I tried this. It works great! I also found a 0 - 30 gauge. Makes it a bit more accurate. The bad news is I have to replace the rings in both cylinders. : (
lol i'm a mechanic and i've done this. I had a universal compression gauge and a leftover regulator from doing some body work. i decided to just put a small brass fitting between them, fill it with JB weld and drill a 1mm hole through it. later on, i decided to put a really nice 6-bearing brass quick coupling between the regulator and restrictor, so when I'm done with it, I can simply pop it apart and use each component individually again. it looks like a big, hideous transformer or something, but it works!
Most mechanics already own a compression gauge, and you can install a quick disconnect on the compression gauge hose to use the hose and plug adapter with a leakdown tester.
Ian, I've experienced the same thing on smaller engines especially on single cylinders. You can use 15psi with this DIY tester, however that math is not as easy as 100 psi. Formula is ((regulated - pressure drop)/regulated)*100. Let's say regulated is 15psi, you would have to measure pressure drop at 14.25psi for a 5% leak down.
Having problems with my Suzuki SV. Cam timing is a PITA. New cam chain on order. I have 4% leak down but it doesn't tell you if your oil rings are bad. 50 psi set, connect motor, 48 psi is 4% leak down.
I think that I need to buy one since they sell them on eBay for $34 AUD anyway, my dads Honda HRU217D lawnmower which runs the GSV190 engine is burning a bit of oil on startup & it's hard to start. The specifications from Honda tell me that the compression is at the recommended 71 PSI but I'm not convinced that the rings aren't worn,it has a decompressor so the compression is a bit lower. My point is adding oil into the combustion chamber raises it up to 100 PSI,so it sounds like it's a piston ring issue. I think that a leakdown test is the way to go,that's probably why Briggs & Stratton don't release official compression figures, it sounds like that I can't rely on Hondas data ! I actually did find the starting problem, I had to adjust the throttle cable as the choke was sticking open slightly, so it starts first pull now. A leakdown tester will still give me a more accurate reading & let me know if the rings are starting to go bad & cause oil burning !
I do have footage of a bike that has a nice leak in intake valve. I also have to leak down a bike in the next few days. I'll try to put a vid together for you.
I found it at Princess Auto. It's not that great really. It's a liquid filled gauge, and the needle drifts a lot. It served my purpose, but I will continue to look for a better 0 - 30 gauge.
I have tried this on several motorcycle and small engines and found that 100psi is way too much pressure for these tiny cylinders. The piston gets forced down to BDC every time. True leak down testers for small engines like Motion Pro and Harbour freight use only 15psi.
hey Matt thanks for video bro i have a question,i seen another video where they say on the hose where you break and put the end of the spark plug to weld my question is would jb weld hold that amount of pressure for this i can weld it i just thought it might be easier and get a better hold since its so small anyway thanks for any info on this
+Tim Fox Because you are forcing air IN on a leak down test, while a compression test forces air OUT. The schrader valve is there for a compression test, and to retain air pressure so you can read the gauge.
Why was a #60/.04" hole chosen for the size of the restriction and how was this determined? I'm assuming it has something to do with the volume of air that could conceivably leak past the rings/valves etc but I'm not sure. Is there a formula to calculate a restriction size for different operating pressures? I imagine a larger hole at 100psi would give you a lower value for the leak percentage so this is relatively important.....
The .040" hole is good for engines up to 1000 cu in. Check it out for yourself at wikipedia. The operating pressure does not matter, since you are figuring a percentage of pressure drop.
I have mine made up but not connected to the bike with just air flowing the gauge is showing about 40psi not almost 0 like yours. Do I make the drilled hole in the epoxy smaller? Bigger?
I read the wiki article and I don't believe the orifice is needed if you are using a single gauge. The orifice inside the regulator is sufficient. It is only when using two gauges that you need an orifice between them, because you are making a differential pressure measurement and the passage between the first and second gauge needs to be relatively small to restrict flow and maintain accuracy.
Hi. Just wonder if you can tell me what the problem is with my engine. cylinder 3 has only around 25 psi. And the rest 160 psi. The engine is tuned up from 150 hp to 280 hp. And the spear plugs is dry and werry white. Hope you can respond. Thanks from Norway.th-cam.com/video/YlJduTNkIRQ/w-d-xo.html
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I tried this. It works great! I also found a 0 - 30 gauge. Makes it a bit more accurate. The bad news is I have to replace the rings in both cylinders. : (
lol i'm a mechanic and i've done this. I had a universal compression gauge and a leftover regulator from doing some body work. i decided to just put a small brass fitting between them, fill it with JB weld and drill a 1mm hole through it. later on, i decided to put a really nice 6-bearing brass quick coupling between the regulator and restrictor, so when I'm done with it, I can simply pop it apart and use each component individually again. it looks like a big, hideous transformer or something, but it works!
