I put a balloon on the end of mine, rather than using my thumb!!As per my OTC gauges, I used 75PSI to do my test. All 4 cylinders were good only losses approx 1%.
My mums 2003 Corolla with 110K miles on it had exactly 2% leakage on all 4 cylinders. Supply pressure was 100psi, cylinder pressure was 98psi. Orifice was .040” (1mm)
@@turdpike yeah and I drove that thing regularly... and regularly visited the rev limiter. But always serviced on time with quality synthetic oil and filter.
Hello, thinking about buying a MT-324 snap on leak down tester from eBay, planning to do a leak down test on my 2008 Crf250r. I’m not sure what size the adaptor is that come with it, are they universal or will I possibly have to buy a new adaptor hose? Thanks!
Mr. Pike III. Does the diameter of the orifice (40th) matter ? - is it a percentage of that specific hose bore or is it more "needs a small hole" sort of thing?
It’s somewhat of an arbitrary size, of course different size holes will reveal different results. But from what I’ve read .040” (#60 drill bit) is what the FAA recommends as a standard. From my interview searching I see the number come up lots
2007 yz250f I do leak down test at 100 psi in and second gauge only lifts to 8 psi. I hear lots of air hissing from carb. I’m assuming it jump time or a valve issue. Also compression test to 75 psi full throttle if I add one table spoon oil it raises compression to 130 🤷🏻♂️ HELP!!! 😝
You’re spot on with your assumptions. If it’s 100% correctly timed and you’re 100% confident you’re on TDC of the compression stroke, then I’d suspect valve seat/sealing surface bad or no valve clearance. This is of course assuming the engine is timed properly and you’re in the correct position while testing. If either of these is wrong, well, there’s your answer. The oil to increase compression would make sense to help make a temporary seal on piston rings and valve seats (if they were leaking). Not a great way to increase sealing but does work a little bit nonetheless
@@turdpike 07 yz250f just bought the bike. I found it took a few kicks to start. I thought that was odd but I haven’t been on a bike for 23 years so it’s all new to me again. I only rode it for maybe 15 minutes. It was ripping pretty good. I was quite impressed by the power compared to the old 80 model bikes I had as a kid. I noticed it was boiling and hot. I really didn’t think it was hot for long but who knows just what temp it got to. Shut it down and returned the next day to give it a go but it wouldn’t start. Only get a backfire occasionally from exhaust. Thin I did the whole leak down compression thing. Guess I’ll check the timing on it today and report what I find.
Is it possible to have a new piston and rings but a bad cylinder that will cause it to be really hard to start? I have a crf450 that just will not go anymore, it used to rollstart and it has new valves and everything.
Hmm, is the timing for sure set correctly after all that valve work? And you’re 100% positive the valve clearances are in spec? It’s more likely something else than low compression , but anything is possible. I’d chase the other stuff first. Double and triple check your timing. Make sure you have spark/ carb cleaned too. All the usual stuff
Yeah that's what everyone's been saying haha. I have done everything I can think of and timing is spot on with a new chain, stator is new, has good spark etch. Carb is good. A while ago I had it running really well for about 2 hours, after roll starting. Then it wouldn't do much of anything after that
Ah so the stator was changed? Did you torque the nut on the flywheel 100% properly and to spec? I’ve had one slip on the crankshaft before, you wouldn’t this it’s possible because it’s keyed but I can say from first hand experience it can. And if that slips too much your spark timing is off. Won’t run. You’ll see spark, but it won’t be at the right time
@@turdpike the fitting with the little orifice, can you tell me what that brass fitting is called i suppose its a hex nipple? it's a solid fitting with threads on both sides that you drilled a hole through? only fittings I can find are way too large of hole already in them, they aren't solid
![BOWKYLION - วิงวอน (ex-change) [Official MV]](http://i.ytimg.com/vi/cLdnZWDaO-w/mqdefault.jpg)
I'm glad it's not just me who's compressor scares the living daylights out of when it fires up!!
Hi mate something I do to determine the compression stroke is put a balloon over the end of the pipe & it will start to inflate!
I put a balloon on the end of mine, rather than using my thumb!!As per my OTC gauges, I used 75PSI to do my test. All 4 cylinders were good only losses approx 1%.
