KbxSrx
TY 4 Stroke Guru
How do I do this, is it like a compression tes, pressure up with a handheld pump with a gauge, and see how long it takes to lose pressure? I know you have to make sure you are past TDC so valves are all closed.....
I know I could have just googled it, just thought I would share.
After talking with dealers today at the Calgary Bike show, I am thinking it may be a good idea for 4 strokers to do a leak down test before adding huge boost. And during, after.......
I know I could have just googled it, just thought I would share.
After talking with dealers today at the Calgary Bike show, I am thinking it may be a good idea for 4 strokers to do a leak down test before adding huge boost. And during, after.......
Travis Moore
Expert
In a nutshell, you are putting the cylinder at TDC compression(all valves closed), putting XXX about of air pressure in the cylinder, and measuring the % of that first pressure number that leaks by the rings/valves etc. Example, if you pressurize the cylinder with 100 psi of air, and 10 psi of it escapes, your leakdown % is 10%. Anything up to 10% leakdown is acceptable, and over 15 percent i would start thinking repairs. The nice thing about boost is the more you leakdown, the more air you can put in.
FYI, i have heard that a healthy RX1 motor can leak as little as 1%. I check my compression on a normal basis, or if i think it is warranted(IE ran too much boost etc). If i did not like the compression #s, i would then do a leakdown to try to narrow the problem down.
My motor right now compression tests 215psi across all cylinders with the intercooler off, holding the vaccum slide up, and the throttle wide open, letting it crank about 10 times. It will test about 30 psi less with the IC on!!!
FYI, i have heard that a healthy RX1 motor can leak as little as 1%. I check my compression on a normal basis, or if i think it is warranted(IE ran too much boost etc). If i did not like the compression #s, i would then do a leakdown to try to narrow the problem down.
My motor right now compression tests 215psi across all cylinders with the intercooler off, holding the vaccum slide up, and the throttle wide open, letting it crank about 10 times. It will test about 30 psi less with the IC on!!!
KbxSrx
TY 4 Stroke Guru
I heard today, that if you experience pressure loss, it may mean that it is strongly inavdiseable to boost it. Also, leak down may be caused by water ingestion, which damages the intake valves, and adding an aluminum intercooler that heats up, cools down, repeat constantly, may introduce a lot more condensation into the engine, worsening the problem.
I am doing it as soon as I get home.
What do I use to put air in to pressure it up? Is there something commercially available?
I am doing it as soon as I get home.
What do I use to put air in to pressure it up? Is there something commercially available?
Travis Moore
Expert
KbxSrx said:
You need a leakdown tester to test leakdown %. As far as the water, yeah if you suck enough water in to bend a valve you are going to have a high leakdown %, but you will not need a tester to know that! Intercooler condensation effecting leakdown %'s?! HAHA I hope you never listen to whoever told you that again..
KbxSrx
TY 4 Stroke Guru
Travis- I dont think its that they are bending, more that maybe condensation is causing corrosion maybe?
KbxSrx
TY 4 Stroke Guru
http://www.racerpartswholesale.com/long29a.htm
Engine Leakdown Tester
Operating Instructions
Warm the motor up to normal operating temperature.
Remove all spark plugs. Put transmission in neutral. Block wheels.
Remove the rocker arms of the cylinder to be checked.
Important note: TURN THE CRANKSHAFT SO THAT THE PISTON IS AT BOTTOM DEAD CENTER. If you do not, the motor will suddenly turn over when you connect the air, possibly causing serious injury to you or someone else working on the motor.
Screw the hose into the spark plug hole of the cylinder to be tested. Be sure that it is tight enough to completely seal. Leakage here will give you a false reading - lower than true leakdown.
Connect the hose to the tester and to your air supply. Ideally it should be between 110 and 125 psi (175 psi MAX) and be clean and moisture free.
Adjust the regulator until the left gauge reads 100 psi. (See Note A below if you air supply cannot maintain 100 psi on the left gauge.)
At this point the right gauge will display the leakdown as a %. For example 92 psi on the right = 92% leakdown or 8% leakage (100 - 92 = 8). See the chart below for leakage %. If you get an extremely low leakdown % and the motor seems to be running well check for a blockage in the precision restriction between the gauges.
It is best to lower the regulator setting before disconnecting either air line to avoid rapid pressure changes to the gauges.
NOTE A: If your air supply cannot maintain 100 psi on the left gauge you may use a lower pressure. Use the chart below or divide the right gauge by the left gauge pressure for the %.
% leakage 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% 11% 12% 13% 14% 15%
100 psi on left gauge 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85
85 psi 84 83 82 81 81 80 79 78 77 76 76 75 74 73 72
70 psi 69 69 68 67 66 66 65 64 64 63 62 61 61 60 59
Talk to your engine builder about what leakdown % should be expected on new and used motors. Most leakage is past the rings which, when worn, can't seal the compression properly and costs you power. Once you have established a maximum leakage before rebuild, test your motor often to keep it running its best.
makit yourself leakdown tester
http://www.650motorcycles.com/LeakDownTester.html
Engine Leakdown Tester
Operating Instructions
Warm the motor up to normal operating temperature.
Remove all spark plugs. Put transmission in neutral. Block wheels.
Remove the rocker arms of the cylinder to be checked.
Important note: TURN THE CRANKSHAFT SO THAT THE PISTON IS AT BOTTOM DEAD CENTER. If you do not, the motor will suddenly turn over when you connect the air, possibly causing serious injury to you or someone else working on the motor.
Screw the hose into the spark plug hole of the cylinder to be tested. Be sure that it is tight enough to completely seal. Leakage here will give you a false reading - lower than true leakdown.
Connect the hose to the tester and to your air supply. Ideally it should be between 110 and 125 psi (175 psi MAX) and be clean and moisture free.
Adjust the regulator until the left gauge reads 100 psi. (See Note A below if you air supply cannot maintain 100 psi on the left gauge.)
At this point the right gauge will display the leakdown as a %. For example 92 psi on the right = 92% leakdown or 8% leakage (100 - 92 = 8). See the chart below for leakage %. If you get an extremely low leakdown % and the motor seems to be running well check for a blockage in the precision restriction between the gauges.
It is best to lower the regulator setting before disconnecting either air line to avoid rapid pressure changes to the gauges.
NOTE A: If your air supply cannot maintain 100 psi on the left gauge you may use a lower pressure. Use the chart below or divide the right gauge by the left gauge pressure for the %.
% leakage 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% 11% 12% 13% 14% 15%
100 psi on left gauge 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85
85 psi 84 83 82 81 81 80 79 78 77 76 76 75 74 73 72
70 psi 69 69 68 67 66 66 65 64 64 63 62 61 61 60 59
Talk to your engine builder about what leakdown % should be expected on new and used motors. Most leakage is past the rings which, when worn, can't seal the compression properly and costs you power. Once you have established a maximum leakage before rebuild, test your motor often to keep it running its best.
makit yourself leakdown tester
http://www.650motorcycles.com/LeakDownTester.html
KbxSrx
TY 4 Stroke Guru
Travis Moore
Expert
KbxSrx said:
Dont beleive it at all, and even if it were true, wouldent the water in the motor do the same?!