I have since modified it a bit. Watch it here: th-cam.com/video/tiza8Zdnvik/w-d-xo.html
Most mechanics already own a compression gauge, and you can install a quick disconnect on the compression gauge hose to use the hose and plug adapter with a leakdown tester.
Ian, I've experienced the same thing on smaller engines especially on single cylinders. You can use 15psi with this DIY tester, however that math is not as easy as 100 psi.
Formula is ((regulated - pressure drop)/regulated)*100. Let's say regulated is 15psi, you would have to measure pressure drop at 14.25psi for a 5% leak down.
Having problems with my Suzuki SV. Cam timing is a PITA. New cam chain on order. I have 4% leak down but it doesn't tell you if your oil rings are bad. 50 psi set, connect motor, 48 psi is 4% leak down.
I just went to home depot and bought a sioux chief gas test gauge 0-30psi. I'll give it a try since I have to test a 06' KX250F. Vids will follow.
I think that I need to buy one since they sell them on eBay for $34 AUD anyway, my dads Honda HRU217D lawnmower which runs the GSV190 engine is burning a bit of oil on startup & it's hard to start.
The specifications from Honda tell me that the compression is at the recommended 71 PSI but I'm not convinced that the rings aren't worn,it has a decompressor so the compression is a bit lower.
My point is adding oil into the combustion chamber raises it up to 100 PSI,so it sounds like it's a piston ring issue.
I think that a leakdown test is the way to go,that's probably why Briggs & Stratton don't release official compression figures, it sounds like that I can't rely on Hondas data !
I actually did find the starting problem, I had to adjust the throttle cable as the choke was sticking open slightly, so it starts first pull now.
A leakdown tester will still give me a more accurate reading & let me know if the rings are starting to go bad & cause oil burning !
Watched this then remembered making one like this ages ago, you can also use a tire inflator (gun type is better as it leaks slightly) in a pinch
I do have footage of a bike that has a nice leak in intake valve. I also have to leak down a bike in the next few days. I'll try to put a vid together for you.
Without a restrictor, pressure drop could not be measured. Go to wikipedia and type in "leak down tester" for more info.
I found it at Princess Auto. It's not that great really. It's a liquid filled gauge, and the needle drifts a lot. It served my purpose, but I will continue to look for a better 0 - 30 gauge.
I have tried this on several motorcycle and small engines and found that 100psi is way too much pressure for these tiny cylinders. The piston gets forced down to BDC every time. True leak down testers for small engines like Motion Pro and Harbour freight use only 15psi.
Thank u sir
Sorry to hear about the rings.
I also want to replace my gauges. Where did you buy yours? Home Depot?
My HF tester is junk. Going to make one of these!
Good Job
why is the restrictor so important?
hey Matt thanks for video bro i have a question,i seen another video where they say on the hose where you break and put the end of the spark plug to weld my question is would jb weld hold that amount of pressure for this i can weld it i just thought it might be easier and get a better hold since its so small anyway thanks for any info on this
Shannon Fraiser Can you share the link to video so I can see what you are talking about?
Can you explain why do you have to remove the schrader valve?
+Tim Fox Because you are forcing air IN on a leak down test, while a compression test forces air OUT. The schrader valve is there for a compression test, and to retain air pressure so you can read the gauge.
Why was a #60/.04" hole chosen for the size of the restriction and how was this determined? I'm assuming it has something to do with the volume of air that could conceivably leak past the rings/valves etc but I'm not sure. Is there a formula to calculate a restriction size for different operating pressures? I imagine a larger hole at 100psi would give you a lower value for the leak percentage so this is relatively important.....
The .040" hole is good for engines up to 1000 cu in. Check it out for yourself at wikipedia. The operating pressure does not matter, since you are figuring a percentage of pressure drop.
MatthewMCRepair g
I have mine made up but not connected to the bike with just air flowing the gauge is showing about 40psi not almost 0 like yours. Do I make the drilled hole in the epoxy smaller? Bigger?
What size hole did you drill? Starting pressure 100 psi?
MatthewMCRepair it was tiny tiny. I’ll toss a micrometer on it tonight to see. And yes 100psi.
MatthewMCRepair will this skew he results??
Read this: en.wikipedia.org/wiki/Leak-down_tester
I read the wiki article and I don't believe the orifice is needed if you are using a single gauge. The orifice inside the regulator is sufficient. It is only when using two gauges that you need an orifice between them, because you are making a differential pressure measurement and the passage between the first and second gauge needs to be relatively small to restrict flow and maintain accuracy.
Hi. Just wonder if you can tell me what the problem is with my engine. cylinder 3 has only around 25 psi. And the rest 160 psi. The engine is tuned up from 150 hp to 280 hp. And the spear plugs is dry and werry white. Hope you can respond. Thanks from Norway.th-cam.com/video/YlJduTNkIRQ/w-d-xo.html
Put that cylinder at top dead center and blow air into spark plug hole. It will either leak past rings, valves, or head gasket.
Thanks for your reespond. :)