My mums 2003 Corolla with 110K miles on it had exactly 2% leakage on all 4 cylinders. Supply pressure was 100psi, cylinder pressure was 98psi. Orifice was .040” (1mm)
That’s impressive! Can’t kill those old Corolla’s
@@turdpike yeah and I drove that thing regularly... and regularly visited the rev limiter. But always serviced on time with quality synthetic oil and filter.
helpful vid, will be doin same test soon
Hello, thinking about buying a MT-324 snap on leak down tester from eBay, planning to do a leak down test on my 2008 Crf250r. I’m not sure what size the adaptor is that come with it, are they universal or will I possibly have to buy a new adaptor hose? Thanks!
What are all the parts you bought at hardware store?
Mr. Pike III. Does the diameter of the orifice (40th) matter ? - is it a percentage of that specific hose bore or is it more "needs a small hole" sort of thing?
It’s somewhat of an arbitrary size, of course different size holes will reveal different results. But from what I’ve read .040” (#60 drill bit) is what the FAA recommends as a standard. From my interview searching I see the number come up lots
@@turdpikeOK thanks. I guess we could calibrate on a new run-in engine at 5hrs or something - to get a "perfect" benchmark for that set-up.
Dope vid love the knowledge
Was the piston during the test on its own TDC?
Yes, piston has to be at TDC on the compression stroke
2007 yz250f I do leak down test at 100 psi in and second gauge only lifts to 8 psi. I hear lots of air hissing from carb. I’m assuming it jump time or a valve issue. Also compression test to 75 psi full throttle if I add one table spoon oil it raises compression to 130 🤷🏻♂️ HELP!!! 😝
You’re spot on with your assumptions. If it’s 100% correctly timed and you’re 100% confident you’re on TDC of the compression stroke, then I’d suspect valve seat/sealing surface bad or no valve clearance.
This is of course assuming the engine is timed properly and you’re in the correct position while testing. If either of these is wrong, well, there’s your answer.
The oil to increase compression would make sense to help make a temporary seal on piston rings and valve seats (if they were leaking). Not a great way to increase sealing but does work a little bit nonetheless
@@turdpike 07 yz250f just bought the bike. I found it took a few kicks to start. I thought that was odd but I haven’t been on a bike for 23 years so it’s all new to me again. I only rode it for maybe 15 minutes. It was ripping pretty good. I was quite impressed by the power compared to the old 80 model bikes I had as a kid. I noticed it was boiling and hot. I really didn’t think it was hot for long but who knows just what temp it got to. Shut it down and returned the next day to give it a go but it wouldn’t start. Only get a backfire occasionally from exhaust. Thin I did the whole leak down compression thing. Guess I’ll check the timing on it today and report what I find.
Any luck?
@@bayhi1fatz what did you find was wrong?
Love it!
Why or how dis you determined 80psi to run your test at?
Thanks.
Actually is a standard set by the FAA oddly enough. They also state that engines up to 16L require a .040” restrictor hole within the tester
100psi is better. The higher the pressure the better the resolution if using a common analog pressure gauge.
Is it possible to have a new piston and rings but a bad cylinder that will cause it to be really hard to start? I have a crf450 that just will not go anymore, it used to rollstart and it has new valves and everything.
Yes, might not be making enough compression. Performing this test will show that
@@turdpike it feels like it has heaps of compression but is it possible its not right still?
Hmm, is the timing for sure set correctly after all that valve work? And you’re 100% positive the valve clearances are in spec? It’s more likely something else than low compression , but anything is possible. I’d chase the other stuff first. Double and triple check your timing. Make sure you have spark/ carb cleaned too. All the usual stuff
Yeah that's what everyone's been saying haha. I have done everything I can think of and timing is spot on with a new chain, stator is new, has good spark etch. Carb is good. A while ago I had it running really well for about 2 hours, after roll starting. Then it wouldn't do much of anything after that
Ah so the stator was changed? Did you torque the nut on the flywheel 100% properly and to spec? I’ve had one slip on the crankshaft before, you wouldn’t this it’s possible because it’s keyed but I can say from first hand experience it can. And if that slips too much your spark timing is off. Won’t run. You’ll see spark, but it won’t be at the right time
What’s a ffffore stroke?
It’s this dumb thing that wastes strokes...
@@turdpike the fitting with the little orifice, can you tell me what that brass fitting is called i suppose its a hex nipple? it's a solid fitting with threads on both sides that you drilled a hole through? only fittings I can find are way too large of hole already in them, they aren't solid
@@coloradodirtbike5930 correct, you won’t find one. I filled the hole with JB weld and then drilled the epoxy
@@turdpike do you need a regulator near the Guage that you read, if I already have a regulator coming off of my air compressor?
@@coloradodirtbike5930 nope you don’t, you can just use the one on the tank