLOmofo]

I made a tool to clamp on to the flywheel ring gear. With it you can stop rotation of the crankshaft and perform a leak down at almost any point. One piece of aluminum cut to sorta match the gear tooth and just a little bit thinner than the ring gear. Two other pieces to clamp to the ring gear. Rotate the flywheel to where you want and clamp the tool so it rests against the starter. Slowly introduce air pressure to make sure the clamp is on the correct side of the starter.
I found extreme wear above the exhaust port with this tool. The rings were broaching the cylinder above the ports.

 

[allimax]

Gary, if you get some time take a picture or two and post. That's a great idea. I can generally get 2 out of 4 cylinders to stay first try. Your way would make it 6 for 6.

 

[allison8503]

Not an expert on this but there should be a slight difference in the way the piston and ring are sealed depending on if it is on compression or power. The piston has a natural rock on either side of tdc and the rod angle combined with any offset in wrist pin bore might cause a difference. Bill Gohr can do a much better job explaining than me. I have seen it on the gauge so it is measurable.

Hit the nail on the head on why to turn it different directions on different sides