Leakdown Tester

[Chip M]

I just wanted to show (off) the leakdown tester I finished today as it was you guys idea anyway. I hope to have my squish down numbers by tomorrow and I will post in hopes of some ideas to what my problem is. If anyone has seen my recent posts I seem to be low on power but sounds strong and idles good as well as runs though the gears with no bog or break-up. My compression is 162/165 (way too high?) and is what I thought a relatively stock machine. Leakdown test holds pressure without any drop. Many thanks to all that have helped me this far and I will have the squish numbers tomorrow. I cut some radius grooves in the tester to fit the boots like the carb does. Gotta love the knobby tire pressure gauge. lol....Thanks again

 

 

 

96 Banshee-64.75 mm bore

V Force Reeds/Cages

ProDesign Cool Head

FMF Gold Series Fatty's- Powercore 2 Silencers

K&N Air Filter-stock box w/lid-no snorkel

Timing +4

Presently 300 main jets-27.5 pilots

93 octane gas

@ sea level-80 deg. F

Hard trail / MX style riding

 

 

[Jereme6655]

Looks like a decent job there chip. but I see one problem with it......the gauge you used it too high of a pressure type gauge. I'd be concerned that your not going to be able to comfortably see 6 psi on that gauge. Personally I use a distal tire gauge. Put a little air in and check the amount with the digital reader off of the valve stem. Then dust the amount and le the test begin.

[Chip M]

Looks like a decent job there chip. but I see one problem with it......the gauge you used it too high of a pressure type gauge. I'd be concerned that your not going to be able to comfortably see 6 psi on that gauge. Personally I use a distal tire gauge. Put a little air in and check the amount with the digital reader off of the valve stem. Then dust the amount and le the test begin.

 

Jereme,

I had thought the same thing when I was shopping for a gauge to use. Most of them were 0-150 . I felt lucky to find a 0-30 but actually wanted a 0-15. I have seen them online but could not get one locally. I checked it at 10 psi before I installed it in the tester and it was very close. I will keep my eyes open for one but the leakdown went well this time. Thanks for the input.

[do-work-son]

Looks good .. Can ya post a list of parts yeah needed for this like sizes of freeze plugs and PVC thanks

[Chip M]

Looks good .. Can ya post a list of parts yeah needed for this like sizes of freeze plugs and PVC thanks

 

(2 pcs.)freeze plugs adjustable from 1 1/4 to 1 3/8 inch

(2 pcs.) 1 inch PVC Sch.40...cut at 2 1/2 inches long

(2 pcs.) 1 inch PVC caps... I used sch.40 but sch. 80 would give you more meat to thread when you tap it

(1 pc.) Low pressure tire guage....mine had threads holding the tip on that you are suppose to use to check tire pressure

(1 pc.) Screw in valve stem

 

total cost less than 14 bucks

Be sure to check the thread size on both your stem and gauge or you will have to adjust instructions to suit

 

 

Drill the ends of both caps with 21/32 drill (I used letter Q drill but 21/32 is easier to find). Then I tapped the holes with a 1/8-27 pipe tap, I have heard you do not need to tap you can just screw the stem and gauge in to cut threads but is up to you. If you use a tap be careful not to thread in the full length of the tap. It is tapered and will make your tapped hole to big and the threads on the stem/gauge will bottom out. You want the stem/gauge to lock down on the taper of the tapped hole before you run out thread on the stem/gauge. Cement your caps on one end of each of your PVC tubes. Primer first is a good idea. Push on all the way and hold for a minute. Now you can screw in your valve/stem. I used a little PVC cement (blue is good and thick) to make sure I had a good seal. Put very little cement on the threads of the valve/gauge and be careful not to get inside of the stem/gauge. I used a Q-tip to apply cement. If you think your holes came out too loose, teflon tape will tighten up a loose hole, before the cement of course. I cut the grooves in mine in a lathe. They match the grooves in my carbs and just let the tubes snap into place. I do not know if they help seal, it is just something I did because I was in the lathe when I made mine. Not necessary. Good luck with your build.

[do-work-son]

This is all on stock cylinder and carbs ? Awesome wright up thanks ..

[Mustang_Gay81]

im just curious why the method of leak down testing isnt with vacuum instead of pressurizing it?isnt pressurizing the engine dangerous to seals and gaskets?

[Chip M]

This is all on stock cylinder and carbs ? Awesome wright up thanks ..

Yes stock carbs and cylinder

[Chip M]

im just curious why the method of leak down testing isnt with vacuum instead of pressurizing it?isnt pressurizing the engine dangerous to seals and gaskets?

 

I do not know too much about the process. This was my first attempt at the tester and the test itself also. I have read that you need to be careful NOT to go above the 6 psi for the reason you stated.

[Jereme6655]

It can be dangerous if you use more than 6psi as you can start pushing the seals out. But the pressure test is more readily able to be done by Joe Schmoe at his house than trying to see him rig something up to draw a vacuum on a motor...

[blast off]

im just curious why the method of leak down testing isnt with vacuum instead of pressurizing it?isnt pressurizing the engine dangerous to seals and gaskets?

 

 

Also, if you do find a leak, when you spray soapy water on it, it will bubble. if there is vacuum it will just suck it in and it would be harder to find the leak, not to mention pumping water in your engine.

[bansheesandrider]

A 2 stroke crankcase sees both vacumn and pressure so it is OK, that and being able to see the bubbles is why we use pressure.

[Mustang_Gay81]

Yea that makes sense duh how would you know if it aint bubbling.

 

Ok that was kind of a dumb question.lol